Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010100974X/de1172sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010100974X/de1172Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010100974X/de1172IIsup3.hkl |
CCDC references: 173360; 173361
(2,4,7-Trimethylindenyl)lithium was prepared according to published procedures (Kaminsky et al., 1995). Octacarbonyldicobalt(0) was sublimed prior to use. Iodine was used without further purification.
Bis(2,4,7-trimethylindenyl)cobalt(II), (I). A solution of iodine (2.03 g, 8.00 mmol) in THF (40 ml) was slowly reacted at 273 K with Co2(CO)8 (2.73 g, 7.98 mmol) (gas evolution). After stirring for 30 min (2,4,7-trimethylindenyl)lithium (2.66 g, 16.2 mmol) was slowly added to the green solution. The brown suspension was stirred 20 h at this temperature, before the solvent was removed under vacuum. Purification by column chromatography (Al2O3, n-hexane) and recrystallization from warm n-hexane gave 1.11 g (37%) deep red crystals of (I); m.p. 440 K. MS (353 K): m/z 373 (100) [M]+, 358 (18) [C23H23Co]+, 343 (10) [C22H20Co]+, 215 (28) [C12H12Co]+, 186.5 (30) [M]2+, 157 (45) [C12H13]+, 141 (42) [C11H9]+, 127 (10) [C10H7]+, 115 (11) [C9H7]+. IR (KBr): ¯ν 3022 (w), 2911 (w), 1806 (m), 1618 (w), 1591 (m), 1497 (s), 1451 (s), 1436 (s), 1371 (m), 1330 (m), 1269 (m), 1164 (m), 1129 (m), 1031 (s), 948 (s), 826 (m), 800 (w), 731 (m), 613 (m), 559 (m) cm-1.
rac-1,1'-Bis(2,4,7-trimethylindene), (II). A yellow solution of (2,4,7-trimethylindenyl)lithium (1.68 g, 10.23 mmol) in THF (30 ml) was slowly reacted at room temperature with iodine (1.43 g, 5.63 mmol). The brown solution was stirred 40 h at this temperature, before it was hydrolysed with water (10 ml). The mixture was acidified with 1M HCl and extracted three times with diethyl ether (20 ml). The combined organic fractions were dried with magnesium sulfate and purified by column chromatography (Al2O3, n-hexane). Recrystallization from n-hexane at 245 K gave 1.63 g (51%) colorless crystals of 2; m.p. 445 K. 1H-NMR (CDCl3): δ 6.99 (d, 3J = 7.7 Hz, 2H, H5,5',H6,6'), 6.89 (d, 3J = 7.7 Hz, 2H, H5,5',H6,6'), 6.44 (s, 2H, H3,3'), 4.41 (s, 2H, H1,1'), 2.62 (s, 6H, H11,11', H12,12'), 2.31 (s, 6H, H11,11', H12,12'), 1.19 (s, 6H, H10,10'). 13C{1H}-NMR (CDCl3): δ 148.11, 144.09, 143.88, 129.87, 126.33 (C2,2', C4,4', C7,7', C8,8', C9,9'), 128.24, 126.45, 125.73 (C3,3', C5,5', C6,6'), 50.57 (C1,1'), 19.63, 17.91, 16.05 (C10,10', C11,11', C12,12'). MS (473 K): m/z 315 (58) [C24H27]+, 314 (100) [M]+,299 (6) [C23H23]+, 157 (94) [C12H13]+, 142 (78) [C11H10]+, 127 (10) [C10H7]+, 115 (32) [C9H7]+. IR(KBr): ν 3038 (m), 2955 (m), 2905 (m), 1870 (w), 1617 (m), 1594 (m), 1495 (s), 1440 (s), 1375 (s), 1248 (w), 1143 (w), 1029 (m), 909 (m), 850 (m), 801 (s), 737 (s), 708 (m), 552 (w), 522 (m) cm-1. Analysis calculated for C24H26 (314.47 g/mol): C 91.67, H 8.33%. Found: C 92.06, H 7.98%.
The structure of 2 was solved by direct methods (SHELXS) (Sheldrick, 1997) and completed by full-matrix least squares refinement against F2 (SHELX97) (Sheldrick, 1997). The hydrogen atoms in (II) situated situated on the aromatic carbons and the stereocentres (C1 and C1') were found from the Fourier map and refined isotropically whereas those on the methyl moieties were placed in idealized positions with the C—C—C—H torsion angles allowed rotation and their isotropic displacement parameters fixed at 1.5 times the equivalent isotropic displacement parameters of the parent carbon atoms. ORTEP-III (Farrugia, 1997) was used to generate figures of 1 and 2 at the 50% probability level.
