2-(Tricyclo[3.3.1.13,7]dec-2-ylamino)ethanol hemihydrate

Boyle, G.A.; Govender, T.; Kruger, H.G.; Onajole, O.K.

doi:10.1107/S1600536808016851

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 64| Part 7| July 2008| Page o1228

doi:10.1107/S1600536808016851

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2-(Tricyclo[3.3.1.1^3,7]dec-2-ylamino)ethanol hemihydrate

Grant A. Boyle,^a Thavendran Govender,^b ^* Hendrik G. Kruger ^a and Oluseye K. Onajole ^a

^aSchool of Chemistry, University of KwaZulu-Natal, Durban, 4000, South Africa, and ^bSchool of Pharmacy and Pharmacology, University of KwaZulu-Natal, Durban, 4000, South Africa
^*Correspondence e-mail: govenderthav@ukzn.ac.za

(Received 19 May 2008; accepted 3 June 2008; online 7 June 2008)

The title adamantane derivative, C₁₂H₂₁NO·0.5H₂O, was synthesized as part of an investigation into the biological activities of cage amino–alcohol compounds as potential anti-tuberculosis agents. The structure displays intermolecular O—H⋯N, N—H⋯O, O—H⋯O hydrogen bonding and a layered packing structure with distinct hydrophilic and hydrophobic regions. The water molecule lies on a twofold rotation axis.

Related literature

For related literature, see: Bogatcheva et al. (2006 ); du Pont de Nemours and Co. (1969 ); Lee et al. (2003 ); Tripathi et al. (2006 ).

Experimental

Crystal data

C₁₂H₂₁NO·0.5H₂O
M_r = 204.31
Monoclinic, C 2/c
a = 11.6739 (3) Å
b = 6.5043 (2) Å
c = 28.6241 (7) Å
β = 99.8620 (10)°
V = 2141.33 (10) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 173 (2) K
0.56 × 0.43 × 0.18 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: none
13147 measured reflections
2584 independent reflections
2352 reflections with I > 2σ(I)
R_int = 0.058

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.112
S = 1.07
2584 reflections
141 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1C⋯N1ⁱ	0.84	1.86	2.7007 (12)	175
N1—H1B⋯O1Wⁱⁱ	0.849 (16)	2.398 (16)	3.2241 (12)	164.6 (14)
O1W—H1W⋯O1ⁱⁱⁱ	0.863 (16)	1.963 (17)	2.8147 (12)	168.7 (16)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) x, y-1, z; (iii) $[-x+2, y, -z+{\script{3\over 2}}]$ .

Data collection: APEX2 (Bruker, 2005 ); cell refinement: SAINT-Plus (Bruker, 1999 ); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: Mercury (Macrae et al., 2006 ) and ORTEP-3 (Farrugia, 1997 ); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808016851/hg2403sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808016851/hg2403Isup2.hkl

checkCIF report

Comment top

The title compound, an adamantane derivative, was synthesized as part of an ongoing study to evaluate the biological activity of such compounds as potential anti-tuberculosis agents (Bogatcheva et al. (2006), Lee et al. (2003), Tripathi et al. (2006)). Although the compound is known (du Pont de Nemours and Co.; 1969), its crystal structure has not been reported.

The compound contains a polycyclic (lipophilic) hydrocarbon region, polar amine and hydroxyl units, and crystallizes with half a water molecule in the asymmetric unit (Fig.1)- the water molecule being situated on a crystallographic 2-fold axis at (1, y, 3/4). The title molecule exhibits several C–C bond lengths in the adamantane skeleton that deviate from the expected value of 1.54 Å. This has been observed previously and is typical for these types of compounds.

The structure exhibits intermolecular hydrogen bonding between O1 and N1 of adjacent molecules as well as between O1 and O1W of the water molecule (Fig. 2). There is also a complex network of short contacts between the molecules in structure. These intermolecular interactions result in a layered structure with distinct hydrophilic and hydrophobic regions (Fig. 3). The adamantane skeleton forms the hydrophobic layer while the polar hydroxyl and amino moeties constitute the hydrophilic region.

Related literature top

For related literature, see: Bogatcheva et al. (2006); du Pont de Nemours and Co. (1969); Lee et al. (2003); Tripathi et al. (2006).

