2,5-Dioxopyrrolidin-1-yl adamantane-1-carboxyl­ate

Liu, J.; Clegg, J.K.; Codd, R.

doi:10.1107/S1600536809024209

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 65| Part 8| August 2009| Pages o1740-o1741

doi:10.1107/S1600536809024209

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2,5-Dioxopyrrolidin-1-yl adamantane-1-carboxylate

Joe Liu,^a Jack K. Clegg ^b and Rachel Codd ^a ^*

^aSchool of Medical Sciences (Pharmacology) and Bosch Institute, D06, The University of Sydney, New South Wales 2006, Australia, and ^bCentre for Heavy Metals Research, School of Chemistry, F11, University of Sydney, New South Wales 2006, Australia
^*Correspondence e-mail: rcodd@med.usyd.edu.au

(Received 29 May 2009; accepted 24 June 2009; online 4 July 2009)

The title compound, C₁₅H₁₉NO₄, contains one crystallographically independent molecule in the asymmetric unit. The N—O—C—O torsion angle is 1.97 (9)°. The two pairs of vicinal H atoms that lie above or below the plane defined by the five-membered pyrrolidine-2,5-dione ring are an average of 6.57 (5)° from being eclipsed. The average absolute C—C—C—C torsion angle in the adamantane skeleton, in which each fused cyclohexane ring is in a chair configuration, is 59.99 (5)°. The crystal packing is unremarkable.

Related literature

For the biological activity of adamantane-1-carboxylic acid derivatives, see: De Felice et al. (2007 ); Jia et al. (2005 ); Stouffer et al. (2008 ). For related structures, see: Molčanov et al. (2006 ); Thackeray & White (1977 ); Homan et al. (1997 ). For related structures produced via biocatalysis, see: Bailey et al. (1996 ); Ridyard et al. (1996 ). For the structure of a derivative of the title compound, see the following paper: Liu et al. (2009 ).

Experimental

Crystal data

C₁₅H₁₉NO₄
M_r = 277.31
Monoclinic, P 2₁ /n
a = 6.6711 (3) Å
b = 29.4502 (14) Å
c = 7.0291 (3) Å
β = 104.447 (2)°
V = 1337.26 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 150 K
0.30 × 0.28 × 0.10 mm

Data collection

Bruker APEXII–FR591 diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2007 ) T_min = 0.888, T_max = 0.990
51912 measured reflections
6819 independent reflections
6104 reflections with I > 2σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.120
S = 1.08
6819 reflections
181 parameters
H-atom parameters constrained
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: APEX2 (Bruker, 2003 ); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT and XPREP (Bruker, 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 (Farrugia, 1997 ), WinGX32 (Farrugia, 1999 ) and POV-RAY (Cason, 2002 ); software used to prepare material for publication: enCIFer (Allen et al., 2004 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809024209/bg2265sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809024209/bg2265Isup2.hkl

checkCIF report

Comment top

Adamantane-1-carboxylate-2,5-pyrrolidinedione (I) (Fig. 1.) was prepared in our laboratory as part of our bioconjugate program in drug design. Adamantane-1-carboxylic acid belongs to a family of functionalized polycyclic cage-based compounds that have relevance in the design of therapeutics, with several compounds in clinical use for the treatment of influenza (amantadine) (Stouffer et al., 2008), Alzheimer's disease (memantine) (De Felice et al., 2007) and pulmonary tuberculosis (SQ109) (Jia et al., 2005). The torsional bond in I defined by atoms N1—O2—C11—O1 is 1.97 (9) °. The distance between the 2,5-pyrrolidinedione-derived oxo groups and the carbonyl O atom in I (O1) is 3.52 (1) Å (O4–O1) or 3.39 (1) Å (O3—O1); this difference arises from the O4 group lying 0.10 (1) Å below the plane defined by N1, C13 and C14 and the O3 group lying 0.28 (1) Å above this same plane and on the same side as O1. Amide conjugates of adamantane-1-carboxylic acid might furnish compounds with the ability to traverse cell membranes.

Related literature top

For the biological activity of adamantane-1-carboxylic acid derivatives, see: De Felice et al. (2007); Jia et al. (2005); Stouffer et al. (2008). For related structures, see: Molčanov et al. (2006); Thackeray & White (1977); Homan et al. (1997). For related structures produced via biocatalysis, see: Bailey et al. (1996); Ridyard et al. (1996). For the structure of a derivative of the title compound, see the next paper in this journal: Liu et al. (2009).

