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Acta Cryst. (2009). E65, m1343    [ doi:10.1107/S1600536809040537 ]

Tricarbonyl([eta]6-4',7-dimethoxyisoflavone)chromium(0)

J. H. van Tonder, B. C. B. Bezuidenhoudt and J. M. Janse van Rensburg

Abstract top

The metal atom of the Cr(CO)3 unit of the title compound, [Cr(C17H14O4)(CO)3], is coordinated to the methoxyphenyl ring of the isoflavone ligand; the Cr(CO)3 unit exhibits a three-legged piano-stool conformation. The aromatic ring of the methoxyphenyl group is twisted by 42.49 (9)° with respect to the [gamma]-pyrone ring. In the fused-ring, the dihedral angle between the phenylene and [gamma]-pyrone rings is 3.08 (13)°.

Comment top

Tricarbonyl(arene)chromium complexes have recieved much attention due to their use as intermediates in regioselective reactions (Dominique et al., 1999), as well as for their photochromic properties (Hannesschlager et al., 1999).

The title compound, (I), [Cr(CO)3(C17H14O4)], where (C17H14O4) = 4',7-dimethoxyisoflavone, crystallized in the monoclinic space group P21/c, with Z = 4 (Fig.1). For the title compound the molecular structure displays the Cr(CO)3 moiety complexation to the phenyl ring, exhibiting the known three-legged piano-stool conformation. This conformation is expected for a tricarbonyl-metal with an η6-coordinated arene. The Cr—C(arene) distances range from 2.188 (2) to 2.262 (2) Å. The longest Cr—C(arene) bond is Cr—C4', that in turn is bonded to the O4'—C41' methoxy group. This bond elongation is probably due to the methoxy group that weakens the π-interaction ability of C4' towards the chromium metal centre. The Cr-arene(centroid) distance is 1.7205 (4) Å. The Cr—C(carbonyl) bond distances range from 1.827 (3) to 1.855 (3) Å and the carbonyl distances of C11—O1, C12—O2 and C13—O3 are 1.158 (3), 1.154 (3) and 1.150 (3) Å respectively. These distances are within the normal range, see Allen (2002). The phenyl ring is essentialy planar (r.m.s of fitted atoms C1'-C6' = 0.0119 Å). Slight molecular disorder is displayed by a twist in the isoflavone backbone, that forms a dihedral angle of 42.49 (9)° between the phenyl and γ-pyrone ring and a dihedral angle of 41.1 (1)° between the phenyl and the benzopyrone ring system. A dihedral angle of 3.08 (13)° is also present between the benzene and the γ-pyrone ring, with a r.m.s of fitted atoms C2—C10 and O5 of 0.0387 Å. The O4'—C41' methoxy group on the phenyl ring bends towards the Cr(CO)3 moiety, forming the C5'-C4'-O4'-C41' tortion angle of 15.9 (4)°. The O7—C71 methoxy group on the benzene ring is also slightly displaced from the benzene ring plane, shown by the C8—C7—O7—C71 tortion angle of 175.0 (3)°. Other molecular geometrical parameters is in good agreement with literature values, see Allen (2002). Selected geometrical parameters is presented in Table 1.

As illustrated in Fig.2 the molecular packing is such that a benzene ring of one molecule is above the γ-pyrone ring of a neighbouring molecule, separated by a plane to plane distance of 3.369 Å and a centroid to centroid distance of 4.281 Å.

Related literature top

For tricarbonyl(arene)chromium complexes in regioselective reactions, see: Dominique et al. (1999). For their photochromic properties, see: Hannesschlager et al. (1999). For Cr(CO)3 complexation to the aromatic ring of flavanone, see: Dominique et al. (1999). For Cr(CO)3 complexation to (1,3-dimethoxybenzene), see: Zeller et al. (2004). For comparison bond distances, see: Allen (2002). For the synthesis of 4',7-dimethoxyisoflavone, see: Thakkar & Cushman (1995).

