4′,5′,6′,7′-Tetra­chloro­spiro­[cyclo­hex-2-ene-1,2′-indan]-1′,3′-dione

McSweeney, N.; Pratt, A.C.; Long, C.; Howie, R.A.

doi:10.1107/S1600536805015904

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 61| Part 6| June 2005| Pages o1904-o1906

https://doi.org/10.1107/S1600536805015904

4′,5′,6′,7′-Tetrachlorospiro[cyclohex-2-ene-1,2′-indan]-1′,3′-dione

Nigel McSweeney,^a Albert C. Pratt,^a Conor Long ^a and R. Alan Howie ^b ^*

^aSchool of Chemical Sciences, Dublin City University, Dublin 9, Ireland, and ^bDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
^*Correspondence e-mail: r.a.howie@abdn.ac.uk

(Received 17 May 2005; accepted 18 May 2005; online 28 May 2005)

The title compound, C₁₄H₈Cl₄O₂, has been isolated following irradiation of a dichloromethane solution of N-acetyltetrachlorophthalimide and cyclohexene. The structure refinement is slightly compromised by the disorder over two positions of equal occupancy of a methylene group β to the spiro C atom.

Comment

The photochemistry of phthalimides has been extensively investigated over the past three decades and has yielded a rich diversity of molecular transformations, which have been reviewed by Kanaoka (1978 ), Coyle (1984 ) and Oelgemöller & Griesbeck (2002 ). Unsymmetrical 1,4-cycloaddition occurs across the benzo ring of N-benzoylphthalimide on irradiation in the presence of cyclohexene (McSweeney et al., 2005 ), and similar 1,4-photocycloaddition occurs between N-ethyl-3,4,5,6-tetrachlorophthalimide and cyclohexene (Grimley et al., 2005 ). The title compound, (I), and rel-(2S,7R)-8,9,11,12-tetrachlorotricyclo[6.2.2.0^2,7]dodeca-9,11-diene-1,10-dicarboximide, (II), are products of the photochemical reaction between N-acetyl-3,4,5,6-tetrachlorophthalimide, (III), and cyclohexene in dichloromethane. Compound (II) is simply a further example of a compound resulting from 1,4-cycloaddition but (I), the structure of which is presented here, is more unusual.

Formation of (I) most likely occurs via a sequence involving photoinitiated electron transfer/allylic proton transfer from cyclohexene to N-acetyltetrachlorophthalimide followed by radical coupling, to yield the corresponding cyclohexenyl carbinol. Subsequent thermal ring opening to give the corresponding acyclic imido ketone, followed by enolization and ring closure with elimination of acetamide, would yield the observed dione (I).

The molecule of (I) is shown in Fig. 1. The majority of the bond lengths and angles are as expected for a molecule of this kind, but some data relating to particular features of the molecular geometry are given in Table 1.

In the course of refinement, the methylene group β to the spiro C atom was found to be disordered over two sites of equal occupancy, C13A and C13B. It is to this disorder, and possible limitations in modelling it, that the surprising variation in the length of the bonds to C13A and C13B and the unusual C13B—C14—C1 angle of 119.3 (6)° are attributed. Prolonged and ultimately wholly unsuccessful attempts were made to investigate an alternative model for the disorder in this part of the molecule, in which the entire cyclohexene ring was disordered over two orientations related by rotation through 180° about the vector between atoms C1 and C12. The relevant torsion angles in Table 1 show that atoms C13A and C13B each lie at the apex of a triangular flap which adopts two orientations, one tilted above and one below the plane of the other atoms in the cyclohexene ring. Other torsion angles in Table 1 reveal that the five-membered ring defined by C1–C3/C8/C9 is puckered, with pucker parameters (Cremer & Pople, 1975 ) of Q₂ = 0.117 (5) Å and φ₂ = 348 (2)° corresponding most closely to a twist conformation with twist about the C9—C1 bond.