Experimental top

A mixture of 2-adamantanone (2 g, 13 mmol) and 2-aminoethanol (1 g, 16 mmol) in 20 ml of methanol was stirred under dinitrogen atmosphere at room temperature for 2 h. The mixture was cooled to zero degrees using an external ice bath after with NaBH₄ (1 g, 26 mmol) was added slowly over a 30 minutes. The mixture was stirred for overnight at room temperature after which it was concentrated in vacuo and excess NaBH₄ was quenched by adding 40 ml of 10% HCl and the product was also extracted as its HCl salt in the process. The aqueous solution was washed with 2x20ml of dichloromethane, after which the aqueous layer was basified (pH 12) with NH₄OH and the product was extracted from the mixture with dichloromethane (2x30ml), the solvent was dried over Na₂SO₄ and concentrated in vacuo. The product was recrystallized from dichloromethane, thereby affording pure 2-aminoethanol adamantane (2 g, 77% yield).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures top

	Fig. 1. The ORTEP (Farrugia, 1997) diagram of the title compound showing the displacement ellipsoids for non-hydrogen atoms at the 50% probability level.
	Fig. 2. Figure depicting the intermolecular hydrogen bonding.
	Fig. 3. Packing diagram depicting layered structure as seen down the b-axis.

2-(Tricyclo[3.3.1.1^3,7]dec-2-ylamino)ethanol hemihydrate top

Crystal data top

C₁₂H₂₁NO·0.5H₂O	F(000) = 904
M_r = 204.31	D_x = 1.267 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 7587 reflections
a = 11.6739 (3) Å	θ = 2.9–28.3°
b = 6.5043 (2) Å	µ = 0.08 mm⁻¹
c = 28.6241 (7) Å	T = 173 K
β = 99.862 (1)°	Plate, colourless
V = 2141.33 (10) Å³	0.56 × 0.43 × 0.18 mm
Z = 8

Data collection top

Bruker SMART CCD area-detector diffractometer	2352 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.058
Graphite monochromator	θ_max = 28.0°, θ_min = 1.4°
phi and ω scans	h = −15→15
13147 measured reflections	k = −8→8
2584 independent reflections	l = −37→37

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.112	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ²(F_o²) + (0.0507P)² + 1.5961P] where P = (F_o² + 2F_c²)/3
2584 reflections	(Δ/σ)_max = 0.001
141 parameters	Δρ_max = 0.39 e Å⁻³
0 restraints	Δρ_min = −0.19 e Å⁻³

Crystal data top

C₁₂H₂₁NO·0.5H₂O	V = 2141.33 (10) Å³
M_r = 204.31	Z = 8
Monoclinic, C2/c	Mo Kα radiation
a = 11.6739 (3) Å	µ = 0.08 mm⁻¹
b = 6.5043 (2) Å	T = 173 K
c = 28.6241 (7) Å	0.56 × 0.43 × 0.18 mm
β = 99.862 (1)°

Data collection top

Bruker SMART CCD area-detector diffractometer	2352 reflections with I > 2σ(I)
13147 measured reflections	R_int = 0.058
2584 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	0 restraints
wR(F²) = 0.112	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	Δρ_max = 0.39 e Å⁻³
2584 reflections	Δρ_min = −0.19 e Å⁻³
141 parameters

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.

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 > σ(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

