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

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ISSN: 2056-9890

Crystal structure of a new monoclinic polymorph of 2,4-di­hy­droxy­benzaldehyde 4-methyl­thio­semi­carbazone

aBangladesh Petroleum Exploration and Production Co. Ltd (BAPEX), 4 Karwan Bazar, BAPEX Bhabon, Dhaka 1215, Bangladesh, bDepartment of Chemistry, College of Science, University of Basrah, Basra 61004, Iraq, and cDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
*Correspondence e-mail: salambpx@yahoo.com, edward.tiekink@gmail.com

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 1 December 2014; accepted 1 December 2014; online 1 January 2015)

The title compound, C9H11N3O2S, is a second monoclinic (P21/c) polymorph of the previously reported Cc form [Tan et al. (2008b[Tan, K. W., Ng, C. H., Maah, M. J. & Ng, S. W. (2008b). Acta Cryst. E64, o2224.]). Acta Cryst. E64, o2224]. The mol­ecule is non-planar, with the dihedral angle between the N3CS residue (r.m.s. deviation = 0.0816 Å) and the benzene ring being 21.36 (4)°. The conformation about the C=N bond [1.292 (2) Å] is E, the two N-bound H atoms are anti, and the inner hy­droxy O-bound and outer amide N-bound H atoms form intra­molecular hydrogen bonds to the imine N atom. Crucially, the H atom of the outer hy­droxy group is approximately syn to the H atom of the benzene C atom connecting the two C atoms bearing the hy­droxy substituents. This arrangement enables the formation of supra­molecular tubes aligned along [010] and sustained by N—H⋯O, O—H⋯S and N—H⋯S hydrogen bonds; the tubes pack with no specific inter­actions between them. While the mol­ecular structure in the Cc form is comparable, the H atom of the outer hy­droxy group is approximately anti, rather than syn. This different orientation leads to the formation a three-dimensional architecture based on N—H⋯O and O—H⋯S hydrogen bonds.

1. Chemical context

In a review of the biological applications of metal complexes of thio­semicarbazone derivatives, Dilworth & Hueting (2012[Dilworth, J. R. & Hueting, R. (2012). Inorg. Chim. Acta, 389, 3-15.]) highlighted the various biological roles exhibited by this class of compound. Thus, these may have therapeutic potential, for example being cytotoxic and capable of inhibiting both ribonuclease reductase and topoisomerase II. Metal complexes of thio­semicarbazones can also function as diagnostic agents in imaging/diagnostic applications. In the context of this bio­logical relevance, the specific title compound of the present report has been coordinated as an N,O,S-tridentate dianion to zinc(II) and the resultant complex explored for activity against prostate cancer (Tan et al., 2012[Tan, K. W., Seng, H. L., Lim, F. S., Cheah, S.-C., Ng, C. H., Koo, K. S., Mustafa, M. R., Ng, S. W. & Maah, M. J. (2012). Polyhedron, 38, 275-284.]).

[Scheme 1]

The crystal structure of the title mol­ecule has been reported previously as a Cc polymorph (Tan et al., 2008b[Tan, K. W., Ng, C. H., Maah, M. J. & Ng, S. W. (2008b). Acta Cryst. E64, o2224.]). Following on from previous structural work on related compounds (Affan et al., 2013[Affan, M. A., Jessop, P. G., Salam, M. A., Halim, S. N. B. A. & Tiekink, E. R. T. (2013). Acta Cryst. E69, o1273.]), the title compound was prepared and routine screening of the crystals indicated that this crystallizes as a second monoclinic (P21/c) polymorph. The crystal and mol­ecular structure of the second form of the title compound is reported herein and compared with the original Cc polymorph.