Experimental top

4',7-Dimethoxyisoflavone was prepared as previously described by Thakkar & Cushman (1995). A solution of 4',7-Dimethoxyisoflavone (1.28 g, 4.5 mmol) and Cr(CO)6 (1.00 g, 4.6 mmol: 1 eq.) in Bu2O:THF (9:1; 10 ml per 100 mg Cr(CO)6 was degassed with argon, using standard Schlenk techniques, and refluxed (48 h) under an oxygen free atmosphere. The reaction mixture was cooled to room temperature and the solvent evaporated in vacuo. Purification through flash column-chromatography yielded tricarbonyl(B-η6-4',7-dimethoxyisoflavone)-chromium(0) (0.48 g; 25.0%) as a yellow solid. Recrystallization from diethyl ether yielded yellow cuboidal crystals.

Rf 0.18 (Hexane: Acetone; 8:2); Mp 127.0 °C; Note: A, B and C-ring labelling refers to the benzene, phenyl and γ-pyrone rings respectively. 1H NMR (600 MHz, CDCl3) δ p.p.m. 8.15 (1H, d, J = 9.04 Hz, H-5), 8.09 (1H, s, H-2), 7.01 (1H, dd, J = 1.88, 9.04 Hz, H-6), 6.86 (1H, d, J = 1.88 Hz, H-8), 5.85 (2H, d, J = 6.78 Hz, H-2' and H-6'), 5.21 (2H, d, J = 6.78 Hz, H-3' and H-5'), 3.92 (3H, s, –OCH3), 3.75 (3H, s, –OCH3); 13C NMR (151 MHz, CDCl3) δ p.p.m. 55.88 (–OCH3), 56.06 (–OCH3), 77.37 (C-3' and C-5'), 94.71, 97.63 (C-2' and C-6'), 100.45 (C-8), 115.32 (C-6), 117.67, 121.16, 127.71 (C-5), 143.39 (C(i)-OCH3 B-ring), 154.78 (C-2), 158.07, 164.60, 175.26 (C-4), 232.89 (Cr—CO); MS (MS Scheme 3) m/z 362 (M+-2CO, 0.5%), 343 (2.1), 282 (100.0), 267 (20.8), 252 (3.0), 239 (10.9), 224 (3.7), 211 (3.8), 196 (3.5), 183 (1.2), 168 (2.9), 150 (12.9), 141 (6.1), 131 (69.5), 122 (10.7), 107 (7.9), 103 (2.4).

Refinement top

The H atoms were positioned geometrically and refined using a riding model with fixed C—H distances of 0.93 Å (CH) [Uiso(H) = 1.2Ueq] and 0.96 Å (CH3) [Uiso(H) = 1.5Ueq] respectively. Initial positions of methyl H-atoms were obtained from fourier difference and refined as a fixed rotor.

