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Acta Cryst. (2010). E66, m907-m908    [ doi:10.1107/S1600536810024992 ]

Racemic tricarbonyl([eta]6-7-methoxyflavan)chromium(0)

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

Abstract top

In the title compound [systematic name: tricarbonyl([eta]6-7-methoxy-2-phenyl-3,4-dihydro-2H-1-benzopyran)chromium(0)], [Cr(C16H16O2)(CO)3], the Cr(CO)3 unit is coordinated by the phenylene ring of the flavan ligand, exhibiting a three-legged piano-stool conformation, with a point to plane distance of 1.750 (1) Å. The phenyl ring is twisted away from the fused ring system by 36.49 (5)° (r.m.s. deviation = 0.027 Å; fitted atoms are the C6 ring and the attached fused-ring C and O atoms). The dihydropyran ring displays a distorted envelope configuration by displacement of the phenyl-bearing and the adjacent ring C atoms from the fused-ring system plane by 0.356 (2) and 0.402 (2) Å, respectively.

Comment top

The title compound, (I), [Cr(C16H16O2)(CO)3], where (C16H16O2) = 7-methoxyflavan, has been examined due to the general biological activity of flavanoids (Rice-Evans & Packer, 2003) and the use of tricarbonyl(arene)chromium complexes in regioselective organic synthesis (Muschalek et al., 2007).

As with the tricarbonyl(η6-flavanone)chromium(0) complex reported by Dominique et al. (1999), the Cr(CO)3 unit of the title compound is coordinated by the phenylene ring of the flavanoid backbone (Fig.1). The chromium metal centre is displaced by 1.750 (1) Å from the A-η6-coordinated arene ring centre. The dihydropyran ring displays a distorted envelope configuration by displacement of atoms C2 and C3 from the fused ring system plane, with distances of 0.356 (2) and 0.402 (2) Å respectively (r.m.s. of fitted atoms C4, C10, C5, C6, C7, C8, C9 and O5 = 0.027 °). Further molecular disorder is displayed by the phenyl ring twist away from the fused ring system plane, by 36.49 (5)°.

The molecular packing displays two types of soft intermolecular contacts, this between O2···H8 [2.682 (1) Å] forming a O2···H8—C8 angle of 152.5 (1)° and O1···H6 [2.459 (1) Å] forming a O1···H6—C6 angle of 125.9 (1)° (Fig.2).

Related literature top

7-Methoxyflavan was synthesized via hydrogenation from 7-methoxyflavanone, as described by Sato et al. (2006). For coordination of 7-methoxyflavan to chromium, see: Müller et al. (1999). The importance of flavonoids in biological investigations is described in Rice-Evans & Packer (2003). For Cr(CO)3 coordination to the phenylene ring of a flavanone compound, see: Dominique et al. (1999). For comparison bond distances, see: Allen et al. (1987). For related structures, see: van Tonder et al. (2009a,b). For the use of tricarbonyl(arene)chromium complexes in regioselective organic synthesis, see: Muschalek et al. (2007).

Experimental top

7-Methoxyflavan was synthesised via H2SO4 catalyzed hydrogenation (5 bar) over 10% Pd/C from 7-methoxyflavanone, as described by Sato et al. (2006). 7-Methoxyflavan-4-one (1.00 g; 3.9 mmol), 10 % Pd/C (0.10 g), 3 M H2SO4 (aq.) (1 ml), EtOH (30 ml). Purification by means of flash column-chromatography yielded 7-methoxyflavan (0.67 g; 70.6%) as a colourless oil.

Rf 0.65 (H:DCM:EtOAc; 50:50:1); 1H NMR (600 MHz, CDCl3) δ ppm 7.44 – 7.41 (2H, m, H-2' and H-6'), 7.40 – 7.37 (2H, m, H-3' and H-5'), 7.34 – 7.31 (1H, m, H-4'), 6.99 – 6.97 (1H, m, H-5), 6.50 – 6.47 (2H, m, H-6 and H-8), 5.05 (1H, dd, J = 2.37, 10.19 Hz, H-2), 3.77 (3H, s, -OCH3), 2.92 (1H, ddd, J = 6.02, 10.92, 16.08 Hz, H-4(a)), 2.74 (1H, ddd, J = 3.40, 5.12, 16.08 Hz, H-4(e)), 2.22 – 2.18 (1H, m, H-3), 2.11– 2.04 (1H, m, H-3); 13C NMR (600 MHz, CDCl3) δ ppm 24.47 (C-4), 30.19 (C-3), 55.38 (-OCH3), 77.98 (C-2), 101.71 (C-6/8), 107.54 (C-6/8), 114.01, 126.11, 127.93, 128.61, 130.05, 141.79, 155.91, 155.91, 159.23