2. Structural commentary

The mol­ecular structure found in the new monoclinic (P21/c) polymorph is shown in Fig. 1[link]. The mol­ecule is non-planar with a twist about the C1—N2 bond being evident as seen in (i) the N3—N2—C1—S1 torsion angle of 164.83 (11)° and (ii) the dihedral angle between the N3CS residue (r.m.s. deviation = 0.0816 Å) and benzene ring of 21.36 (4)°. The conformation about the C3=N3 bond [1.292 (2) Å] is E, the two N-bound H atoms are anti, and within the mol­ecule, both the O1- and N1-bound H atoms form intra­molecular hydrogen bonds to the imine-N3 atom, Table 1[link]. The O2—H2o H atom is approximately syn to the C6—H6 H atom.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1o⋯N3 0.83 (2) 1.97 (2) 2.6992 (17) 147 (2)
N1—H1n⋯N3 0.815 (19) 2.35 (2) 2.7080 (19) 107.1 (16)
O2—H2o⋯S1i 0.90 (2) 2.37 (2) 3.1918 (12) 152 (2)
N1—H1n⋯S1ii 0.815 (19) 2.763 (18) 3.3883 (13) 134.9 (17)
N2—H2n⋯O1iii 0.90 (2) 2.08 (2) 2.9527 (17) 162 (2)
Symmetry codes: (i) -x+1, -y+1, -z+2; (ii) x, y-1, z; (iii) x, y+1, z.
[Figure 1]
Figure 1
The mol­ecular structure of the title compound in the P21/c polymorph, showing the atom labelling and displacement ellipsoids at the 70% probability level.

To a first approximation, the mol­ecular structure found in the Cc polymorph (Tan et al., 2008b[Tan, K. W., Ng, C. H., Maah, M. J. & Ng, S. W. (2008b). Acta Cryst. E64, o2224.]), reported to be isolated also from an ethanol solution, is similar, but two significant differences are noted. These are highlighted in the overlay diagram shown in Fig. 2[link]. With the N3—N2—C1—S1 torsion angle being −172.5 (2)°, the twist about the C1—N2 bond deviates by about 8°, toward planarity, from that in the P21/c form. However, the dihedral angle between the N3CS residue and benzene ring of 23.1 (9)° is a little wider in the Cc form as the terminal methyl group is slightly twisted out of the CN3S plane: the C2—N1—C1—S1 torsion angle is −3.1 (5)° cf. to 1.2 (2)° in the P21/c form. The major and most significant difference arises in the relative orientation of the outer hy­droxy group where the H2o atom is anti to the C6—H6 H atom cf. approximately syn in the P21/c form. This has a major consequence upon the crystal packing in the two forms as discussed in §3.

[Figure 2]
Figure 2
Overlay diagram of the mol­ecules in the P21/n polymorph (red image) and in the Cc form (blue). The mol­ecules have been overlapped so the benzene rings are coincident.

The calculated density for the P21/c form is 1.496 g cm−3 and the packing efficiency (KPI), calculated by PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]), is 73.1%. These values are lower than the comparable values in the Cc form, i.e. 1.521 g cm−3 and 74.4%, respectively, suggesting that the Cc form is the more stable.

3. Supra­molecular features

In the crystal packing of the P21/c polymorph, conventional hydrogen bonding inter­actions lead to the formation of a supra­molecular tube, Fig. 3[link] and Table 1[link]. Here, the inner N2—H2n atom forms a hydrogen bond to a translationally related inner O1 atom, and the bifurcated S1 atom accepts hydrogen bonds from the outer, centrosymmetically related, O2—H2o and a translationally related, outer N1—H1n atom. The tubes are aligned along the b axis and pack with no specific inter­molecular inter­actions between them, Fig. 4[link]. A distinctive crystal packing pattern is noted in the Cc polymorph (Tan et al., 2008b[Tan, K. W., Ng, C. H., Maah, M. J. & Ng, S. W. (2008b). Acta Cryst. E64, o2224.]). Here, the inner N2—H2n atom forms a hydrogen bond to a glide-related inner O1 atom, leading to a supra­molecular layer that stacks along the a axis. The S1 atoms project to one side of the layer and the outer O2—H2o atoms, with the anti disposition (see above), lie to the other. These form hydrogen bonds so that a three-dimensional architecture ensues, Fig. 5[link]. In this scenario, the outer N1—H1n atom only participates in an intra­molecular hydrogen bond to the N3 atom, as does in the inner O1—H1o atom.

[Figure 3]
Figure 3
Supra­molecular tube along the b axis in the structure of the P21/c polymorph sustained by N—H⋯O, O—H⋯S and N—H⋯S hydrogen bonds, shown as blue, orange and brown dashed lines, respectively (see Table 1[link] for details).
[Figure 4]
Figure 4
View in projection down the b axis of the unit-cell contents of the P21/c polymorph, highlighting the packing of the supra­molecular tubes.
[Figure 5]
Figure 5
View in projection down the b axis of the unit-cell contents of the Cc polymorph, highlighting the the stacking of the layers along the a axis, sustained by N—H⋯O hydrogen bonds (blue dashed lines), and their connection by O—H⋯S hydrogen bonds (orange dashed lines).