	x	y	z	U_iso*/U_eq
C1	0.76341 (9)	−0.06132 (17)	0.61221 (4)	0.0189 (2)
H1	0.6899	−0.0946	0.6241	0.023*
C2	0.81420 (9)	0.13986 (16)	0.63482 (3)	0.0156 (2)
H2	0.7582	0.2520	0.6229	0.019*
C3	0.92859 (10)	0.18681 (17)	0.61700 (4)	0.0181 (2)
H3	0.9635	0.3162	0.6321	0.022*
C4	1.01487 (10)	0.00885 (18)	0.62888 (4)	0.0205 (2)
H4A	1.0880	0.0411	0.6173	0.025*
H4B	1.0334	−0.0096	0.6637	0.025*
C5	0.96251 (10)	−0.18982 (17)	0.60569 (4)	0.0208 (2)
H5	1.0189	−0.3054	0.6137	0.025*
C6	0.93562 (11)	−0.16124 (19)	0.55178 (4)	0.0243 (3)
H6A	1.0082	−0.1301	0.5396	0.029*
H6B	0.9023	−0.2896	0.5366	0.029*
C7	0.84905 (11)	0.01531 (19)	0.53962 (4)	0.0240 (3)
H7	0.8313	0.0338	0.5044	0.029*
C8	0.73704 (10)	−0.0346 (2)	0.55821 (4)	0.0250 (3)
H8A	0.7025	−0.1627	0.5433	0.030*
H8B	0.6802	0.0781	0.5499	0.030*
C9	0.85024 (10)	−0.23740 (17)	0.62443 (4)	0.0208 (2)
H9A	0.8159	−0.3668	0.6101	0.025*
H9B	0.8677	−0.2561	0.6593	0.025*
C10	0.90159 (11)	0.21388 (18)	0.56282 (4)	0.0241 (3)
H10A	0.8462	0.3288	0.5546	0.029*
H10B	0.9739	0.2475	0.5507	0.029*
C11	0.83975 (9)	0.33596 (16)	0.70953 (4)	0.0170 (2)
H11A	0.7728	0.4258	0.6973	0.020*
H11B	0.9109	0.4007	0.7018	0.020*
C12	0.85067 (10)	0.31373 (16)	0.76292 (4)	0.0186 (2)
H12A	0.7770	0.2587	0.7706	0.022*
H12B	0.9132	0.2141	0.7745	0.022*
N1	0.82297 (8)	0.13298 (14)	0.68680 (3)	0.0156 (2)
O1	0.87618 (7)	0.50454 (12)	0.78653 (3)	0.01947 (19)
H1C	0.8167	0.5477	0.7963	0.029*
O1W	1.0000	0.82045 (19)	0.7500	0.0240 (3)
H1B	0.8774 (13)	0.053 (2)	0.6990 (5)	0.024 (4)*
H1W	1.0445 (14)	0.737 (3)	0.7380 (6)	0.037 (4)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0192 (5)	0.0197 (5)	0.0178 (5)	−0.0041 (4)	0.0030 (4)	−0.0029 (4)
C2	0.0175 (5)	0.0146 (5)	0.0146 (5)	0.0007 (4)	0.0027 (4)	0.0003 (4)
C3	0.0224 (5)	0.0155 (5)	0.0172 (5)	−0.0032 (4)	0.0059 (4)	−0.0004 (4)
C4	0.0178 (5)	0.0236 (6)	0.0200 (5)	0.0000 (4)	0.0033 (4)	−0.0024 (4)
C5	0.0247 (6)	0.0180 (5)	0.0198 (5)	0.0045 (4)	0.0038 (4)	−0.0010 (4)
C6	0.0310 (6)	0.0236 (6)	0.0193 (5)	0.0008 (5)	0.0072 (4)	−0.0046 (4)
C7	0.0313 (6)	0.0265 (6)	0.0138 (5)	0.0015 (5)	0.0030 (4)	0.0010 (4)
C8	0.0245 (6)	0.0296 (6)	0.0188 (5)	−0.0003 (5)	−0.0023 (4)	−0.0036 (4)
C9	0.0300 (6)	0.0137 (5)	0.0189 (5)	−0.0029 (4)	0.0048 (4)	−0.0006 (4)
C10	0.0339 (6)	0.0206 (6)	0.0195 (5)	0.0004 (5)	0.0092 (4)	0.0040 (4)
C11	0.0207 (5)	0.0133 (5)	0.0170 (5)	0.0003 (4)	0.0033 (4)	−0.0009 (4)
C12	0.0239 (5)	0.0151 (5)	0.0172 (5)	−0.0006 (4)	0.0049 (4)	−0.0010 (4)
N1	0.0189 (4)	0.0131 (4)	0.0149 (4)	0.0008 (3)	0.0033 (3)	−0.0003 (3)
O1	0.0195 (4)	0.0188 (4)	0.0208 (4)	−0.0012 (3)	0.0054 (3)	−0.0058 (3)
O1W	0.0293 (6)	0.0175 (6)	0.0259 (6)	0.000	0.0064 (5)	0.000

