research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 72| Part 5| May 2016| Pages 751-755

Crystal structure and hydrogen bonding in the water-stabilized proton-transfer salt brucinium 4-amino­phenyl­arsonate tetra­hydrate

aScience and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia
*Correspondence e-mail: g.smith@qut.edu.au

Edited by A. J. Lough, University of Toronto, Canada (Received 11 April 2016; accepted 19 April 2016; online 29 April 2016)

In the structure of the brucinium salt of 4-amino­phenyl­arsonic acid (p-arsanilic acid), systematically 2,3-dimeth­oxy-10-oxostrychnidinium 4-amino­phenyl­ar­son­ate tetra­hydrate, (C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O, the brucinium cations form the characteristic undulating and overlapping head-to-tail layered brucine substructures packed along [010]. The arsanilate anions and the water mol­ecules of solvation are accommodated between the layers and are linked to them through a primary cation N—H⋯O(anion) hydrogen bond, as well as through water O—H⋯O hydrogen bonds to brucinium and arsanilate ions as well as bridging water O-atom acceptors, giving an overall three-dimensional network structure.

1. Chemical context

The Strychnos alkaloid base brucine, (2,3-di­meth­oxy­strychnidin-10-one; BRU) has been extensively employed as a resolving agent for chiral organic compounds (Wilen, 1972[Wilen, S. H. (1972). Tables of Resolving Agents and Optical Resolutions, edited by E. N. Eliel, pp. 68-71. London: University of Notre Dame.]). With chiral acids, the separation is achieved through proton-transfer to N19 of the strychnidine cage (pKa2 = 11.7; O'Neil, 2001[O'Neil, M. J. (2001). Editor. The Merck Index, 13th ed., p. 243. Whitehouse Station, NJ: Merck and Co., Inc.]), followed by separation of the resultant crystalline salt products by fractional crystallization. Similar effects are achieved with the essentially identical Strychnos alkaloid strychnine but separation efficiency favours brucine. This is probably because of the formation in the crystal of characteristic brucinium host substructures comprising head-to-tail undulating layers of brucine mol­ecules or cations which accommodate selectively the hydrogen-bonded guest mol­ecules in the crystal structure. A characteristic of the substructure is the repeat inter­val in the layer of ca 12.3 Å along a 21 screw axis in the crystal, which is reflected in the unit-cell dimension, with brucine being predominantly in the monoclinic space group P21 or the ortho­rhom­bic space group P212121 (Smith, Wermuth & White, 2006[Smith, G., Wermuth, U. D. & White, J. M. (2006). Acta Cryst. C62, o353-o357.]; Smith, Wermuth, Young & White, 2006[Smith, G., Wermuth, U. D., Young, D. J. & White, J. M. (2006). Acta Cryst. E62, o1553-o1555.]).

[Scheme 1]

This example of mol­ecular recognition was described in the early structure determinations of brucinium benzoyl-D-alanin­ate (Gould & Walkinshaw, 1984[Gould, R. O., Kelly, R. & Walkinshaw, M. D. (1985). J. Chem. Soc. Perkin Trans. 2, pp. 847-852.]) and in the structures of the pseudopolymorphic brucine solvates, brucine–MeOH (1:1) and brucine–EtOH–water (1/1/2) (Glover et al., 1985[Glover, S. S. B., Gould, R. O. & Walkinshaw, M. D. (1985). Acta Cryst. C41, 990-994.]). The guest mol­ecules are accommodated inter­stitially within the layers and are commonly accompanied by compatible polar solvent mol­ecules, usually generating high-dimensional hydrogen-bonded crystal structures.

Currently, a large number of structures of brucine compounds with chiral organic mol­ecules, including both acids and non-acids are known, but in addition those with achiral compounds also feature. Of inter­est to us have been the structures of brucinium proton-transfer salts with largely simple organic acids, prepared under aqueous alcoholic conditions, the crystalline products being stabilized by solvent mol­ecules. Water-stabilized achiral carboxyl­ate examples include BRU+ hydrogen fumarate·1.5H2O (Dijksma, Gould, Parsons & Walkinshaw, 1998[Dijksma, F. J. J., Gould, R. O., Parsons, S. & Walkinshaw, M. D. (1998). Acta Cryst. C54, 1948-1951.]), BRU+ di­hydrogen citrate·3H2O (Smith, Wermuth & White, 2005[Smith, G., Wermuth, U. D. & White, J. M. (2005). Acta Cryst. C61, o621-o624.]) and BRU+ benzo­ate·3H2O (Białońska & Ciunik, 2006b[Białońska, A. & Ciunik, Z. (2006b). Acta Cryst. E62, o5817-o5819.]).

Other organic acids besides carboxyl­ates may be included among the set but fewer structural examples are known, e.g. sulfonates (BRU+ toluene-4-sulfonate·3H2O; Smith, Wermuth, Healy et al., 2005[Smith, G., Wermuth, U. D., Healy, P. C., Young, D. J. & White, J. M. (2005). Acta Cryst. E61, o2646-o2648.]). However, no brucinium arsonate structures are known, so that the reaction of brucine with 4-amino­phenyl­arsonic acid (p-arsanilic acid) in 2-propanol/water was carried out, resulting in the formation of the crystalline hydrated title salt, C23H27N2O4+· C6H7AsNO3·4H2O, and the structure is reported herein. The acid has biological significance as an anti-helminth in veterinary applications (Thomas, 1905[Thomas, H. W. (1905). Proc. Roy. Soc. B: Biol. Sci. 76, 589-591.]; Steverding, 2010[Steverding, D. (2010). Parasites Vectors, 3, 15.]) and as a monohydrated sodium salt (atox­yl) which had early usage as an anti-syphilitic (Ehrlich & Bertheim, 1907[Ehrlich, P. & Bertheim, A. (1907). Berichte, pp. 3292-3297.]; Bosch & Rosich, 2008[Bosch, F. & Rosich, L. (2008). Pharmacology, 82, 171-179.]). Simple p-arsanilate salt structures are not common in the Cambridge Structural Database (Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]), with only the NH4+ and K+ salts (Smith & Wermuth, 2014[Smith, G. & Wermuth, U. D. (2014). Acta Cryst. C70, 738-741.]) and the guanidinium salts (Smith & Wermuth, 2010[Smith, G. & Wermuth, U. D. (2010). Acta Cryst. E66, o1893-o1894.]; Latham et al., 2011[Latham, K., Downs, J. E., Rix, C. J. & White, J. M. (2011). J. Mol. Struct. 987, 74-85.]) being known.

2. Structural commentary

The asymmetric unit of the title salt comprises a brucinium cation, a p-arsanilate anion A and four water mol­ecules of solvation, (O1W–O4W), all inter-associated through hydrogen bonds (Fig. 1[link]). Protonation has occurred as expected at N19 of the brucine cage, the invoked Peerdeman (1956[Peerdeman, A. F. (1956). Acta Cryst. 9, 824.]) absolute configuration for the strychnidinium mol­ecule giving the overall Cahn–Ingold stereochemistry of the cation as C7(R), C8(S), C12(S), C13(R), C14(R), C16(S) and the additional introduced (S) chiral centre at N19.

[Figure 1]
Figure 1
Mol­ecular configuration and atom-numbering scheme for the brucinium cation, p-arsanilate anion A and the four water mol­ecules of solvation in the asymmetric unit of the title salt. Inter-species hydrogen bonds are shown as dashed lines. Non-H atoms are shown as 40% probability displacement ellipsoids.