Experimental top

A white precipitate of I was formed after the addition of water (1 ml) to a cooled solution of DMF (10 ml) containing N-hydroxysuccinimide (NHS: 0.29 g, 2.55 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC: 0.39 g, 2.00 mmol) and adamantane-1-carboxylic acid (0.46 g, 2.55 mmol) that had been heated to 40 ° C for 4 h. The product was dried in vacuo; colourless crystals of I appeared after approximately 1 month from a 4.5 mg mL^-1 solution of I in ethanol:water (7:3).

Computing details top

Data collection: APEX2 (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003) and XPREP (Bruker, 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997), WinGX32 (Farrugia, 1999) and POV-RAY (Cason, 2002); software used to prepare material for publication: enCIFer (Allen et al., 2004).

Figures top

Fig. 1. ORTEP representation of I shown with 50% probability ellipsoids.

2,5-Dioxopyrrolidin-1-yl adamantane-1-carboxylate top

Crystal data top

C₁₅H₁₉NO₄	F(000) = 592
M_r = 277.31	D_x = 1.377 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 9946 reflections
a = 6.6711 (3) Å	θ = 2.8–37.1°
b = 29.4502 (14) Å	µ = 0.10 mm⁻¹
c = 7.0291 (3) Å	T = 150 K
β = 104.447 (2)°	Plate, colourless
V = 1337.26 (10) Å³	0.30 × 0.28 × 0.10 mm
Z = 4

Data collection top

Bruker APEXII–FR591 diffractometer	6819 independent reflections
Radiation source: rotating anode	6104 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.032
ω+ϕ scans	θ_max = 37.2°, θ_min = 2.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 2007)	h = −11→11
T_min = 0.888, T_max = 0.990	k = −49→50
51912 measured reflections	l = −11→11

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) = 0.120	H-atom parameters constrained
S = 1.08	w = 1/[σ²(F_o²) + (0.057P)² + 0.2898P] where P = (F_o² + 2F_c²)/3
6819 reflections	(Δ/σ)_max < 0.001
181 parameters	Δρ_max = 0.44 e Å⁻³
0 restraints	Δρ_min = −0.29 e Å⁻³

Crystal data top

C₁₅H₁₉NO₄	V = 1337.26 (10) Å³
M_r = 277.31	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 6.6711 (3) Å	µ = 0.10 mm⁻¹
b = 29.4502 (14) Å	T = 150 K
c = 7.0291 (3) Å	0.30 × 0.28 × 0.10 mm
β = 104.447 (2)°

Data collection top

Bruker APEXII–FR591 diffractometer	6819 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2007)	6104 reflections with I > 2σ(I)
T_min = 0.888, T_max = 0.990	R_int = 0.032
51912 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	0 restraints
wR(F²) = 0.120	H-atom parameters constrained
S = 1.08	Δρ_max = 0.44 e Å⁻³
6819 reflections	Δρ_min = −0.29 e Å⁻³
181 parameters

Special details top

Experimental. The crystal was coated in Exxon Paratone N hydrocarbon oil and mounted on a thin mohair fibre attached to a copper pin. Upon mounting on the diffractometer, the crystal was quenched to 150(K) under a cold nitrogen gas stream supplied by an Oxford Cryosystems Cryostream and data were collected at this temperature.

