Methyl 9H-xanthene-9-carboxyl­ate

Dean, P.M.; Turanjanin, J.; MacFarlane, D.R.

doi:10.1107/S1600536808005990

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 64| Part 5| May 2008| Page o854

doi:10.1107/S1600536808005990

Open

access

Methyl 9H-xanthene-9-carboxylate

Pamela M. Dean,^a ^* Jelena Turanjanin ^a and Douglas R. MacFarlane ^a

^aSchool of Chemistry, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
^*Correspondence e-mail: pamela.dean@sci.monash.edu.au

(Received 20 February 2008; accepted 4 March 2008; online 16 April 2008)

The title compound, C₁₅H₁₂O₃, was obtained unintentionally as the by-product of an attempted recrystallization from methanol of propantheline bromide, an antimuscarinic drug. The xanthone unit is folded, with a dihedral angle of 24.81 (9)° between the benzene rings. The ester substituent adopts a trans staggered conformation, with a C—C—O—C torsion angle of 178.4 (1)°. The molecules pack in distinct layers, facilitated by C—H⋯π and weak π–π ring interactions. A weak C—H⋯O interaction also occurs; however, no classical hydrogen bonding is observed.

Related literature

For details of the first spectroscopic evidence of the transesterification of propantheline bromide by methanol to 9H-xanthene-9-carboxylic acid methyl ester, see: Avdovich et al. (1986 ). For a description of the comparative effectiveness of propantheline bromide for the treatment of neurogenic detrusor overactivity, see: George et al. (2007 ).

Experimental

Crystal data

C₁₅H₁₂O₃
M_r = 240.25
Monoclinic, C 2/c
a = 25.6601 (16) Å
b = 5.7624 (3) Å
c = 15.7578 (9) Å
β = 92.933 (4)°
V = 2327.0 (2) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 123 (2) K
0.50 × 0.50 × 0.50 mm

Data collection

Bruker Kappa APEXII diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.932, T_max = 0.954
11906 measured reflections
2672 independent reflections
1985 reflections with I > 2σ(I)
R_int = 0.050

Refinement

R[F² > 2σ(F²)] = 0.050
wR(F²) = 0.106
S = 1.05
2672 reflections
166 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C15—H15C⋯O2ⁱ	0.98	2.53	3.407 (3)	149
C3—H3⋯Cg2ⁱⁱ	0.95	2.95	3.668 (2)	133
C11—H11⋯Cg1ⁱⁱⁱ	0.95	3.18	3.825 (2)	127
C15—H15B⋯Cg1^iv	0.98	3.06	3.432 (2)	104
C15—H15C⋯Cg1^iv	0.98	3.11	3.432 (2)	101
Symmetry codes: (i) x, y-1, z; (ii) $[x, -y, z-{\script{1\over 2}}]$ ; (iii) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (iv) -x+1, -y, -z+1. Cg1 is the centroid of ring C1–C6; Cg2 is the centroid of ring C8–C13.

Table 2
Geometrical parameters (Å, °) of the inter-ring π—π interactions

CgI	CgJ	Cg⋯Cg	α	Symmetry position of CgJ
Cg1	Cg2	5.590 (1)	59.44	x, 1 − y, $[-{\script{1\over 2}}]$ + z
Cg1	Cg2	4.944 (1)	24.81	$[{\script{1\over 2}}]$ − x, $[{\script{1\over 2}}]$ − y, 1 − z
Cg2	Cg1	4.863 (1)	59.44	x, −y, $[{\script{1\over 2}}]$ + z
Cg2	Cg2	3.684 (1)	0.03	$[{\script{1\over 2}}]$ − x, $[{\script{1\over 2}}]$ − y, 1 − z
α is the dihedral angle between planes I and J, CgI is the centroid of plane I and CgJ the centroid of plane J. Cg1 is the centroid of ring C1–C6; Cg2 is the centroid of ring C8–C13.

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: APEX2; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: POV-RAY for Windows (Persistence of Vision, 1999 ); software used to prepare material for publication: PLATON (Spek, 2003 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808005990/wn2242sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808005990/wn2242Isup2.hkl

checkCIF report

Comment top

It was found that propantheline bromide (George et al., 2007) undergoes facile transesterification by methanol to produce the by-product 9H-xanthene-9-carboxylic acid methyl ester (Avdovich et al., 1986). Surprisingly, the structural elucidation of this analogue (Fig. 1) has not been reported in the literature until now. Now the structural determination and analysis is briefly described.