Geometric parameters (Å, º) top

C1—C9	1.5297 (16)	C7—C8	1.5287 (17)
C1—C8	1.5334 (15)	C7—C10	1.5316 (17)
C1—C2	1.5334 (14)	C7—H7	1.0000
C1—H1	1.0000	C8—H8A	0.9900
C2—N1	1.4745 (12)	C8—H8B	0.9900
C2—C3	1.5395 (15)	C9—H9A	0.9900
C2—H2	1.0000	C9—H9B	0.9900
C3—C4	1.5339 (15)	C10—H10A	0.9900
C3—C10	1.5388 (15)	C10—H10B	0.9900
C3—H3	1.0000	C11—N1	1.4700 (13)
C4—C5	1.5314 (16)	C11—C12	1.5187 (14)
C4—H4A	0.9900	C11—H11A	0.9900
C4—H4B	0.9900	C11—H11B	0.9900
C5—C9	1.5305 (16)	C12—O1	1.4200 (13)
C5—C6	1.5324 (15)	C12—H12A	0.9900
C5—H5	1.0000	C12—H12B	0.9900
C6—C7	1.5299 (17)	N1—H1B	0.849 (16)
C6—H6A	0.9900	O1—H1C	0.8400
C6—H6B	0.9900	O1W—H1W	0.863 (16)

C9—C1—C8	109.03 (9)	C6—C7—C10	109.54 (10)
C9—C1—C2	110.44 (9)	C8—C7—H7	109.5
C8—C1—C2	108.97 (9)	C6—C7—H7	109.5
C9—C1—H1	109.5	C10—C7—H7	109.5
C8—C1—H1	109.5	C7—C8—C1	109.82 (9)
C2—C1—H1	109.5	C7—C8—H8A	109.7
N1—C2—C1	110.79 (8)	C1—C8—H8A	109.7
N1—C2—C3	115.22 (8)	C7—C8—H8B	109.7
C1—C2—C3	108.91 (8)	C1—C8—H8B	109.7
N1—C2—H2	107.2	H8A—C8—H8B	108.2
C1—C2—H2	107.2	C1—C9—C5	110.01 (9)
C3—C2—H2	107.2	C1—C9—H9A	109.7
C4—C3—C10	108.86 (9)	C5—C9—H9A	109.7
C4—C3—C2	110.53 (9)	C1—C9—H9B	109.7
C10—C3—C2	108.48 (9)	C5—C9—H9B	109.7
C4—C3—H3	109.6	H9A—C9—H9B	108.2
C10—C3—H3	109.6	C7—C10—C3	109.77 (9)
C2—C3—H3	109.6	C7—C10—H10A	109.7
C5—C4—C3	110.03 (9)	C3—C10—H10A	109.7
C5—C4—H4A	109.7	C7—C10—H10B	109.7
C3—C4—H4A	109.7	C3—C10—H10B	109.7
C5—C4—H4B	109.7	H10A—C10—H10B	108.2
C3—C4—H4B	109.7	N1—C11—C12	109.98 (8)
H4A—C4—H4B	108.2	N1—C11—H11A	109.7
C9—C5—C4	108.72 (9)	C12—C11—H11A	109.7
C9—C5—C6	109.72 (9)	N1—C11—H11B	109.7
C4—C5—C6	109.38 (9)	C12—C11—H11B	109.7
C9—C5—H5	109.7	H11A—C11—H11B	108.2
C4—C5—H5	109.7	O1—C12—C11	111.73 (8)
C6—C5—H5	109.7	O1—C12—H12A	109.3
C7—C6—C5	109.49 (9)	C11—C12—H12A	109.3
C7—C6—H6A	109.8	O1—C12—H12B	109.3
C5—C6—H6A	109.8	C11—C12—H12B	109.3
C7—C6—H6B	109.8	H12A—C12—H12B	107.9
C5—C6—H6B	109.8	C11—N1—C2	113.60 (8)
H6A—C6—H6B	108.2	C11—N1—H1B	109.6 (10)
C8—C7—C6	109.42 (10)	C2—N1—H1B	110.6 (10)
C8—C7—C10	109.34 (10)	C12—O1—H1C	109.5