The highest density peak is 0.86 located 0.96 Å from O1 and the deepest hole is -0.41 located at 0.54 Å from Cr.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus (Bruker, 2004); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. A view of (I) showing the atom-numbering scheme with displacement ellipsoids at the 30% probability level.
[Figure 2] Fig. 2. Indication of molecular packing in the unit-cell. Symmetry operators 1) x; y; z. 2) x; 0.5 - y; -1/2 + z. 3) 1 - x; 1/2 + y; 1.5 - z. 4) 1 - x; 1 - y; 1 - z.
Tricarbonyl(η6-4',7-dimethoxyisoflavone)chromium(0) top
Crystal data top
[Cr(C17H14O4)(CO)3]F(000) = 856
Mr = 418.31Dx = 1.609 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3261 reflections
a = 12.3454 (7) Åθ = 2.8–28.3°
b = 17.9984 (8) ŵ = 0.71 mm−1
c = 7.9988 (4) ÅT = 173 K
β = 103.733 (2)°Block, yellow
V = 1726.50 (15) Å30.43 × 0.23 × 0.1 mm
Z = 4
Data collection top
Bruker APEXII CCD
diffractometer		4145 independent reflections
Radiation source: fine-focus sealed tube3393 reflections with I > 2σ(I)
graphiteRint = 0.027
φ and ω scansθmax = 28°, θmin = 1.7°
Absorption correction: multi-scan
(SADABS; Bruker, 2004)		h = −16→9
Tmin = 0.751, Tmax = 0.933k = −23→21
9320 measured reflectionsl = −10→9
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.044 w = 1/[σ2(Fo2) + (0.0453P)2 + 2.2801P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.117(Δ/σ)max < 0.001
S = 1.08Δρmax = 0.86 e Å−3
4145 reflectionsΔρmin = −0.41 e Å−3
255 parameters
Crystal data top
[Cr(C17H14O4)(CO)3]V = 1726.50 (15) Å3
Mr = 418.31Z = 4
Monoclinic, P21/cMo Kα radiation
a = 12.3454 (7) ŵ = 0.71 mm−1
b = 17.9984 (8) ÅT = 173 K
c = 7.9988 (4) Å0.43 × 0.23 × 0.1 mm
β = 103.733 (2)°
Data collection top
Bruker APEXII CCD
diffractometer		4145 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)		3393 reflections with I > 2σ(I)
Tmin = 0.751, Tmax = 0.933Rint = 0.027
9320 measured reflectionsθmax = 28°
Refinement top
R[F2 > 2σ(F2)] = 0.044H-atom parameters constrained
wR(F2) = 0.117Δρmax = 0.86 e Å−3
S = 1.08Δρmin = −0.41 e Å−3
4145 reflectionsAbsolute structure: ?