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	1.22052 (11)	0.15040 (3)	0.40895 (12)	0.02581 (14)
H1A	1.2692	0.1204	0.3753	0.031*
H1B	1.3395	0.1666	0.4946	0.031*
C2	1.04957 (11)	0.14401 (2)	0.51785 (10)	0.02258 (13)
H2	1.1055	0.1262	0.6407	0.027*
C3	0.86612 (11)	0.11819 (2)	0.38550 (10)	0.02168 (12)
H3A	0.7567	0.1135	0.4562	0.026*
H3B	0.9127	0.0881	0.3509	0.026*
C4	0.77940 (9)	0.146072 (19)	0.19724 (8)	0.01413 (9)
C5	0.95139 (10)	0.15250 (3)	0.08694 (9)	0.02086 (11)
H5A	0.9979	0.1225	0.0507	0.025*
H5B	0.8966	0.1700	−0.0352	0.025*
C6	1.13503 (10)	0.17802 (3)	0.22017 (11)	0.02310 (12)
H6	1.2464	0.1821	0.1491	0.028*
C7	1.06322 (11)	0.22477 (2)	0.27366 (11)	0.02349 (13)
H7A	1.1817	0.2414	0.3574	0.028*
H7B	1.0089	0.2427	0.1527	0.028*
C8	0.89390 (11)	0.21863 (2)	0.38360 (10)	0.01981 (11)
H8	0.8472	0.2491	0.4188	0.024*
C9	0.97680 (12)	0.19081 (3)	0.57139 (10)	0.02357 (13)
H9A	0.8665	0.1869	0.6417	0.028*
H9B	1.0939	0.2071	0.6593	0.028*
C10	0.70934 (10)	0.19322 (2)	0.25152 (10)	0.01816 (10)
H10A	0.6530	0.2110	0.1304	0.022*
H10B	0.5985	0.1897	0.3214	0.022*
C11	0.59920 (9)	0.12338 (2)	0.05527 (9)	0.01710 (10)
C12	0.27538 (10)	0.04257 (2)	−0.03135 (10)	0.01826 (10)
C13	0.14462 (10)	0.02270 (2)	−0.22012 (10)	0.02094 (11)
H13A	0.0197	0.0415	−0.2712	0.025*
H13B	0.1006	−0.0086	−0.1981	0.025*
C14	0.28296 (11)	0.02249 (2)	−0.36545 (10)	0.02184 (12)
H14A	0.3150	−0.0090	−0.3971	0.026*
H14B	0.2134	0.0382	−0.4888	0.026*
C15	0.47840 (10)	0.04733 (2)	−0.26279 (10)	0.01859 (11)
N1	0.46311 (9)	0.054259 (19)	−0.07064 (8)	0.01894 (10)
O1	0.45874 (9)	0.14099 (2)	−0.06059 (9)	0.02874 (13)
O2	0.61824 (8)	0.075815 (16)	0.06775 (8)	0.02138 (10)
O3	0.62486 (10)	0.05906 (2)	−0.32307 (10)	0.02936 (12)
O4	0.23579 (11)	0.04800 (2)	0.12597 (9)	0.02915 (12)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0157 (3)	0.0261 (3)	0.0305 (3)	0.0019 (2)	−0.0038 (2)	−0.0024 (2)
C2	0.0245 (3)	0.0195 (2)	0.0178 (2)	−0.0049 (2)	−0.0058 (2)	0.00400 (19)
C3	0.0244 (3)	0.0172 (2)	0.0185 (2)	−0.0061 (2)	−0.0039 (2)	0.00501 (18)
C4	0.0131 (2)	0.01371 (19)	0.01396 (19)	−0.00133 (16)	0.00043 (16)	0.00029 (15)
C5	0.0171 (2)	0.0291 (3)	0.0169 (2)	−0.0011 (2)	0.00514 (19)	−0.0038 (2)
C6	0.0144 (2)	0.0322 (3)	0.0230 (3)	−0.0042 (2)	0.0052 (2)	−0.0018 (2)
C7	0.0217 (3)	0.0217 (3)	0.0246 (3)	−0.0085 (2)	0.0012 (2)	0.0042 (2)
C8	0.0196 (3)	0.0159 (2)	0.0218 (3)	−0.00142 (18)	0.0012 (2)	−0.00345 (18)
C9	0.0275 (3)	0.0261 (3)	0.0153 (2)	−0.0063 (2)	0.0020 (2)	−0.0037 (2)
C10	0.0148 (2)	0.0168 (2)	0.0216 (2)	0.00051 (17)	0.00218 (19)	−0.00262 (18)
C11	0.0156 (2)	0.0163 (2)	0.0173 (2)	−0.00132 (17)	0.00011 (18)	−0.00125 (17)
C12	0.0194 (2)	0.0146 (2)	0.0210 (2)	−0.00237 (18)	0.0057 (2)	−0.00127 (18)
C13	0.0168 (2)	0.0197 (2)	0.0248 (3)	−0.00409 (19)	0.0022 (2)	−0.0032 (2)
C14	0.0234 (3)	0.0216 (3)	0.0189 (2)	−0.0042 (2)	0.0023 (2)	−0.0043 (2)
C15	0.0193 (2)	0.0166 (2)	0.0199 (2)	−0.00113 (18)	0.0051 (2)	−0.00084 (18)
N1	0.0178 (2)	0.0196 (2)	0.0182 (2)	−0.00664 (17)	0.00223 (17)	−0.00448 (16)
O1	0.0241 (3)	0.0233 (2)	0.0296 (3)	0.00305 (18)	−0.0106 (2)	−0.00286 (19)
O2	0.0205 (2)	0.01610 (18)	0.0224 (2)	−0.00444 (15)	−0.00436 (17)	−0.00179 (15)
O3	0.0271 (3)	0.0312 (3)	0.0341 (3)	−0.0051 (2)	0.0157 (2)	−0.0009 (2)
O4	0.0369 (3)	0.0291 (3)	0.0254 (2)	−0.0057 (2)	0.0152 (2)	−0.0041 (2)