Preparation of the title compound, tricarbonyl(A-η6-7-methoxyflavane)chromium(0), was based on a method described by Müller et al. (1999). A solution of 7-Methoxyflavane (0.27 g, 1.1 mmol) and Cr(CO)6 (0.25 g, 1.1 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(A-η6-7-methoxyflavane)chromium(0) (0.07 g; 16.6.0%) as a yellow solid. Recrystallization from diethyl ether yielded yellow cuboidal crystals.

Rf 0.23 (Hexane: Acetone; 8:2); Mp 148.4 °C; Note: A, B and C-ring labelling refers to the benzene, phenyl and dihydropyrane rings respectively. 1H NMR (600 MHz, CDCl3) δ ppm 7.49 (2H, d, J = 7.15 Hz, H-2' and H-6'), 7.41 (2H, dd, J = 7.15, 8.66 Hz, H-3' and H-5'), 7.39 – 7.35 (1H, m, H-4'), 5.65 (1H, d, J = 6.61 Hz, H-5), 5.15 (1H, s, H-8), 4.90 – 4.86 (2H, m, H-2 and H-6), 3.72 (3H, s, -OCH3), 2.93 (1H, ddd, J = 4.89, 12.43, 15.65 Hz, H-4(a)), 2.54 (1H, dd, J = 4.14, 15.65 Hz, H-4(e)), 2.31 (1H, ddd, J = 4.14, 12.43, 13.68 Hz, H-3(a)), 2.13 (1H, dd, J = 4.89, 13.68 Hz, H-3(e)); 13C NMR (600 MHz, CDCl3) δ ppm 25.52 (C-4), 29.52 (C-3), 55.86 (-OCH3), 68.31 (C-8), 74.42 (C-2/6), 80.56 (C-2/6), 89.11, 94.55 (C-5), 126.61, 128.83, 128.89, 139.62, 140.30, 143.33, 234.44 (-Cr(CO)3); MS m/z 376 (M+, 13.0), 344 (0.2), 320 (0.1), 292 (70.7), 277 (0.2), 256 (0.1), 240 (5.8), 225 (0.5), 209 (0.3), 188 (100.0), 173 (0.4), 146 (10.0), 137 (2.1), 121 (2.0), 104 (5.1).

Refinement top

The H atoms were positioned geometrically and refined using a riding model with fixed C—H distances of 0.93 Å (ArH) [Uiso(H) = 1.2Ueq], 1.00 Å (CH) [Uiso(H) = 1.2Ueq], 0.99 Å (CH2) [Uiso(H) = 1.2Ueq] and 0.96 Å (CH3) [Uiso(H) = 1.5Ueq]. Initial positions of methyl H-atoms were obtained from fourier difference and refined as a fixed rotor.