3. Supra­molecular features

The brucinium cations form into the previously described undulating sheet–host substructures which are considered to be the reason for the mol­ecular recognition peculiar to brucine (Gould & Walkinshaw, 1984[Gould, R. O. & Walkinshaw, M. D. (1984). J. Am. Chem. Soc. 106, 7840-7842.]; Gould et al., 1985[Gould, R. O., Kelly, R. & Walkinshaw, M. D. (1985). J. Chem. Soc. Perkin Trans. 2, pp. 847-852.]; Dijksma, Gould, Parsons & Walkinshaw, 1998[Dijksma, F. J. J., Gould, R. O., Parsons, S. & Walkinshaw, M. D. (1998). Acta Cryst. C54, 1948-1951.]; Dijksma, Gould, Parsons, Taylor & Walkinshaw, 1998[Dijksma, F. J. J., Gould, R. O., Parsons, S., Taylor, J. & Walkinshaw, M. D. (1998). Chem. Commun. pp. 745-746.]; Oshikawa et al., 2002[Oshikawa, T., Pochamroen, S., Takai, N., Ida, N., Takemoto, T. & Yamashita, M. (2002). Heterocycl. Commun. 8, 271-274.]; Białońska & Ciunik, 2004[Białońska, A. & Ciunik, Z. (2004). Acta Cryst. C60, o853-o855.]). In the title salt, these substructures extend along the b-axis direction, with the previously described 21 propagation of the brucinium cations along the ca 12.3 Å axis (Fig. 2[link]). The p-arsanilate anions and the water mol­ecules occupy the inter­stitial spaces in the structure. The protonated N19 atom of the cation gives a single hydrogen-bonding inter­action with a p-arsanilate oxygen acceptor (O12A) while two of the solvent water mol­ecules (O1W and O3W) form hydrogen bonds with the carbonyl O25 atom of the the brucinium cation (Table 1[link]). Within the inter-sheet channels, the p-arsanilate anions are linked head-to-head through an O13A—H⋯O11Aii hydrogen bond while both H atoms of the amine group form hydrogen bonds with water mol­ecules O3W and O4Wi. The water mol­ecules O2W and O4A are further linked to the p-arsanilate O-atom O12A with O2W also linked to O11Aiv. Water mol­ecules O3W and O4Wi give inter-water hydrogen bonds and together with a number of inter-mol­ecular C—H⋯O inter­actions (Table 1[link]) result in an overall three-dimensional network structure (Fig. 3[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N19—H19⋯O12A 0.91 (4) 1.72 (4) 2.610 (3) 168 (4)
N4A—H41A⋯O4Wi 0.89 (3) 2.46 (4) 3.291 (5) 155 (4)
N4A—H42A⋯O3W 0.90 (3) 2.25 (3) 3.137 (6) 169 (4)
O13A—H13A⋯O11Aii 0.90 (4) 1.67 (4) 2.546 (3) 165 (4)
O1W—H11W⋯O25 0.90 (4) 1.95 (4) 2.843 (4) 175 (3)
O1W—H12W⋯O2Wiii 0.90 (3) 1.87 (4) 2.760 (5) 168 (4)
O2W—H21W⋯O12A 0.90 (3) 2.11 (3) 2.945 (4) 153 (4)
O2W—H22W⋯O11Aiv 0.89 (3) 2.07 (4) 2.915 (4) 158 (5)
O3W—H31W⋯O25v 0.91 (4) 2.06 (4) 2.922 (4) 159 (3)
O3W—H32W⋯O4Wvi 0.91 (3) 1.91 (3) 2.791 (4) 164 (3)
O4W—H41W⋯O1Wvii 0.90 (4) 1.88 (4) 2.770 (5) 172 (5)
O4W—H42W⋯O12A 0.89 (4) 1.91 (4) 2.802 (4) 174 (5)
C14—H14⋯O3viii 1.00 2.52 3.363 (4) 142
C15—H151⋯O11Aii 0.99 2.60 3.561 (4) 165
C18—H182⋯O2W 0.99 2.58 3.422 (5) 143
C20—H201⋯O11Aii 0.99 2.41 3.388 (4) 170
C20—H202⋯O13Aiv 0.99 2.43 3.229 (4) 137
Symmetry codes: (i) [x-{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]; (ii) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (iii) [-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iv) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (v) [-x+{\script{1\over 2}}, -y+1, z+{\script{1\over 2}}]; (vi) [x+{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]; (vii) [-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (viii) [-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}].
[Figure 2]
Figure 2
The undulating brucinium sheet substructures in the unit cell of the title salt, less the inter-sheet anion and water mol­ecules, viewed down a. All H atoms except that of the protonated N19 atom have also been removed.
[Figure 3]
Figure 3
A perspective view of the packing in the unit cell, viewed along the approximate a-axial direction, showing the associated anions and the water mol­ecules in the inter­stitial regions of the brucinium layered substructures, with hydrogen-bonding inter­actions shown as dashed lines.

4. Database survey

Inter­stitial water mol­ecules are present in the structures of the brucine pseudo-polymorphic structures, e.g. the common tetra­hydrate form and the 5.2 hydrate (Smith et al., 2006a[Smith, G., Wermuth, U. D., Healy, P. C. & White, J. M. (2006a). Acta Cryst. C62, o203-o207.]) and the dihydrate (Smith et al., 2007[Smith, G., Wermuth, U. D. & White, J. M. (2007). Acta Cryst. C63, o489-o492.]), as well as the mixed solvates BRU–EtOH–H2O (1/1/2) (Glover et al., 1985[Glover, S. S. B., Gould, R. O. & Walkinshaw, M. D. (1985). Acta Cryst. C41, 990-994.]) and BRU–i-PrOH–H2O (1/1/2) (Białońska & Ciunik, 2004[Białońska, A. & Ciunik, Z. (2004). Acta Cryst. C60, o853-o855.]). A large number of water-stabilized brucinium salts of acids are known: with the inorganic sulfate (BRU)2SO4·7H2O (Białońska & Ciunik, 2005[Białońska, A. & Ciunik, Z. (2005). Acta Cryst. E61, o4222-o4224.]) and most commonly with aromatic carboxyl­ates, e.g. the benzoate (a trihydrate; Białońska & Ciunik, 2006b[Białońska, A. & Ciunik, Z. (2006b). Acta Cryst. E62, o5817-o5819.]); the 4-nitro­benzoate (a dihydrate; Białońska & Ciunik, 2007[Białońska, A. & Ciunik, Z. (2007). Acta Cryst. C63, o120-o122.]); the 3,5-di­nitro­benzoate (a trihydrate; Białońska & Ciunik, 2006a[Białońska, A. & Ciunik, Z. (2006a). Acta Cryst. C62, o450-o453.]); the 3,5-di­nitro­salicylate (a monohydrate; Smith et al., 2006a[Smith, G., Wermuth, U. D., Healy, P. C. & White, J. M. (2006a). Acta Cryst. C62, o203-o207.]); the phthalate (a monohydrate; Krishnan, Gayathri, Sivakumar, Gunasekaran & Anbalagen, 2013[Krishnan, P., Gayathri, K., Sivakumar, N., Gunasekaran, B. & Anbalagan, G. (2013). Acta Cryst. E69, o870.]); the hydrogen isophthalate (a trihydrate; Smith, Wermuth, Young & White, 2006[Smith, G., Wermuth, U. D., Young, D. J. & White, J. M. (2006). Acta Cryst. E62, o1553-o1555.]); the hydrogen 3-nitro­phthalate (a dihydrate; Smith, Wermuth, Young & Healy, 2005[Smith, G., Wermuth, U. D., Young, D. J. & Healy, P. C. (2005). Acta Cryst. E61, o2008-o2011.]) and the picramino­benzoate (a monohydrate; Smith & Wermuth, 2011[Smith, G. & Wermuth, U. D. (2011). Acta Cryst. C67, o334-o336.]).

Aliphatic carboxyl­ate examples are: with hydrogen oxalate (a dihydrate; Krishnan, Gayathri, Sivakumar, Chakkaravathi & Anbalagen, 2013[Krishnan, P., Gayathri, K., Sivakumar, N., Chakkaravarthi, G. & Anbalagan, G. (2013). Acta Cryst. E69, o659.]); with hydrogen fumarate (a sesquihydrate; Dijksma, Gould, Parsons & Walkinshaw, 1998[Dijksma, F. J. J., Gould, R. O., Parsons, S. & Walkinshaw, M. D. (1998). Acta Cryst. C54, 1948-1951.]); with hydrogen (S)-malate (a penta­hydrate; Smith, Wermuth & White, 2006[Smith, G., Wermuth, U. D. & White, J. M. (2006). Acta Cryst. C62, o353-o357.]); with di­hydrogen citrate (a trihydrate; Smith, Wermuth & White, 2005[Smith, G., Wermuth, U. D. & White, J. M. (2005). Acta Cryst. C61, o621-o624.]); with L-glycerate (a 4.75 hydrate; Białońska et al., 2005[Białońska, A., Ciunik, Z., Popek, T. & Lis, T. (2005). Acta Cryst. C61, o88-o91.]) and with hydrogen cis-cyclo­hexane-1,2-di­carboxyl­ate (a dihydrate; Smith et al., 2012[Smith, G., Wermuth, U. D. & Williams, M. L. (2012). J. Chem. Crystallogr. 42, 555-559.]). Some sulfonate salts are also known, e.g. with toluene-4-sulfonate (a trihydrate; Smith, Wermuth, Healy et al., 2005[Smith, G., Wermuth, U. D., Healy, P. C., Young, D. J. & White, J. M. (2005). Acta Cryst. E61, o2646-o2648.]); with 3-carb­oxy-4-hy­droxy­benzene­sulfonate (a penta­hydrate; Smith et al., 2006b[Smith, G., Wermuth, U. D., Healy, P. C. & White, J. M. (2006b). Aust. J. Chem. 59, 321-328.]) and with biphenyl-4,4′-di­sulfonate (a hexa­hydrate; Smith et al., 2010[Smith, G., Wermuth, U. D. & Young, D. J. (2010). J. Chem. Crystallogr. 40, 520-525.]).

5. Synthesis and crystallization

The title compound was synthesized by heating together under reflux for 10 min, 1 mmol qu­anti­ties of brucine tetra­hydrate and 4-amino­phenyl­arsonic acid in 50 mL of 80% 2-propanol/water. After concentration to ca 30 mL, partial room-temperature evaporation of the hot-filtered solution gave thin colourless crystal plates of the title compound from which a specimen was cleaved for the X-ray analysis.

6. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. Hydrogen atoms potentially involved in hydrogen-bonding inter­actions were located by difference methods but their positional parameters were constrained in the refinement with N—H and O—H = 0.90 Å, and with Uiso(H) = 1.2Ueq(N) or 1.5Ueq(O). Other H atoms were included in the refinement at calculated positions [C—H(aromatic) = 0.95 Å and C—H (aliphatic) = 0.97–1.00 Å] and treated as riding with Uiso(H) = 1.2Ueq(C). The absolute configuration determined for the parent strychnidinin-10-one mol­ecule (Peerdeman, 1956[Peerdeman, A. F. (1956). Acta Cryst. 9, 824.]) was invoked and was confirmed in the the structure refinement.