Geometric parameters (Å, º) top

C1—C2	1.5354 (12)	C8—C9	1.5348 (10)
C1—C6	1.5395 (11)	C8—C10	1.5386 (9)
C1—H1A	0.9900	C8—H8	1.0000
C1—H1B	0.9900	C9—H9A	0.9900
C2—C9	1.5387 (11)	C9—H9B	0.9900
C2—C3	1.5406 (9)	C10—H10A	0.9900
C2—H2	1.0000	C10—H10B	0.9900
C3—C4	1.5421 (8)	C11—O1	1.1956 (8)
C3—H3A	0.9900	C11—O2	1.4072 (8)
C3—H3B	0.9900	C12—O4	1.2099 (9)
C4—C11	1.5130 (8)	C12—N1	1.3913 (9)
C4—C10	1.5431 (8)	C12—C13	1.5121 (9)
C4—C5	1.5483 (9)	C13—C14	1.5381 (10)
C5—C6	1.5394 (10)	C13—H13A	0.9900
C5—H5A	0.9900	C13—H13B	0.9900
C5—H5B	0.9900	C14—C15	1.5120 (9)
C6—C7	1.5351 (11)	C14—H14A	0.9900
C6—H6	1.0000	C14—H14B	0.9900
C7—C8	1.5301 (11)	C15—O3	1.2083 (9)
C7—H7A	0.9900	C15—N1	1.3946 (9)
C7—H7B	0.9900	N1—O2	1.3849 (7)

C2—C1—C6	109.45 (5)	C7—C8—C10	109.46 (5)
C2—C1—H1A	109.8	C9—C8—C10	108.77 (5)
C6—C1—H1A	109.8	C7—C8—H8	109.5
C2—C1—H1B	109.8	C9—C8—H8	109.5
C6—C1—H1B	109.8	C10—C8—H8	109.5
H1A—C1—H1B	108.2	C8—C9—C2	109.62 (5)
C1—C2—C9	109.33 (6)	C8—C9—H9A	109.7
C1—C2—C3	109.66 (6)	C2—C9—H9A	109.7
C9—C2—C3	109.77 (6)	C8—C9—H9B	109.7
C1—C2—H2	109.4	C2—C9—H9B	109.7
C9—C2—H2	109.4	H9A—C9—H9B	108.2
C3—C2—H2	109.4	C8—C10—C4	109.92 (5)
C2—C3—C4	109.07 (5)	C8—C10—H10A	109.7
C2—C3—H3A	109.9	C4—C10—H10A	109.7
C4—C3—H3A	109.9	C8—C10—H10B	109.7
C2—C3—H3B	109.9	C4—C10—H10B	109.7
C4—C3—H3B	109.9	H10A—C10—H10B	108.2
H3A—C3—H3B	108.3	O1—C11—O2	121.17 (6)
C11—C4—C3	113.39 (5)	O1—C11—C4	128.04 (6)
C11—C4—C10	108.71 (5)	O2—C11—C4	110.74 (5)
C3—C4—C10	109.81 (5)	O4—C12—N1	124.15 (6)
C11—C4—C5	106.85 (5)	O4—C12—C13	130.05 (7)
C3—C4—C5	109.19 (5)	N1—C12—C13	105.80 (5)
C10—C4—C5	108.77 (5)	C12—C13—C14	105.90 (5)
C6—C5—C4	109.37 (5)	C12—C13—H13A	110.6
C6—C5—H5A	109.8	C14—C13—H13A	110.6
C4—C5—H5A	109.8	C12—C13—H13B	110.6
C6—C5—H5B	109.8	C14—C13—H13B	110.6
C4—C5—H5B	109.8	H13A—C13—H13B	108.7
H5A—C5—H5B	108.2	C15—C14—C13	105.66 (5)
C7—C6—C5	109.70 (6)	C15—C14—H14A	110.6
C7—C6—C1	109.50 (6)	C13—C14—H14A	110.6
C5—C6—C1	109.51 (6)	C15—C14—H14B	110.6
C7—C6—H6	109.4	C13—C14—H14B	110.6
C5—C6—H6	109.4	H14A—C14—H14B	108.7
C1—C6—H6	109.4	O3—C15—N1	123.96 (6)
C8—C7—C6	109.43 (5)	O3—C15—C14	130.34 (7)
C8—C7—H7A	109.8	N1—C15—C14	105.68 (5)
C6—C7—H7A	109.8	O2—N1—C12	121.72 (5)
C8—C7—H7B	109.8	O2—N1—C15	121.67 (6)
C6—C7—H7B	109.8	C12—N1—C15	116.30 (5)
H7A—C7—H7B	108.2	N1—O2—C11	111.87 (5)
C7—C8—C9	110.14 (6)