4. Database survey

Given the inter­est in semi­thio­carbazones owing to their biological potential, it is not surprising that a search of Version 5.35 (plus May updates) of the Cambridge Crystallographic Database (Groom & Allen, 2014[Groom, C. R. & Allen, F. H. (2014). Angew. Chem. Int. Ed. 53, 662-671.]) revealed almost 100 hits for the CC(H)=NN(H)C(=S)N(H)C fragment. The only restriction in the search was that the heaviest atom be S. In the absence of this restriction there were nearly 400 hits. Of the smaller set of structures, there was only one pair of polymorphs, namely two triclinic (P[\overline{1}]) forms for salicyl­aldehyde 4-phenyl­thio­semicarbazone, one with Z′ = 3 (Seena et al., 2008[Seena, E. B., Prathapachandra Kurup, M. R. & Suresh, E. (2008). J. Chem. Crystallogr. 38, 93-96.]) and the other with Z′ = 2 (Rubčić et al., 2008[Rubčić, M., Đilović, I., Cindrić, M. & Matković-Čalogović, D. (2008). Acta Cryst. C64, o570-o573.]). The most closely related structure in the literature is the N-Et derivative, reported twice (Tan et al., 2008a[Tan, K. W., Ng, C. H., Maah, M. J. & Ng, S. W. (2008a). Acta Cryst. E64, o2123.]; Hussein et al., 2014[Hussein, M. A., Guan, T. S., Haque, R. A., Ahamed, M. B. K. & Majid, A. M. S. A. (2014). J. Coord. Chem. 67, 714-727.]). This structure exhibits the same mol­ecular attributes as described above for the N-Me polymorphs, i.e. conformation, relative disposition of key atoms and intra­molecular hydrogen bonding.

5. Synthesis and crystallization

A solution of 2,4-di­hydroxy­benzaldehyde (0.65 g, 4.75 mmol) in ethanol (20 ml) was added to a solution of 4-methyl-3-thio­semicarbazide (0.5 g, 4.75 mmol) in ethanol (20 ml). The resulting brown solution was refluxed with stirring for 2 h, and then filtered, washed with ethanol and dried in vacuo over silica gel. The filtrate was left to stand at room temperature for two days after which colourless block-like crystals were obtained (yield 0.79 g, 74%). M.p: 471–473 K. FT–IR (KBr, cm−1) νmax: 3377 (s, OH), 3190 (s, NH), 1615 (m, C=N), 1558 (s, C—O), 1012 (m, N—N), 1360, 845 (w, C=S). Analysis calculated for C9H11N3O2S: C, 47.94; H, 4.88; N, 18.64%. Found: C, 48.0; H, 4.68; N, 18.52%.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. Carbon-bound H-atoms were placed in calculated positions (C—H = 0.95–0.98 Å) and included in the refinement in the riding-model approximation, with Uiso(H) =1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. The O- and N-bound H-atoms were located in a difference Fourier map and freely refined.

Table 2
Experimental details

Crystal data
Chemical formula C9H11N3O2S
Mr 225.27
Crystal system, space group Monoclinic, P21/c
Temperature (K) 100
a, b, c (Å) 7.3058 (2), 6.0582 (1), 22.6041 (6)
β (°) 91.100 (2)
V3) 1000.27 (4)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.31
Crystal size (mm) 0.48 × 0.19 × 0.14
 
Data collection
Diffractometer Bruker APEXII CCD
Absorption correction Multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.])
Tmin, Tmax 0.866, 0.957
No. of measured, independent and observed [I > 2σ(I)] reflections 9696, 2302, 1950
Rint 0.027
(sin θ/λ)max−1) 0.650
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.086, 1.06
No. of reflections 2302
No. of parameters 153
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.30, −0.31
Computer programs: APEX2 and SAINT (Bruker, 2009[Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXS2014 and SHELXL2014 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), QMol (Gans & Shalloway, 2001[Gans, J. & Shalloway, D. (2001). J. Mol. Graph. Model. 19, 557-559.]), DIAMOND (Brandenburg, 2006[Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.]), PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.] and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS2014 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012), QMol (Gans & Shalloway, 2001) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2008), PLATON (Spek, 2009 and publCIF (Westrip, 2010).