255 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Experimental. The intensity data was collected on a Bruker Apex II CCD diffractometer using an exposure time of 10 s/frame. The 509 frames were collected with a frame width of 0.5° covering up to θ = 28° with 99.4% completeness accomplished.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cr0.67866 (3)0.08506 (2)0.83271 (5)0.01520 (12)
C71−0.0137 (3)0.34474 (18)0.1743 (5)0.0415 (8)
H71A−0.01770.36060.290.062*
H71B−0.08450.35590.09260.062*
H71C0.04690.37130.14020.062*
C1'0.5514 (2)0.16695 (13)0.8698 (3)0.0170 (5)
C20.4317 (2)0.26583 (14)0.7185 (3)0.0210 (5)
H20.48590.29860.78380.025*
C2'0.6553 (2)0.20306 (14)0.8800 (3)0.0198 (5)
H2'0.65910.24320.80460.024*
C3'0.7524 (2)0.18039 (14)0.9997 (3)0.0212 (5)
H3'0.82080.20581.00660.025*
C30.4495 (2)0.19286 (14)0.7448 (3)0.0185 (5)
C40.3661 (2)0.13983 (14)0.6510 (3)0.0192 (5)
C4'0.7479 (2)0.11970 (14)1.1093 (3)0.0201 (5)
C50.1963 (2)0.13098 (15)0.4082 (4)0.0248 (6)
H50.20220.07840.41260.03*
C5'0.6471 (2)0.08121 (14)1.0971 (3)0.0182 (5)
H5'0.64420.03951.16880.022*
C60.1094 (2)0.16347 (16)0.2927 (4)0.0272 (6)
H60.05670.13360.21560.033*
C6'0.5506 (2)0.10521 (14)0.9775 (3)0.0185 (5)
H6'0.48280.07890.96920.022*
C70.0986 (2)0.24107 (16)0.2887 (4)0.0246 (6)
C80.1774 (2)0.28543 (15)0.3938 (4)0.0241 (6)
H80.17130.3380.38930.029*
C90.2667 (2)0.25058 (14)0.5070 (3)0.0196 (5)
C100.2769 (2)0.17415 (14)0.5204 (3)0.0196 (5)
C110.6772 (2)0.11149 (14)0.6116 (4)0.0224 (5)
C120.8108 (2)0.03640 (15)0.8470 (4)0.0252 (6)
C130.6030 (2)−0.00087 (14)0.7453 (3)0.0213 (5)
C41'0.8552 (3)0.03005 (17)1.2974 (4)0.0326 (7)
H41A0.80720.02771.37880.049*
H41B0.93280.02121.35870.049*
H41C0.8319−0.00791.20820.049*
O10.6770 (2)0.12958 (12)0.4726 (3)0.0362 (5)
O20.89489 (18)0.00706 (14)0.8540 (3)0.0461 (6)
O30.55781 (18)−0.05454 (11)0.6900 (3)0.0318 (5)
O4'0.84603 (16)0.10203 (11)1.2190 (2)0.0260 (4)
O40.36907 (17)0.07292 (10)0.6784 (3)0.0271 (4)
O50.34364 (15)0.29706 (10)0.6077 (2)0.0227 (4)
O70.00685 (17)0.26705 (12)0.1746 (3)0.0347 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cr0.0162 (2)0.01354 (19)0.0156 (2)−0.00044 (15)0.00332 (14)0.00014 (15)
C710.0309 (16)0.0381 (18)0.050 (2)0.0135 (14)−0.0004 (15)0.0107 (15)
C1'0.0199 (12)0.0159 (11)0.0154 (11)0.0018 (9)0.0048 (9)−0.0032 (9)
C20.0205 (12)0.0201 (12)0.0211 (12)0.0020 (10)0.0024 (10)0.0009 (10)