Table 2
Experimental details

Crystal data
Chemical formula (C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O
Mr 683.58
Crystal system, space group Orthorhombic, P212121
Temperature (K) 200
a, b, c (Å) 7.6553 (3), 12.3238 (5), 31.960 (2)
V3) 3015.2 (3)
Z 4
Radiation type Mo Kα
μ (mm−1) 1.19
Crystal size (mm) 0.36 × 0.34 × 0.10
 
Data collection
Diffractometer Oxford Diffraction Gemini-S CCD-detector diffractometer
Absorption correction Multi-scan (CrysAlis PRO; Rigaku OD, 2015[Rigaku OD (2015). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, England.])
Tmin, Tmax 0.811, 0.980
No. of measured, independent and observed [I > 2σ(I)] reflections 11983, 6980, 5901
Rint 0.032
(sin θ/λ)max−1) 0.693
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.048, 0.096, 1.05
No. of reflections 6980
No. of parameters 433
No. of restraints 14
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.55, −0.46
Absolute structure Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 3672 Friedel pairs
Absolute structure parameter −0.005 (9)
Computer programs: CrysAlis PRO (Rigaku OD, 2015[Rigaku OD (2015). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, England.]), SIR92 (Altomare et al., 1993[Altomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343-350.]), SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) within WinGX (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Chemical context top

The Strychnos alkaloid base brucine, (2,3-di­meth­oxy­strychnidin-10-one; BRU) has been extensively employed as a resolving agent for chiral organic compounds (Wilen, 1972). With chiral acids, the separation is achieved through proton-transfer to N19 of the strychnidine cage (pKa2 = 11.7; O'Neil, 2001), followed by separation of the resultant crystalline salt products by fractional crystallization. Similar effects are achieved with the essentially identical Strychnos alkaloid but separation efficiency favours brucine. This is probably because of the formation in the crystal of characteristic brucinium host substructures comprising head-to-tail undulating layers of brucine molecules or cations which accommodate selectively the hydrogen-bonded guest molecules in the crystal structure. A characteristic of the substructure is the repeat inter­val in the layer of ca 12.3 Å along a 21 screw axis in the crystal, which is reflected in the unit-cell dimension, with brucine being predominantly in the monoclinic space group P21 or the orthorhombic space group P212121 (Smith, Wermuth & White, 2006; Smith, Wermuth, Young & White, 2006).

This example of molecular recognition was described in the early structure determinations of brucinium benzoyl-D-alaninate (Gould & Walkinshaw, 1984) and in the structures of the pseudopolymorphic brucine solvates, brucine–MeOH (1:1) and brucine–EtOH–water (1/1/2) (Glover et al., 1985). The guest molecules are accommodated inter­stitially within the layers and are commonly accompanied by compatible polar solvent molecules, usually generating high-dimensional hydrogen-bonded crystal structures.

Currently, a large number of structures of brucine compounds with chiral organic molecules, including both acids and non-acids are known, but in addition those with achiral compounds also feature. Of inter­est to us have been the structures of brucinium proton-transfer salts with largely simple organic acids, prepared under aqueous alcoholic conditions, the crystalline products being stabilized by solvent molecules. Water-stabilized achiral carboxyl­ate examples include BRU+ hydrogen fumarate·1.5H2O (Dijksma, Gould, Parsons & Walkinshaw, 1998), BRU+ di­hydrogen citrate·3H2O (Smith, Wermuth & White, 2005) and BRU+ benzoate-·3H2O (Bialońska & Ciunik, 2006b).

Other organic acids besides carboxyl­ates may be included among the set but fewer structural examples are known, e.g. sulfonates (BRU+ toluene-4-sulfonate-·3H2O; Smith, Wermuth, Healy et al., 2005). However, no brucinium arsonate structures are known, so that the reaction of brucine with 4-amino­phenyl­arsonic acid (p-arsanilic acid) in 2-propanol/water was carried out, resulting in the formation of the crystalline hydrated title salt, C23H27N2O4+· C6H7AsNO3-·4H2O, and the structure is reported herein. The acid has biological significance as an anti-helminth in veterinary applications (Thomas, 1905; Steverding, 2010) and as a monohydrated sodium salt (atoxyl) which had early usage as an anti-syphilitic (Ehrlich & Bertheim, 1907; Bosch & Rosich, 2008). Simple p-arsanilate salt structures are not common in the Cambridge Structural Database (Groom et al., 2016), with only the NH4+ and K+ salts (Smith & Wermuth, 2014) and the guanidinium salts (Smith & Wermuth, 2010; Latham et al., 2011) being known.

Structural commentary top

The asymmetric unit of the title salt comprises a brucinium cation, a p-arsanilate anion A and four water molecules of solvation, (O1W–O4W), all inter-associated through hydrogen bonds (Fig. 1). Protonation has occurred as expected at N19 of the brucine cage, the invoked Peerdeman (1956) absolute configuration for the strychnidinium molecule giving the overall Cahn–Ingold stereochemistry of the cation as C7(R), C8(S), C12(S), C13(R), C14(R), C16(S) and the additional introduced (S) chiral centre at N19.

Supra­molecular features top

The brucinium cations form into the previously described undulating sheet–host substructures which are considered to be the reason for the molecular recognition peculiar to brucine (Gould & Walkinshaw, 1984; Gould et al., 1985; Dijksma, Gould, Parsons & Walkinshaw, 1998; Dijksma, Gould, Parsons, Taylor & Walkinshaw, 1998; Oshikawa et al., 2002; Bialońska & Ciunik, 2004). In the title salt, these substructures extend along the b-axis direction, with the previously described 21 propagation of the brucinium cations along the ca 12.3 Å b axis (Fig. 2). The p-arsanilate anions and the water molecules occupy the inter­stitial spaces in the structure. The protonated N19 atom of the cation gives a single hydrogen-bonding inter­action with a p-arsanilate oxygen acceptor (O12A) while two of the solvent water molecules (O1W and O3W) form hydrogen bonds with the carbonyl O25 atom of the the brucinium cation (Table 1). Within the inter-sheet channels, the p-arsanilate anions are linked head-to-head through an O13A—H···O11Aii hydrogen bond while both H atoms of the amine group form H bonds with water molecules O3W and O4Wi. The water molecules O2W and O4A are further linked to the p-arsanilate O-atom O12A with O2W also linked to O11Aiv. Water molecules O3W and O4Wi give inter-water hydrogen bonds and together with a number of inter-molecular C—H···O inter­actions (Table 1) result in an overall three-dimensional network structure (Fig. 3).

Database survey top

Inter­stitial water molecules are present in the structures of the brucine pseudo-polymorphic structures, e.g. the common tetra­hydrate form and the 5.2 hydrate (Smith et al., 2006a) and the dihydrate (Smith et al., 2007), as well as the mixed solvates BRU–EtOH–H2O (1/1/2) (Glover et al., 1985) and BRU–i-PrOH–H2O (1/1/2) (Bialońska & Ciunik, 2004). A large number of water-stabilized brucinium salts of acids are known: with the inorganic sulfate (BRU)2SO4·7H2O (Bialońska & Ciunik, 2005) and most commonly with the aromatic carboxyl­ates, e.g. the benzoate (a trihydrate; Bialońska & Ciunik, 2006b); the 4-nitro­benzoate (a dihydrate; Bialońska & Ciunik, 2007); the 3,5-di­nitro­benzoate (a trihydrate; Bialońska & Ciunik, 2006a); the 3,5-di­nitro­salicylate (a monohydrate; Smith et al., 2006a); the phthalate (a monohydrate; Krishnan, Gayathri, Sivakumar, Gunasekaran & Anbalagen, 2013); the hydrogen isophthalate (a trihydrate; Smith, Wermuth, Young & White, 2006); the hydrogen 3-nitro­phthalate (a dihydrate; Smith, Wermuth, Young & Healy, 2005) and the picramino­benzoate (a monohydrate; Smith & Wermuth, 2011).

Aliphatic carboxyl­ate examples are: with hydrogen oxalate (a dihydrate; Krishnan, Gayathri, Sivakumar, Chakkaravathi & Anbalagen, 2013); with hydrogen fumarate (a sesquihydrate; Dijksma, Gould, Parsons & Walkinshaw, 1998); with hydrogen (S)-malate (a penta­hydrate; Smith, Wermuth & White, 2006); with di­hydrogen citrate (a trihydrate; Smith, Wermuth & White, 2005); with L-glycerate (a 4.75 hydrate; Bialońska et al., 2005) and with hydrogen cis-cyclo­hexane-1,2-di­carboxyl­ate (a dihydrate; Smith et al., 2012). Some sulfonate salts are also known, e.g. with toluene-4-sulfonate (a trihydrate; Smith, Wermuth, Healy et al., 2005); with 3-carb­oxy-4-hy­droxy­benzene­sulfonate (a penta­hydrate; Smith et al., 2006b) and with bi­phenyl-4,4'-di­sulfonate (a hexahydrate; Smith et al., 2010).

Synthesis and crystallization top

The title compound was synthesized by heating together under reflux for 10 min, 1 mmol qu­anti­ties of brucine tetra­hydrate and 4-amino­phenyl­arsonic acid in 50 mL of 80% 2-propanol/water. After concentration to ca 30 mL, partial room-temperature evaporation of the hot-filtered solution gave thin colourless crystal plates of the title compound from which a specimen was cleaved for the X-ray analysis.

