Cyclo­hexane-1,3-diyl bis­(N-phenyl­carbamate)

Ghalib, R.M.; Sulaiman, O.; Mehdi, S.H.; Goh, J.H.; Fun, H.-K.

doi:10.1107/S1600536810033817

organic compounds

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ISSN: 2056-9890

Volume 66| Part 9| September 2010| Pages o2406-o2407

https://doi.org/10.1107/S1600536810033817

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Cyclohexane-1,3-diyl bis(N-phenylcarbamate)

Raza Murad Ghalib,^a Othman Sulaiman,^a Sayed Hasan Mehdi,^a Jia Hao Goh ^b ‡ and Hoong-Kun Fun ^b ^*§

^aSchool of Industrial Technology, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
^*Correspondence e-mail: hkfun@usm.my

(Received 18 August 2010; accepted 21 August 2010; online 28 August 2010)

The asymmetric unit of the title compound, C₂₀H₂₂N₂O₄, comprises two crystallographically independent molecules (A and B) with slightly different geometries. The dihedral angle between the two terminal phenyl rings is 61.7 (1)° in molecule A and 29.6 (1)° in B. The cyclohexane rings adopt chair conformations. In the crystal packing, intermolecular N—H⋯O hydrogen bonds interconnect adjacent molecules into a ladder-like structure along the c axis incorporating R₂²(20) ring motifs. The crystal packing is further stabilized by weak intermolecular C—H⋯π interactions.

Related literature

For general background and the synthesis of carbamates, see: Banerjee et al. (1978 ); Ghalib et al. (2010 ); Graia et al. (2009 ); Ibuka et al. (1985 ); Lapidus et al. (1987 ); Loev & Kormendy (1963 ); Niu et al. (2007 ). For ring conformation and puckering analysis, see: Cremer & Pople (1975 ). For graph-set motifs, see: Bernstein et al. (1995 ). For a related structure, see: Ghalib et al. (2010). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ).

Experimental

Crystal data

C₂₀H₂₂N₂O₄
M_r = 354.40
Monoclinic, P 2₁ /c
a = 38.356 (7) Å
b = 9.5453 (16) Å
c = 9.8472 (16) Å
β = 91.034 (3)°
V = 3604.7 (10) Å³
Z = 8
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.55 × 0.15 × 0.13 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.951, T_max = 0.988
30037 measured reflections
10472 independent reflections
6630 reflections with I > 2σ(I)
R_int = 0.057

Refinement

R[F² > 2σ(F²)] = 0.064
wR(F²) = 0.180
S = 1.08
10472 reflections
485 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 and Cg2 are the centroids of C15A–C20A and C1B–C6B phenyl rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1A—H1NA⋯O1Aⁱ	0.83 (2)	2.13 (2)	2.953 (2)	174 (2)
N2A—H2NA⋯O4Aⁱ	0.91 (3)	2.09 (3)	2.934 (2)	154 (2)
N1B—H1NB⋯O1Bⁱⁱ	0.93 (3)	2.10 (3)	2.920 (2)	147 (2)
N2B—H2NB⋯O4Bⁱⁱ	0.88 (3)	2.02 (3)	2.874 (2)	163 (3)
C13A—H13B⋯Cg1ⁱⁱⁱ	0.97	2.86	3.734 (2)	151
C13B—H13C⋯Cg2^iv	0.97	2.86	3.732 (2)	150
Symmetry codes: (i) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (iii) -x+1, -y, -z+1; (iv) -x, -y+2, -z.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536810033817/ci5161sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810033817/ci5161Isup2.hkl

checkCIF report

Comment top

Carbamates are a well-known class of organic compounds. They can be prepared by nickel-catalyzed coupling of CO₂ and amines (Niu et al., 2007), by stirring of alcohols including steroids as well as primary and secondary alcohols, polyols, phenols with sodium cyanate and trifluoroacetic acid (Loev & Kormendy, 1963), by carbonylation of aromatic nitro compounds (Lapidus et al., 1987), by the reaction of isocyanates with alcohols in presence of Lewis acid (Ibuka et al., 1985) and by the reaction of an amine and an alcohol with phosgene. Phytosterol, β-sitosterol, stigmasterol, cholesterol, cyclohexanol and α-terpineol react with phenyl isocyanate to give carbamates (Banerjee et al., 1978; Graia et al., 2009; Ghalib et al., 2010). In the present work, the title compound has been synthesized by the reaction of cyclohexane-1,3-diol with phenylisocyanate in the presence of catalytic amount of HCl in chloroform solvent.

The asymmetric unit of the title compound comprises of two crystallographically independent molecules, designated A and B (Fig. 1). The orientation of the C1–C6 phenyl ring with respect to the rest of the molecule is different in A and B, as shown in the superposition of the non-H atoms of molecules A and B (Fig. 2) using XP in SHELXTL (Sheldrick, 2008); the r.m.s. deviation is 0.474 Å.

In each molecule, the cyclohexane ring (C8-C13) adopts a chair conformation; the puckering parameters are Q = 0.566 (2) Å, θ = 176.6 (2)°, φ = 328 (4)° for molecule A and Q = 0.566 (2) Å, θ = 176.2 (2)°, φ = 283 (4)° for molecule B. The dihedral angle between the C1–C6 and C15–C20 phenyl rings is 61.7 (1)° in molecule A and 29.6 (1)° in B. The geometric parameters are consistent with a related structure (Ghalib et al., 2010).

In the crystal packing, intermolecular N1A—H1NA···O1A, N2A—H2NA···O4A, N1B—H1NB···O1B, N2B—H2NB···O4B hydrogen bonds (Table 1) link adjacent molecules into one-dimensional chains incorporating R²₂(20) ring motifs (Bernstein et al., 1995) along the c axis (Fig. 3). Further stabilization of the crystal packing is provided by weak intermolecular C13A—H13B···Cg1 and C13B—H13C···Cg2 interactions (Table 1) where Cg1 and Cg2 are the centroids of C15A-C20A and C1B-C6B phenyl rings, respectively.