The packing of the molecules of (I) in the unit cell (Fig. 2) brings about overlap of the rings defined by atoms C3–C8 related in pairs by crystallographic centres of symmetry (symmetry code: 1 − x, 1 − y, 1 − z), in which the distance between the ring centroids, the perpendicular distance between the rings and the lateral displacement or slippage of the rings are 3.983, 3.624 and 1.652 Å, respectively. There are no other intermolecular contacts of any significance.

Figure 1
The molecular structure of (I)

. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small circles of arbitrary radii. The only component of the disorder noted elsewhere which is shown here is that which is compatible with C13A.

Figure 2
The unit-cell contents of (I)

. Displacement ellipsoids are drawn at the 10% probability level and H atoms have been omitted for clarity. Selected atoms are labelled. Atom C13A is the only representative of the disorder noted elsewhere which is shown here. [Symmetry codes (i) 1 − x, 1 − y, 1 − z; (ii) x, $[{1\over 2}]$ − y, $[{1\over 2}]$ + z; (iii) 1 − x, $[{1\over 2}]$ + y, $[{1\over 2}]$ − z.]

Experimental

Compound (I) was one of three products of the irradiation through Pyrex for 30 h of N-acetyl-3,4,5,6-tetrachlorophthalimide, (III), (3.08 g, 9.4 mmol) and cyclohexene (15.80 g, 192.7 mmol) in dichloromethane (300 ml). The solvents were removed under vacuum and the resulting mixture separated using a Chromatotron and a 4 mm plate. The eluent was a mixture of dichloromethane and light petroleum (b.p. 313–333 K) (2:98, increased stepwise to 60:40). This gave, in order of recovery from the plate, firstly compound (I), a yellow crystalline solid (15 mg, 5%), m.p. 401–404 K (from chloroform–light petroleum b.p. 363–373 K) [IR (ν_max, cm⁻¹): 2938 (aliphatic CH), 1749 (C=O), 1533 (C=C), 1284 and 1207; ¹H NMR (270 MHz, CDCl₃, δ, p.p.m.): 6.3 (1H, t of d, J = 9.9 Hz, J = 7.7 Hz), 5.3 (1H, d, J = 9.9 Hz) and 2.2–1.3 (6H, m, aliphatic H); ¹³C NMR (CDCl₃, δ, p.p.m.): 197.1 (carbonyl C) 142.0, 135.6, 135.1, 131.1, 119.8 (unsaturated C), 56.7 (quaternary C), 28.7, 23.9 and 17.7 (aliphatic C)], secondly a mixture of a minor product and (III) as a brown oil (25 mg), thirdly unreacted (III) (2.80 g, 8.6 mmol), identified by comparison of its IR spectrum with that of an authentic sample, and finally the 1,4-adduct, rel-(2S,7R)-8,9,11,12-tetrachlorotricyclo[6.2.2.0^2,7]dodeca-9,11-diene-1,10-dicarboximide, (II), (46 mg, 15%).

Crystal data

C₁₄H₈Cl₄O₂
M_r = 350.00
Monoclinic, P 2₁ /c
a = 10.707 (6) Å
b = 12.103 (8) Å
c = 10.800 (6) Å
β = 91.25 (5)°
V = 1399.2 (14) Å³
Z = 4
D_x = 1.662 Mg m⁻³
Mo Kα radiation
Cell parameters from 14 reflections
θ = 7.7–10.6°
μ = 0.84 mm⁻¹
T = 298 (2) K
Block, yellow
0.60 × 0.60 × 0.20 mm

Data collection

Nicolet P3 four-circle diffractometer
ω/2θ scans
Absorption correction: ψ scan(North et al., 1968 )T_min = 0.565, T_max = 0.845
3222 measured reflections
3222 independent reflections
1634 reflections with I > 2σ(I)
θ_max = 27.6°
h = 0 → 13
k = 0 → 15
l = −14 → 14
2 standard reflections every 50 reflections intensity decay: none