C6—C1—C2—C9	−60.05 (7)	C3—C4—C10—C8	59.67 (7)
C6—C1—C2—C3	60.35 (7)	C5—C4—C10—C8	−59.76 (6)
C1—C2—C3—C4	−60.62 (7)	C3—C4—C11—O1	151.19 (8)
C9—C2—C3—C4	59.51 (8)	C10—C4—C11—O1	28.75 (9)
C2—C3—C4—C11	179.35 (6)	C5—C4—C11—O1	−88.47 (9)
C2—C3—C4—C10	−58.83 (7)	C3—C4—C11—O2	−31.38 (8)
C2—C3—C4—C5	60.35 (7)	C10—C4—C11—O2	−153.82 (5)
C11—C4—C5—C6	176.77 (5)	C5—C4—C11—O2	88.96 (6)
C3—C4—C5—C6	−60.23 (7)	O4—C12—C13—C14	−177.07 (7)
C10—C4—C5—C6	59.58 (7)	N1—C12—C13—C14	2.61 (7)
C4—C5—C6—C7	−60.28 (7)	C12—C13—C14—C15	−6.58 (7)
C4—C5—C6—C1	59.93 (7)	C13—C14—C15—O3	−173.15 (7)
C2—C1—C6—C7	60.38 (7)	C13—C14—C15—N1	8.13 (7)
C2—C1—C6—C5	−59.95 (8)	O4—C12—N1—O2	−3.72 (10)
C5—C6—C7—C8	60.42 (7)	C13—C12—N1—O2	176.58 (5)
C1—C6—C7—C8	−59.79 (7)	O4—C12—N1—C15	−177.39 (7)
C6—C7—C8—C9	59.43 (7)	C13—C12—N1—C15	2.91 (8)
C6—C7—C8—C10	−60.11 (7)	O3—C15—N1—O2	0.32 (10)
C7—C8—C9—C2	−59.33 (7)	C14—C15—N1—O2	179.14 (6)
C10—C8—C9—C2	60.63 (7)	O3—C15—N1—C12	173.99 (7)
C1—C2—C9—C8	59.41 (7)	C14—C15—N1—C12	−7.19 (8)
C3—C2—C9—C8	−60.91 (8)	C12—N1—O2—C11	−89.36 (7)
C7—C8—C10—C4	60.29 (7)	C15—N1—O2—C11	83.97 (7)
C9—C8—C10—C4	−60.09 (7)	O1—C11—O2—N1	1.97 (9)
C11—C4—C10—C8	−175.76 (5)	C4—C11—O2—N1	−175.66 (5)

Experimental details

Crystal data
Chemical formula	C₁₅H₁₉NO₄
M_r	277.31
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	150
a, b, c (Å)	6.6711 (3), 29.4502 (14), 7.0291 (3)
β (°)	104.447 (2)
V (Å³)	1337.26 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.30 × 0.28 × 0.10

Data collection
Diffractometer	Bruker APEXII–FR591 diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2007)
T_min, T_max	0.888, 0.990
No. of measured, independent and observed [I > 2σ(I)] reflections	51912, 6819, 6104
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.850

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.120, 1.08
No. of reflections	6819
No. of parameters	181
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.44, −0.29

Computer programs: APEX2 (Bruker, 2003), SAINT (Bruker, 2003) and XPREP (Bruker, 2003), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), WinGX32 (Farrugia, 1999) and POV-RAY (Cason, 2002), enCIFer (Allen et al., 2004).

Acknowledgements

Support from the NHMRC-Project Grant 570844 (RC) and from the University of Sydney (2009 Bridging Support Grant (RC), co-funded postgraduate scholarship from the Faculty of Medicine (JL)) is gratefully acknowledged.

References

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