The xanthone unit is bent, with the aromatic planes oriented to each other by an interplanar angle of 24.81 (9)°. The ester substituent adopts a trans staggered conformation with a C7—C14—O3—C15 torsion angle of 178.4 (1)°. Additionally, as is typical of an ester, the O3—C14 distance is 1.326 (2) Å and the O3—C15 distance is 1.448 (2) Å, indicating the sp² hybridization of C14.

The overall packing is shown in Fig. 2. Molecules are related by centres of symmetry, resulting in a head-to-head arrangement, that packs in aromatic and non-aromatic layers lying parallel to the (100) plane. Fig. 2 displays the orientation of the molecules, facilitating the weak C—H···O hydrogen bonding between the methyl and carbonyl groups (distance: C15—H15C···O2ⁱ (i = x,y - 1,z) 3.407 (2) Å - see Table 1) and the C—H···π and weak π···π ring interactions (Table 2). A short range contact, 2.683 (2) Å, also occurs between the aromatic C4—H4 and the carbonyl oxygen O2 (distance: C4—H4···O2ⁱⁱ (ii = x,1 - y,-1/2 + z).

Related literature top

For details of the first spectroscopic evidence of the transesterification of propantheline bromide by methanol to 9H-xanthene-9-carboxylic acid methyl ester, see: Avdovich et al. (1986). For a description of the comparative effectiveness of propantheline bromide for the treatment of neurogenic detrusor overactivity, see: George et al. (2007).

Experimental top

The title compound was obtained unintentionally as the product of an attempted recrystallization of propantheline bromide (50 mg) in methanol (2 ml) at room temperature. Crystals resulted after 6 days; these were coated with Paratone N oil (Exxon Chemical Co., TX, USA) immediately after isolation and cooled in a stream of nitrogen vapour on the diffractometer. Melting point: 360.7 K.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: APEX2 (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: POV-RAY for Windows (Persistence of Vision, 1999); software used to prepare material for publication: PLATON (Spek, 2003).

Figures top

	Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level and hydrogen atoms as spheres of arbitrary radius.
	Fig. 2. A ball-and-stick representation of the unit-cell contents, viewed down the b axis.

Methyl 9H-xanthene-9-carboxylate top

Crystal data top

C₁₅H₁₂O₃	F(000) = 1008
M_r = 240.25	D_x = 1.372 Mg m⁻³
Monoclinic, C2/c	Melting point: 360.7 K
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 25.6601 (16) Å	Cell parameters from 1829 reflections
b = 5.7624 (3) Å	θ = 2.6–25.8°
c = 15.7578 (9) Å	µ = 0.10 mm⁻¹
β = 92.933 (4)°	T = 123 K
V = 2327.0 (2) Å³	Prismatic, colourless
Z = 8	0.50 × 0.50 × 0.50 mm

Data collection top

Bruker KappaAPEXII diffractometer	2672 independent reflections
Radiation source: fine-focus sealed tube	1985 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.050
0.5° frames in ϕ and ω scans	θ_max = 27.5°, θ_min = 1.6°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −33→33
T_min = 0.932, T_max = 0.954	k = −7→7
11906 measured reflections	l = −20→20

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.106	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.0212P)² + 2.7981P] where P = (F_o² + 2F_c²)/3
2672 reflections	(Δ/σ)_max < 0.001
166 parameters	Δρ_max = 0.20 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Crystal data top

C₁₅H₁₂O₃	V = 2327.0 (2) Å³
M_r = 240.25	Z = 8
Monoclinic, C2/c	Mo Kα radiation
a = 25.6601 (16) Å	µ = 0.10 mm⁻¹
b = 5.7624 (3) Å	T = 123 K
c = 15.7578 (9) Å	0.50 × 0.50 × 0.50 mm
β = 92.933 (4)°