For both compounds, data collection: COLLECT (Nonius, 1999); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997). Data reduction: DENZO-SMN (Otwinowski & Minor, 1997) for (I); DENZO-SMN for (II). For both compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-III for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
[Co(C12H13)2] | F(000) = 197 |
Mr = 373.38 | Dx = 1.283 Mg m−3 |
Triclinic, P1 | Melting point: 167°C K |
a = 7.4150 (3) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 7.9299 (3) Å | Cell parameters from 4872 reflections |
c = 8.8881 (4) Å | θ = 2.5–26.0° |
α = 81.578 (2)° | µ = 0.89 mm−1 |
β = 69.260 (2)° | T = 173 K |
γ = 85.453 (2)° | Prism, black |
V = 483.27 (3) Å3 | 0.34 × 0.20 × 0.10 mm |
Z = 1 |
Nonius Kappa CCD diffractometer | 1903 independent reflections |
Radiation source: fine-focus sealed tube | 1827 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.044 |
ϕ and ω scans to fill Ewald sphere | θmax = 26.0°, θmin = 2.5° |
Absorption correction: empirical (using intensity measurements) (DENZO-SMN; Otwinowski & Minor, 1997) | h = −8→9 |
Tmin = 0.752, Tmax = 0.916 | k = −9→9 |
4872 measured reflections | l = −10→10 |
Refinement on F2 | Primary atom site location: patterson |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.074 | H-atom parameters constrained |
S = 1.13 | w = 1/[σ2(Fo2) + (0.0242P)2 + 0.2378P] where P = (Fo2 + 2Fc2)/3 |
1903 reflections | (Δ/σ)max = 0.001 |
118 parameters | Δρmax = 0.25 e Å−3 |
0 restraints | Δρmin = −0.46 e Å−3 |
[Co(C12H13)2] | γ = 85.453 (2)° |
Mr = 373.38 | V = 483.27 (3) Å3 |
Triclinic, P1 | Z = 1 |
a = 7.4150 (3) Å | Mo Kα radiation |
b = 7.9299 (3) Å | µ = 0.89 mm−1 |
c = 8.8881 (4) Å | T = 173 K |
α = 81.578 (2)° | 0.34 × 0.20 × 0.10 mm |
β = 69.260 (2)° |
Nonius Kappa CCD diffractometer | 1903 independent reflections |
Absorption correction: empirical (using intensity measurements) (DENZO-SMN; Otwinowski & Minor, 1997) | 1827 reflections with I > 2σ(I) |
Tmin = 0.752, Tmax = 0.916 | Rint = 0.044 |
4872 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.074 | H-atom parameters constrained |
S = 1.13 | Δρmax = 0.25 e Å−3 |
1903 reflections | Δρmin = −0.46 e Å−3 |
118 parameters |
Experimental. All reactions and manipulations were carried out under a dry argon atmosphere using standard Schlenk and vacuum-line techniques. All solvents were dried and purified by conventional methods and were freshly distilled under argon shortly before use. Melting points were measured in sealed capillaries with a Büchi 535 melting point determination apparatus and are uncorrected. NMR spectra were recorded on a Varian VXR 300 spectrometer (1H, 300 MHz; 13C, 75.48 MHz) at 298 K. Chemical shifts are reported in p.p.m. relative to the 1H and 13C residue of the deuterated solvents. The IR spectra were recorded on a Perkin-Elmer 1600 Series FTIR spectrometer. Mass spectra (EI, 70 eV) were obtained using a Micromass (VG) instrument with a 70SE magnet sector. Only characteristic fragments containing the isotopes of the highest abundance are listed. Relative intensities in % are given in parentheses. Elemental analyses were performed on a Fisons CHNS elemental analyser 1108. (2,4,7-Trimethylindenyl)lithium was prepared according to published procedures (Kaminsky et al., 1995). Octacarbonyldicobalt(0) was sublimed prior to use. Iodine was used without further purification. |