Related literature top

For general background and the synthesis of carbamates, see: Banerjee et al. (1978); Ghalib et al. (2010); Graia et al. (2009); Ibuka et al. (1985); Lapidus et al. (1987); Loev & Kormendy (1963); Niu et al. (2007). For ring conformation and puckering analysis, see: Cremer & Pople (1975). For graph-set motifs, see: Bernstein et al. (1995). For a related structure, see: Ghalib et al. (2010). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

Experimental top

A mixture of cyclohexane-1,3-diol (1.005 ml) and phenyl isocyanate (2.174 ml) in a 1:2 molar ratio was stirred in chloroform for 30 minutes in the presence of catalytic amount of HCl. The reaction mixture was dried with rota vapor at low pressure and then crystallized in a 1:1 mixture of chloroform and alcohol to afford colourless needle-like single crystals (yield: 2.60 g, m.p. 489.2 K). The melting point was taken using a Thermo Fisher digital melting point apparatus of IA9000 series and is uncorrected

Structure description top

For general background and the synthesis of carbamates, see: Banerjee et al. (1978); Ghalib et al. (2010); Graia et al. (2009); Ibuka et al. (1985); Lapidus et al. (1987); Loev & Kormendy (1963); Niu et al. (2007). For ring conformation and puckering analysis, see: Cremer & Pople (1975). For graph-set motifs, see: Bernstein et al. (1995). For a related structure, see: Ghalib et al. (2010). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The asymmetric unit of the title compound, showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme.
	Fig. 2. Fit of molecule A (dashed lines) on molecule B (solid lines). H atoms have been omitted for clarity.
	Fig. 3. The crystal structure of the title compound, viewed along the b axis, showing molecular chains along the c axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.

Cyclohexane-1,3-diyl bis(N-phenylcarbamate) top

Crystal data top

C₂₀H₂₂N₂O₄	F(000) = 1504
M_r = 354.40	D_x = 1.306 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3229 reflections
a = 38.356 (7) Å	θ = 3.0–32.1°
b = 9.5453 (16) Å	µ = 0.09 mm⁻¹
c = 9.8472 (16) Å	T = 100 K
β = 91.034 (3)°	Needle, colourless
V = 3604.7 (10) Å³	0.55 × 0.15 × 0.13 mm
Z = 8

Data collection top

Bruker APEXII DUO CCD area-detector diffractometer	10472 independent reflections
Radiation source: fine-focus sealed tube	6630 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.057
φ and ω scans	θ_max = 30.0°, θ_min = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −51→53
T_min = 0.951, T_max = 0.988	k = −11→13
30037 measured reflections	l = −13→13

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)] = 0.064	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.180	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ²(F_o²) + (0.0587P)² + 2.1169P] where P = (F_o² + 2F_c²)/3
10472 reflections	(Δ/σ)_max = 0.001
485 parameters	Δρ_max = 0.33 e Å⁻³
0 restraints	Δρ_min = −0.25 e Å⁻³

Crystal data top

C₂₀H₂₂N₂O₄	V = 3604.7 (10) Å³
M_r = 354.40	Z = 8
Monoclinic, P2₁/c	Mo Kα radiation
a = 38.356 (7) Å	µ = 0.09 mm⁻¹
b = 9.5453 (16) Å	T = 100 K
c = 9.8472 (16) Å	0.55 × 0.15 × 0.13 mm
β = 91.034 (3)°

Data collection top

Bruker APEXII DUO CCD area-detector diffractometer	10472 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	6630 reflections with I > 2σ(I)
T_min = 0.951, T_max = 0.988	R_int = 0.057
30037 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.064	0 restraints
wR(F²) = 0.180	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	Δρ_max = 0.33 e Å⁻³
10472 reflections	Δρ_min = −0.25 e Å⁻³
485 parameters

Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K.