Data collection top

Bruker KappaAPEXII diffractometer	2672 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	1985 reflections with I > 2σ(I)
T_min = 0.932, T_max = 0.954	R_int = 0.050
11906 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.050	0 restraints
wR(F²) = 0.106	H-atom parameters constrained
S = 1.06	Δρ_max = 0.20 e Å⁻³
2672 reflections	Δρ_min = −0.21 e Å⁻³
166 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
O1	0.33199 (5)	−0.0433 (2)	0.46758 (8)	0.0291 (4)
O3	0.44741 (5)	0.1331 (2)	0.55663 (8)	0.0317 (4)
C1	0.35919 (6)	0.0509 (3)	0.40209 (11)	0.0246 (4)
O2	0.46182 (5)	0.5104 (2)	0.57999 (10)	0.0460 (5)
C5	0.41061 (7)	0.3418 (3)	0.33969 (11)	0.0296 (5)
H5	0.4285	0.4860	0.3432	0.036*
C8	0.34065 (6)	0.3209 (3)	0.54356 (11)	0.0270 (5)
C14	0.43644 (7)	0.3568 (3)	0.54706 (11)	0.0269 (4)
C9	0.32151 (7)	0.4651 (4)	0.60572 (11)	0.0340 (5)
H9	0.3374	0.6117	0.6166	0.041*
C4	0.40994 (7)	0.2167 (4)	0.26464 (12)	0.0344 (5)
H4	0.4275	0.2744	0.2174	0.041*
C2	0.35812 (7)	−0.0765 (3)	0.32741 (11)	0.0296 (5)
H2	0.3400	−0.2202	0.3236	0.036*
C12	0.27490 (7)	0.0372 (4)	0.57561 (11)	0.0320 (5)
H12	0.2591	−0.1099	0.5653	0.038*
C10	0.27969 (7)	0.3977 (4)	0.65182 (12)	0.0404 (6)
H10	0.2668	0.4983	0.6936	0.048*
C11	0.25674 (7)	0.1837 (4)	0.63695 (12)	0.0383 (6)
H11	0.2282	0.1369	0.6691	0.046*
C3	0.38359 (7)	0.0071 (4)	0.25876 (12)	0.0336 (5)
H3	0.3831	−0.0792	0.2074	0.040*
C6	0.38552 (6)	0.2600 (3)	0.41010 (11)	0.0255 (4)
C7	0.38629 (7)	0.3930 (3)	0.49288 (11)	0.0265 (5)
H7	0.3828	0.5622	0.4796	0.032*
C13	0.31655 (6)	0.1086 (3)	0.52950 (11)	0.0266 (4)
C15	0.49380 (7)	0.0797 (4)	0.60921 (12)	0.0349 (5)
H15A	0.4911	0.1505	0.6654	0.052*
H15B	0.5245	0.1415	0.5825	0.052*
H15C	0.4972	−0.0889	0.6154	0.052*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0329 (7)	0.0252 (7)	0.0294 (7)	0.0015 (5)	0.0027 (5)	−0.0008 (5)
O3	0.0293 (7)	0.0257 (7)	0.0385 (8)	0.0029 (6)	−0.0121 (5)	−0.0011 (6)
C1	0.0234 (8)	0.0252 (10)	0.0251 (9)	0.0051 (7)	−0.0011 (7)	−0.0002 (7)
O2	0.0419 (8)	0.0328 (8)	0.0611 (10)	−0.0017 (7)	−0.0166 (7)	−0.0116 (7)
C5	0.0264 (9)	0.0298 (10)	0.0324 (10)	0.0028 (8)	−0.0027 (7)	0.0057 (8)
C8	0.0260 (9)	0.0296 (10)	0.0248 (9)	0.0088 (7)	−0.0044 (7)	−0.0016 (7)
C14	0.0281 (9)	0.0249 (10)	0.0276 (9)	0.0000 (8)	0.0010 (7)	−0.0043 (8)
C9	0.0329 (10)	0.0396 (12)	0.0284 (10)	0.0133 (9)	−0.0089 (8)	−0.0074 (8)
C4	0.0309 (10)	0.0457 (13)	0.0267 (10)	0.0086 (9)	0.0019 (7)	0.0050 (9)
C2	0.0288 (9)	0.0280 (10)	0.0314 (10)	0.0060 (8)	−0.0048 (7)	−0.0042 (8)
C12	0.0286 (9)	0.0384 (11)	0.0285 (10)	0.0052 (8)	−0.0038 (7)	0.0087 (8)
C10	0.0360 (10)	0.0603 (15)	0.0245 (10)	0.0203 (10)	−0.0028 (8)	−0.0072 (9)
C11	0.0298 (10)	0.0604 (15)	0.0246 (10)	0.0124 (10)	0.0005 (7)	0.0091 (9)
C3	0.0321 (10)	0.0426 (12)	0.0254 (10)	0.0111 (9)	−0.0044 (7)	−0.0061 (8)
C6	0.0248 (8)	0.0244 (10)	0.0267 (9)	0.0050 (7)	−0.0040 (7)	0.0002 (7)
C7	0.0310 (9)	0.0204 (9)	0.0277 (9)	0.0051 (7)	−0.0037 (7)	−0.0015 (7)
C13	0.0279 (9)	0.0303 (10)	0.0210 (9)	0.0082 (8)	−0.0030 (7)	0.0017 (7)
C15	0.0261 (9)	0.0417 (12)	0.0361 (11)	0.0036 (8)	−0.0071 (8)	0.0010 (9)