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms potentially involved in hydrogen-bonding inter­actions were located by difference methods but their positional parameters were constrained in the refinement with N—H and O—H = 0.90 Å, and with Uiso(H) = 1.2Ueq(N) or 1.5Ueq(O). Other H atoms were included in the refinement at calculated positions [C—H(aromatic) = 0.95 Å and C—H (aliphatic) = 0.97–1.00 Å] and treated as riding with Uiso(H) = 1.2Ueq(C). The absolute configuration determined for the parent strychnidinin-10-one molecule (Peerdeman, 1956) was invoked and was confirmed in the the structure refinement (Flack, 1983) [absolute structure parameter -0.005 (9) for 3672 Friedel pairs].

Structure description top

The Strychnos alkaloid base brucine, (2,3-di­meth­oxy­strychnidin-10-one; BRU) has been extensively employed as a resolving agent for chiral organic compounds (Wilen, 1972). With chiral acids, the separation is achieved through proton-transfer to N19 of the strychnidine cage (pKa2 = 11.7; O'Neil, 2001), followed by separation of the resultant crystalline salt products by fractional crystallization. Similar effects are achieved with the essentially identical Strychnos alkaloid but separation efficiency favours brucine. This is probably because of the formation in the crystal of characteristic brucinium host substructures comprising head-to-tail undulating layers of brucine molecules or cations which accommodate selectively the hydrogen-bonded guest molecules in the crystal structure. A characteristic of the substructure is the repeat inter­val in the layer of ca 12.3 Å along a 21 screw axis in the crystal, which is reflected in the unit-cell dimension, with brucine being predominantly in the monoclinic space group P21 or the orthorhombic space group P212121 (Smith, Wermuth & White, 2006; Smith, Wermuth, Young & White, 2006).

This example of molecular recognition was described in the early structure determinations of brucinium benzoyl-D-alaninate (Gould & Walkinshaw, 1984) and in the structures of the pseudopolymorphic brucine solvates, brucine–MeOH (1:1) and brucine–EtOH–water (1/1/2) (Glover et al., 1985). The guest molecules are accommodated inter­stitially within the layers and are commonly accompanied by compatible polar solvent molecules, usually generating high-dimensional hydrogen-bonded crystal structures.

Currently, a large number of structures of brucine compounds with chiral organic molecules, including both acids and non-acids are known, but in addition those with achiral compounds also feature. Of inter­est to us have been the structures of brucinium proton-transfer salts with largely simple organic acids, prepared under aqueous alcoholic conditions, the crystalline products being stabilized by solvent molecules. Water-stabilized achiral carboxyl­ate examples include BRU+ hydrogen fumarate·1.5H2O (Dijksma, Gould, Parsons & Walkinshaw, 1998), BRU+ di­hydrogen citrate·3H2O (Smith, Wermuth & White, 2005) and BRU+ benzoate-·3H2O (Bialońska & Ciunik, 2006b).

Other organic acids besides carboxyl­ates may be included among the set but fewer structural examples are known, e.g. sulfonates (BRU+ toluene-4-sulfonate-·3H2O; Smith, Wermuth, Healy et al., 2005). However, no brucinium arsonate structures are known, so that the reaction of brucine with 4-amino­phenyl­arsonic acid (p-arsanilic acid) in 2-propanol/water was carried out, resulting in the formation of the crystalline hydrated title salt, C23H27N2O4+· C6H7AsNO3-·4H2O, and the structure is reported herein. The acid has biological significance as an anti-helminth in veterinary applications (Thomas, 1905; Steverding, 2010) and as a monohydrated sodium salt (atoxyl) which had early usage as an anti-syphilitic (Ehrlich & Bertheim, 1907; Bosch & Rosich, 2008). Simple p-arsanilate salt structures are not common in the Cambridge Structural Database (Groom et al., 2016), with only the NH4+ and K+ salts (Smith & Wermuth, 2014) and the guanidinium salts (Smith & Wermuth, 2010; Latham et al., 2011) being known.

The asymmetric unit of the title salt comprises a brucinium cation, a p-arsanilate anion A and four water molecules of solvation, (O1W–O4W), all inter-associated through hydrogen bonds (Fig. 1). Protonation has occurred as expected at N19 of the brucine cage, the invoked Peerdeman (1956) absolute configuration for the strychnidinium molecule giving the overall Cahn–Ingold stereochemistry of the cation as C7(R), C8(S), C12(S), C13(R), C14(R), C16(S) and the additional introduced (S) chiral centre at N19.

The brucinium cations form into the previously described undulating sheet–host substructures which are considered to be the reason for the molecular recognition peculiar to brucine (Gould & Walkinshaw, 1984; Gould et al., 1985; Dijksma, Gould, Parsons & Walkinshaw, 1998; Dijksma, Gould, Parsons, Taylor & Walkinshaw, 1998; Oshikawa et al., 2002; Bialońska & Ciunik, 2004). In the title salt, these substructures extend along the b-axis direction, with the previously described 21 propagation of the brucinium cations along the ca 12.3 Å b axis (Fig. 2). The p-arsanilate anions and the water molecules occupy the inter­stitial spaces in the structure. The protonated N19 atom of the cation gives a single hydrogen-bonding inter­action with a p-arsanilate oxygen acceptor (O12A) while two of the solvent water molecules (O1W and O3W) form hydrogen bonds with the carbonyl O25 atom of the the brucinium cation (Table 1). Within the inter-sheet channels, the p-arsanilate anions are linked head-to-head through an O13A—H···O11Aii hydrogen bond while both H atoms of the amine group form H bonds with water molecules O3W and O4Wi. The water molecules O2W and O4A are further linked to the p-arsanilate O-atom O12A with O2W also linked to O11Aiv. Water molecules O3W and O4Wi give inter-water hydrogen bonds and together with a number of inter-molecular C—H···O inter­actions (Table 1) result in an overall three-dimensional network structure (Fig. 3).

Inter­stitial water molecules are present in the structures of the brucine pseudo-polymorphic structures, e.g. the common tetra­hydrate form and the 5.2 hydrate (Smith et al., 2006a) and the dihydrate (Smith et al., 2007), as well as the mixed solvates BRU–EtOH–H2O (1/1/2) (Glover et al., 1985) and BRU–i-PrOH–H2O (1/1/2) (Bialońska & Ciunik, 2004). A large number of water-stabilized brucinium salts of acids are known: with the inorganic sulfate (BRU)2SO4·7H2O (Bialońska & Ciunik, 2005) and most commonly with the aromatic carboxyl­ates, e.g. the benzoate (a trihydrate; Bialońska & Ciunik, 2006b); the 4-nitro­benzoate (a dihydrate; Bialońska & Ciunik, 2007); the 3,5-di­nitro­benzoate (a trihydrate; Bialońska & Ciunik, 2006a); the 3,5-di­nitro­salicylate (a monohydrate; Smith et al., 2006a); the phthalate (a monohydrate; Krishnan, Gayathri, Sivakumar, Gunasekaran & Anbalagen, 2013); the hydrogen isophthalate (a trihydrate; Smith, Wermuth, Young & White, 2006); the hydrogen 3-nitro­phthalate (a dihydrate; Smith, Wermuth, Young & Healy, 2005) and the picramino­benzoate (a monohydrate; Smith & Wermuth, 2011).

Aliphatic carboxyl­ate examples are: with hydrogen oxalate (a dihydrate; Krishnan, Gayathri, Sivakumar, Chakkaravathi & Anbalagen, 2013); with hydrogen fumarate (a sesquihydrate; Dijksma, Gould, Parsons & Walkinshaw, 1998); with hydrogen (S)-malate (a penta­hydrate; Smith, Wermuth & White, 2006); with di­hydrogen citrate (a trihydrate; Smith, Wermuth & White, 2005); with L-glycerate (a 4.75 hydrate; Bialońska et al., 2005) and with hydrogen cis-cyclo­hexane-1,2-di­carboxyl­ate (a dihydrate; Smith et al., 2012). Some sulfonate salts are also known, e.g. with toluene-4-sulfonate (a trihydrate; Smith, Wermuth, Healy et al., 2005); with 3-carb­oxy-4-hy­droxy­benzene­sulfonate (a penta­hydrate; Smith et al., 2006b) and with bi­phenyl-4,4'-di­sulfonate (a hexahydrate; Smith et al., 2010).

Synthesis and crystallization top

The title compound was synthesized by heating together under reflux for 10 min, 1 mmol qu­anti­ties of brucine tetra­hydrate and 4-amino­phenyl­arsonic acid in 50 mL of 80% 2-propanol/water. After concentration to ca 30 mL, partial room-temperature evaporation of the hot-filtered solution gave thin colourless crystal plates of the title compound from which a specimen was cleaved for the X-ray analysis.

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms potentially involved in hydrogen-bonding inter­actions were located by difference methods but their positional parameters were constrained in the refinement with N—H and O—H = 0.90 Å, and with Uiso(H) = 1.2Ueq(N) or 1.5Ueq(O). Other H atoms were included in the refinement at calculated positions [C—H(aromatic) = 0.95 Å and C—H (aliphatic) = 0.97–1.00 Å] and treated as riding with Uiso(H) = 1.2Ueq(C). The absolute configuration determined for the parent strychnidinin-10-one molecule (Peerdeman, 1956) was invoked and was confirmed in the the structure refinement (Flack, 1983) [absolute structure parameter -0.005 (9) for 3672 Friedel pairs].