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

	x	y	z	U_iso*/U_eq
O1A	0.32324 (4)	0.22226 (16)	0.31570 (14)	0.0210 (3)
O2A	0.35690 (3)	0.27958 (16)	0.49976 (14)	0.0213 (3)
O3A	0.47863 (3)	0.24586 (16)	0.53335 (14)	0.0218 (3)
O4A	0.51876 (4)	0.22687 (17)	0.36729 (14)	0.0259 (3)
N1A	0.30419 (4)	0.19662 (19)	0.53465 (18)	0.0198 (4)
N2A	0.53147 (4)	0.17410 (19)	0.59053 (17)	0.0194 (4)
C1A	0.25950 (5)	0.0743 (2)	0.3965 (2)	0.0215 (4)
H1AA	0.2760	0.0475	0.3335	0.026*
C2A	0.22478 (6)	0.0356 (2)	0.3788 (2)	0.0265 (5)
H2AA	0.2180	−0.0166	0.3031	0.032*
C3A	0.20014 (6)	0.0740 (3)	0.4726 (2)	0.0290 (5)
H3AA	0.1769	0.0486	0.4594	0.035*
C4A	0.21015 (6)	0.1504 (3)	0.5862 (2)	0.0296 (5)
H4AA	0.1937	0.1747	0.6501	0.036*
C5A	0.24475 (5)	0.1909 (2)	0.6053 (2)	0.0235 (4)
H5AA	0.2514	0.2426	0.6816	0.028*
C6A	0.26940 (5)	0.1536 (2)	0.5095 (2)	0.0194 (4)
C7A	0.32746 (5)	0.2314 (2)	0.4382 (2)	0.0165 (4)
C8A	0.38682 (5)	0.3068 (2)	0.4156 (2)	0.0180 (4)
H8AA	0.3848	0.2531	0.3310	0.022*
C9A	0.38944 (5)	0.4620 (2)	0.3841 (2)	0.0213 (4)
H9AA	0.3875	0.5155	0.4673	0.026*
H9AB	0.3704	0.4891	0.3235	0.026*
C10A	0.42429 (5)	0.4948 (2)	0.3174 (2)	0.0213 (4)
H10A	0.4252	0.4481	0.2300	0.026*
H10B	0.4260	0.5949	0.3017	0.026*
C11A	0.45518 (5)	0.4471 (2)	0.4063 (2)	0.0210 (4)
H11A	0.4768	0.4662	0.3603	0.025*
H11B	0.4554	0.4987	0.4912	0.025*
C12A	0.45230 (5)	0.2912 (2)	0.4349 (2)	0.0176 (4)
H12A	0.4548	0.2383	0.3503	0.021*
C13A	0.41781 (5)	0.2548 (2)	0.4998 (2)	0.0172 (4)
H13A	0.4171	0.2963	0.5897	0.021*
H13B	0.4162	0.1539	0.5101	0.021*
C14A	0.51069 (5)	0.2170 (2)	0.4859 (2)	0.0180 (4)
C15A	0.56754 (5)	0.1433 (2)	0.5863 (2)	0.0179 (4)
C16A	0.58223 (5)	0.0713 (2)	0.6959 (2)	0.0206 (4)
H16A	0.5681	0.0404	0.7656	0.025*
C17A	0.61787 (6)	0.0451 (2)	0.7023 (2)	0.0255 (5)
H17A	0.6275	−0.0020	0.7767	0.031*
C18A	0.63918 (5)	0.0888 (2)	0.5979 (2)	0.0259 (5)
H18A	0.6631	0.0721	0.6022	0.031*
C19A	0.62432 (5)	0.1581 (2)	0.4871 (2)	0.0240 (5)
H19A	0.6384	0.1858	0.4159	0.029*
C20A	0.58872 (5)	0.1867 (2)	0.4809 (2)	0.0195 (4)
H20A	0.5791	0.2345	0.4069	0.023*
O1B	−0.02136 (4)	0.77244 (17)	0.13203 (14)	0.0242 (3)
O2B	0.01910 (3)	0.75338 (16)	−0.03230 (14)	0.0207 (3)
O3B	0.14054 (3)	0.71216 (15)	0.00059 (14)	0.0189 (3)
O4B	0.17604 (4)	0.74059 (17)	0.18627 (14)	0.0242 (3)
N1B	−0.03341 (4)	0.82633 (18)	−0.09211 (17)	0.0179 (3)
N2B	0.19386 (4)	0.78876 (19)	−0.03047 (18)	0.0184 (4)
C1B	−0.09132 (5)	0.8200 (2)	0.0143 (2)	0.0191 (4)
H1BA	−0.0825	0.7705	0.0888	0.023*
C2B	−0.12654 (5)	0.8537 (2)	0.0058 (2)	0.0232 (4)
H2BA	−0.1412	0.8270	0.0754	0.028*
C3B	−0.14022 (5)	0.9265 (2)	−0.1049 (2)	0.0243 (5)
H3BA	−0.1639	0.9480	−0.1099	0.029*
C4B	−0.11823 (5)	0.9667 (2)	−0.2078 (2)	0.0233 (4)
H4BA	−0.1272	1.0157	−0.2822	0.028*
C5B	−0.08294 (5)	0.9346 (2)	−0.2011 (2)	0.0195 (4)
H5BA	−0.0684	0.9622	−0.2707	0.023*
C6B	−0.06928 (5)	0.8607 (2)	−0.08937 (19)	0.0157 (4)
C7B	−0.01295 (5)	0.7830 (2)	0.0140 (2)	0.0172 (4)
C8B	0.04525 (5)	0.7077 (2)	0.06741 (19)	0.0165 (4)
H8BA	0.0429	0.7617	0.1514	0.020*
C9B	0.04178 (5)	0.5521 (2)	0.0974 (2)	0.0184 (4)
H9BA	0.0412	0.4998	0.0129	0.022*
H9BB	0.0202	0.5348	0.1441	0.022*
C10B	0.07256 (5)	0.5031 (2)	0.1857 (2)	0.0192 (4)
H10C	0.0703	0.4034	0.2029	0.023*
H10D	0.0721	0.5512	0.2724	0.023*
C11B	0.10739 (5)	0.5314 (2)	0.1179 (2)	0.0194 (4)
H11C	0.1264	0.5028	0.1780	0.023*
H11D	0.1088	0.4774	0.0348	0.023*
C12B	0.11062 (5)	0.6861 (2)	0.08605 (19)	0.0160 (4)
H12B	0.1130	0.7398	0.1706	0.019*
C13B	0.07986 (5)	0.7408 (2)	0.0023 (2)	0.0168 (4)
H13C	0.0821	0.8415	−0.0080	0.020*
H13D	0.0803	0.6992	−0.0875	0.020*
C14B	0.17103 (5)	0.7465 (2)	0.0642 (2)	0.0162 (4)
C15B	0.22895 (5)	0.8287 (2)	−0.00429 (19)	0.0178 (4)
C16B	0.24314 (6)	0.9297 (2)	−0.0886 (2)	0.0247 (5)
H16B	0.2294	0.9715	−0.1560	0.030*
C17B	0.27798 (6)	0.9682 (3)	−0.0719 (3)	0.0342 (6)
H17B	0.2877	1.0338	−0.1299	0.041*
C18B	0.29811 (6)	0.9090 (3)	0.0306 (3)	0.0374 (6)
H18B	0.3212	0.9362	0.0428	0.045*
C19B	0.28398 (6)	0.8100 (3)	0.1147 (3)	0.0337 (6)
H19B	0.2976	0.7708	0.1839	0.040*
C20B	0.24941 (5)	0.7677 (2)	0.0972 (2)	0.0251 (5)
H20B	0.2401	0.6992	0.1532	0.030*