The highest density peak is 0.25 located 0.66 Å from C1' and the deepest hole is -0.40 located at 0.50 Å from Cr.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus and XPREP (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) 1 - x; 0.5 + y; 1.5 - z.
tricarbonyl(η6-7-methoxy-2-phenyl-3,4-dihydro-2H- 1-benzopyran)chromium(0) top
Crystal data top
[Cr(C16H16O2)(CO)3]F(000) = 776
Mr = 376.32Dx = 1.509 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 5285 reflections
a = 9.8422 (2) Åθ = 2.2–28.3°
b = 12.3850 (3) ŵ = 0.72 mm−1
c = 15.0146 (3) ÅT = 173 K
β = 115.171 (1)°Prism, yellow
V = 1656.42 (6) Å30.41 × 0.34 × 0.24 mm
Z = 4
Data collection top
Bruker APEXII CCD
diffractometer		3224 reflections with I > 2σ(I)
φ and ω scansRint = 0.030
Absorption correction: multi-scan
(Bruker, 2004)		θmax = 28°, θmin = 2.2°
Tmin = 0.757, Tmax = 0.847h = −11→12
12982 measured reflectionsk = −16→16
3985 independent reflectionsl = −19→19
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.030 w = 1/[σ2(Fo2) + (0.0444P)2 + 0.0884P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.085(Δ/σ)max = 0.001
S = 1.07Δρmax = 0.25 e Å−3
3985 reflectionsΔρmin = −0.40 e Å−3
227 parameters
Crystal data top
[Cr(C16H16O2)(CO)3]V = 1656.42 (6) Å3
Mr = 376.32Z = 4
Monoclinic, P21/cMo Kα radiation
a = 9.8422 (2) ŵ = 0.72 mm−1
b = 12.3850 (3) ÅT = 173 K
c = 15.0146 (3) Å0.41 × 0.34 × 0.24 mm
β = 115.171 (1)°
Data collection top
Bruker APEXII CCD
diffractometer		3985 independent reflections
Absorption correction: multi-scan
(Bruker, 2004)		3224 reflections with I > 2σ(I)
Tmin = 0.757, Tmax = 0.847Rint = 0.030
12982 measured reflectionsθmax = 28°
Refinement top
R[F2 > 2σ(F2)] = 0.030H-atom parameters constrained
wR(F2) = 0.085Δρmax = 0.25 e Å−3
S = 1.07Δρmin = −0.40 e Å−3
3985 reflectionsAbsolute structure: ?
227 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Experimental. The intensity data was collected on a Bruker Apex II CCD diffractometer using a frame width of 0.5° covering up to θ = 28° with 100 % completeness accomplished.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C1'1.01976 (18)0.59116 (14)0.84890 (12)0.0260 (3)
C2'0.9566 (2)0.69062 (15)0.85055 (13)0.0325 (4)
H2'0.85060.69880.82130.039*
C20.92726 (18)0.49179 (14)0.80339 (12)0.0268 (4)
H20.97030.45530.76180.032*
C3'1.0487 (2)0.77884 (16)0.89526 (14)0.0385 (4)
H3'1.00520.84710.89580.046*
C30.92236 (18)0.41073 (13)0.87814 (12)0.0276 (4)
H3A0.87550.44430.91810.033*