C2'0.0242 (13)0.0139 (11)0.0208 (12)−0.0011 (9)0.0047 (10)−0.0009 (9)
C3'0.0204 (12)0.0188 (12)0.0228 (13)−0.0029 (10)0.0020 (10)−0.0026 (10)
C30.0185 (12)0.0199 (12)0.0177 (12)0.0012 (9)0.0058 (10)0.0018 (10)
C40.0187 (12)0.0188 (12)0.0203 (12)0.0014 (9)0.0054 (10)0.0015 (10)
C4'0.0218 (12)0.0192 (12)0.0173 (12)0.0002 (10)0.0007 (10)−0.0037 (10)
C50.0249 (13)0.0200 (13)0.0277 (14)−0.0016 (10)0.0028 (11)0.0021 (11)
C5'0.0272 (13)0.0156 (11)0.0124 (11)0.0003 (10)0.0060 (9)0.0014 (9)
C60.0227 (13)0.0291 (14)0.0268 (14)−0.0044 (11)0.0002 (11)0.0029 (12)
C6'0.0191 (12)0.0193 (12)0.0179 (12)−0.0008 (9)0.0059 (10)−0.0012 (9)
C70.0173 (12)0.0293 (14)0.0269 (14)0.0042 (10)0.0049 (10)0.0086 (11)
C80.0241 (13)0.0209 (13)0.0268 (14)0.0044 (10)0.0049 (11)0.0062 (11)
C90.0187 (12)0.0215 (12)0.0190 (12)0.0012 (10)0.0051 (10)0.0006 (10)
C100.0187 (12)0.0198 (12)0.0209 (12)0.0004 (9)0.0056 (10)0.0027 (10)
C110.0237 (13)0.0178 (12)0.0247 (14)−0.0014 (10)0.0038 (10)−0.0025 (10)
C120.0245 (13)0.0227 (13)0.0260 (14)0.0002 (11)0.0013 (11)−0.0061 (11)
C130.0242 (13)0.0210 (13)0.0199 (12)−0.0013 (10)0.0073 (10)0.0001 (10)
C41'0.0289 (15)0.0312 (15)0.0324 (16)0.0028 (12)−0.0033 (12)0.0096 (13)
O10.0576 (15)0.0321 (11)0.0212 (10)−0.0032 (10)0.0140 (10)0.0037 (9)
O20.0268 (12)0.0449 (14)0.0615 (16)0.0122 (10)0.0002 (11)−0.0138 (12)
O30.0364 (12)0.0229 (10)0.0373 (12)−0.0090 (9)0.0110 (9)−0.0063 (9)
O4'0.0216 (9)0.0258 (10)0.0255 (10)−0.0009 (7)−0.0041 (8)0.0029 (8)
O40.0275 (10)0.0177 (9)0.0312 (11)−0.0030 (7)−0.0030 (8)0.0048 (8)
O50.0232 (9)0.0172 (9)0.0253 (10)0.0024 (7)0.0009 (8)0.0008 (7)
O70.0233 (10)0.0340 (12)0.0410 (13)0.0039 (8)−0.0038 (9)0.0103 (10)
Geometric parameters (Å, °) top
Cr—C111.827 (3)C4—C101.463 (3)
Cr—C121.831 (3)C4'—O4'1.354 (3)
Cr—C131.855 (3)C4'—C5'1.407 (4)
Cr—C2'2.188 (2)C5—C61.369 (4)
Cr—C6'2.200 (2)C5—C101.405 (4)
Cr—C1'2.225 (2)C5—H50.95
Cr—C3'2.231 (3)C5'—C6'1.407 (3)
Cr—C5'2.241 (2)C5'—H5'0.95
Cr—C4'2.262 (2)C6—C71.403 (4)
C71—O71.421 (4)C6—H60.95
C71—H71A0.98C6'—H6'0.95
C71—H71B0.98C7—O71.358 (3)
C71—H71C0.98C7—C81.379 (4)
C1'—C6'1.407 (3)C8—C91.398 (4)
C1'—C2'1.423 (3)C8—H80.95
C1'—C31.484 (3)C9—O51.374 (3)
C2—C31.340 (4)C9—C101.383 (4)
C2—O51.351 (3)C11—O11.158 (3)