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. Crystals of (I) and (II) suitable for single-crystal X-ray diffraction analysis were obtained by recrystallization from n-hexane. Low temperature (173 K) X-ray diffraction data were collected on an Enraf–Nonius KappaCCD diffractometer (Mo Kα radiation, λ = 0.71073 Å) (Nonius, 1999), and scaled and reduced using [DENZO-SMN] (Otwinowski & Minor, 1997). The structure of (I) was solved by interpretation of a Patterson synthesis which yielded the postion of the cobalt atom (SHELXS) (Sheldrick, 1997). The remaining non-hydrogen atoms were found by difference Fourier map, refined by full-matrix least-squares refinement against F2 (SHELXL97) (Sheldrick, 1997) and allowed anisotropic thermal motion. Although it was possible to locate most of the hydrogen atoms in (I) by Fourier map, all hydrogen atoms were placed in idealized positions with their isotropic displacement parameters fixed at 1.2 (aromatic H atoms) and 1.5 (methyl H atoms) times the equivalent isotropic displacement parameters of their parent atoms. |
x | y | z | Uiso*/Ueq | ||
C21 | 0.3764 (3) | 0.9123 (3) | 0.7093 (3) | 0.0460 (6) | |
H21C | 0.4655 | 0.8174 | 0.6696 | 0.069* | |
H21B | 0.4485 | 1.0044 | 0.7219 | 0.069* | |
H21A | 0.3120 | 0.9545 | 0.6314 | 0.069* | |
C2 | 0.2281 (3) | 0.8518 (2) | 0.8702 (2) | 0.0255 (4) | |
C1 | 0.0506 (3) | 0.7779 (2) | 0.8960 (2) | 0.0250 (4) | |
H1 | −0.0003 | 0.7662 | 0.8139 | 0.030* | |
C9 | −0.0410 (3) | 0.7231 (2) | 1.0672 (2) | 0.0223 (4) | |
C8 | −0.2161 (3) | 0.6403 (2) | 1.1557 (3) | 0.0339 (5) | |
C7 | −0.2609 (3) | 0.6081 (3) | 1.3208 (3) | 0.0491 (7) | |
H7 | −0.3760 | 0.5501 | 1.3839 | 0.059* | |
C6 | −0.1444 (4) | 0.6569 (3) | 1.4002 (3) | 0.0497 (7) | |
H6 | −0.1823 | 0.6293 | 1.5145 | 0.060* | |
C5 | 0.0230 (3) | 0.7435 (3) | 1.3184 (2) | 0.0354 (5) | |
C4 | 0.0766 (3) | 0.7760 (2) | 1.1476 (2) | 0.0223 (4) | |
C3 | 0.2378 (3) | 0.8639 (2) | 1.0248 (2) | 0.0241 (4) | |
H3 | 0.3342 | 0.9203 | 1.0443 | 0.029* | |
C81 | −0.3421 (3) | 0.5924 (3) | 1.0702 (4) | 0.0520 (7) | |
H81B | −0.4565 | 0.5363 | 1.1496 | 0.078* | |
H81A | −0.2703 | 0.5143 | 0.9921 | 0.078* | |
H81C | −0.3820 | 0.6953 | 1.0128 | 0.078* | |
C51 | 0.1488 (4) | 0.8009 (4) | 1.4010 (3) | 0.0572 (8) | |
H51B | 0.0947 | 0.7634 | 1.5178 | 0.086* | |
H51A | 0.1545 | 0.9256 | 1.3822 | 0.086* | |
H51C | 0.2791 | 0.7511 | 1.3568 | 0.086* | |
Co | 0.0000 | 1.0000 | 1.0000 | 0.01748 (12) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C21 | 0.0413 (13) | 0.0403 (13) | 0.0340 (12) | 0.0054 (10) | 0.0109 (10) | 0.0007 (10) |
C2 | 0.0249 (10) | 0.0208 (9) | 0.0240 (10) | 0.0067 (7) | −0.0023 (8) | −0.0009 (7) |
C1 | 0.0315 (10) | 0.0217 (9) | 0.0250 (10) | 0.0062 (8) | −0.0144 (8) | −0.0051 (8) |
C9 | 0.0211 (9) | 0.0141 (8) | 0.0312 (10) | 0.0038 (7) | −0.0096 (8) | −0.0020 (7) |
C8 | 0.0224 (10) | 0.0155 (9) | 0.0566 (14) | 0.0018 (7) | −0.0075 (9) | 0.0011 (9) |
C7 | 0.0331 (12) | 0.0313 (12) | 0.0561 (16) | −0.0005 (10) | 0.0098 (11) | 0.0139 (11) |
C6 | 0.0614 (17) | 0.0398 (13) | 0.0263 (12) | 0.0139 (12) | 0.0017 (11) | 0.0119 (10) |
C5 | 0.0493 (13) | 0.0305 (11) | 0.0252 (11) | 0.0149 (10) | −0.0159 (10) | −0.0010 (8) |
C4 | 0.0243 (9) | 0.0186 (9) | 0.0235 (10) | 0.0069 (7) | −0.0100 (8) | −0.0006 (7) |
C3 | 0.0191 (9) | 0.0196 (9) | 0.0348 (11) | 0.0033 (7) | −0.0121 (8) | −0.0026 (8) |
C81 | 0.0305 (12) | 0.0276 (11) | 0.104 (2) | −0.0008 (9) | −0.0301 (13) | −0.0102 (13) |
C51 | 0.087 (2) | 0.0606 (17) | 0.0384 (14) | 0.0211 (15) | −0.0416 (15) | −0.0133 (12) |
Co | 0.01790 (19) | 0.01635 (18) | 0.01786 (19) | 0.00179 (12) | −0.00674 (14) | −0.00104 (13) |
C21—C2 | 1.501 (3) | C6—H6 | 0.9500 |
C21—H21C | 0.9800 | C5—C4 | 1.415 (3) |
C21—H21B | 0.9800 | C5—C51 | 1.506 (3) |
C21—H21A | 0.9800 | C4—C3 | 1.446 (3) |
C2—C1 | 1.413 (3) | C4—Co | 2.2100 (17) |
C2—C3 | 1.418 (3) | C3—Co | 2.0562 (17) |