H3B1.02570.38860.9230.033*
C40.83175 (18)0.31200 (14)0.82448 (12)0.0272 (4)
H4A0.89080.26870.7980.033*
H4B0.81070.26630.87130.033*
C4'1.2029 (2)0.76723 (16)0.93867 (13)0.0380 (4)
H4'1.26540.82720.96960.046*
C5'1.2657 (2)0.66846 (16)0.93694 (13)0.0360 (4)
H5'1.37170.66030.9670.043*
C50.56441 (18)0.27492 (13)0.69612 (12)0.0260 (4)
H50.57230.20370.72140.031*
C60.43161 (18)0.30503 (13)0.61485 (12)0.0263 (3)
H60.35320.25410.58420.032*
C6'1.17553 (18)0.58135 (15)0.89185 (12)0.0295 (4)
H6'1.22010.51380.890.035*
C70.41667 (18)0.41122 (13)0.57975 (11)0.0247 (3)
C80.53223 (18)0.48677 (13)0.62755 (12)0.0251 (3)
H80.51830.56060.60850.03*
C90.66817 (17)0.45213 (14)0.70352 (12)0.0242 (3)
C100.68615 (17)0.34612 (13)0.74146 (12)0.0237 (3)
C110.56076 (19)0.50205 (13)0.85013 (13)0.0269 (4)
C120.42375 (19)0.32289 (14)0.82151 (13)0.0295 (4)
C130.29284 (19)0.48252 (14)0.70530 (13)0.0298 (4)
C710.17072 (19)0.37892 (16)0.45371 (13)0.0335 (4)
H71A0.20290.31810.42550.05*
H71B0.08940.41790.4010.05*
H71C0.13490.35180.50130.05*
O10.61634 (16)0.55726 (10)0.91861 (10)0.0436 (4)
O20.39278 (16)0.26735 (12)0.87217 (10)0.0486 (4)
O30.17872 (15)0.52563 (12)0.67906 (11)0.0482 (4)
O50.77684 (12)0.52853 (9)0.73998 (9)0.0305 (3)
O70.29490 (12)0.45045 (10)0.50235 (8)0.0303 (3)
Cr0.47389 (3)0.413031 (19)0.743218 (18)0.01990 (9)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C1'0.0229 (8)0.0363 (9)0.0193 (8)−0.0040 (7)0.0096 (7)0.0017 (7)
C2'0.0282 (9)0.0401 (10)0.0317 (10)−0.0012 (8)0.0152 (8)0.0017 (8)
C20.0198 (8)0.0364 (9)0.0228 (8)−0.0006 (7)0.0077 (7)0.0013 (7)
C3'0.0494 (11)0.0344 (10)0.0391 (11)−0.0015 (9)0.0259 (10)0.0000 (8)
C30.0239 (8)0.0319 (9)0.0230 (8)0.0030 (7)0.0062 (7)0.0046 (7)
C40.0241 (8)0.0281 (8)0.0265 (9)0.0044 (7)0.0079 (7)0.0039 (7)
C4'0.0444 (11)0.0425 (11)0.0286 (10)−0.0176 (9)0.0170 (9)−0.0023 (8)
C5'0.0278 (9)0.0524 (12)0.0263 (9)−0.0110 (9)0.0100 (8)0.0034 (8)
C50.0286 (8)0.0203 (8)0.0280 (9)0.0025 (7)0.0110 (7)−0.0027 (6)
C60.0261 (8)0.0254 (8)0.0256 (8)−0.0011 (7)0.0092 (7)−0.0063 (7)
C6'0.0248 (8)0.0389 (10)0.0247 (9)−0.0013 (7)0.0105 (7)0.0037 (7)
C70.0209 (8)0.0331 (9)0.0195 (8)0.0020 (7)0.0081 (6)0.0009 (7)
C80.0243 (8)0.0279 (8)0.0232 (8)−0.0002 (7)0.0102 (7)0.0061 (7)
C90.0211 (8)0.0306 (8)0.0216 (8)−0.0023 (7)0.0098 (7)0.0017 (7)
C100.0229 (8)0.0258 (8)0.0227 (8)0.0021 (6)0.0101 (7)−0.0003 (6)
C110.0281 (9)0.0203 (8)0.0292 (9)0.0040 (7)0.0090 (7)0.0041 (7)
C120.0291 (9)0.0308 (9)0.0269 (9)−0.0074 (7)0.0104 (7)−0.0030 (7)