C2—H20.95C12—O21.154 (3)
C2'—C3'1.406 (4)C13—O31.150 (3)
C2'—H2'0.95C41'—O4'1.432 (3)
C3'—C4'1.410 (4)C41'—H41A0.98
C3'—H3'0.95C41'—H41B0.98
C3—C41.472 (3)C41'—H41C0.98
C4—O41.223 (3)
C11—Cr—C1289.38 (12)C4'—C3'—Cr72.89 (14)
C11—Cr—C1387.92 (12)C2'—C3'—H3'120.2
C12—Cr—C1389.19 (12)C4'—C3'—H3'120.2
C11—Cr—C2'86.74 (11)Cr—C3'—H3'129.5
C12—Cr—C2'127.26 (11)C2—C3—C4119.1 (2)
C13—Cr—C2'143.03 (11)C2—C3—C1'119.7 (2)
C11—Cr—C6'128.55 (11)C4—C3—C1'121.2 (2)
C12—Cr—C6'141.88 (11)O4—C4—C10121.9 (2)
C13—Cr—C6'88.62 (10)O4—C4—C3124.0 (2)
C2'—Cr—C6'66.94 (10)C10—C4—C3114.0 (2)
C11—Cr—C1'96.39 (11)O4'—C4'—C5'124.7 (2)
C12—Cr—C1'162.83 (11)O4'—C4'—C3'115.1 (2)
C13—Cr—C1'107.12 (10)C5'—C4'—C3'120.2 (2)
C2'—Cr—C1'37.61 (9)O4'—C4'—Cr129.89 (18)
C6'—Cr—C1'37.09 (9)C5'—C4'—Cr70.96 (14)
C11—Cr—C3'106.73 (11)C3'—C4'—Cr70.53 (15)
C12—Cr—C3'95.71 (11)C6—C5—C10121.1 (3)
C13—Cr—C3'164.55 (11)C6—C5—H5119.4
C2'—Cr—C3'37.07 (9)C10—C5—H5119.4
C6'—Cr—C3'78.48 (10)C6'—C5'—C4'119.2 (2)
C1'—Cr—C3'67.15 (9)C6'—C5'—Cr69.97 (14)
C11—Cr—C5'163.24 (11)C4'—C5'—Cr72.62 (14)
C12—Cr—C5'106.15 (11)C6'—C5'—H5'120.4
C13—Cr—C5'98.36 (10)C4'—C5'—H5'120.4
C2'—Cr—C5'78.88 (9)Cr—C5'—H5'129.3
C6'—Cr—C5'36.93 (9)C5—C6—C7119.7 (3)
C1'—Cr—C5'66.93 (9)C5—C6—H6120.2
C3'—Cr—C5'66.21 (9)C7—C6—H6120.2
C11—Cr—C4'142.14 (11)C5'—C6'—C1'122.1 (2)
C12—Cr—C4'86.93 (11)C5'—C6'—Cr73.10 (14)
C13—Cr—C4'129.64 (11)C1'—C6'—Cr72.42 (14)
C2'—Cr—C4'66.30 (9)C5'—C6'—H6'119
C6'—Cr—C4'65.90 (9)C1'—C6'—H6'119
C1'—Cr—C4'78.58 (9)Cr—C6'—H6'127.7
C3'—Cr—C4'36.57 (9)O7—C7—C8124.4 (3)
C5'—Cr—C4'36.43 (9)O7—C7—C6114.7 (3)
O7—C71—H71A109.5C8—C7—C6120.9 (2)
O7—C71—H71B109.5C7—C8—C9117.9 (2)
H71A—C71—H71B109.5C7—C8—H8121
O7—C71—H71C109.5C9—C8—H8121
H71A—C71—H71C109.5O5—C9—C10121.5 (2)
H71B—C71—H71C109.5O5—C9—C8115.8 (2)
C6'—C1'—C2'117.5 (2)C10—C9—C8122.7 (2)
C6'—C1'—C3122.2 (2)C9—C10—C5117.6 (2)
C2'—C1'—C3120.2 (2)C9—C10—C4121.0 (2)
C6'—C1'—Cr70.49 (14)C5—C10—C4121.4 (2)
C2'—C1'—Cr69.80 (14)O1—C11—Cr178.7 (2)
C3—C1'—Cr129.11 (17)O2—C12—Cr178.4 (3)
C3—C2—O5126.0 (2)O3—C13—Cr178.8 (2)
C3—C2—H2117O4'—C41'—H41A109.5
O5—C2—H2117O4'—C41'—H41B109.5
C3'—C2'—C1'121.2 (2)H41A—C41'—H41B109.5
C3'—C2'—Cr73.13 (15)O4'—C41'—H41C109.5
C1'—C2'—Cr72.59 (14)H41A—C41'—H41C109.5
C3'—C2'—H2'119.4H41B—C41'—H41C109.5