2,4-Dihydroxybenzaldehyde 4-methylthiosemicarbazone top
Crystal data top
C9H11N3O2SF(000) = 472
Mr = 225.27Dx = 1.496 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 7.3058 (2) ÅCell parameters from 3917 reflections
b = 6.0582 (1) Åθ = 3.3–29.8°
c = 22.6041 (6) ŵ = 0.31 mm1
β = 91.100 (2)°T = 100 K
V = 1000.27 (4) Å3Block, colourless
Z = 40.48 × 0.19 × 0.14 mm
Data collection top
Bruker APEXII CCD
diffractometer
2302 independent reflections
Radiation source: sealed tube1950 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.027
φ and ω scansθmax = 27.5°, θmin = 1.8°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 99
Tmin = 0.866, Tmax = 0.957k = 77
9696 measured reflectionsl = 2924
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.035H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.086 w = 1/[σ2(Fo2) + (0.0336P)2 + 0.7405P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max = 0.001
2302 reflectionsΔρmax = 0.30 e Å3
153 parametersΔρmin = 0.31 e Å3
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
S10.15271 (5)1.11056 (7)1.14702 (2)0.01707 (12)
O10.33247 (16)0.2527 (2)1.00557 (5)0.0174 (3)
H1o0.301 (3)0.362 (4)1.0247 (11)0.044 (7)*
O20.45517 (16)0.0527 (2)0.80619 (5)0.0204 (3)
H2o0.541 (3)0.033 (4)0.8232 (11)0.051 (7)*
N10.15573 (18)0.6695 (2)1.14178 (6)0.0148 (3)
H1n0.153 (3)0.557 (3)1.1220 (9)0.019 (5)*
N20.15295 (18)0.8552 (2)1.05291 (6)0.0152 (3)
H2n0.183 (3)0.984 (4)1.0359 (9)0.029 (5)*
N30.19726 (17)0.6617 (2)1.02301 (6)0.0139 (3)
C10.1544 (2)0.8599 (3)1.11312 (7)0.0135 (3)
C20.1526 (2)0.6471 (3)1.20604 (7)0.0197 (4)
H2A0.26990.69681.22310.030*
H2B0.13260.49201.21640.030*
H2C0.05340.73741.22170.030*
C30.1997 (2)0.6841 (3)0.96619 (7)0.0141 (3)
H30.15920.81970.94940.017*
C40.2616 (2)0.5119 (3)0.92679 (7)0.0137 (3)
C50.3302 (2)0.3078 (3)0.94674 (7)0.0135 (3)
C60.3978 (2)0.1534 (3)0.90734 (7)0.0154 (3)
H60.44610.01730.92140.019*
C70.3941 (2)0.1999 (3)0.84699 (7)0.0157 (3)
C80.3264 (2)0.4006 (3)0.82584 (7)0.0177 (3)
H80.32390.43120.78460.021*
C90.2630 (2)0.5540 (3)0.86554 (7)0.0168 (3)
H90.21920.69200.85120.020*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0239 (2)0.0115 (2)0.0158 (2)0.00296 (15)0.00059 (15)0.00209 (15)
O10.0274 (6)0.0135 (6)0.0114 (6)0.0017 (5)0.0029 (5)0.0007 (5)
O20.0214 (6)0.0243 (7)0.0154 (6)0.0041 (5)0.0010 (5)0.0062 (5)
N10.0223 (7)0.0099 (7)0.0120 (7)0.0017 (5)0.0015 (5)0.0019 (6)
N20.0215 (7)0.0103 (7)0.0137 (7)0.0012 (5)0.0019 (5)0.0007 (5)
N30.0163 (6)0.0116 (6)0.0139 (7)0.0005 (5)0.0011 (5)0.0023 (5)
C10.0119 (7)0.0145 (8)0.0141 (8)0.0005 (6)0.0004 (6)0.0009 (6)