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2015); cell refinement: CrysAlis PRO (Rigaku OD, 2015); data reduction: CrysAlis PRO (Rigaku OD, 2015); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. Molecular configuration and atom-numbering scheme for the brucinium cation, p-arsanilate anion A and the four water molecules of solvation in the asymmetric unit of the title salt. Inter-species hydrogen bonds are shown as dashed lines. Non-H atoms are shown as 40% probability displacement ellipsoids.
[Figure 2] Fig. 2. The undulating brucinium sheet substructures in the unit cell of the title salt, less the inter-sheet anion and water molecules, viewed down a. All H atoms except that of the protonated N19 atom have also been removed.
[Figure 3] Fig. 3. A perspective view of the packing in the unit cell, viewed along the approximate a-axial direction, showing the associated anions and the water molecules in the interstitial regions of the brucinium layered substructures, with hydrogen-bonding interactions shown as dashed lines.
2,3-Dimethoxy-10-oxostrychnidinium 4-aminophenylarsonate tetrahydrate top
Crystal data top
(C23H27N2O4)[As(C6H7N)O2(OH)]·4H2OF(000) = 1432
Mr = 683.58Dx = 1.506 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 2822 reflections
a = 7.6553 (3) Åθ = 3.4–27.9°
b = 12.3238 (5) ŵ = 1.19 mm1
c = 31.960 (2) ÅT = 200 K
V = 3015.2 (3) Å3Plate, colourless
Z = 40.36 × 0.34 × 0.10 mm
Data collection top
Oxford Diffraction Gemini-S CCD-detector
diffractometer
6980 independent reflections
Radiation source: Enhance (Mo) X-ray source5901 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.032
Detector resolution: 16.077 pixels mm-1θmax = 29.5°, θmin = 3.1°
ω scansh = 106
Absorption correction: multi-scan
(CrysAlis PRO; Rigaku OD, 2015)
k = 1616
Tmin = 0.811, Tmax = 0.980l = 4325
11983 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.048H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.096 w = 1/[σ2(Fo2) + (0.0414P)2 + 0.2011P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
6980 reflectionsΔρmax = 0.55 e Å3
433 parametersΔρmin = 0.46 e Å3
14 restraintsAbsolute structure: Flack (1983), 3672 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.005 (9)
Crystal data top
(C23H27N2O4)[As(C6H7N)O2(OH)]·4H2OV = 3015.2 (3) Å3
Mr = 683.58Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 7.6553 (3) ŵ = 1.19 mm1
b = 12.3238 (5) ÅT = 200 K
c = 31.960 (2) Å0.36 × 0.34 × 0.10 mm
Data collection top
Oxford Diffraction Gemini-S CCD-detector
diffractometer
6980 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Rigaku OD, 2015)
5901 reflections with I > 2σ(I)
Tmin = 0.811, Tmax = 0.980Rint = 0.032
11983 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.048H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.096Δρmax = 0.55 e Å3
S = 1.05Δρmin = 0.46 e Å3
6980 reflectionsAbsolute structure: Flack (1983), 3672 Friedel pairs
433 parametersAbsolute structure parameter: 0.005 (9)
14 restraints
Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O20.2664 (3)0.56076 (19)0.24172 (7)0.0288 (8)
O30.2324 (3)0.44912 (19)0.17363 (7)0.0251 (7)
O240.2010 (3)0.13571 (17)0.32202 (7)0.0224 (7)
O250.2193 (4)0.0496 (2)0.19539 (7)0.0336 (9)
N90.1591 (3)0.1193 (2)0.25929 (8)0.0192 (7)
N190.1326 (4)0.2044 (2)0.39973 (8)0.0220 (8)
C10.2107 (4)0.4025 (3)0.28549 (10)0.0220 (10)
C20.2316 (4)0.4525 (3)0.24709 (10)0.0206 (10)
C30.2176 (4)0.3914 (3)0.21006 (10)0.0200 (9)
C40.1912 (4)0.2806 (2)0.21125 (9)0.0192 (9)
C50.1762 (5)0.2319 (2)0.25023 (10)0.0186 (9)
C60.1822 (5)0.2909 (3)0.28690 (9)0.0200 (9)
C70.1402 (4)0.2196 (3)0.32382 (10)0.0194 (9)
C80.1639 (4)0.1035 (3)0.30544 (9)0.0178 (9)
C100.2084 (5)0.0380 (3)0.23349 (10)0.0224 (10)
C110.2482 (5)0.0701 (3)0.25362 (11)0.0244 (11)
C120.3195 (5)0.0703 (3)0.29876 (10)0.0216 (10)
C130.3369 (4)0.0468 (3)0.31477 (9)0.0173 (9)
C140.3946 (4)0.0634 (3)0.36027 (10)0.0208 (10)
C150.4243 (4)0.1858 (3)0.36540 (11)0.0217 (10)
C160.2486 (5)0.2415 (3)0.36351 (10)0.0215 (10)
C170.0479 (4)0.2361 (3)0.33974 (11)0.0236 (11)
C180.0461 (4)0.1812 (3)0.38190 (10)0.0236 (10)
C200.2066 (5)0.1088 (3)0.42293 (9)0.0234 (10)
C210.2646 (4)0.0242 (3)0.39246 (10)0.0221 (10)
C220.2076 (5)0.0761 (3)0.39424 (10)0.0235 (10)
C230.2581 (5)0.1618 (3)0.36323 (11)0.0269 (11)
C250.2845 (6)0.6248 (3)0.27850 (12)0.0400 (14)
C260.2222 (4)0.3880 (3)0.13581 (10)0.0263 (10)
As1A0.18853 (4)0.38087 (2)0.50015 (1)0.0194 (1)
O11A0.0706 (3)0.2967 (2)0.52906 (7)0.0288 (8)
O12A0.1351 (3)0.37219 (19)0.44956 (7)0.0256 (7)
O13A0.4046 (3)0.3544 (2)0.50798 (9)0.0361 (9)
N4A0.1284 (6)0.8469 (3)0.55939 (14)0.0526 (15)
C1A0.1723 (5)0.5265 (2)0.51885 (9)0.0213 (9)
C2A0.0081 (5)0.5733 (3)0.52485 (11)0.0277 (11)
C3A0.0043 (6)0.6792 (3)0.53827 (11)0.0320 (12)
C4A0.1423 (6)0.7411 (3)0.54628 (12)0.0314 (13)
C5A0.3047 (6)0.6939 (3)0.53962 (11)0.0324 (11)
C6A0.3193 (5)0.5885 (3)0.52554 (10)0.0271 (10)
O1W0.4311 (4)0.0600 (3)0.13578 (10)0.0461 (11)
O2W0.2441 (4)0.3881 (3)0.43528 (11)0.0521 (11)
O3W0.4514 (4)0.8770 (3)0.61869 (11)0.0587 (12)
O4W0.2795 (4)0.5374 (3)0.40023 (10)0.0511 (11)
H10.215700.443800.310600.0260*
H40.183700.239200.186300.0230*
H80.064400.056300.314300.0210*
H120.437200.105500.299000.0260*
H130.427100.082700.296900.0210*
H140.508000.024800.364800.0250*
H160.267400.321500.366100.0260*
H190.122 (6)0.258 (3)0.4190 (11)0.0620*
H220.130500.095400.416300.0280*
H1110.334100.108100.235700.0290*
H1120.139600.113700.253300.0290*
H1510.481500.200800.392600.0260*
H1520.500900.213000.342700.0260*
H1710.076100.314200.342400.0280*
H1720.133600.201500.320800.0280*
H1810.064700.102100.378900.0280*
H1820.138500.211200.400200.0280*
H2010.307000.132300.440200.0280*
H2020.116700.078100.441800.0280*
H2310.386800.170100.363200.0320*
H2320.206300.231900.371800.0320*
H2510.308700.700200.270700.0600*
H2520.381200.596600.295400.0600*
H2530.176000.621600.294700.0600*
H2610.233800.436900.111800.0390*
H2620.109300.350700.134400.0390*
H2630.316600.334300.135200.0390*
H2A0.094700.532300.519700.0330*
H3A0.116500.710400.542100.0390*
H5A0.407400.734900.544900.0390*
H6A0.431600.558500.520400.0330*
H13A0.445 (6)0.298 (3)0.4931 (13)0.0770*
H41A0.022 (3)0.876 (4)0.5617 (15)0.0620*