C2—Co | 2.0672 (17) | C3—H3 | 0.9500 |
C1—C9 | 1.445 (3) | C81—H81B | 0.9800 |
C1—Co | 2.0553 (18) | C81—H81A | 0.9800 |
C1—H1 | 0.9500 | C81—H81C | 0.9800 |
C9—C8 | 1.413 (3) | C51—H51B | 0.9800 |
C9—C4 | 1.427 (3) | C51—H51A | 0.9800 |
C9—Co | 2.2056 (17) | C51—H51C | 0.9800 |
C8—C7 | 1.374 (3) | Co—C1i | 2.0553 (18) |
C8—C81 | 1.496 (3) | Co—C3i | 2.0562 (17) |
C7—C6 | 1.399 (4) | Co—C2i | 2.0672 (18) |
C7—H7 | 0.9500 | Co—C9i | 2.2056 (17) |
C6—C5 | 1.375 (4) | Co—C4i | 2.2100 (17) |
C2—C21—H21C | 109.5 | H81A—C81—H81C | 109.5 |
C2—C21—H21B | 109.5 | C5—C51—H51B | 109.5 |
H21C—C21—H21B | 109.5 | C5—C51—H51A | 109.5 |
C2—C21—H21A | 109.5 | H51B—C51—H51A | 109.5 |
H21C—C21—H21A | 109.5 | C5—C51—H51C | 109.5 |
H21B—C21—H21A | 109.5 | H51B—C51—H51C | 109.5 |
C1—C2—C3 | 107.39 (16) | H51A—C51—H51C | 109.5 |
C1—C2—C21 | 126.50 (19) | C1i—Co—C1 | 180.0 |
C3—C2—C21 | 126.07 (19) | C1i—Co—C3i | 67.42 (7) |
C1—C2—Co | 69.49 (10) | C1—Co—C3i | 112.58 (7) |
C3—C2—Co | 69.46 (10) | C1i—Co—C3 | 112.58 (7) |
C21—C2—Co | 124.70 (14) | C1—Co—C3 | 67.42 (7) |
C2—C1—C9 | 108.98 (16) | C3i—Co—C3 | 180.000 (1) |
C2—C1—Co | 70.40 (10) | C1i—Co—C2i | 40.10 (8) |
C9—C1—Co | 75.90 (10) | C1—Co—C2i | 139.90 (8) |
C2—C1—H1 | 125.5 | C3i—Co—C2i | 40.23 (8) |
C9—C1—H1 | 125.5 | C3—Co—C2i | 139.77 (8) |
Co—C1—H1 | 119.9 | C1i—Co—C2 | 139.90 (8) |
C8—C9—C4 | 121.08 (19) | C1—Co—C2 | 40.10 (8) |
C8—C9—C1 | 131.74 (19) | C3i—Co—C2 | 139.77 (8) |
C4—C9—C1 | 107.11 (16) | C3—Co—C2 | 40.23 (8) |
C8—C9—Co | 127.07 (13) | C2i—Co—C2 | 180.000 (1) |
C4—C9—Co | 71.32 (10) | C1i—Co—C9i | 39.44 (7) |
C1—C9—Co | 64.66 (10) | C1—Co—C9i | 140.56 (7) |
C7—C8—C9 | 116.3 (2) | C3i—Co—C9i | 65.65 (7) |
C7—C8—C81 | 123.3 (2) | C3—Co—C9i | 114.35 (7) |
C9—C8—C81 | 120.4 (2) | C2i—Co—C9i | 65.89 (7) |
C8—C7—C6 | 122.9 (2) | C2—Co—C9i | 114.11 (7) |
C8—C7—H7 | 118.5 | C1i—Co—C9 | 140.56 (7) |
C6—C7—H7 | 118.5 | C1—Co—C9 | 39.44 (7) |
C5—C6—C7 | 122.3 (2) | C3i—Co—C9 | 114.35 (7) |
C5—C6—H6 | 118.9 | C3—Co—C9 | 65.65 (7) |
C7—C6—H6 | 118.9 | C2i—Co—C9 | 114.11 (7) |
C6—C5—C4 | 116.6 (2) | C2—Co—C9 | 65.89 (7) |
C6—C5—C51 | 123.4 (2) | C9i—Co—C9 | 180.0 |
C4—C5—C51 | 120.0 (2) | C1i—Co—C4i | 65.47 (7) |
C5—C4—C9 | 120.78 (18) | C1—Co—C4i | 114.53 (7) |
C5—C4—C3 | 131.90 (19) | C3i—Co—C4i | 39.41 (7) |
C9—C4—C3 | 107.29 (16) | C3—Co—C4i | 140.59 (7) |
C5—C4—Co | 128.43 (13) | C2i—Co—C4i | 65.81 (7) |
C9—C4—Co | 70.98 (10) | C2—Co—C4i | 114.19 (7) |
C3—C4—Co | 64.54 (9) | C9i—Co—C4i | 37.71 (7) |
C2—C3—C4 | 108.65 (16) | C9—Co—C4i | 142.29 (7) |
C2—C3—Co | 70.30 (10) | C1i—Co—C4 | 114.53 (7) |
C4—C3—Co | 76.04 (10) | C1—Co—C4 | 65.47 (7) |
C2—C3—H3 | 125.7 | C3i—Co—C4 | 140.59 (7) |
C4—C3—H3 | 125.7 | C3—Co—C4 | 39.41 (7) |
Co—C3—H3 | 119.7 | C2i—Co—C4 | 114.19 (7) |
C8—C81—H81B | 109.5 | C2—Co—C4 | 65.81 (7) |
C8—C81—H81A | 109.5 | C9i—Co—C4 | 142.29 (7) |
H81B—C81—H81A | 109.5 | C9—Co—C4 | 37.71 (7) |
C8—C81—H81C | 109.5 | C4i—Co—C4 | 180.000 (1) |
H81B—C81—H81C | 109.5 |
Symmetry code: (i) −x, −y+2, −z+2. |
C24H26 | Dx = 1.162 Mg m−3 |
Mr = 314.47 | Melting point: 172°C K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 12.1229 (4) Å | Cell parameters from 8928 reflections |
b = 9.6880 (4) Å | θ = 2.5–27.4° |
c = 15.7045 (6) Å | µ = 0.07 mm−1 |
β = 102.942 (2)° | T = 173 K |
V = 1797.59 (12) Å3 | Prism, colourless |
Z = 4 | 0.39 × 0.25 × 0.17 mm |
F(000) = 680 |
Nonius Kappa CCD diffractometer | 4024 independent reflections |
Radiation source: fine-focus sealed tube | 2298 reflections with I > \2s(I) |
Graphite monochromator | Rint = 0.040 |
ϕ and ω scans to fill Ewald sphere | θmax = 27.4°, θmin = 2.5° |