H1NA	0.3111 (6)	0.219 (2)	0.612 (2)	0.014 (6)*
H2NA	0.5227 (7)	0.181 (3)	0.676 (3)	0.048 (8)*
H1NB	−0.0234 (7)	0.824 (3)	−0.177 (3)	0.038 (7)*
H2NB	0.1855 (6)	0.795 (3)	−0.114 (3)	0.031 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1A	0.0194 (7)	0.0295 (8)	0.0140 (7)	−0.0001 (6)	−0.0018 (5)	0.0010 (6)
O2A	0.0154 (6)	0.0328 (8)	0.0156 (7)	−0.0043 (6)	0.0008 (5)	−0.0037 (6)
O3A	0.0153 (6)	0.0357 (9)	0.0142 (7)	0.0044 (6)	−0.0003 (5)	0.0007 (6)
O4A	0.0215 (7)	0.0415 (9)	0.0147 (7)	0.0057 (7)	0.0007 (6)	0.0019 (7)
N1A	0.0174 (8)	0.0301 (10)	0.0118 (8)	−0.0032 (7)	−0.0010 (6)	−0.0028 (7)
N2A	0.0176 (8)	0.0271 (9)	0.0136 (8)	0.0022 (7)	−0.0005 (6)	0.0017 (7)
C1A	0.0207 (9)	0.0231 (10)	0.0206 (10)	−0.0015 (8)	−0.0035 (8)	0.0004 (8)
C2A	0.0260 (11)	0.0282 (12)	0.0251 (11)	−0.0075 (9)	−0.0090 (9)	0.0016 (9)
C3A	0.0187 (10)	0.0334 (13)	0.0346 (13)	−0.0067 (9)	−0.0050 (9)	0.0081 (10)
C4A	0.0204 (10)	0.0326 (12)	0.0361 (13)	−0.0001 (9)	0.0058 (9)	0.0038 (10)
C5A	0.0204 (10)	0.0276 (11)	0.0225 (11)	−0.0009 (8)	0.0020 (8)	−0.0022 (9)
C6A	0.0166 (9)	0.0199 (10)	0.0214 (10)	−0.0024 (7)	−0.0017 (8)	0.0027 (8)
C7A	0.0155 (9)	0.0179 (9)	0.0161 (10)	0.0012 (7)	−0.0032 (7)	−0.0013 (7)
C8A	0.0158 (8)	0.0230 (10)	0.0154 (9)	−0.0015 (7)	0.0021 (7)	−0.0004 (8)
C9A	0.0209 (9)	0.0215 (10)	0.0215 (10)	0.0025 (8)	−0.0017 (8)	0.0009 (8)
C10A	0.0281 (10)	0.0168 (10)	0.0190 (10)	−0.0029 (8)	−0.0010 (8)	0.0000 (8)
C11A	0.0204 (9)	0.0241 (11)	0.0185 (10)	−0.0056 (8)	0.0028 (8)	−0.0012 (8)
C12A	0.0157 (9)	0.0240 (10)	0.0131 (9)	0.0014 (7)	−0.0025 (7)	−0.0007 (8)
C13A	0.0169 (9)	0.0204 (10)	0.0143 (9)	0.0000 (7)	0.0014 (7)	0.0019 (7)
C14A	0.0157 (9)	0.0222 (10)	0.0161 (9)	0.0010 (7)	0.0006 (7)	−0.0013 (8)
C15A	0.0186 (9)	0.0178 (9)	0.0173 (10)	0.0013 (7)	−0.0015 (7)	−0.0030 (8)
C16A	0.0244 (10)	0.0201 (10)	0.0172 (10)	0.0033 (8)	−0.0023 (8)	−0.0026 (8)
C17A	0.0276 (11)	0.0243 (11)	0.0243 (11)	0.0062 (9)	−0.0076 (9)	−0.0041 (9)
C18A	0.0184 (10)	0.0280 (12)	0.0310 (12)	0.0037 (8)	−0.0049 (9)	−0.0061 (10)
C19A	0.0210 (10)	0.0222 (11)	0.0288 (12)	0.0001 (8)	0.0021 (8)	−0.0021 (9)
C20A	0.0205 (9)	0.0199 (10)	0.0181 (10)	0.0015 (8)	−0.0001 (8)	0.0010 (8)
O1B	0.0218 (7)	0.0381 (9)	0.0128 (7)	0.0066 (6)	−0.0001 (6)	0.0021 (6)
O2B	0.0144 (6)	0.0333 (8)	0.0145 (7)	0.0035 (6)	−0.0014 (5)	0.0018 (6)
O3B	0.0142 (6)	0.0283 (8)	0.0142 (7)	−0.0040 (6)	0.0004 (5)	−0.0019 (6)
O4B	0.0204 (7)	0.0407 (9)	0.0115 (7)	−0.0029 (6)	−0.0017 (5)	0.0021 (6)
N1B	0.0164 (8)	0.0256 (9)	0.0116 (8)	0.0022 (7)	0.0000 (6)	0.0010 (7)
N2B	0.0148 (7)	0.0281 (9)	0.0123 (8)	−0.0021 (7)	−0.0012 (6)	0.0010 (7)
C1B	0.0202 (9)	0.0201 (10)	0.0170 (10)	0.0005 (8)	−0.0010 (8)	−0.0016 (8)
C2B	0.0197 (9)	0.0252 (11)	0.0249 (11)	0.0004 (8)	0.0025 (8)	−0.0029 (9)
C3B	0.0178 (9)	0.0238 (11)	0.0312 (12)	0.0037 (8)	−0.0046 (8)	−0.0030 (9)
C4B	0.0252 (10)	0.0210 (10)	0.0233 (11)	0.0038 (8)	−0.0083 (8)	−0.0021 (8)
C5B	0.0244 (10)	0.0196 (10)	0.0145 (9)	0.0019 (8)	−0.0023 (8)	0.0003 (8)
C6B	0.0158 (8)	0.0174 (9)	0.0139 (9)	0.0009 (7)	−0.0028 (7)	−0.0034 (7)
C7B	0.0174 (9)	0.0195 (10)	0.0146 (9)	0.0001 (7)	−0.0002 (7)	−0.0018 (8)
C8B	0.0151 (8)	0.0223 (10)	0.0121 (9)	0.0012 (7)	−0.0020 (7)	0.0001 (7)
C9B	0.0174 (9)	0.0223 (10)	0.0154 (9)	−0.0038 (7)	−0.0008 (7)	−0.0009 (8)
C10B	0.0222 (9)	0.0184 (10)	0.0169 (10)	−0.0032 (8)	−0.0003 (8)	0.0015 (8)
C11B	0.0197 (9)	0.0204 (10)	0.0179 (10)	0.0027 (8)	−0.0010 (7)	0.0017 (8)
C12B	0.0136 (8)	0.0210 (10)	0.0134 (9)	−0.0011 (7)	0.0007 (7)	0.0002 (7)
C13B	0.0162 (9)	0.0183 (10)	0.0159 (10)	−0.0013 (7)	−0.0022 (7)	0.0019 (7)
C14B	0.0145 (8)	0.0202 (10)	0.0138 (9)	0.0001 (7)	−0.0002 (7)	0.0001 (7)
C15B	0.0163 (9)	0.0235 (10)	0.0137 (9)	−0.0022 (8)	0.0014 (7)	−0.0048 (8)
C16B	0.0256 (10)	0.0243 (11)	0.0242 (11)	−0.0037 (9)	0.0001 (8)	0.0014 (9)
C17B	0.0333 (12)	0.0316 (13)	0.0379 (14)	−0.0133 (10)	0.0046 (11)	−0.0009 (11)
C18B	0.0209 (11)	0.0450 (15)	0.0462 (16)	−0.0111 (10)	−0.0010 (10)	−0.0063 (13)
C19B	0.0217 (11)	0.0485 (16)	0.0306 (13)	0.0002 (10)	−0.0066 (9)	−0.0002 (11)
C20B	0.0181 (9)	0.0359 (12)	0.0212 (11)	−0.0019 (9)	−0.0020 (8)	0.0044 (9)