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.070
wR(F²) = 0.198
S = 0.99
3222 reflections
190 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.102P)²] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

C1—C10	1.521 (6)
C1—C9	1.524 (6)
C1—C14	1.525 (6)
C1—C2	1.525 (6)
C12—C13A	1.519 (8)
C12—C13B	1.495 (8)
C13A—C14	1.441 (8)
C13B—C14	1.449 (8)

C10—C1—C9	112.0 (4)
C10—C1—C14	112.4 (4)
C9—C1—C14	108.0 (4)
C10—C1—C2	112.7 (4)
C9—C1—C2	102.8 (3)
C14—C1—C2	108.4 (4)
C14—C13A—C12	114.8 (7)
C14—C13B—C12	115.8 (7)
C13A—C14—C1	115.1 (6)
C13B—C14—C1	119.3 (6)

C9—C1—C2—C3	−10.3 (4)
C1—C2—C3—C8	5.1 (4)
C2—C3—C8—C9	2.8 (5)
C3—C8—C9—C1	−9.6 (5)
C8—C9—C1—C2	11.9 (4)
C14—C1—C10—C11	−4.3 (7)
C1—C10—C11—C12	−2.4 (9)
C10—C11—C12—C13A	−16.1 (9)
C10—C11—C12—C13B	25.4 (9)
C13A—C14—C1—C10	31.2 (8)
C13B—C14—C1—C10	−14.3 (9)

The atom of the cyclohexene ring β to the spiro atom, C1, is disordered over two sites of equal occupancy, C13A and C13B, which results in corresponding disorder and partial occupancy for the H atoms on these C atoms and also on the neighbouring atoms, C12 and C14. During refinement, bond distances involving C13A and C13B were restrained to 1.50 (1) Å. H atoms were placed in calculated positions, taking full account of the disorder noted above, with C—H set to 0.93 and 0.97 Å for alkene and methylene H atoms, respectively, and refined with a riding model, with U_iso(H) = 1.2U_eq(C) in all cases.

Data collection: Nicolet P3 Software (Nicolet, 1980 ); cell refinement: Nicolet P3 Software; data reduction: RDNIC (Howie, 1980 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536805015904/lh6435sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536805015904/lh6435Isup2.hkl

Computing details top

Data collection: Nicolet P3 software (Nicolet, 1980); cell refinement: Nicolet P3 software; data reduction: RDNIC (Howie, 1980); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003).

4',5',6',7'-Tetrachlorospiro[cyclohex-2-ene-1,2'-indan]-1',3'-dione top

Crystal data top

C₁₄H₈Cl₄O₂	F(000) = 704
M_r = 350.00	D_x = 1.662 Mg m⁻³
Monoclinic, P2₁/c	Melting point = 401–404 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 10.707 (6) Å	Cell parameters from 14 reflections
b = 12.103 (8) Å	θ = 7.7–10.6°
c = 10.800 (6) Å	µ = 0.84 mm⁻¹
β = 91.25 (5)°	T = 298 K
V = 1399.2 (14) Å³	Block, yellow
Z = 4	0.60 × 0.60 × 0.20 mm

Data collection top

Nicolet P3 four-circle diffractometer	1634 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	R_int = 0.000
Graphite monochromator	θ_max = 27.6°, θ_min = 1.9°
ω/2θ scans	h = 0→13
Absorption correction: ψ scan (North et al., 1968)	k = 0→15
T_min = 0.565, T_max = 0.845	l = −14→14
3222 measured reflections	2 standard reflections every 50 reflections
3222 independent reflections	intensity decay: none

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)] = 0.070	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.198	H-atom parameters constrained
S = 0.99	w = 1/[σ²(F_o²) + (0.102P)²] where P = (F_o² + 2F_c²)/3
3222 reflections	(Δ/σ)_max < 0.001
190 parameters	Δρ_max = 0.35 e Å⁻³
4 restraints	Δρ_min = −0.31 e Å⁻³

Special details top

Experimental. Scan rates, dependent on prescan intensity (Ip), were in the range 58.6 (Ip>2500) to 5.33 (Ip<150) ° 2θ min^-1. Scan widths, dependent on 2θ, were in the range 2.4 to 2.7 ° 2θ. Stationary crystal, stationary counter background counts were taken on either side of the peak each for 25% of the total (peak plus background) count time.