Absorption correction: empirical (using intensity measurements) (DENZO-SMN; Otwinowski & Minor, 1997) | h = −15→13 |
Tmin = 0.975, Tmax = 0.989 | k = −12→12 |
8928 measured reflections | l = −18→20 |
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)] = 0.048 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.115 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.95 | w = 1/[σ2(Fo2) + (0.0538P)2] where P = (Fo2 + 2Fc2)/3 |
4024 reflections | (Δ/σ)max < 0.001 |
255 parameters | Δρmax = 0.19 e Å−3 |
0 restraints | Δρmin = −0.17 e Å−3 |
C24H26 | V = 1797.59 (12) Å3 |
Mr = 314.47 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 12.1229 (4) Å | µ = 0.07 mm−1 |
b = 9.6880 (4) Å | T = 173 K |
c = 15.7045 (6) Å | 0.39 × 0.25 × 0.17 mm |
β = 102.942 (2)° |
Nonius Kappa CCD diffractometer | 4024 independent reflections |
Absorption correction: empirical (using intensity measurements) (DENZO-SMN; Otwinowski & Minor, 1997) | 2298 reflections with I > \2s(I) |
Tmin = 0.975, Tmax = 0.989 | Rint = 0.040 |
8928 measured reflections |
R[F2 > 2σ(F2)] = 0.048 | 0 restraints |
wR(F2) = 0.115 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.95 | Δρmax = 0.19 e Å−3 |
4024 reflections | Δρmin = −0.17 e Å−3 |
255 parameters |
Experimental. All reactions and manipulations were carried out under a dry argon atmosphere using standard Schlenk and vacuum-line techniques. All solvents were dried and purified by conventional methods and were freshly distilled under argon shortly before use. Melting points were measured in sealed capillaries with a Büchi 535 melting point determination apparatus and are uncorrected. NMR spectra were recorded on a Varian VXR 300 spectrometer (1H, 300 MHz; 13C, 75.48 MHz) at 298 K. Chemical shifts are reported in p.p.m. relative to the 1H and 13C residue of the deuterated solvents. The IR spectra were recorded on a Perkin-Elmer 1600 Series FTIR spectrometer. Mass spectra (EI, 70 eV) were obtained using a Micromass (VG) instrument with a 70SE magnet sector. Only characteristic fragments containing the isotopes of the highest abundance are listed. Relative intensities in % are given in parentheses. Elemental analyses were performed on a Fisons CHNS elemental analyser 1108. (2,4,7-Trimethylindenyl)lithium was prepared according to published procedures (Kaminsky et al., 1995). Octacarbonyldicobalt(0) was sublimed prior to use. Iodine was used without further purification. |
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. Crystals of (I) and (II) suitable for single-crystal X-ray diffraction analysis were obtained by recrystallization from n-hexane. Low temperature (173 K) X-ray diffraction data were collected on an Enraf–Nonius KappaCCD diffractometer (Mo Kα radiation, λ = 0.71073 Å) (Nonius, 1999), and scaled and reduced using [DENZO-SMN] (Otwinowski & Minor, 1997). The structure of (I) was solved by interpretation of a Patterson synthesis which yielded the postion of the cobalt atom (SHELXS) (Sheldrick, 1997). The remaining non-hydrogen atoms were found by difference Fourier map, refined by full-matrix least-squares refinement against F2 (SHELXL97) (Sheldrick, 1997) and allowed anisotropic thermal motion. Although it was possible to locate most of the hydrogen atoms in (I) by Fourier map, all hydrogen atoms were placed in idealized positions with their isotropic displacement parameters fixed at 1.2 (aromatic H atoms) and 1.5 (methyl H atoms) times the equivalent isotropic displacement parameters of their parent atoms. |
x | y | z | Uiso*/Ueq | ||
C1' | 0.32627 (13) | 0.41750 (16) | 0.04239 (10) | 0.0279 (4) | |
C2' | 0.37242 (14) | 0.27708 (16) | 0.07574 (10) | 0.0318 (4) | |