C1'—C2'—H2'119.4C4'—O4'—C41'117.5 (2)
Cr—C2'—H2'126.9C2—O5—C9117.9 (2)
C2'—C3'—C4'119.7 (2)C7—O7—C71117.4 (2)
C2'—C3'—Cr69.80 (14)
C11—Cr—C1'—C6'153.08 (16)C5'—Cr—C4'—O4'119.8 (3)
C12—Cr—C1'—C6'−97.9 (4)C11—Cr—C4'—C5'152.16 (18)
C13—Cr—C1'—C6'63.30 (16)C12—Cr—C4'—C5'−122.82 (17)
C2'—Cr—C1'—C6'−130.8 (2)C13—Cr—C4'—C5'−36.4 (2)
C3'—Cr—C1'—C6'−101.42 (16)C2'—Cr—C4'—C5'103.89 (16)
C5'—Cr—C1'—C6'−28.66 (14)C6'—Cr—C4'—C5'29.69 (14)
C4'—Cr—C1'—C6'−64.94 (15)C1'—Cr—C4'—C5'66.45 (15)
C11—Cr—C1'—C2'−76.17 (16)C3'—Cr—C4'—C5'133.3 (2)
C12—Cr—C1'—C2'32.8 (4)C11—Cr—C4'—C3'18.8 (2)
C13—Cr—C1'—C2'−165.95 (15)C12—Cr—C4'—C3'103.85 (17)
C6'—Cr—C1'—C2'130.8 (2)C13—Cr—C4'—C3'−169.74 (16)
C3'—Cr—C1'—C2'29.33 (15)C2'—Cr—C4'—C3'−29.44 (15)
C5'—Cr—C1'—C2'102.09 (16)C6'—Cr—C4'—C3'−103.64 (17)
C4'—Cr—C1'—C2'65.82 (15)C1'—Cr—C4'—C3'−66.88 (16)
C11—Cr—C1'—C336.9 (2)C5'—Cr—C4'—C3'−133.3 (2)
C12—Cr—C1'—C3145.9 (4)O4'—C4'—C5'—C6'−180.0 (2)
C13—Cr—C1'—C3−52.9 (2)C3'—C4'—C5'—C6'−1.6 (4)
C2'—Cr—C1'—C3113.1 (3)Cr—C4'—C5'—C6'−54.1 (2)
C6'—Cr—C1'—C3−116.1 (3)O4'—C4'—C5'—Cr−125.9 (3)
C3'—Cr—C1'—C3142.4 (2)C3'—C4'—C5'—Cr52.5 (2)
C5'—Cr—C1'—C3−144.8 (2)C11—Cr—C5'—C6'34.8 (4)
C4'—Cr—C1'—C3178.9 (2)C12—Cr—C5'—C6'−167.93 (16)
C6'—C1'—C2'—C3'−3.3 (4)C13—Cr—C5'—C6'−76.34 (16)
C3—C1'—C2'—C3'178.8 (2)C2'—Cr—C5'—C6'66.23 (15)
Cr—C1'—C2'—C3'−56.9 (2)C1'—Cr—C5'—C6'28.78 (14)
C6'—C1'—C2'—Cr53.6 (2)C3'—Cr—C5'—C6'102.91 (16)
C3—C1'—C2'—Cr−124.3 (2)C4'—Cr—C5'—C6'131.2 (2)
C11—Cr—C2'—C3'−123.62 (17)C11—Cr—C5'—C4'−96.4 (4)
C12—Cr—C2'—C3'−36.9 (2)C12—Cr—C5'—C4'60.89 (17)
C13—Cr—C2'—C3'154.20 (18)C13—Cr—C5'—C4'152.48 (16)
C6'—Cr—C2'—C3'101.74 (17)C2'—Cr—C5'—C4'−64.95 (15)
C1'—Cr—C2'—C3'131.5 (2)C6'—Cr—C5'—C4'−131.2 (2)
C5'—Cr—C2'—C3'65.04 (16)C1'—Cr—C5'—C4'−102.40 (16)
C4'—Cr—C2'—C3'29.07 (15)C3'—Cr—C5'—C4'−28.27 (14)
C11—Cr—C2'—C1'104.87 (16)C10—C5—C6—C7−1.7 (4)
C12—Cr—C2'—C1'−168.40 (16)C4'—C5'—C6'—C1'−0.4 (4)
C13—Cr—C2'—C1'22.7 (2)Cr—C5'—C6'—C1'−55.7 (2)
C6'—Cr—C2'—C1'−29.77 (14)C4'—C5'—C6'—Cr55.4 (2)
C3'—Cr—C2'—C1'−131.5 (2)C2'—C1'—C6'—C5'2.8 (4)
C5'—Cr—C2'—C1'−66.47 (15)C3—C1'—C6'—C5'−179.4 (2)
C4'—Cr—C2'—C1'−102.44 (16)Cr—C1'—C6'—C5'56.1 (2)
C1'—C2'—C3'—C4'1.5 (4)C2'—C1'—C6'—Cr−53.3 (2)
Cr—C2'—C3'—C4'−55.2 (2)C3—C1'—C6'—Cr124.6 (2)