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	Occ. (<1)
Cl1	0.42407 (12)	0.27220 (12)	0.56551 (12)	0.0807 (4)
Cl2	0.26701 (12)	0.39876 (13)	0.36470 (16)	0.0964 (5)
Cl3	0.39920 (16)	0.53456 (14)	0.16260 (14)	0.1076 (6)
Cl4	0.68790 (16)	0.54769 (13)	0.15811 (12)	0.0962 (5)
O1	0.9009 (3)	0.4407 (3)	0.3086 (3)	0.0906 (11)
O2	0.7026 (3)	0.2471 (3)	0.6235 (4)	0.0966 (12)
C1	0.8496 (4)	0.3105 (4)	0.4690 (4)	0.0613 (11)
C2	0.8224 (4)	0.3959 (4)	0.3681 (4)	0.0603 (11)
C3	0.6848 (4)	0.4098 (3)	0.3562 (4)	0.0512 (10)
C4	0.6158 (5)	0.4693 (3)	0.2691 (4)	0.0601 (11)
C5	0.4859 (5)	0.4653 (4)	0.2719 (4)	0.0669 (13)
C6	0.4279 (4)	0.4035 (4)	0.3622 (4)	0.0603 (11)
C7	0.4971 (4)	0.3466 (3)	0.4518 (4)	0.0547 (10)
C8	0.6262 (4)	0.3494 (3)	0.4455 (3)	0.0493 (9)
C9	0.7226 (4)	0.2951 (4)	0.5276 (4)	0.0618 (11)
C10	0.9483 (4)	0.3491 (4)	0.5627 (4)	0.0704 (13)
H10	0.9378	0.4171	0.6012	0.084*
C11	1.0475 (5)	0.2905 (5)	0.5912 (5)	0.0806 (15)
H11	1.1051	0.3211	0.6471	0.097*
C12	1.0753 (5)	0.1795 (4)	0.5418 (5)	0.0883 (16)
H12A	1.1062	0.1325	0.6085	0.106*	0.50
H12B	1.1401	0.1852	0.4807	0.106*	0.50
H12C	1.0471	0.1237	0.5993	0.106*	0.50
H12D	1.1649	0.1713	0.5337	0.106*	0.50
C13A	0.9592 (9)	0.1280 (8)	0.4827 (10)	0.082 (3)	0.50
H13A	0.9845	0.0660	0.4322	0.098*	0.50
H13B	0.9074	0.0992	0.5479	0.098*	0.50
C13B	1.0123 (9)	0.1623 (11)	0.4184 (8)	0.080 (3)	0.50
H13C	1.0615	0.1987	0.3560	0.096*	0.50
H13D	1.0126	0.0838	0.4001	0.096*	0.50
C14	0.8849 (5)	0.2020 (5)	0.4070 (6)	0.101 (2)
H14A	0.8088	0.1640	0.3815	0.121*	0.50
H14B	0.9307	0.2187	0.3327	0.121*	0.50
H14C	0.8310	0.1449	0.4391	0.121*	0.50
H14D	0.8649	0.2091	0.3193	0.121*	0.50