C9—C1—C2—N1	−69.54 (11)	C6—C7—C8—C1	60.43 (12)
C8—C1—C2—N1	170.72 (9)	C10—C7—C8—C1	−59.53 (12)
C9—C1—C2—C3	58.18 (11)	C9—C1—C8—C7	−60.00 (12)
C8—C1—C2—C3	−61.56 (11)	C2—C1—C8—C7	60.61 (12)
N1—C2—C3—C4	67.40 (11)	C8—C1—C9—C5	59.43 (11)
C1—C2—C3—C4	−57.78 (11)	C2—C1—C9—C5	−60.27 (11)
N1—C2—C3—C10	−173.32 (9)	C4—C5—C9—C1	60.16 (11)
C1—C2—C3—C10	61.50 (11)	C6—C5—C9—C1	−59.42 (11)
C10—C3—C4—C5	−59.70 (12)	C8—C7—C10—C3	59.75 (12)
C2—C3—C4—C5	59.36 (11)	C6—C7—C10—C3	−60.14 (12)
C3—C4—C5—C9	−59.71 (11)	C4—C3—C10—C7	59.61 (12)
C3—C4—C5—C6	60.09 (12)	C2—C3—C10—C7	−60.72 (12)
C9—C5—C6—C7	59.30 (12)	N1—C11—C12—O1	175.36 (9)
C4—C5—C6—C7	−59.87 (12)	C12—C11—N1—C2	−178.67 (8)
C5—C6—C7—C8	−59.80 (12)	C1—C2—N1—C11	−164.04 (9)
C5—C6—C7—C10	60.05 (12)	C3—C2—N1—C11	71.76 (11)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1C···N1ⁱ	0.84	1.86	2.7007 (12)	175
N1—H1B···O1Wⁱⁱ	0.849 (16)	2.398 (16)	3.2241 (12)	164.6 (14)
O1W—H1W···O1ⁱⁱⁱ	0.863 (16)	1.963 (17)	2.8147 (12)	168.7 (16)

Symmetry codes: (i) −x+3/2, y+1/2, −z+3/2; (ii) x, y−1, z; (iii) −x+2, y, −z+3/2.

Experimental details

Crystal data
Chemical formula	C₁₂H₂₁NO·0.5H₂O
M_r	204.31
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	173
a, b, c (Å)	11.6739 (3), 6.5043 (2), 28.6241 (7)
β (°)	99.862 (1)
V (Å³)	2141.33 (10)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.56 × 0.43 × 0.18

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	13147, 2584, 2352
R_int	0.058
(sin θ/λ)_max (Å⁻¹)	0.660

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.112, 1.07
No. of reflections	2584
No. of parameters	141
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.39, −0.19

Computer programs: APEX2 (Bruker, 2005), SAINT-Plus (Bruker, 1999), Mercury (Macrae et al., 2006) and ORTEP-3 (Farrugia, 1997), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1C···N1ⁱ	0.84	1.86	2.7007 (12)	175
N1—H1B···O1Wⁱⁱ	0.849 (16)	2.398 (16)	3.2241 (12)	164.6 (14)
O1W—H1W···O1ⁱⁱⁱ	0.863 (16)	1.963 (17)	2.8147 (12)	168.7 (16)

Symmetry codes: (i) −x+3/2, y+1/2, −z+3/2; (ii) x, y−1, z; (iii) −x+2, y, −z+3/2.

Acknowledgements

We thank Dr Manuel Fernandes of the Jan Boeyens Structural Chemistry Laboratory at the University of the Witwatersrand for his assistance in the acquisition of the crystallographic data. This work was supported by grants from the National Research Foundation (South Africa), GUN 2046819, the University of KwaZulu–Natal and Aspen Pharmacare.

References

Bogatcheva, E., Hanrahan, C., Nikonenko, B., Samala, R., Chen, P., Gearhart, J., Barbosa, F., Einck, L., Nacy, C. A. & Protopopova, M. (2006). J. Med. Chem. 49, 3045–3048. Web of Science CrossRef PubMed CAS Google Scholar
Bruker (1999). SAINT-Plus (includes XPREP and SADABS). Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2005). APEX2. Bruker AXS Inc., Madison,Wisconsin, USA. Google Scholar
du Pont de Nemours, E. I., and Co. (1969). Patent No. GB 1 157 143 19 690 702. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Lee, R. E., Protopopova, M., Crooks, E., Slayden, R. A., Terrot, M. & Barry, C. E. (2003). J. Comb. Chem. 5, 172–187. Web of Science CrossRef PubMed CAS Google Scholar
Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tripathi, R. P., Saxena, N., Tiwari, V. K., Verma, S. S., Chaturvedi, V., Manju, Y. K., Srivastva, A. K., Gaikwad, A. & Sinha, S. (2006). Bioorg. Med. Chem. 14, 8186–8196. Web of Science CrossRef PubMed CAS Google Scholar