C3' | 0.47144 (14) | 0.29238 (18) | 0.13340 (11) | 0.0321 (4) | |
C4' | 0.50410 (13) | 0.43735 (17) | 0.14293 (10) | 0.0283 (4) | |
C5' | 0.59865 (13) | 0.50017 (18) | 0.19482 (10) | 0.0310 (4) | |
C6' | 0.60693 (15) | 0.64328 (19) | 0.18761 (11) | 0.0349 (4) | |
C7' | 0.52654 (14) | 0.71824 (19) | 0.12854 (11) | 0.0337 (4) | |
C8' | 0.43161 (13) | 0.65562 (17) | 0.07589 (10) | 0.0278 (4) | |
C9' | 0.42029 (12) | 0.51389 (17) | 0.08623 (9) | 0.0263 (4) | |
C1 | 0.20819 (12) | 0.45156 (18) | 0.06305 (10) | 0.0285 (4) | |
C2 | 0.20290 (13) | 0.42382 (16) | 0.15800 (10) | 0.0301 (4) | |
C3 | 0.12171 (13) | 0.33183 (18) | 0.16064 (11) | 0.0322 (4) | |
C4 | 0.06320 (12) | 0.28934 (16) | 0.07224 (10) | 0.0287 (4) | |
C5 | −0.02501 (13) | 0.19661 (17) | 0.04455 (10) | 0.0317 (4) | |
C6 | −0.06325 (14) | 0.18135 (19) | −0.04575 (11) | 0.0365 (4) | |
C7 | −0.01900 (14) | 0.25960 (18) | −0.10465 (12) | 0.0354 (4) | |
C8 | 0.06907 (13) | 0.35400 (17) | −0.07652 (10) | 0.0309 (4) | |
C9 | 0.11181 (12) | 0.36429 (16) | 0.01299 (10) | 0.0285 (4) | |
C21' | 0.31596 (15) | 0.14399 (18) | 0.04438 (12) | 0.0446 (5) | |
H2A' | 0.3655 | 0.0670 | 0.0687 | 0.067* | |
H2B' | 0.3007 | 0.1408 | −0.0196 | 0.067* | |
H2C' | 0.2445 | 0.1367 | 0.0634 | 0.067* | |
C51' | 0.68845 (14) | 0.4180 (2) | 0.25575 (11) | 0.0444 (5) | |
H5A' | 0.7436 | 0.4811 | 0.2909 | 0.067* | |
H5B' | 0.7269 | 0.3575 | 0.2216 | 0.067* | |
H5C' | 0.6533 | 0.3620 | 0.2944 | 0.067* | |
C81' | 0.34786 (14) | 0.73807 (17) | 0.01021 (11) | 0.0371 (4) | |
H8A' | 0.3209 | 0.6825 | −0.0425 | 0.056* | |
H8B' | 0.3845 | 0.8219 | −0.0049 | 0.056* | |
H8C' | 0.2836 | 0.7636 | 0.0353 | 0.056* | |
C21 | 0.27482 (14) | 0.49640 (19) | 0.23449 (10) | 0.0386 (4) | |
H2A | 0.2512 | 0.4694 | 0.2879 | 0.058* | |
H2B | 0.2661 | 0.5964 | 0.2262 | 0.058* | |
H2C | 0.3543 | 0.4710 | 0.2395 | 0.058* | |
C51 | −0.07702 (14) | 0.11717 (18) | 0.10792 (11) | 0.0426 (5) | |
H5A | −0.0183 | 0.0631 | 0.1469 | 0.064* | |
H5B | −0.1353 | 0.0549 | 0.0756 | 0.064* | |
H5C | −0.1113 | 0.1817 | 0.1425 | 0.064* | |
C81 | 0.11204 (14) | 0.44128 (18) | −0.14145 (10) | 0.0395 (5) | |
H8A | 0.1342 | 0.5322 | −0.1160 | 0.059* | |
H8B | 0.0522 | 0.4521 | −0.1945 | 0.059* | |
H8C | 0.1777 | 0.3963 | −0.1562 | 0.059* | |
H1' | 0.3159 (11) | 0.4216 (14) | −0.0213 (9) | 0.022 (4)* | |
H3' | 0.5160 (13) | 0.2192 (16) | 0.1627 (10) | 0.036 (5)* | |
H6' | 0.6729 (14) | 0.6948 (17) | 0.2269 (10) | 0.046 (5)* | |
H7' | 0.5360 (12) | 0.8199 (17) | 0.1219 (9) | 0.030 (4)* | |
H1 | 0.1941 (12) | 0.5510 (16) | 0.0498 (9) | 0.029 (4)* | |
H3 | 0.1029 (12) | 0.2972 (15) | 0.2164 (10) | 0.036 (4)* | |
H6 | −0.1254 (14) | 0.1129 (16) | −0.0662 (10) | 0.044 (5)* | |
H7 | −0.0531 (13) | 0.2474 (15) | −0.1687 (11) | 0.040 (5)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1' | 0.0277 (9) | 0.0279 (10) | 0.0285 (9) | 0.0015 (7) | 0.0071 (8) | −0.0019 (8) |
C2' | 0.0324 (10) | 0.0279 (10) | 0.0395 (10) | 0.0009 (8) | 0.0174 (8) | −0.0008 (8) |
C3' | 0.0302 (10) | 0.0309 (11) | 0.0375 (10) | 0.0061 (8) | 0.0123 (8) | 0.0065 (8) |
C4' | 0.0279 (9) | 0.0321 (10) | 0.0274 (8) | 0.0030 (8) | 0.0115 (7) | 0.0014 (8) |
C5' | 0.0247 (9) | 0.0414 (11) | 0.0278 (8) | 0.0010 (8) | 0.0079 (7) | −0.0001 (8) |
C6' | 0.0280 (9) | 0.0433 (12) | 0.0338 (10) | −0.0046 (9) | 0.0078 (8) | −0.0090 (9) |
C7' | 0.0337 (10) | 0.0288 (10) | 0.0422 (10) | −0.0046 (9) | 0.0158 (9) | −0.0065 (9) |
C8' | 0.0265 (9) | 0.0284 (9) | 0.0313 (9) | 0.0017 (8) | 0.0121 (7) | −0.0010 (8) |
C9' | 0.0245 (8) | 0.0296 (9) | 0.0269 (8) | −0.0003 (7) | 0.0099 (7) | −0.0025 (7) |
C1 | 0.0265 (9) | 0.0267 (10) | 0.0325 (9) | 0.0009 (8) | 0.0069 (8) | −0.0005 (8) |