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0699 (8)	0.0889 (9)	0.0838 (8)	−0.0202 (7)	0.0105 (6)	0.0018 (7)
Cl2	0.0533 (7)	0.1046 (11)	0.1306 (13)	0.0062 (7)	−0.0184 (7)	−0.0185 (9)
Cl3	0.1207 (13)	0.1032 (12)	0.0969 (11)	0.0347 (9)	−0.0414 (9)	0.0129 (8)
Cl4	0.1232 (13)	0.1006 (11)	0.0647 (8)	−0.0101 (9)	0.0021 (8)	0.0265 (7)
O1	0.072 (2)	0.118 (3)	0.082 (2)	−0.032 (2)	0.0081 (19)	−0.001 (2)
O2	0.080 (2)	0.119 (3)	0.089 (3)	−0.012 (2)	−0.018 (2)	0.050 (2)
C1	0.049 (2)	0.068 (3)	0.066 (3)	0.001 (2)	−0.015 (2)	−0.012 (2)
C2	0.055 (3)	0.070 (3)	0.056 (3)	−0.014 (2)	0.000 (2)	−0.016 (2)
C3	0.059 (2)	0.051 (2)	0.043 (2)	−0.0055 (19)	−0.0059 (18)	−0.0110 (18)
C4	0.074 (3)	0.055 (3)	0.051 (2)	−0.006 (2)	−0.007 (2)	−0.005 (2)
C5	0.087 (4)	0.053 (3)	0.060 (3)	0.015 (2)	−0.024 (2)	−0.009 (2)
C6	0.054 (2)	0.055 (3)	0.071 (3)	0.001 (2)	−0.006 (2)	−0.020 (2)
C7	0.062 (3)	0.046 (2)	0.055 (2)	−0.0013 (19)	−0.001 (2)	−0.0098 (18)
C8	0.053 (2)	0.045 (2)	0.049 (2)	0.0008 (18)	−0.0028 (18)	−0.0078 (18)
C9	0.062 (3)	0.059 (3)	0.063 (3)	−0.004 (2)	−0.011 (2)	0.004 (2)
C10	0.057 (3)	0.071 (3)	0.083 (3)	−0.004 (2)	−0.018 (2)	−0.022 (3)
C11	0.060 (3)	0.104 (4)	0.077 (3)	−0.008 (3)	−0.014 (2)	−0.018 (3)
C12	0.074 (3)	0.082 (4)	0.108 (4)	0.009 (3)	−0.017 (3)	0.002 (3)
C13A	0.089 (9)	0.069 (7)	0.089 (8)	0.005 (6)	0.009 (7)	−0.016 (6)
C13B	0.086 (8)	0.090 (8)	0.063 (6)	0.019 (7)	−0.001 (6)	−0.007 (6)
C14	0.086 (4)	0.092 (4)	0.123 (5)	0.010 (3)	−0.025 (4)	−0.048 (4)

Geometric parameters (Å, º) top

Cl1—C7	1.724 (4)	C10—H10	0.9300
Cl2—C6	1.724 (5)	C11—C12	1.479 (7)
Cl3—C5	1.706 (5)	C11—H11	0.9300
Cl4—C4	1.725 (5)	C12—C13A	1.519 (8)
O1—C2	1.199 (5)	C12—C13B	1.495 (8)
O2—C9	1.211 (5)	C12—H12A	0.9700
C1—C10	1.521 (6)	C12—H12B	0.9700
C1—C9	1.524 (6)	C12—H12C	0.9700
C1—C14	1.525 (6)	C12—H12D	0.9700
C1—C2	1.525 (6)	C13A—C14	1.441 (8)
C2—C3	1.485 (6)	C13A—H13A	0.9700
C3—C8	1.373 (5)	C13A—H13B	0.9700
C3—C4	1.386 (6)	C13B—C14	1.449 (8)
C4—C5	1.392 (7)	C13B—H13C	0.9700
C5—C6	1.386 (7)	C13B—H13D	0.9700
C6—C7	1.389 (6)	C14—H14A	0.9700
C7—C8	1.386 (6)	C14—H14B	0.9700
C8—C9	1.498 (6)	C14—H14C	0.9700
C10—C11	1.308 (7)	C14—H14D	0.9700