Geometric parameters (Å, º) top

O1A—C7A	1.218 (2)	O1B—C7B	1.216 (2)
O2A—C7A	1.352 (2)	O2B—C7B	1.349 (2)
O2A—C8A	1.451 (2)	O2B—C8B	1.457 (2)
O3A—C14A	1.352 (2)	O3B—C14B	1.357 (2)
O3A—C12A	1.453 (2)	O3B—C12B	1.457 (2)
O4A—C14A	1.218 (2)	O4B—C14B	1.215 (2)
N1A—C7A	1.356 (2)	N1B—C7B	1.360 (3)
N1A—C6A	1.414 (3)	N1B—C6B	1.415 (2)
N1A—H1NA	0.83 (2)	N1B—H1NB	0.92 (3)
N2A—C14A	1.354 (3)	N2B—C14B	1.352 (2)
N2A—C15A	1.416 (2)	N2B—C15B	1.418 (2)
N2A—H2NA	0.92 (3)	N2B—H2NB	0.88 (3)
C1A—C2A	1.390 (3)	C1B—C2B	1.390 (3)
C1A—C6A	1.392 (3)	C1B—C6B	1.393 (2)
C1A—H1AA	0.93	C1B—H1BA	0.93
C2A—C3A	1.383 (3)	C2B—C3B	1.387 (3)
C2A—H2AA	0.93	C2B—H2BA	0.93
C3A—C4A	1.383 (3)	C3B—C4B	1.384 (3)
C3A—H3AA	0.93	C3B—H3BA	0.93
C4A—C5A	1.392 (3)	C4B—C5B	1.388 (3)
C4A—H4AA	0.93	C4B—H4BA	0.93
C5A—C6A	1.394 (3)	C5B—C6B	1.400 (3)
C5A—H5AA	0.93	C5B—H5BA	0.93
C8A—C9A	1.517 (3)	C8B—C13B	1.518 (2)
C8A—C13A	1.520 (3)	C8B—C9B	1.520 (3)
C8A—H8AA	0.98	C8B—H8BA	0.98
C9A—C10A	1.532 (3)	C9B—C10B	1.527 (3)
C9A—H9AA	0.97	C9B—H9BA	0.97
C9A—H9AB	0.97	C9B—H9BB	0.97
C10A—C11A	1.530 (3)	C10B—C11B	1.528 (3)
C10A—H10A	0.97	C10B—H10C	0.97
C10A—H10B	0.97	C10B—H10D	0.97
C11A—C12A	1.519 (3)	C11B—C12B	1.515 (3)
C11A—H11A	0.97	C11B—H11C	0.97
C11A—H11B	0.97	C11B—H11D	0.97
C12A—C13A	1.520 (2)	C12B—C13B	1.520 (3)
C12A—H12A	0.98	C12B—H12B	0.98
C13A—H13A	0.97	C13B—H13C	0.97
C13A—H13B	0.97	C13B—H13D	0.97
C15A—C16A	1.390 (3)	C15B—C20B	1.388 (3)
C15A—C20A	1.393 (3)	C15B—C16B	1.390 (3)
C16A—C17A	1.390 (3)	C16B—C17B	1.393 (3)
C16A—H16A	0.93	C16B—H16B	0.93
C17A—C18A	1.389 (3)	C17B—C18B	1.381 (4)
C17A—H17A	0.93	C17B—H17B	0.93
C18A—C19A	1.390 (3)	C18B—C19B	1.375 (3)
C18A—H18A	0.93	C18B—H18B	0.93
C19A—C20A	1.393 (3)	C19B—C20B	1.394 (3)
C19A—H19A	0.93	C19B—H19B	0.93
C20A—H20A	0.93	C20B—H20B	0.93