C130.0274 (9)0.0331 (9)0.0280 (9)−0.0003 (7)0.0108 (7)−0.0054 (7)
C710.0206 (8)0.0466 (11)0.0286 (9)−0.0041 (8)0.0058 (7)0.0003 (8)
O10.0546 (9)0.0264 (6)0.0327 (7)0.0063 (6)0.0020 (7)−0.0075 (6)
O20.0537 (9)0.0537 (9)0.0381 (8)−0.0232 (7)0.0195 (7)0.0062 (7)
O30.0302 (7)0.0592 (9)0.0495 (9)0.0148 (7)0.0115 (7)−0.0084 (7)
O50.0203 (6)0.0333 (7)0.0295 (6)−0.0058 (5)0.0024 (5)0.0110 (5)
O70.0231 (6)0.0369 (7)0.0243 (6)−0.0018 (5)0.0037 (5)0.0050 (5)
Cr0.02079 (14)0.01811 (14)0.02113 (14)−0.00032 (10)0.00923 (11)0.00022 (10)
Geometric parameters (Å, °) top
C1'—C2'1.385 (3)C6—C71.401 (2)
C1'—C6'1.393 (2)C6—Cr2.2350 (16)
C1'—C21.510 (2)C6—H60.95
C2'—C3'1.396 (3)C6'—H6'0.95
C2'—H2'0.95C7—O71.3558 (19)
C2—O51.4513 (19)C7—C81.411 (2)
C2—C31.522 (2)C7—Cr2.2729 (16)
C2—H21C8—C91.406 (2)
C3'—C4'1.381 (3)C8—Cr2.2424 (16)
C3'—H3'0.95C8—H80.95
C3—C41.526 (2)C9—O51.3568 (19)
C3—H3A0.99C9—C101.412 (2)
C3—H3B0.99C9—Cr2.2838 (16)
C4—C101.505 (2)C10—Cr2.2580 (16)
C4—H4A0.99C11—O11.160 (2)
C4—H4B0.99C11—Cr1.8319 (17)
C4'—C5'1.375 (3)C12—O21.159 (2)
C4'—H4'0.95C12—Cr1.8344 (18)
C5'—C6'1.378 (2)C13—O31.151 (2)
C5'—H5'0.95C13—Cr1.8376 (18)
C5—C61.407 (2)C71—O71.433 (2)
C5—C101.408 (2)C71—H71A0.98
C5—Cr2.1808 (16)C71—H71B0.98
C5—H50.95C71—H71C0.98
C2'—C1'—C6'118.91 (16)O5—C9—C8115.42 (14)
C2'—C1'—C2122.96 (15)O5—C9—C10122.93 (14)
C6'—C1'—C2118.12 (15)C8—C9—C10121.58 (15)
C1'—C2'—C3'120.00 (16)O5—C9—Cr130.27 (11)
C1'—C2'—H2'120C8—C9—Cr70.31 (9)
C3'—C2'—H2'120C10—C9—Cr70.90 (9)
O5—C2—C1'106.96 (13)C5—C10—C9116.89 (14)
O5—C2—C3110.32 (13)C5—C10—C4122.62 (14)
C1'—C2—C3113.95 (14)C9—C10—C4120.46 (14)
O5—C2—H2108.5C5—C10—Cr68.55 (9)
C1'—C2—H2108.5C9—C10—Cr72.88 (9)
C3—C2—H2108.5C4—C10—Cr130.77 (11)
C4'—C3'—C2'120.27 (18)O1—C11—Cr179.12 (15)
C4'—C3'—H3'119.9O2—C12—Cr178.82 (16)
C2'—C3'—H3'119.9O3—C13—Cr178.24 (16)
C2—C3—C4109.51 (14)O7—C71—H71A109.5
C2—C3—H3A109.8O7—C71—H71B109.5
C4—C3—H3A109.8H71A—C71—H71B109.5
C2—C3—H3B109.8O7—C71—H71C109.5
C4—C3—H3B109.8H71A—C71—H71C109.5
H3A—C3—H3B108.2H71B—C71—H71C109.5
C10—C4—C3110.43 (13)C9—O5—C2117.07 (12)
C10—C4—H4A109.6C7—O7—C71117.83 (13)
C3—C4—H4A109.6C11—Cr—C1287.55 (7)
C10—C4—H4B109.6C11—Cr—C1391.11 (7)
C3—C4—H4B109.6C12—Cr—C1389.65 (8)
H4A—C4—H4B108.1C11—Cr—C5130.80 (7)
C5'—C4'—C3'119.72 (18)C12—Cr—C589.36 (7)
C5'—C4'—H4'120.1C13—Cr—C5137.98 (7)
C3'—C4'—H4'120.1C11—Cr—C6164.20 (7)
C4'—C5'—C6'120.35 (17)C12—Cr—C6100.73 (7)
C4'—C5'—H5'119.8C13—Cr—C6102.28 (7)
C6'—C5'—H5'119.8C5—Cr—C637.14 (6)