H42A0.227 (3)0.861 (4)0.5735 (13)0.0620*
H11W0.360 (5)0.029 (4)0.1548 (10)0.0770*
H12W0.358 (5)0.071 (4)0.1141 (10)0.0770*
H21W0.134 (3)0.406 (4)0.4425 (16)0.0770*
H22W0.273 (7)0.328 (2)0.4492 (14)0.0770*
H31W0.406 (6)0.917 (3)0.6400 (11)0.0770*
H32W0.548 (4)0.917 (3)0.6129 (15)0.0770*
H41W0.378 (4)0.512 (4)0.3885 (15)0.0770*
H42W0.242 (7)0.483 (3)0.4163 (13)0.0770*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O20.0412 (17)0.0165 (12)0.0288 (13)0.0036 (11)0.0025 (12)0.0002 (10)
O30.0292 (13)0.0255 (13)0.0207 (12)0.0021 (11)0.0027 (10)0.0008 (10)
O240.0244 (12)0.0185 (11)0.0243 (11)0.0011 (11)0.0001 (11)0.0000 (9)
O250.0533 (19)0.0281 (14)0.0195 (12)0.0026 (14)0.0064 (13)0.0055 (10)
N90.0226 (14)0.0182 (12)0.0168 (12)0.0001 (13)0.0003 (11)0.0035 (11)
N190.0261 (15)0.0230 (15)0.0169 (14)0.0009 (12)0.0011 (12)0.0052 (12)
C10.0251 (19)0.0207 (17)0.0203 (16)0.0005 (14)0.0011 (15)0.0087 (13)
C20.0181 (18)0.0173 (16)0.0263 (18)0.0022 (13)0.0011 (15)0.0004 (14)
C30.0169 (17)0.0247 (17)0.0183 (15)0.0004 (15)0.0021 (13)0.0018 (14)
C40.0200 (16)0.0229 (16)0.0148 (14)0.0001 (15)0.0007 (15)0.0046 (12)
C50.0196 (17)0.0181 (15)0.0181 (15)0.0014 (14)0.0008 (15)0.0012 (12)
C60.0196 (16)0.0213 (15)0.0192 (15)0.0022 (15)0.0023 (15)0.0000 (13)
C70.0228 (17)0.0176 (16)0.0177 (16)0.0017 (13)0.0007 (14)0.0031 (13)
C80.0193 (16)0.0188 (16)0.0153 (14)0.0002 (14)0.0004 (13)0.0039 (12)
C100.0214 (18)0.0235 (17)0.0224 (17)0.0025 (16)0.0005 (16)0.0059 (14)
C110.030 (2)0.0184 (17)0.0248 (18)0.0021 (14)0.0014 (16)0.0066 (14)
C120.0204 (17)0.0190 (16)0.0255 (17)0.0035 (16)0.0024 (16)0.0047 (13)
C130.0137 (16)0.0175 (15)0.0208 (16)0.0005 (13)0.0031 (13)0.0038 (12)
C140.0164 (17)0.0248 (18)0.0211 (17)0.0020 (14)0.0029 (14)0.0028 (14)
C150.0210 (18)0.0250 (18)0.0192 (17)0.0039 (15)0.0021 (15)0.0058 (15)
C160.0291 (18)0.0173 (16)0.0182 (16)0.0043 (13)0.0024 (15)0.0043 (13)
C170.0249 (19)0.0242 (19)0.0216 (17)0.0053 (15)0.0030 (15)0.0054 (14)
C180.0186 (17)0.0283 (19)0.0239 (18)0.0018 (15)0.0061 (15)0.0032 (15)
C200.0289 (18)0.0239 (17)0.0175 (15)0.0004 (17)0.0029 (15)0.0001 (14)
C210.0204 (17)0.0257 (18)0.0201 (16)0.0025 (14)0.0065 (14)0.0003 (14)
C220.0229 (18)0.0272 (17)0.0205 (16)0.0019 (15)0.0026 (16)0.0032 (13)
C230.0284 (19)0.0210 (17)0.0314 (19)0.0009 (14)0.0039 (16)0.0031 (15)
C250.062 (3)0.0220 (19)0.036 (2)0.004 (2)0.002 (2)0.0032 (17)
C260.0268 (19)0.0317 (19)0.0204 (15)0.0005 (17)0.0019 (14)0.0030 (16)
As1A0.0219 (2)0.0175 (1)0.0187 (1)0.0005 (1)0.0006 (2)0.0038 (2)
O11A0.0363 (15)0.0273 (13)0.0229 (12)0.0063 (12)0.0047 (11)0.0041 (11)
O12A0.0368 (14)0.0204 (12)0.0197 (11)0.0008 (11)0.0016 (10)0.0054 (10)
O13A0.0239 (12)0.0339 (14)0.0505 (19)0.0038 (11)0.0055 (13)0.0178 (13)
N4A0.060 (3)0.0279 (19)0.070 (3)0.0095 (18)0.011 (2)0.0174 (18)
C1A0.0328 (19)0.0171 (15)0.0139 (15)0.0015 (15)0.0001 (16)0.0007 (12)
C2A0.0270 (19)0.0250 (19)0.031 (2)0.0009 (15)0.0045 (17)0.0009 (16)
C3A0.042 (2)0.026 (2)0.028 (2)0.0090 (17)0.0073 (18)0.0008 (16)
C4A0.048 (3)0.0208 (18)0.0254 (18)0.0027 (17)0.0018 (18)0.0023 (15)
C5A0.043 (2)0.0239 (18)0.0303 (19)0.0078 (19)0.0059 (19)0.0012 (15)
C6A0.0313 (19)0.0277 (18)0.0224 (16)0.0030 (17)0.0018 (18)0.0022 (14)
O1W0.0439 (18)0.0500 (19)0.0445 (18)0.0115 (16)0.0045 (15)0.0085 (16)
O2W0.0453 (17)0.053 (2)0.058 (2)0.0021 (17)0.0002 (16)0.0257 (18)
O3W0.059 (2)0.059 (2)0.058 (2)0.0071 (19)0.0088 (17)0.0055 (18)
O4W0.050 (2)0.0452 (19)0.058 (2)0.0023 (16)0.0108 (17)0.0184 (16)
Geometric parameters (Å, º) top
As1A—O12A1.671 (2)C13—C141.534 (4)
As1A—O13A1.704 (2)C14—C211.511 (5)
As1A—C1A1.896 (3)C14—C151.534 (5)
As1A—O11A1.657 (2)C15—C161.511 (5)
O2—C21.371 (4)C17—C181.508 (5)
O2—C251.423 (4)C20—C211.494 (5)
O3—C261.426 (4)C21—C221.312 (5)
O3—C31.369 (4)C22—C231.499 (5)
O24—C231.425 (4)C1—H10.9500
O24—C121.423 (4)C4—H40.9500
O25—C101.229 (4)C8—H81.0000
O13A—H13A0.90 (4)C11—H1110.9900
O1W—H12W0.90 (3)C11—H1120.9900
O1W—H11W0.90 (4)C12—H121.0000
O2W—H22W0.89 (3)C13—H131.0000
O2W—H21W0.90 (3)C14—H141.0000
O3W—H32W0.91 (3)C15—H1520.9900
O3W—H31W0.91 (4)C15—H1510.9900
N9—C51.424 (4)C16—H161.0000
N9—C101.351 (4)C17—H1710.9900
N9—C81.488 (4)C17—H1720.9900
N19—C161.529 (4)C18—H1820.9900
N19—C181.509 (4)C18—H1810.9900
N19—C201.503 (4)C20—H2020.9900
O4W—H42W0.89 (4)C20—H2010.9900
O4W—H41W0.90 (4)C22—H220.9500
N19—H190.91 (4)C23—H2320.9900
N4A—C4A1.374 (5)C23—H2310.9900
N4A—H41A0.89 (3)C25—H2520.9800
N4A—H42A0.90 (3)C25—H2510.9800
C1—C21.383 (5)C25—H2530.9800
C1—C61.393 (5)C26—H2620.9800
C2—C31.407 (5)C26—H2630.9800
C3—C41.381 (4)C26—H2610.9800
C4—C51.388 (4)C1A—C6A1.377 (5)
C5—C61.380 (4)C1A—C2A1.396 (5)
C6—C71.506 (5)C2A—C3A1.377 (5)
C7—C171.541 (4)C3A—C4A1.381 (6)
C7—C161.540 (5)C4A—C5A1.389 (6)
C7—C81.557 (5)C5A—C6A1.379 (5)
C8—C131.527 (5)C2A—H2A0.9500
C10—C111.511 (5)C3A—H3A0.9500
C11—C121.543 (5)C5A—H5A0.9500
C12—C131.537 (5)C6A—H6A0.9500
O12A—As1A—C1A110.46 (12)N9—C8—H8110.00
O13A—As1A—C1A101.45 (14)C7—C8—H8110.00
O12A—As1A—O13A111.55 (13)C13—C8—H8110.00
O11A—As1A—C1A112.41 (13)C12—C11—H111108.00
O11A—As1A—O12A111.48 (11)C10—C11—H111108.00
O11A—As1A—O13A109.09 (12)C10—C11—H112108.00
C2—O2—C25117.1 (3)H111—C11—H112107.00
C3—O3—C26116.2 (3)C12—C11—H112108.00
C12—O24—C23114.5 (3)O24—C12—H12109.00
As1A—O13A—H13A114 (3)C13—C12—H12109.00
H11W—O1W—H12W102 (3)C11—C12—H12109.00
H21W—O2W—H22W108 (5)C8—C13—H13107.00
H31W—O3W—H32W100 (4)C12—C13—H13107.00
C8—N9—C10120.1 (3)C14—C13—H13106.00
C5—N9—C10125.0 (3)C15—C14—H14109.00
C5—N9—C8109.1 (2)C21—C14—H14109.00
C16—N19—C18107.3 (2)C13—C14—H14109.00
C16—N19—C20112.9 (3)H151—C15—H152109.00
C18—N19—C20112.3 (3)C16—C15—H151110.00
H41W—O4W—H42W104 (4)C16—C15—H152110.00
C20—N19—H19106 (2)C14—C15—H151110.00
C18—N19—H19108 (3)C14—C15—H152110.00
C16—N19—H19110 (3)N19—C16—H16108.00
H41A—N4A—H42A130 (4)C15—C16—H16108.00
C4A—N4A—H42A106 (3)C7—C16—H16109.00
C4A—N4A—H41A119 (3)C7—C17—H171111.00
C2—C1—C6119.1 (3)C7—C17—H172111.00
O2—C2—C1124.6 (3)C18—C17—H171111.00
O2—C2—C3115.5 (3)C18—C17—H172111.00
C1—C2—C3120.0 (3)H171—C17—H172109.00
O3—C3—C2115.5 (3)H181—C18—H182109.00
O3—C3—C4123.3 (3)C17—C18—H182111.00
C2—C3—C4121.2 (3)N19—C18—H182111.00
C3—C4—C5117.7 (3)C17—C18—H181111.00
C4—C5—C6122.1 (3)N19—C18—H181111.00
N9—C5—C4127.7 (3)C21—C20—H201110.00