Geometric parameters (Å, º) top

O1—C13	1.384 (2)	C4—C3	1.385 (3)
O1—C1	1.386 (2)	C4—H4	0.9500
O3—C14	1.326 (2)	C2—C3	1.379 (3)
O3—C15	1.448 (2)	C2—H2	0.9500
C1—C6	1.384 (2)	C12—C11	1.382 (3)
C1—C2	1.386 (2)	C12—C13	1.385 (2)
O2—C14	1.201 (2)	C12—H12	0.9500
C5—C4	1.384 (3)	C10—C11	1.381 (3)
C5—C6	1.393 (2)	C10—H10	0.9500
C5—H5	0.9500	C11—H11	0.9500
C8—C13	1.384 (3)	C3—H3	0.9500
C8—C9	1.393 (2)	C6—C7	1.512 (2)
C8—C7	1.509 (2)	C7—H7	1.0000
C14—C7	1.522 (2)	C15—H15A	0.9800
C9—C10	1.382 (3)	C15—H15B	0.9800
C9—H9	0.9500	C15—H15C	0.9800

C13—O1—C1	116.79 (14)	C11—C10—H10	120.1
C14—O3—C15	115.78 (14)	C9—C10—H10	120.1
C6—C1—O1	122.37 (15)	C10—C11—C12	120.52 (18)
C6—C1—C2	121.80 (16)	C10—C11—H11	119.7
O1—C1—C2	115.83 (16)	C12—C11—H11	119.7
C4—C5—C6	121.21 (18)	C2—C3—C4	120.11 (17)
C4—C5—H5	119.4	C2—C3—H3	119.9
C6—C5—H5	119.4	C4—C3—H3	119.9
C13—C8—C9	117.98 (17)	C1—C6—C5	117.73 (16)
C13—C8—C7	120.76 (15)	C1—C6—C7	120.31 (16)
C9—C8—C7	121.26 (17)	C5—C6—C7	121.95 (16)
O2—C14—O3	124.06 (17)	C8—C7—C6	109.91 (15)
O2—C14—C7	124.42 (16)	C8—C7—C14	108.79 (14)
O3—C14—C7	111.45 (15)	C6—C7—C14	112.80 (14)
C10—C9—C8	120.9 (2)	C8—C7—H7	108.4
C10—C9—H9	119.6	C6—C7—H7	108.4
C8—C9—H9	119.6	C14—C7—H7	108.4
C5—C4—C3	119.72 (18)	C8—C13—O1	122.03 (15)
C5—C4—H4	120.1	C8—C13—C12	121.96 (17)
C3—C4—H4	120.1	O1—C13—C12	116.00 (17)
C3—C2—C1	119.42 (18)	O3—C15—H15A	109.5
C3—C2—H2	120.3	O3—C15—H15B	109.5
C1—C2—H2	120.3	H15A—C15—H15B	109.5
C11—C12—C13	118.81 (19)	O3—C15—H15C	109.5
C11—C12—H12	120.6	H15A—C15—H15C	109.5
C13—C12—H12	120.6	H15B—C15—H15C	109.5
C11—C10—C9	119.83 (18)