C6—C5—C10122.61 (15)C11—Cr—C8104.82 (7)
C6—C5—Cr73.52 (9)C12—Cr—C8166.28 (7)
C10—C5—Cr74.51 (9)C13—Cr—C895.93 (7)
C6—C5—H5118.7C5—Cr—C878.10 (6)
C10—C5—H5118.7C6—Cr—C865.85 (6)
Cr—C5—H5125C11—Cr—C1098.15 (7)
C7—C6—C5119.02 (15)C12—Cr—C10106.65 (7)
C7—C6—Cr73.38 (9)C13—Cr—C10161.49 (7)
C5—C6—Cr69.34 (9)C5—Cr—C1036.94 (6)
C7—C6—H6120.5C6—Cr—C1066.68 (6)
C5—C6—H6120.5C8—Cr—C1066.26 (6)
Cr—C6—H6129C11—Cr—C7139.56 (7)
C5'—C6'—C1'120.73 (17)C12—Cr—C7132.48 (7)
C5'—C6'—H6'119.6C13—Cr—C784.71 (7)
C1'—C6'—H6'119.6C5—Cr—C765.78 (6)
O7—C7—C6124.88 (15)C6—Cr—C736.20 (6)
O7—C7—C8115.21 (14)C8—Cr—C736.40 (6)
C6—C7—C8119.89 (14)C10—Cr—C777.84 (6)
O7—C7—Cr130.14 (11)C11—Cr—C988.31 (7)
C6—C7—Cr70.42 (9)C12—Cr—C9141.22 (7)
C8—C7—Cr70.62 (9)C13—Cr—C9128.98 (7)
C9—C8—C7119.56 (15)C5—Cr—C965.09 (6)
C9—C8—Cr73.51 (9)C6—Cr—C976.78 (6)
C7—C8—Cr72.98 (9)C8—Cr—C936.18 (6)
C9—C8—H8120.2C10—Cr—C936.22 (6)
C7—C8—H8120.2C7—Cr—C964.57 (6)
Cr—C8—H8124.9
C6'—C1'—C2'—C3'−0.4 (3)C7—C6—Cr—C9−64.80 (10)
C2—C1'—C2'—C3'178.97 (16)C5—C6—Cr—C966.02 (10)
C2'—C1'—C2—O517.3 (2)C9—C8—Cr—C1165.59 (11)
C6'—C1'—C2—O5−163.39 (14)C7—C8—Cr—C11−165.45 (10)
C2'—C1'—C2—C3−104.93 (18)C9—C8—Cr—C12−88.2 (3)
C6'—C1'—C2—C374.42 (19)C7—C8—Cr—C1240.8 (3)
C1'—C2'—C3'—C4'−0.5 (3)C9—C8—Cr—C13158.32 (10)
O5—C2—C3—C461.99 (17)C7—C8—Cr—C13−72.72 (10)
C1'—C2—C3—C4−177.69 (14)C9—C8—Cr—C5−63.83 (10)
C2—C3—C4—C10−47.68 (18)C7—C8—Cr—C565.13 (10)
C2'—C3'—C4'—C5'0.6 (3)C9—C8—Cr—C6−100.86 (11)
C3'—C4'—C5'—C6'0.3 (3)C7—C8—Cr—C628.10 (9)
C10—C5—C6—C7−2.7 (2)C9—C8—Cr—C10−26.92 (10)
Cr—C5—C6—C756.02 (14)C7—C8—Cr—C10102.04 (10)
C10—C5—C6—Cr−58.68 (14)C9—C8—Cr—C7−128.96 (15)
C4'—C5'—C6'—C1'−1.2 (3)C7—C8—Cr—C9128.96 (15)
C2'—C1'—C6'—C5'1.2 (3)C5—C10—Cr—C11155.21 (10)
C2—C1'—C6'—C5'−178.16 (16)C9—C10—Cr—C11−75.77 (10)
C5—C6—C7—O7−179.96 (15)C4—C10—Cr—C1140.00 (16)
Cr—C6—C7—O7−125.88 (16)C5—C10—Cr—C1265.34 (11)
C5—C6—C7—C8−1.7 (2)C9—C10—Cr—C12−165.64 (10)
Cr—C6—C7—C852.36 (14)C4—C10—Cr—C12−49.87 (16)
C5—C6—C7—Cr−54.07 (13)C5—C10—Cr—C13−85.5 (2)
O7—C7—C8—C9−174.85 (14)C9—C10—Cr—C1343.5 (3)
C6—C7—C8—C96.7 (2)C4—C10—Cr—C13159.3 (2)
Cr—C7—C8—C959.01 (14)C9—C10—Cr—C5129.02 (14)
O7—C7—C8—Cr126.14 (13)C4—C10—Cr—C5−115.21 (18)
C6—C7—C8—Cr−52.27 (14)C5—C10—Cr—C6−29.40 (9)
C7—C8—C9—O5175.10 (14)C9—C10—Cr—C699.61 (10)
Cr—C8—C9—O5−126.16 (14)C4—C10—Cr—C6−144.62 (16)
C7—C8—C9—C10−7.7 (2)C5—C10—Cr—C8−102.12 (10)
Cr—C8—C9—C1051.09 (14)C9—C10—Cr—C826.90 (9)
C7—C8—C9—Cr−58.74 (14)C4—C10—Cr—C8142.67 (16)
C6—C5—C10—C91.9 (2)C5—C10—Cr—C7−65.70 (10)