C7A—O2A—C8A	117.89 (15)	C7B—O2B—C8B	117.06 (14)
C14A—O3A—C12A	117.13 (15)	C14B—O3B—C12B	117.12 (14)
C7A—N1A—C6A	125.41 (18)	C7B—N1B—C6B	127.13 (16)
C7A—N1A—H1NA	112.3 (15)	C7B—N1B—H1NB	116.4 (17)
C6A—N1A—H1NA	121.2 (15)	C6B—N1B—H1NB	116.2 (17)
C14A—N2A—C15A	127.07 (16)	C14B—N2B—C15B	125.39 (18)
C14A—N2A—H2NA	117.3 (18)	C14B—N2B—H2NB	115.7 (16)
C15A—N2A—H2NA	114.6 (18)	C15B—N2B—H2NB	118.8 (16)
C2A—C1A—C6A	119.43 (19)	C2B—C1B—C6B	119.5 (2)
C2A—C1A—H1AA	120.3	C2B—C1B—H1BA	120.2
C6A—C1A—H1AA	120.3	C6B—C1B—H1BA	120.2
C3A—C2A—C1A	120.7 (2)	C3B—C2B—C1B	121.13 (19)
C3A—C2A—H2AA	119.6	C3B—C2B—H2BA	119.4
C1A—C2A—H2AA	119.6	C1B—C2B—H2BA	119.4
C2A—C3A—C4A	119.8 (2)	C4B—C3B—C2B	119.13 (19)
C2A—C3A—H3AA	120.1	C4B—C3B—H3BA	120.4
C4A—C3A—H3AA	120.1	C2B—C3B—H3BA	120.4
C3A—C4A—C5A	120.4 (2)	C3B—C4B—C5B	120.7 (2)
C3A—C4A—H4AA	119.8	C3B—C4B—H4BA	119.6
C5A—C4A—H4AA	119.8	C5B—C4B—H4BA	119.6
C4A—C5A—C6A	119.6 (2)	C4B—C5B—C6B	119.94 (18)
C4A—C5A—H5AA	120.2	C4B—C5B—H5BA	120.0
C6A—C5A—H5AA	120.2	C6B—C5B—H5BA	120.0
C1A—C6A—C5A	120.07 (19)	C1B—C6B—C5B	119.55 (18)
C1A—C6A—N1A	122.74 (18)	C1B—C6B—N1B	123.52 (18)
C5A—C6A—N1A	117.16 (19)	C5B—C6B—N1B	116.87 (16)
O1A—C7A—O2A	124.28 (17)	O1B—C7B—O2B	124.40 (19)
O1A—C7A—N1A	126.79 (19)	O1B—C7B—N1B	126.90 (18)
O2A—C7A—N1A	108.94 (17)	O2B—C7B—N1B	108.70 (15)
O2A—C8A—C9A	110.34 (15)	O2B—C8B—C13B	104.44 (15)
O2A—C8A—C13A	104.39 (15)	O2B—C8B—C9B	111.20 (16)
C9A—C8A—C13A	112.13 (17)	C13B—C8B—C9B	111.45 (15)
O2A—C8A—H8AA	110.0	O2B—C8B—H8BA	109.9
C9A—C8A—H8AA	110.0	C13B—C8B—H8BA	109.9
C13A—C8A—H8AA	110.0	C9B—C8B—H8BA	109.9
C8A—C9A—C10A	110.43 (16)	C8B—C9B—C10B	109.91 (16)
C8A—C9A—H9AA	109.6	C8B—C9B—H9BA	109.7
C10A—C9A—H9AA	109.6	C10B—C9B—H9BA	109.7
C8A—C9A—H9AB	109.6	C8B—C9B—H9BB	109.7
C10A—C9A—H9AB	109.6	C10B—C9B—H9BB	109.7
H9AA—C9A—H9AB	108.1	H9BA—C9B—H9BB	108.2
C11A—C10A—C9A	111.48 (16)	C9B—C10B—C11B	111.69 (16)
C11A—C10A—H10A	109.3	C9B—C10B—H10C	109.3
C9A—C10A—H10A	109.3	C11B—C10B—H10C	109.3
C11A—C10A—H10B	109.3	C9B—C10B—H10D	109.3
C9A—C10A—H10B	109.3	C11B—C10B—H10D	109.3
H10A—C10A—H10B	108.0	H10C—C10B—H10D	107.9
C12A—C11A—C10A	109.87 (17)	C12B—C11B—C10B	109.78 (16)
C12A—C11A—H11A	109.7	C12B—C11B—H11C	109.7
C10A—C11A—H11A	109.7	C10B—C11B—H11C	109.7
C12A—C11A—H11B	109.7	C12B—C11B—H11D	109.7
C10A—C11A—H11B	109.7	C10B—C11B—H11D	109.7
H11A—C11A—H11B	108.2	H11C—C11B—H11D	108.2
O3A—C12A—C11A	111.31 (16)	O3B—C12B—C11B	110.74 (15)
O3A—C12A—C13A	104.54 (15)	O3B—C12B—C13B	103.88 (14)
C11A—C12A—C13A	111.63 (16)	C11B—C12B—C13B	112.44 (16)
O3A—C12A—H12A	109.7	O3B—C12B—H12B	109.9
C11A—C12A—H12A	109.7	C11B—C12B—H12B	109.9
C13A—C12A—H12A	109.7	C13B—C12B—H12B	109.9
C12A—C13A—C8A	111.94 (16)	C8B—C13B—C12B	112.05 (16)
C12A—C13A—H13A	109.2	C8B—C13B—H13C	109.2
C8A—C13A—H13A	109.2	C12B—C13B—H13C	109.2
C12A—C13A—H13B	109.2	C8B—C13B—H13D	109.2
C8A—C13A—H13B	109.2	C12B—C13B—H13D	109.2
H13A—C13A—H13B	107.9	H13C—C13B—H13D	107.9
O4A—C14A—O3A	124.35 (19)	O4B—C14B—N2B	127.10 (19)
O4A—C14A—N2A	126.63 (18)	O4B—C14B—O3B	124.41 (16)
O3A—C14A—N2A	109.01 (16)	N2B—C14B—O3B	108.48 (16)
C16A—C15A—C20A	119.49 (18)	C20B—C15B—C16B	119.92 (19)
C16A—C15A—N2A	117.55 (17)	C20B—C15B—N2B	122.74 (18)
C20A—C15A—N2A	122.91 (19)	C16B—C15B—N2B	117.30 (19)
C17A—C16A—C15A	120.56 (19)	C15B—C16B—C17B	119.9 (2)
C17A—C16A—H16A	119.7	C15B—C16B—H16B	120.1
C15A—C16A—H16A	119.7	C17B—C16B—H16B	120.1
C18A—C17A—C16A	120.3 (2)	C18B—C17B—C16B	120.0 (2)
C18A—C17A—H17A	119.9	C18B—C17B—H17B	120.0
C16A—C17A—H17A	119.9	C16B—C17B—H17B	120.0
C17A—C18A—C19A	119.06 (19)	C19B—C18B—C17B	120.0 (2)
C17A—C18A—H18A	120.5	C19B—C18B—H18B	120.0
C19A—C18A—H18A	120.5	C17B—C18B—H18B	120.0
C18A—C19A—C20A	121.02 (19)	C18B—C19B—C20B	120.6 (2)
C18A—C19A—H19A	119.5	C18B—C19B—H19B	119.7
C20A—C19A—H19A	119.5	C20B—C19B—H19B	119.7
C15A—C20A—C19A	119.6 (2)	C15B—C20B—C19B	119.5 (2)
C15A—C20A—H20A	120.2	C15B—C20B—H20B	120.3
C19A—C20A—H20A	120.2	C19B—C20B—H20B	120.3