C2 | 0.0288 (9) | 0.0309 (10) | 0.0311 (9) | 0.0054 (8) | 0.0076 (7) | −0.0035 (8) |
C3 | 0.0312 (9) | 0.0361 (10) | 0.0309 (9) | 0.0050 (8) | 0.0101 (8) | 0.0026 (8) |
C4 | 0.0239 (9) | 0.0293 (10) | 0.0332 (9) | 0.0053 (8) | 0.0067 (8) | −0.0007 (8) |
C5 | 0.0244 (9) | 0.0319 (10) | 0.0389 (10) | 0.0023 (8) | 0.0074 (8) | 0.0017 (8) |
C6 | 0.0251 (9) | 0.0373 (11) | 0.0457 (11) | −0.0005 (9) | 0.0047 (8) | −0.0071 (9) |
C7 | 0.0271 (9) | 0.0450 (12) | 0.0321 (10) | 0.0049 (9) | 0.0025 (8) | −0.0039 (9) |
C8 | 0.0246 (8) | 0.0338 (10) | 0.0341 (9) | 0.0070 (8) | 0.0062 (8) | −0.0026 (8) |
C9 | 0.0239 (8) | 0.0284 (9) | 0.0330 (9) | 0.0048 (7) | 0.0064 (7) | −0.0024 (8) |
C21' | 0.0404 (10) | 0.0301 (11) | 0.0652 (13) | −0.0019 (9) | 0.0157 (10) | −0.0059 (9) |
C51' | 0.0333 (10) | 0.0607 (13) | 0.0377 (10) | −0.0006 (10) | 0.0047 (8) | 0.0080 (9) |
C81' | 0.0360 (10) | 0.0306 (10) | 0.0466 (11) | 0.0020 (8) | 0.0135 (9) | 0.0027 (8) |
C21 | 0.0373 (10) | 0.0431 (11) | 0.0363 (9) | −0.0029 (9) | 0.0096 (8) | −0.0088 (9) |
C51 | 0.0350 (10) | 0.0415 (12) | 0.0510 (11) | −0.0056 (9) | 0.0091 (9) | 0.0049 (9) |
C81 | 0.0352 (10) | 0.0501 (12) | 0.0335 (9) | 0.0037 (9) | 0.0079 (8) | 0.0031 (9) |
C1'—C9' | 1.515 (2) | C5—C6 | 1.398 (2) |
C1'—C2' | 1.519 (2) | C5—C51 | 1.504 (2) |
C1'—C1 | 1.572 (2) | C6—C7 | 1.393 (2) |
C1'—H1' | 0.980 (13) | C6—H6 | 1.001 (17) |
C2'—C3' | 1.340 (2) | C7—C8 | 1.400 (2) |
C2'—C21' | 1.491 (2) | C7—H7 | 1.006 (16) |
C3'—C4' | 1.458 (2) | C8—C9 | 1.389 (2) |
C3'—H3' | 0.946 (16) | C8—C81 | 1.505 (2) |
C4'—C5' | 1.389 (2) | C21'—H2A' | 0.9800 |
C4'—C9' | 1.404 (2) | C21'—H2B' | 0.9800 |
C5'—C6' | 1.396 (2) | C21'—H2C' | 0.9800 |
C5'—C51' | 1.506 (2) | C51'—H5A' | 0.9800 |
C6'—C7' | 1.390 (2) | C51'—H5B' | 0.9800 |
C6'—H6' | 1.024 (17) | C51'—H5C' | 0.9800 |
C7'—C8' | 1.396 (2) | C81'—H8A' | 0.9800 |
C7'—H7' | 1.000 (16) | C81'—H8B' | 0.9800 |
C8'—C9' | 1.393 (2) | C81'—H8C' | 0.9800 |
C8'—C81' | 1.505 (2) | C21—H2A | 0.9800 |
C1—C9 | 1.512 (2) | C21—H2B | 0.9800 |
C1—C2 | 1.531 (2) | C21—H2C | 0.9800 |
C1—H1 | 0.993 (15) | C51—H5A | 0.9800 |
C2—C3 | 1.335 (2) | C51—H5B | 0.9800 |
C2—C21 | 1.493 (2) | C51—H5C | 0.9800 |
C3—C4 | 1.469 (2) | C81—H8A | 0.9800 |
C3—H3 | 1.010 (15) | C81—H8B | 0.9800 |
C4—C5 | 1.390 (2) | C81—H8C | 0.9800 |
C4—C9 | 1.409 (2) | ||
C9'—C1'—C2' | 102.35 (13) | C7—C6—C5 | 121.77 (17) |
C9'—C1'—C1 | 113.84 (12) | C7—C6—H6 | 121.4 (9) |
C2'—C1'—C1 | 113.52 (12) | C5—C6—H6 | 116.8 (9) |
C9'—C1'—H1' | 110.5 (8) | C6—C7—C8 | 121.73 (16) |
C2'—C1'—H1' | 109.9 (8) | C6—C7—H7 | 117.9 (9) |
C1—C1'—H1' | 106.7 (8) | C8—C7—H7 | 120.4 (9) |
C3'—C2'—C21' | 126.47 (16) | C9—C8—C7 | 116.85 (15) |
C3'—C2'—C1' | 109.81 (15) | C9—C8—C81 | 122.57 (15) |
C21'—C2'—C1' | 123.66 (15) | C7—C8—C81 | 120.57 (15) |
C2'—C3'—C4' | 110.95 (16) | C8—C9—C4 | 120.99 (15) |
C2'—C3'—H3' | 125.0 (10) | C8—C9—C1 | 129.51 (14) |
C4'—C3'—H3' | 124.1 (10) | C4—C9—C1 | 109.48 (13) |
C5'—C4'—C9' | 121.72 (15) | C2'—C21'—H2A' | 109.5 |
C5'—C4'—C3' | 130.67 (15) | C2'—C21'—H2B' | 109.5 |
C9'—C4'—C3' | 107.61 (14) | H2A'—C21'—H2B' | 109.5 |
C4'—C5'—C6' | 116.88 (16) | C2'—C21'—H2C' | 109.5 |
C4'—C5'—C51' | 121.69 (15) | H2A'—C21'—H2C' | 109.5 |
C6'—C5'—C51' | 121.43 (16) | H2B'—C21'—H2C' | 109.5 |
C7'—C6'—C5' | 121.36 (17) | C5'—C51'—H5A' | 109.5 |
C7'—C6'—H6' | 118.9 (9) | C5'—C51'—H5B' | 109.5 |
C5'—C6'—H6' | 119.7 (9) | H5A'—C51'—H5B' | 109.5 |
C6'—C7'—C8' | 121.99 (17) | C5'—C51'—H5C' | 109.5 |
C6'—C7'—H7' | 120.3 (9) | H5A'—C51'—H5C' | 109.5 |
C8'—C7'—H7' | 117.7 (9) | H5B'—C51'—H5C' | 109.5 |
C9'—C8'—C7' | 116.67 (15) | C8'—C81'—H8A' | 109.5 |