C13—O1—C1—C6	21.8 (2)	C13—C8—C7—C6	22.5 (2)
C13—O1—C1—C2	−157.71 (15)	C9—C8—C7—C6	−157.52 (16)
C15—O3—C14—O2	−1.3 (3)	C13—C8—C7—C14	−101.48 (18)
C15—O3—C14—C7	−178.43 (14)	C9—C8—C7—C14	78.5 (2)
C13—C8—C9—C10	0.0 (3)	C1—C6—C7—C8	−22.1 (2)
C7—C8—C9—C10	179.99 (16)	C5—C6—C7—C8	157.52 (16)
C6—C5—C4—C3	0.5 (3)	C1—C6—C7—C14	99.48 (19)
C6—C1—C2—C3	−0.5 (3)	C5—C6—C7—C14	−80.9 (2)
O1—C1—C2—C3	179.03 (15)	O2—C14—C7—C8	−105.6 (2)
C8—C9—C10—C11	0.6 (3)	O3—C14—C7—C8	71.48 (18)
C9—C10—C11—C12	−0.7 (3)	O2—C14—C7—C6	132.14 (19)
C13—C12—C11—C10	0.1 (3)	O3—C14—C7—C6	−50.7 (2)
C1—C2—C3—C4	0.0 (3)	C9—C8—C13—O1	178.26 (15)
C5—C4—C3—C2	0.0 (3)	C7—C8—C13—O1	−1.7 (2)
O1—C1—C6—C5	−178.53 (15)	C9—C8—C13—C12	−0.6 (3)
C2—C1—C6—C5	1.0 (2)	C7—C8—C13—C12	179.41 (16)
O1—C1—C6—C7	1.1 (2)	C1—O1—C13—C8	−21.5 (2)
C2—C1—C6—C7	−179.37 (15)	C1—O1—C13—C12	157.43 (15)
C4—C5—C6—C1	−1.0 (2)	C11—C12—C13—C8	0.5 (3)
C4—C5—C6—C7	179.39 (16)	C11—C12—C13—O1	−178.37 (15)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C15—H15C···O2ⁱ	0.98	2.53	3.407 (3)	149
C3—H3···Cg2ⁱⁱ	0.95	2.95	3.668 (2)	133
C11—H11···Cg1ⁱⁱⁱ	0.95	3.18	3.825 (2)	127
C15—H15B···Cg1^iv	0.98	3.06	3.432 (2)	104
C15—H15C···Cg1^iv	0.98	3.11	3.432 (2)	101

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

Experimental details

Crystal data
Chemical formula	C₁₅H₁₂O₃
M_r	240.25
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	123
a, b, c (Å)	25.6601 (16), 5.7624 (3), 15.7578 (9)
β (°)	92.933 (4)
V (Å³)	2327.0 (2)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.50 × 0.50 × 0.50

Data collection
Diffractometer	Bruker KappaAPEXII diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.932, 0.954
No. of measured, independent and observed [I > 2σ(I)] reflections	11906, 2672, 1985
R_int	0.050
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.050, 0.106, 1.06
No. of reflections	2672
No. of parameters	166
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.20, −0.21

Computer programs: APEX2 (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), POV-RAY for Windows (Persistence of Vision, 1999), PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C15—H15C···O2ⁱ	0.98	2.53	3.407 (3)	149
C3—H3···Cg2ⁱⁱ	0.95	2.95	3.668 (2)	133
C11—H11···Cg1ⁱⁱⁱ	0.95	3.18	3.825 (2)	127
C15—H15B···Cg1^iv	0.98	3.06	3.432 (2)	104
C15—H15C···Cg1^iv	0.98	3.11	3.432 (2)	101

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

Geometrical parameters (Å, °) of the inter-ring π—π interactions. α is the dihedral angle between planes I and J, CgI is the centroid of plane I and CgJ the centroid of plane J. top

CgI	CgJ	Cg···Cg	α	Symmetry position of CgJ
Cg1	Cg2	5.590 (1)	59.44	x,1-y,-1/2+z
Cg1	Cg2	4.944 (1)	24.81	1/2-x,1/2-y,1-z
Cg2	Cg1	4.863 (1)	59.44	x,-y,1/2+z
Cg2	Cg2	3.684 (1)	0.03	1/2-x,1/2-y,1-z

Notes: Cg1 is the centroid of ring C1/C6; Cg2 is the centroid of ring C8/C13.

Acknowledgements

PMD is grateful to Monash University for the Monash Graduate Scholarship and Monash International Postgraduate Research Scholarship, and to Monash University, School of Chemistry for funding for JT.

References

Avdovich, H. W., By, A. W., Ethier, J. C. & Neville, G. A. (1986). J. Forensic Sci. Soc. 19, 241–249. CrossRef CAS Google Scholar
Bruker (2005). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
George, J., Tharion, G., Richard, J., Macaden, A. S., Thomas, R. & Bhattacharji, S. (2007). The Scientific World Journal, 7, 1683–1690. CrossRef CAS Google Scholar
Persistence of Vision (1999). POV-RAY for Windows. Persistence of Vision Development Team, Victoria, Australia. 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