C20.0279 (9)0.0177 (8)0.0137 (8)0.0017 (7)0.0020 (6)0.0019 (7)
C30.0144 (7)0.0125 (7)0.0153 (8)0.0008 (6)0.0001 (6)0.0006 (6)
C40.0140 (7)0.0143 (8)0.0129 (7)0.0016 (6)0.0011 (6)0.0002 (6)
C50.0145 (7)0.0150 (8)0.0110 (7)0.0036 (6)0.0004 (5)0.0005 (6)
C60.0150 (7)0.0136 (8)0.0177 (8)0.0006 (6)0.0018 (6)0.0009 (6)
C70.0139 (7)0.0180 (8)0.0152 (8)0.0016 (6)0.0025 (6)0.0043 (6)
C80.0184 (7)0.0240 (9)0.0106 (7)0.0022 (6)0.0006 (6)0.0008 (7)
C90.0163 (7)0.0187 (8)0.0153 (8)0.0008 (6)0.0005 (6)0.0027 (7)
Geometric parameters (Å, º) top
S1—C11.7011 (16)C2—H2B0.9800
O1—C51.3707 (19)C2—H2C0.9800
O1—H1o0.83 (3)C3—C41.449 (2)
O2—C71.3640 (19)C3—H30.9500
O2—H2o0.90 (3)C4—C51.405 (2)
N1—C11.323 (2)C4—C91.408 (2)
N1—C21.459 (2)C5—C61.389 (2)
N1—H1n0.81 (2)C6—C71.393 (2)
N2—C11.361 (2)C6—H60.9500
N2—N31.3945 (18)C7—C81.394 (2)
N2—H2n0.90 (2)C8—C91.378 (2)
N3—C31.292 (2)C8—H80.9500
C2—H2A0.9800C9—H90.9500
C5—O1—H1o108.3 (17)C4—C3—H3118.5
C7—O2—H2o108.9 (16)C5—C4—C9117.76 (14)
C1—N1—C2124.63 (14)C5—C4—C3123.32 (14)
C1—N1—H1n117.4 (14)C9—C4—C3118.82 (14)
C2—N1—H1n117.9 (14)O1—C5—C6117.41 (14)
C1—N2—N3120.33 (13)O1—C5—C4121.55 (14)
C1—N2—H2n114.2 (13)C6—C5—C4121.04 (14)
N3—N2—H2n117.6 (13)C5—C6—C7119.46 (15)
C3—N3—N2113.67 (13)C5—C6—H6120.3
N1—C1—N2118.11 (14)C7—C6—H6120.3
N1—C1—S1123.91 (12)O2—C7—C6122.00 (15)
N2—C1—S1117.98 (12)O2—C7—C8117.19 (14)
N1—C2—H2A109.5C6—C7—C8120.81 (14)
N1—C2—H2B109.5C9—C8—C7119.10 (15)
H2A—C2—H2B109.5C9—C8—H8120.4
N1—C2—H2C109.5C7—C8—H8120.4
H2A—C2—H2C109.5C8—C9—C4121.80 (15)
H2B—C2—H2C109.5C8—C9—H9119.1
N3—C3—C4123.08 (15)C4—C9—H9119.1
N3—C3—H3118.5
C1—N2—N3—C3176.54 (14)C3—C4—C5—C6176.13 (14)
C2—N1—C1—N2178.35 (14)O1—C5—C6—C7178.45 (13)
C2—N1—C1—S11.2 (2)C4—C5—C6—C71.3 (2)
N3—N2—C1—N115.6 (2)C5—C6—C7—O2178.64 (14)
N3—N2—C1—S1164.83 (11)C5—C6—C7—C81.1 (2)
N2—N3—C3—C4173.05 (13)O2—C7—C8—C9179.92 (14)
N3—C3—C4—C52.2 (2)C6—C7—C8—C90.2 (2)
N3—C3—C4—C9178.56 (14)C7—C8—C9—C41.3 (2)
C9—C4—C5—O1179.49 (14)C5—C4—C9—C81.0 (2)
C3—C4—C5—O14.1 (2)C3—C4—C9—C8177.60 (14)
C9—C4—C5—C60.3 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1o···N30.83 (2)1.97 (2)2.6992 (17)147 (2)
N1—H1n···N30.815 (19)2.35 (2)2.7080 (19)107.1 (16)
O2—H2o···S1i0.90 (2)2.37 (2)3.1918 (12)152 (2)
N1—H1n···S1ii0.815 (19)2.763 (18)3.3883 (13)134.9 (17)
N2—H2n···O1iii0.90 (2)2.08 (2)2.9527 (17)162 (2)
Symmetry codes: (i) x+1, y+1, z+2; (ii) x, y1, z; (iii) x, y+1, z.
 

Acknowledgements

The authors wish to thank the BAPEX, Bangladesh, for financial support.

References

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