C6A—C1A—C2A—C3A	−0.6 (3)	C6B—C1B—C2B—C3B	0.5 (3)
C1A—C2A—C3A—C4A	−0.7 (3)	C1B—C2B—C3B—C4B	−0.4 (3)
C2A—C3A—C4A—C5A	1.2 (4)	C2B—C3B—C4B—C5B	0.1 (3)
C3A—C4A—C5A—C6A	−0.3 (3)	C3B—C4B—C5B—C6B	0.1 (3)
C2A—C1A—C6A—C5A	1.5 (3)	C2B—C1B—C6B—C5B	−0.3 (3)
C2A—C1A—C6A—N1A	179.8 (2)	C2B—C1B—C6B—N1B	−177.38 (19)
C4A—C5A—C6A—C1A	−1.1 (3)	C4B—C5B—C6B—C1B	0.0 (3)
C4A—C5A—C6A—N1A	−179.5 (2)	C4B—C5B—C6B—N1B	177.30 (18)
C7A—N1A—C6A—C1A	34.4 (3)	C7B—N1B—C6B—C1B	−18.0 (3)
C7A—N1A—C6A—C5A	−147.2 (2)	C7B—N1B—C6B—C5B	164.83 (19)
C8A—O2A—C7A—O1A	−7.5 (3)	C8B—O2B—C7B—O1B	−1.0 (3)
C8A—O2A—C7A—N1A	172.67 (16)	C8B—O2B—C7B—N1B	178.74 (16)
C6A—N1A—C7A—O1A	−5.5 (3)	C6B—N1B—C7B—O1B	−3.8 (3)
C6A—N1A—C7A—O2A	174.33 (18)	C6B—N1B—C7B—O2B	176.52 (18)
C7A—O2A—C8A—C9A	99.4 (2)	C7B—O2B—C8B—C13B	−157.19 (16)
C7A—O2A—C8A—C13A	−139.95 (17)	C7B—O2B—C8B—C9B	82.5 (2)
O2A—C8A—C9A—C10A	169.92 (16)	O2B—C8B—C9B—C10B	171.80 (14)
C13A—C8A—C9A—C10A	54.0 (2)	C13B—C8B—C9B—C10B	55.7 (2)
C8A—C9A—C10A—C11A	−56.4 (2)	C8B—C9B—C10B—C11B	−57.9 (2)
C9A—C10A—C11A—C12A	57.4 (2)	C9B—C10B—C11B—C12B	57.0 (2)
C14A—O3A—C12A—C11A	−83.1 (2)	C14B—O3B—C12B—C11B	−93.5 (2)
C14A—O3A—C12A—C13A	156.25 (17)	C14B—O3B—C12B—C13B	145.54 (16)
C10A—C11A—C12A—O3A	−172.51 (14)	C10B—C11B—C12B—O3B	−170.03 (15)
C10A—C11A—C12A—C13A	−56.1 (2)	C10B—C11B—C12B—C13B	−54.3 (2)
O3A—C12A—C13A—C8A	174.99 (15)	O2B—C8B—C13B—C12B	−174.04 (15)
C11A—C12A—C13A—C8A	54.5 (2)	C9B—C8B—C13B—C12B	−53.9 (2)
O2A—C8A—C13A—C12A	−172.95 (15)	O3B—C12B—C13B—C8B	173.31 (15)
C9A—C8A—C13A—C12A	−53.5 (2)	C11B—C12B—C13B—C8B	53.5 (2)
C12A—O3A—C14A—O4A	0.2 (3)	C15B—N2B—C14B—O4B	3.0 (3)
C12A—O3A—C14A—N2A	−178.81 (16)	C15B—N2B—C14B—O3B	−177.74 (18)
C15A—N2A—C14A—O4A	5.8 (4)	C12B—O3B—C14B—O4B	9.2 (3)
C15A—N2A—C14A—O3A	−175.19 (18)	C12B—O3B—C14B—N2B	−170.07 (16)
C14A—N2A—C15A—C16A	−165.8 (2)	C14B—N2B—C15B—C20B	33.7 (3)
C14A—N2A—C15A—C20A	16.8 (3)	C14B—N2B—C15B—C16B	−148.7 (2)
C20A—C15A—C16A—C17A	1.4 (3)	C20B—C15B—C16B—C17B	0.8 (3)
N2A—C15A—C16A—C17A	−176.11 (19)	N2B—C15B—C16B—C17B	−176.9 (2)
C15A—C16A—C17A—C18A	−1.0 (3)	C15B—C16B—C17B—C18B	−1.9 (4)
C16A—C17A—C18A—C19A	−0.5 (3)	C16B—C17B—C18B—C19B	1.3 (4)
C17A—C18A—C19A—C20A	1.5 (3)	C17B—C18B—C19B—C20B	0.3 (4)
C16A—C15A—C20A—C19A	−0.4 (3)	C16B—C15B—C20B—C19B	0.8 (3)
N2A—C15A—C20A—C19A	176.97 (19)	N2B—C15B—C20B—C19B	178.4 (2)
C18A—C19A—C20A—C15A	−1.1 (3)	C18B—C19B—C20B—C15B	−1.4 (4)