N9—C5—C6110.1 (3)N19—C20—H202110.00
C5—C6—C7110.5 (3)H201—C20—H202108.00
C1—C6—C7129.4 (3)N19—C20—H201110.00
C1—C6—C5119.9 (3)C21—C20—H202110.00
C6—C7—C8102.5 (3)C23—C22—H22118.00
C16—C7—C17102.0 (3)C21—C22—H22118.00
C6—C7—C17112.4 (3)O24—C23—H232109.00
C8—C7—C17110.8 (3)O24—C23—H231109.00
C6—C7—C16115.4 (3)H231—C23—H232108.00
C8—C7—C16114.1 (3)C22—C23—H232109.00
C7—C8—C13116.6 (3)C22—C23—H231109.00
N9—C8—C7104.5 (3)H251—C25—H253109.00
N9—C8—C13106.0 (2)H252—C25—H253110.00
O25—C10—C11120.7 (3)H251—C25—H252109.00
O25—C10—N9122.5 (3)O2—C25—H253109.00
N9—C10—C11116.8 (3)O2—C25—H251110.00
C10—C11—C12118.1 (3)O2—C25—H252109.00
O24—C12—C11105.3 (3)O3—C26—H261110.00
O24—C12—C13114.4 (3)H261—C26—H262109.00
C11—C12—C13109.9 (3)H261—C26—H263109.00
C8—C13—C12106.8 (3)H262—C26—H263109.00
C8—C13—C14112.0 (3)O3—C26—H262110.00
C12—C13—C14117.8 (3)O3—C26—H263109.00
C13—C14—C15106.0 (3)As1A—C1A—C2A119.6 (3)
C15—C14—C21109.8 (3)C2A—C1A—C6A119.0 (3)
C13—C14—C21114.4 (3)As1A—C1A—C6A121.4 (3)
C14—C15—C16108.1 (3)C1A—C2A—C3A119.8 (4)
C7—C16—C15115.7 (3)C2A—C3A—C4A121.7 (4)
N19—C16—C7105.0 (3)N4A—C4A—C5A120.9 (4)
N19—C16—C15110.5 (3)N4A—C4A—C3A121.2 (4)
C7—C17—C18103.1 (3)C3A—C4A—C5A117.9 (4)
N19—C18—C17105.1 (3)C4A—C5A—C6A121.1 (4)
N19—C20—C21109.7 (2)C1A—C6A—C5A120.5 (4)
C14—C21—C20114.6 (3)C1A—C2A—H2A120.00
C14—C21—C22123.4 (3)C3A—C2A—H2A120.00
C20—C21—C22122.0 (3)C2A—C3A—H3A119.00
C21—C22—C23123.3 (3)C4A—C3A—H3A119.00
O24—C23—C22111.9 (3)C6A—C5A—H5A119.00
C6—C1—H1120.00C4A—C5A—H5A119.00
C2—C1—H1120.00C1A—C6A—H6A120.00
C5—C4—H4121.00C5A—C6A—H6A120.00
C3—C4—H4121.00
O11A—As1A—C1A—C2A51.9 (3)C17—C7—C8—C13140.8 (3)
O11A—As1A—C1A—C6A130.0 (2)C6—C7—C16—N19153.5 (3)
O12A—As1A—C1A—C2A73.4 (3)C8—C7—C16—N1988.2 (3)
O12A—As1A—C1A—C6A104.8 (3)C8—C7—C16—C1533.9 (4)
O13A—As1A—C1A—C2A168.3 (3)C17—C7—C16—N1931.3 (3)
O13A—As1A—C1A—C6A13.6 (3)C17—C7—C16—C15153.4 (3)
C25—O2—C2—C11.0 (5)C6—C7—C17—C18166.0 (3)
C25—O2—C2—C3178.9 (3)C8—C7—C17—C1880.1 (3)
C26—O3—C3—C2178.7 (3)C6—C7—C16—C1584.4 (4)
C26—O3—C3—C41.1 (4)C6—C7—C8—N917.5 (3)
C23—O24—C12—C1369.2 (4)C6—C7—C8—C1399.1 (3)
C12—O24—C23—C2287.0 (4)C16—C7—C8—N9142.9 (3)
C23—O24—C12—C11170.0 (3)C16—C7—C8—C1326.3 (4)
C8—N9—C5—C63.2 (4)C17—C7—C8—N9102.6 (3)
C8—N9—C5—C4174.7 (3)C16—C7—C17—C1841.8 (3)
C5—N9—C10—O2524.5 (5)N9—C8—C13—C1271.7 (3)
C10—N9—C5—C422.1 (6)N9—C8—C13—C14158.0 (3)
C10—N9—C5—C6155.9 (3)C7—C8—C13—C1442.2 (4)
C5—N9—C8—C713.4 (3)C7—C8—C13—C12172.5 (3)
C5—N9—C8—C13110.4 (3)O25—C10—C11—C12150.9 (4)
C10—N9—C8—C7167.6 (3)N9—C10—C11—C1229.9 (5)
C10—N9—C8—C1343.9 (4)C10—C11—C12—C130.2 (4)
C8—N9—C10—O25174.4 (3)C10—C11—C12—O24123.5 (3)
C8—N9—C10—C116.3 (5)C11—C12—C13—C849.1 (3)
C5—N9—C10—C11156.3 (3)O24—C12—C13—C869.1 (3)
C20—N19—C16—C1510.7 (4)O24—C12—C13—C1457.9 (4)
C16—N19—C18—C1716.7 (3)C11—C12—C13—C14176.1 (3)
C18—N19—C16—C79.6 (3)C12—C13—C14—C15172.5 (3)
C18—N19—C16—C15134.9 (3)C8—C13—C14—C1563.1 (3)
C20—N19—C16—C7114.7 (3)C8—C13—C14—C2158.1 (4)
C18—N19—C20—C2174.2 (3)C12—C13—C14—C2166.4 (4)
C20—N19—C18—C17141.3 (3)C15—C14—C21—C22176.6 (3)
C16—N19—C20—C2147.3 (4)C21—C14—C15—C1654.5 (3)
C2—C1—C6—C7174.0 (3)C13—C14—C15—C1669.6 (3)
C6—C1—C2—O2177.6 (3)C15—C14—C21—C204.2 (4)
C6—C1—C2—C32.3 (5)C13—C14—C21—C20123.2 (3)
C2—C1—C6—C50.4 (5)C13—C14—C21—C2257.6 (5)
C1—C2—C3—C43.1 (5)C14—C15—C16—N1962.7 (3)
O2—C2—C3—O33.0 (4)C14—C15—C16—C756.4 (4)
O2—C2—C3—C4176.9 (3)C7—C17—C18—N1936.4 (3)
C1—C2—C3—O3177.1 (3)N19—C20—C21—C1456.0 (4)
O3—C3—C4—C5179.2 (3)N19—C20—C21—C22124.8 (4)
C2—C3—C4—C51.0 (5)C20—C21—C22—C23177.7 (3)
C3—C4—C5—N9176.0 (3)C14—C21—C22—C233.2 (5)
C3—C4—C5—C61.8 (5)C21—C22—C23—O2462.7 (5)
N9—C5—C6—C79.0 (4)As1A—C1A—C2A—C3A179.7 (3)
N9—C5—C6—C1175.6 (3)C6A—C1A—C2A—C3A1.6 (5)
C4—C5—C6—C12.5 (6)As1A—C1A—C6A—C5A179.2 (3)
C4—C5—C6—C7172.9 (3)C2A—C1A—C6A—C5A2.7 (5)
C5—C6—C7—C16141.2 (3)C1A—C2A—C3A—C4A0.4 (5)
C1—C6—C7—C8168.6 (4)C2A—C3A—C4A—N4A179.6 (4)
C1—C6—C7—C1644.0 (5)C2A—C3A—C4A—C5A1.2 (5)
C1—C6—C7—C1772.5 (5)N4A—C4A—C5A—C6A178.5 (4)
C5—C6—C7—C816.6 (4)C3A—C4A—C5A—C6A0.1 (5)
C5—C6—C7—C17102.4 (4)C4A—C5A—C6A—C1A1.8 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N19—H19···O12A0.91 (4)1.72 (4)2.610 (3)168 (4)
N4A—H41A···O4Wi0.89 (3)2.46 (4)3.291 (5)155 (4)
N4A—H42A···O3W0.90 (3)2.25 (3)3.137 (6)169 (4)
O13A—H13A···O11Aii0.90 (4)1.67 (4)2.546 (3)165 (4)
O1W—H11W···O250.90 (4)1.95 (4)2.843 (4)175 (3)
O1W—H12W···O2Wiii0.90 (3)1.87 (4)2.760 (5)168 (4)
O2W—H21W···O12A0.90 (3)2.11 (3)2.945 (4)153 (4)
O2W—H22W···O11Aiv0.89 (3)2.07 (4)2.915 (4)158 (5)
O3W—H31W···O25v0.91 (4)2.06 (4)2.922 (4)159 (3)
O3W—H32W···O4Wvi0.91 (3)1.91 (3)2.791 (4)164 (3)
O4W—H41W···O1Wvii0.90 (4)1.88 (4)2.770 (5)172 (5)
O4W—H42W···O12A0.89 (4)1.91 (4)2.802 (4)174 (5)
C4—H4···O250.952.372.900 (4)115
C6A—H6A···O13A0.952.553.011 (4)110
C8—H8···O241.002.603.009 (4)104
C14—H14···O3viii1.002.523.363 (4)142
C15—H151···O11Aii0.992.603.561 (4)165
C18—H182···O2W0.992.583.422 (5)143
C20—H201···O11Aii0.992.413.388 (4)170
C20—H202···O13Aiv0.992.433.229 (4)137
Symmetry codes: (i) x1/2, y+3/2, z+1; (ii) x+1/2, y+1/2, z+1; (iii) x, y1/2, z+1/2; (iv) x1/2, y+1/2, z+1; (v) x+1/2, y+1, z+1/2; (vi) x+1/2, y+3/2, z+1; (vii) x+1, y+1/2, z+1/2; (viii) x+1, y1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N19—H19···O12A0.91 (4)1.72 (4)2.610 (3)168 (4)
N4A—H41A···O4Wi0.89 (3)2.46 (4)3.291 (5)155 (4)
N4A—H42A···O3W0.90 (3)2.25 (3)3.137 (6)169 (4)
O13A—H13A···O11Aii0.90 (4)1.67 (4)2.546 (3)165 (4)
O1W—H11W···O250.90 (4)1.95 (4)2.843 (4)175 (3)
O1W—H12W···O2Wiii0.90 (3)1.87 (4)2.760 (5)168 (4)
O2W—H21W···O12A0.90 (3)2.11 (3)2.945 (4)153 (4)
O2W—H22W···O11Aiv0.89 (3)2.07 (4)2.915 (4)158 (5)
O3W—H31W···O25v0.91 (4)2.06 (4)2.922 (4)159 (3)
O3W—H32W···O4Wvi0.91 (3)1.91 (3)2.791 (4)164 (3)
O4W—H41W···O1Wvii0.90 (4)1.88 (4)2.770 (5)172 (5)
O4W—H42W···O12A0.89 (4)1.91 (4)2.802 (4)174 (5)
C14—H14···O3viii1.002.523.363 (4)142
C15—H151···O11Aii0.992.603.561 (4)165
C18—H182···O2W0.992.583.422 (5)143
C20—H201···O11Aii0.992.413.388 (4)170
C20—H202···O13Aiv0.992.433.229 (4)137
Symmetry codes: (i) x1/2, y+3/2, z+1; (ii) x+1/2, y+1/2, z+1; (iii) x, y1/2, z+1/2; (iv) x1/2, y+1/2, z+1; (v) x+1/2, y+1, z+1/2; (vi) x+1/2, y+3/2, z+1; (vii) x+1, y+1/2, z+1/2; (viii) x+1, y1/2, z+1/2.