C1'—C2'—C3'—Cr56.7 (2)C11—Cr—C6'—C5'−167.85 (15)
C11—Cr—C3'—C2'60.24 (18)C12—Cr—C6'—C5'19.0 (2)
C12—Cr—C3'—C2'151.31 (17)C13—Cr—C6'—C5'105.92 (16)
C13—Cr—C3'—C2'−100.7 (4)C2'—Cr—C6'—C5'−102.57 (16)
C6'—Cr—C3'—C2'−66.83 (16)C1'—Cr—C6'—C5'−132.7 (2)
C1'—Cr—C3'—C2'−29.73 (15)C3'—Cr—C6'—C5'−65.54 (15)
C5'—Cr—C3'—C2'−103.53 (17)C4'—Cr—C6'—C5'−29.31 (14)
C4'—Cr—C3'—C2'−131.7 (2)C11—Cr—C6'—C1'−35.1 (2)
C11—Cr—C3'—C4'−168.06 (16)C12—Cr—C6'—C1'151.72 (18)
C12—Cr—C3'—C4'−76.99 (17)C13—Cr—C6'—C1'−121.35 (16)
C13—Cr—C3'—C4'31.0 (5)C2'—Cr—C6'—C1'30.16 (14)
C2'—Cr—C3'—C4'131.7 (2)C3'—Cr—C6'—C1'67.20 (15)
C6'—Cr—C3'—C4'64.87 (16)C5'—Cr—C6'—C1'132.7 (2)
C1'—Cr—C3'—C4'101.97 (17)C4'—Cr—C6'—C1'103.42 (16)
C5'—Cr—C3'—C4'28.17 (15)C5—C6—C7—O7−177.2 (3)
O5—C2—C3—C4−2.0 (4)C5—C6—C7—C83.3 (4)
O5—C2—C3—C1'179.2 (2)O7—C7—C8—C9179.0 (3)
C6'—C1'—C3—C2142.3 (3)C6—C7—C8—C9−1.6 (4)
C2'—C1'—C3—C2−39.9 (4)C7—C8—C9—O5179.3 (2)
Cr—C1'—C3—C2−127.5 (2)C7—C8—C9—C10−1.8 (4)
C6'—C1'—C3—C4−36.6 (3)O5—C9—C10—C5−177.9 (2)
C2'—C1'—C3—C4141.3 (2)C8—C9—C10—C53.3 (4)
Cr—C1'—C3—C453.6 (3)O5—C9—C10—C44.3 (4)
C2—C3—C4—O4−172.4 (3)C8—C9—C10—C4−174.6 (2)
C1'—C3—C4—O46.4 (4)C6—C5—C10—C9−1.5 (4)
C2—C3—C4—C107.1 (4)C6—C5—C10—C4176.3 (3)
C1'—C3—C4—C10−174.1 (2)O4—C4—C10—C9171.3 (3)
C2'—C3'—C4'—O4'179.6 (2)C3—C4—C10—C9−8.3 (4)
Cr—C3'—C4'—O4'125.8 (2)O4—C4—C10—C5−6.5 (4)
C2'—C3'—C4'—C5'1.1 (4)C3—C4—C10—C5174.0 (2)
Cr—C3'—C4'—C5'−52.7 (2)C5'—C4'—O4'—C41'15.9 (4)
C2'—C3'—C4'—Cr53.8 (2)C3'—C4'—O4'—C41'−162.6 (2)
C11—Cr—C4'—O4'−88.0 (3)Cr—C4'—O4'—C41'−77.7 (3)
C12—Cr—C4'—O4'−3.0 (2)C3—C2—O5—C9−2.6 (4)
C13—Cr—C4'—O4'83.4 (3)C10—C9—O5—C21.4 (4)
C2'—Cr—C4'—O4'−136.3 (3)C8—C9—O5—C2−179.7 (2)
C6'—Cr—C4'—O4'149.5 (3)C8—C7—O7—C71−5.5 (4)
C1'—Cr—C4'—O4'−173.8 (2)C6—C7—O7—C71175.0 (3)
C3'—Cr—C4'—O4'−106.9 (3)
Acknowledgements top

Financial assistance from the University of the Free State and SASOL to JHvT is gratefully acknowledged. Opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of SASOL. We would like to express our gratitude to the School of Chemistry at the University of the Witwatersrand for the use of the diffractometer. Special thanks are due to Dr M .A. Fernandes.

references
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