Hydrogen-bond geometry (Å, º) top

Cg1 and Cg2 are the centroids of C15A–C20A and C1B–C6B phenyl rings, respectively.

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H1NA···O1Aⁱ	0.83 (2)	2.13 (2)	2.953 (2)	174 (2)
N2A—H2NA···O4Aⁱ	0.91 (3)	2.09 (3)	2.934 (2)	154 (2)
N1B—H1NB···O1Bⁱⁱ	0.93 (3)	2.10 (3)	2.920 (2)	147 (2)
N2B—H2NB···O4Bⁱⁱ	0.88 (3)	2.02 (3)	2.874 (2)	163 (3)
C13A—H13B···Cg1ⁱⁱⁱ	0.97	2.86	3.734 (2)	151
C13B—H13C···Cg2^iv	0.97	2.86	3.732 (2)	150

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

Experimental details

Crystal data
Chemical formula	C₂₀H₂₂N₂O₄
M_r	354.40
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	38.356 (7), 9.5453 (16), 9.8472 (16)
β (°)	91.034 (3)
V (Å³)	3604.7 (10)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.55 × 0.15 × 0.13

Data collection
Diffractometer	Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.951, 0.988
No. of measured, independent and observed [I > 2σ(I)] reflections	30037, 10472, 6630
R_int	0.057
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.064, 0.180, 1.08
No. of reflections	10472
No. of parameters	485
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.33, −0.25

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg1 and Cg2 are the centroids of C15A–C20A and C1B–C6B phenyl rings, respectively.

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H1NA···O1Aⁱ	0.83 (2)	2.13 (2)	2.953 (2)	174 (2)
N2A—H2NA···O4Aⁱ	0.91 (3)	2.09 (3)	2.934 (2)	154 (2)
N1B—H1NB···O1Bⁱⁱ	0.93 (3)	2.10 (3)	2.920 (2)	147 (2)
N2B—H2NB···O4Bⁱⁱ	0.88 (3)	2.02 (3)	2.874 (2)	163 (3)
C13A—H13B···Cg1ⁱⁱⁱ	0.97	2.86	3.734 (2)	151
C13B—H13C···Cg2^iv	0.97	2.86	3.732 (2)	150

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

Footnotes

‡Thomson Reuters ResearcherID: C-7576-2009.

§Thomson Reuters ResearcherID: A-3561-2009

Acknowledgements

The authors thank Universiti Sains Malaysia (USM) for the University Grant (No. 1001/PTEKIND/8140152). HKF and JHG thank USM for the Research University Golden Goose Grant (No. 1001/PFIZIK/811012). RMG and SHM thank USM for postdoctoral fellowships. JHG also thanks USM for a USM fellowship.

References

Banerjee, S., Dutta, S. & Chakraborti, S. K. (1978). J. Indian Chem. Soc. 55, 284–286. CAS Google Scholar
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105–107. CrossRef CAS Web of Science IUCr Journals Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Ghalib, R. M., Sulaiman, O., Mehdi, S. H., Goh, J. H. & Fun, H.-K. (2010). Acta Cryst. E66, o1889–o1890. Web of Science CSD CrossRef IUCr Journals Google Scholar
Graia, M., Raza Murad, G., Krimi Ammar, M., Mehdi, S. H. & Hashim, R. (2009). Acta Cryst. E65, o3231. Web of Science CSD CrossRef IUCr Journals Google Scholar
Ibuka, T., Chu, G. N., Aoyagi, T., Kitada, K., Tsukida, T. & Yoneda, F. (1985). Chem. Pharm. Bull. 33, 451–453. CrossRef CAS Google Scholar
Lapidus, A. L., Pirozhkov, S. D., Kapkin, V. D. & Krylova, A. Y. (1987). Org. Tech. 13, 160. Google Scholar
Loev, B. & Kormendy, M. F. (1963). J. Org. Chem. 28, 3421–3426. CrossRef CAS Google Scholar
Niu, D. F., Zhang, L., Xiao, L. P., Luo, Y. W. & Lu, J. X. (2007). Appl. Organomet. Chem. 21, 941–944. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar

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Volume 66| Part 9| September 2010| Pages o2406-o2407

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