Experimental details

Crystal data
Chemical formula(C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O
Mr683.58
Crystal system, space groupOrthorhombic, P212121
Temperature (K)200
a, b, c (Å)7.6553 (3), 12.3238 (5), 31.960 (2)
V3)3015.2 (3)
Z4
Radiation typeMo Kα
µ (mm1)1.19
Crystal size (mm)0.36 × 0.34 × 0.10
Data collection
DiffractometerOxford Diffraction Gemini-S CCD-detector
diffractometer
Absorption correctionMulti-scan
(CrysAlis PRO; Rigaku OD, 2015)
Tmin, Tmax0.811, 0.980
No. of measured, independent and
observed [I > 2σ(I)] reflections
11983, 6980, 5901
Rint0.032
(sin θ/λ)max1)0.693
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.048, 0.096, 1.05
No. of reflections6980
No. of parameters433
No. of restraints14
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.55, 0.46
Absolute structureFlack (1983), 3672 Friedel pairs
Absolute structure parameter0.005 (9)

Computer programs: CrysAlis PRO (Rigaku OD, 2015), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012), PLATON (Spek, 2009).

 

Acknowledgements

The authors acknowledge support from the Science and Engineering Faculty, Queensland University of Technology.

References

First citationAltomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343–350.  CrossRef Web of Science IUCr Journals Google Scholar
First citationBiałońska, A. & Ciunik, Z. (2004). Acta Cryst. C60, o853–o855.  CrossRef IUCr Journals Google Scholar
First citationBiałońska, A. & Ciunik, Z. (2005). Acta Cryst. E61, o4222–o4224.  CrossRef IUCr Journals Google Scholar
First citationBiałońska, A. & Ciunik, Z. (2006a). Acta Cryst. C62, o450–o453.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationBiałońska, A. & Ciunik, Z. (2006b). Acta Cryst. E62, o5817–o5819.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationBiałońska, A. & Ciunik, Z. (2007). Acta Cryst. C63, o120–o122.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationBiałońska, A., Ciunik, Z., Popek, T. & Lis, T. (2005). Acta Cryst. C61, o88–o91.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationBosch, F. & Rosich, L. (2008). Pharmacology, 82, 171–179.  Web of Science CrossRef PubMed CAS Google Scholar
First citationDijksma, F. J. J., Gould, R. O., Parsons, S., Taylor, J. & Walkinshaw, M. D. (1998). Chem. Commun. pp. 745–746.  Web of Science CSD CrossRef Google Scholar
First citationDijksma, F. J. J., Gould, R. O., Parsons, S. & Walkinshaw, M. D. (1998). Acta Cryst. C54, 1948–1951.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationEhrlich, P. & Bertheim, A. (1907). Berichte, pp. 3292–3297.  Google Scholar
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationGlover, S. S. B., Gould, R. O. & Walkinshaw, M. D. (1985). Acta Cryst. C41, 990–994.  CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationGould, R. O., Kelly, R. & Walkinshaw, M. D. (1985). J. Chem. Soc. Perkin Trans. 2, pp. 847–852.  CSD CrossRef Web of Science Google Scholar
First citationGould, R. O. & Walkinshaw, M. D. (1984). J. Am. Chem. Soc. 106, 7840–7842.  CSD CrossRef CAS Web of Science Google Scholar
First citationGroom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179.  CSD CrossRef IUCr Journals Google Scholar
First citationKrishnan, P., Gayathri, K., Sivakumar, N., Chakkaravarthi, G. & Anbalagan, G. (2013). Acta Cryst. E69, o659.  CrossRef IUCr Journals Google Scholar
First citationKrishnan, P., Gayathri, K., Sivakumar, N., Gunasekaran, B. & Anbalagan, G. (2013). Acta Cryst. E69, o870.  CrossRef IUCr Journals Google Scholar
First citationLatham, K., Downs, J. E., Rix, C. J. & White, J. M. (2011). J. Mol. Struct. 987, 74–85.  Web of Science CSD CrossRef CAS Google Scholar
First citationO'Neil, M. J. (2001). Editor. The Merck Index, 13th ed., p. 243. Whitehouse Station, NJ: Merck and Co., Inc.  Google Scholar
First citationOshikawa, T., Pochamroen, S., Takai, N., Ida, N., Takemoto, T. & Yamashita, M. (2002). Heterocycl. Commun. 8, 271–274.  CrossRef CAS Google Scholar
First citationPeerdeman, A. F. (1956). Acta Cryst. 9, 824.  CrossRef IUCr Journals Web of Science Google Scholar
First citationRigaku OD (2015). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, England.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSmith, G. & Wermuth, U. D. (2010). Acta Cryst. E66, o1893–o1894.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationSmith, G. & Wermuth, U. D. (2011). Acta Cryst. C67, o334–o336.  CrossRef IUCr Journals Google Scholar
First citationSmith, G. & Wermuth, U. D. (2014). Acta Cryst. C70, 738–741.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSmith, G., Wermuth, U. D., Healy, P. C. & White, J. M. (2006a). Acta Cryst. C62, o203–o207.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationSmith, G., Wermuth, U. D., Healy, P. C. & White, J. M. (2006b). Aust. J. Chem. 59, 321–328.  Google Scholar
First citationSmith, G., Wermuth, U. D., Healy, P. C., Young, D. J. & White, J. M. (2005). Acta Cryst. E61, o2646–o2648.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationSmith, G., Wermuth, U. D. & White, J. M. (2005). Acta Cryst. C61, o621–o624.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationSmith, G., Wermuth, U. D. & White, J. M. (2006). Acta Cryst. C62, o353–o357.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationSmith, G., Wermuth, U. D. & White, J. M. (2007). Acta Cryst. C63, o489–o492.  CrossRef IUCr Journals Google Scholar
First citationSmith, G., Wermuth, U. D. & Williams, M. L. (2012). J. Chem. Crystallogr. 42, 555–559.  CrossRef CAS Google Scholar
First citationSmith, G., Wermuth, U. D. & Young, D. J. (2010). J. Chem. Crystallogr. 40, 520–525.  CrossRef CAS Google Scholar
First citationSmith, G., Wermuth, U. D., Young, D. J. & Healy, P. C. (2005). Acta Cryst. E61, o2008–o2011.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSmith, G., Wermuth, U. D., Young, D. J. & White, J. M. (2006). Acta Cryst. E62, o1553–o1555.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSteverding, D. (2010). Parasites Vectors, 3, 15.  Web of Science CrossRef PubMed Google Scholar
First citationThomas, H. W. (1905). Proc. Roy. Soc. B: Biol. Sci. 76, 589–591.  Google Scholar
First citationWilen, S. H. (1972). Tables of Resolving Agents and Optical Resolutions, edited by E. N. Eliel, pp. 68–71. London: University of Notre Dame.  Google Scholar

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Volume 72| Part 5| May 2016| Pages 751-755
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