Cr—C5—C10—C9−56.37 (13)C9—C10—Cr—C763.32 (10)
C6—C5—C10—C4−176.23 (15)C4—C10—Cr—C7179.09 (16)
Cr—C5—C10—C4125.55 (15)C5—C10—Cr—C9−129.02 (14)
C6—C5—C10—Cr58.22 (14)C4—C10—Cr—C9115.77 (18)
O5—C9—C10—C5−179.62 (15)O7—C7—Cr—C11−85.11 (17)
C8—C9—C10—C53.3 (2)C6—C7—Cr—C11155.29 (11)
Cr—C9—C10—C554.18 (13)C8—C7—Cr—C1121.99 (14)
O5—C9—C10—C4−1.5 (2)O7—C7—Cr—C1285.04 (17)
C8—C9—C10—C4−178.53 (15)C6—C7—Cr—C12−34.57 (13)
Cr—C9—C10—C4−127.70 (15)C8—C7—Cr—C12−167.87 (11)
O5—C9—C10—Cr126.20 (16)O7—C7—Cr—C130.38 (15)
C8—C9—C10—Cr−50.83 (14)C6—C7—Cr—C13−119.22 (11)
C3—C4—C10—C5−163.05 (15)C8—C7—Cr—C13107.48 (11)
C3—C4—C10—C918.9 (2)O7—C7—Cr—C5149.67 (16)
C3—C4—C10—Cr−74.28 (18)C6—C7—Cr—C530.06 (9)
C8—C9—O5—C2−167.67 (14)C8—C7—Cr—C5−103.24 (10)
C10—C9—O5—C215.1 (2)O7—C7—Cr—C6119.60 (19)
Cr—C9—O5—C2107.28 (16)C8—C7—Cr—C6−133.30 (14)
C1'—C2—O5—C9−169.74 (13)O7—C7—Cr—C8−107.10 (18)
C3—C2—O5—C9−45.31 (19)C6—C7—Cr—C8133.30 (14)
C6—C7—O7—C711.2 (2)O7—C7—Cr—C10−173.42 (16)
C8—C7—O7—C71−177.07 (14)C6—C7—Cr—C1066.97 (10)
Cr—C7—O7—C71−91.82 (17)C8—C7—Cr—C10−66.33 (10)
C6—C5—Cr—C11−164.93 (10)O7—C7—Cr—C9−137.65 (16)
C10—C5—Cr—C11−33.24 (13)C6—C7—Cr—C9102.75 (10)
C6—C5—Cr—C12108.86 (11)C8—C7—Cr—C9−30.55 (9)
C10—C5—Cr—C12−119.45 (10)O5—C9—Cr—C11−11.15 (14)
C6—C5—Cr—C1320.10 (15)C8—C9—Cr—C11−118.27 (11)
C10—C5—Cr—C13151.78 (11)C10—C9—Cr—C11106.27 (10)
C10—C5—Cr—C6131.69 (15)O5—C9—Cr—C12−95.13 (17)
C6—C5—Cr—C8−65.53 (10)C8—C9—Cr—C12157.75 (12)
C10—C5—Cr—C866.16 (10)C10—C9—Cr—C1222.30 (15)
C6—C5—Cr—C10−131.69 (15)O5—C9—Cr—C1378.91 (16)
C6—C5—Cr—C7−29.35 (10)C8—C9—Cr—C13−28.21 (13)
C10—C5—Cr—C7102.34 (10)C10—C9—Cr—C13−163.67 (10)
C6—C5—Cr—C9−101.28 (11)O5—C9—Cr—C5−148.41 (16)
C10—C5—Cr—C930.41 (9)C8—C9—Cr—C5104.47 (11)
C7—C6—Cr—C11−84.6 (3)C10—C9—Cr—C5−30.99 (9)
C5—C6—Cr—C1146.3 (3)O5—C9—Cr—C6174.13 (15)
C7—C6—Cr—C12154.79 (10)C8—C9—Cr—C667.01 (10)
C5—C6—Cr—C12−74.38 (11)C10—C9—Cr—C6−68.45 (10)
C7—C6—Cr—C1362.79 (11)O5—C9—Cr—C8107.12 (18)
C5—C6—Cr—C13−166.38 (11)C10—C9—Cr—C8−135.45 (15)
C7—C6—Cr—C5−130.82 (15)O5—C9—Cr—C10−117.42 (18)
C7—C6—Cr—C8−28.25 (9)C8—C9—Cr—C10135.45 (15)
C5—C6—Cr—C8102.57 (11)O5—C9—Cr—C7137.85 (16)
C7—C6—Cr—C10−101.56 (10)C8—C9—Cr—C730.73 (10)
C5—C6—Cr—C1029.26 (9)C10—C9—Cr—C7−104.73 (10)
C5—C6—Cr—C7130.82 (15)
Acknowledgements top

Financial assistance from the University of the Free State and SASOL to JHvanT 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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