C10—C1—C9	112.0 (4)	C11—C12—C13A	110.8 (6)
C10—C1—C14	112.4 (4)	C11—C12—C13B	111.0 (6)
C9—C1—C14	108.0 (4)	C11—C12—H12A	109.5
C10—C1—C2	112.7 (4)	C13A—C12—H12A	109.5
C9—C1—C2	102.8 (3)	C11—C12—H12B	109.5
C14—C1—C2	108.4 (4)	C13A—C12—H12B	109.5
O1—C2—C3	127.4 (5)	H12A—C12—H12B	108.1
O1—C2—C1	124.4 (4)	C11—C12—H12C	109.4
C3—C2—C1	108.2 (4)	C13B—C12—H12C	109.4
C8—C3—C4	120.5 (4)	C11—C12—H12D	109.4
C8—C3—C2	110.3 (4)	C13B—C12—H12D	109.4
C4—C3—C2	129.1 (4)	H12C—C12—H12D	108.0
C3—C4—C5	119.1 (4)	C14—C13A—C12	114.8 (7)
C3—C4—Cl4	121.2 (4)	C14—C13A—H13A	108.6
C5—C4—Cl4	119.8 (4)	C12—C13A—H13A	108.6
C6—C5—C4	119.8 (4)	C14—C13A—H13B	108.6
C6—C5—Cl3	120.4 (4)	C12—C13A—H13B	108.6
C4—C5—Cl3	119.8 (4)	H13A—C13A—H13B	107.5
C5—C6—C7	121.2 (4)	C14—C13B—C12	115.8 (7)
C5—C6—Cl2	119.5 (4)	C14—C13B—H13C	108.3
C7—C6—Cl2	119.3 (4)	C12—C13B—H13C	108.3
C8—C7—C6	118.1 (4)	C14—C13B—H13D	108.3
C8—C7—Cl1	121.1 (3)	C12—C13B—H13D	108.3
C6—C7—Cl1	120.8 (4)	H13C—C13B—H13D	107.4
C3—C8—C7	121.3 (4)	C13A—C14—C1	115.1 (6)
C3—C8—C9	109.2 (4)	C13B—C14—C1	119.3 (6)
C7—C8—C9	129.4 (4)	C13A—C14—H14A	108.5
O2—C9—C8	125.8 (4)	C1—C14—H14A	108.5
O2—C9—C1	126.2 (4)	C13A—C14—H14B	108.5
C8—C9—C1	108.1 (4)	C1—C14—H14B	108.5
C11—C10—C1	122.6 (4)	H14A—C14—H14B	107.5
C11—C10—H10	118.7	C13B—C14—H14C	107.5
C1—C10—H10	118.7	C1—C14—H14C	107.5
C10—C11—C12	125.2 (5)	C13B—C14—H14D	107.5
C10—C11—H11	117.4	C1—C14—H14D	107.5
C12—C11—H11	117.4	H14C—C14—H14D	107.0

C9—C1—C2—C3	−10.3 (4)	C10—C11—C12—C13B	25.4 (9)
C1—C2—C3—C8	5.1 (4)	C11—C12—C13A—C14	42.8 (11)
C2—C3—C8—C9	2.8 (5)	C11—C12—C13B—C14	−42.1 (12)
C3—C8—C9—C1	−9.6 (5)	C12—C13A—C14—C1	−51.8 (11)
C8—C9—C1—C2	11.9 (4)	C12—C13B—C14—C1	38.6 (14)
C14—C1—C10—C11	−4.3 (7)	C13A—C14—C1—C10	31.2 (8)
C1—C10—C11—C12	−2.4 (9)	C13B—C14—C1—C10	−14.3 (9)
C10—C11—C12—C13A	−16.1 (9)

Acknowledgements

NM thanks Dublin City University for a studentship.

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