C9'—C8'—C81' | 122.29 (15) | C8'—C81'—H8B' | 109.5 |
C7'—C8'—C81' | 121.02 (15) | H8A'—C81'—H8B' | 109.5 |
C8'—C9'—C4' | 121.23 (14) | C8'—C81'—H8C' | 109.5 |
C8'—C9'—C1' | 129.69 (14) | H8A'—C81'—H8C' | 109.5 |
C4'—C9'—C1' | 109.08 (14) | H8B'—C81'—H8C' | 109.5 |
C9—C1—C2 | 102.25 (12) | C2—C21—H2A | 109.5 |
C9—C1—C1' | 114.12 (12) | C2—C21—H2B | 109.5 |
C2—C1—C1' | 113.77 (13) | H2A—C21—H2B | 109.5 |
C9—C1—H1 | 110.9 (9) | C2—C21—H2C | 109.5 |
C2—C1—H1 | 109.4 (8) | H2A—C21—H2C | 109.5 |
C1'—C1—H1 | 106.4 (8) | H2B—C21—H2C | 109.5 |
C3—C2—C21 | 126.23 (15) | C5—C51—H5A | 109.5 |
C3—C2—C1 | 109.85 (14) | C5—C51—H5B | 109.5 |
C21—C2—C1 | 123.84 (14) | H5A—C51—H5B | 109.5 |
C2—C3—C4 | 111.15 (15) | C5—C51—H5C | 109.5 |
C2—C3—H3 | 124.1 (9) | H5A—C51—H5C | 109.5 |
C4—C3—H3 | 124.8 (9) | H5B—C51—H5C | 109.5 |
C5—C4—C9 | 122.19 (14) | C8—C81—H8A | 109.5 |
C5—C4—C3 | 130.66 (14) | C8—C81—H8B | 109.5 |
C9—C4—C3 | 107.14 (14) | H8A—C81—H8B | 109.5 |
C4—C5—C6 | 116.30 (15) | C8—C81—H8C | 109.5 |
C4—C5—C51 | 122.07 (14) | H8A—C81—H8C | 109.5 |
C6—C5—C51 | 121.63 (15) | H8B—C81—H8C | 109.5 |
Experimental details
(I) | (II) | |
Crystal data | ||
Chemical formula | [Co(C12H13)2] | C24H26 |
Mr | 373.38 | 314.47 |
Crystal system, space group | Triclinic, P1 | Monoclinic, P21/c |
Temperature (K) | 173 | 173 |
a, b, c (Å) | 7.4150 (3), 7.9299 (3), 8.8881 (4) | 12.1229 (4), 9.6880 (4), 15.7045 (6) |
α, β, γ (°) | 81.578 (2), 69.260 (2), 85.453 (2) | 90, 102.942 (2), 90 |
V (Å3) | 483.27 (3) | 1797.59 (12) |
Z | 1 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.89 | 0.07 |
Crystal size (mm) | 0.34 × 0.20 × 0.10 | 0.39 × 0.25 × 0.17 |
Data collection | ||
Diffractometer | Nonius Kappa CCD diffractometer | Nonius Kappa CCD diffractometer |
Absorption correction | Empirical (using intensity measurements) (DENZO-SMN; Otwinowski & Minor, 1997) | Empirical (using intensity measurements) (DENZO-SMN; Otwinowski & Minor, 1997) |
Tmin, Tmax | 0.752, 0.916 | 0.975, 0.989 |
No. of measured, independent and observed reflections | 4872, 1903, 1827 [I > 2σ(I)] | 8928, 4024, 2298 [I > \2s(I)] |
Rint | 0.044 | 0.040 |
(sin θ/λ)max (Å−1) | 0.617 | 0.648 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.074, 1.13 | 0.048, 0.115, 0.95 |
No. of reflections | 1903 | 4024 |
No. of parameters | 118 | 255 |
H-atom treatment | H-atom parameters constrained | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.25, −0.46 | 0.19, −0.17 |
Computer programs: COLLECT (Nonius, 1999), DENZO-SMN (Otwinowski & Minor, 1997), DENZO-SMN, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-III for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).
C21—C2 | 1.501 (3) | C9—C4 | 1.427 (3) |
C2—C1 | 1.413 (3) | C9—Co | 2.2056 (17) |
C2—C3 | 1.418 (3) | C4—C3 | 1.446 (3) |
C2—Co | 2.0672 (17) | C4—Co | 2.2100 (17) |
C1—C9 | 1.445 (3) | C3—Co | 2.0562 (17) |
C1—Co | 2.0553 (18) | ||
C1—C2—C3 | 107.39 (16) | C4—C9—Co | 71.32 (10) |
C1—C2—Co | 69.49 (10) | C1—C9—Co | 64.66 (10) |
C3—C2—Co | 69.46 (10) | C9—C4—C3 | 107.29 (16) |
C21—C2—Co | 124.70 (14) | C9—C4—Co | 70.98 (10) |
C2—C1—C9 | 108.98 (16) | C3—C4—Co | 64.54 (9) |
C2—C1—Co | 70.40 (10) | C2—C3—C4 | 108.65 (16) |
C9—C1—Co | 75.90 (10) | C2—C3—Co | 70.30 (10) |
C4—C9—C1 | 107.11 (16) | C4—C3—Co | 76.04 (10) |
C1'—C9' | 1.515 (2) | C1—C9 | 1.512 (2) |
C1'—C2' | 1.519 (2) | C1—C2 | 1.531 (2) |
C1'—C1 | 1.572 (2) | C2—C3 | 1.335 (2) |
C2'—C3' | 1.340 (2) | C2—C21 | 1.493 (2) |
C2'—C21' | 1.491 (2) | C3—C4 | 1.469 (2) |
C3'—C4' | 1.458 (2) | C4—C9 | 1.409 (2) |
C4'—C9' | 1.404 (2) | ||
C9'—C1'—C2' | 102.35 (13) | C9—C1—C2 | 102.25 (12) |
C9'—C1'—C1 | 113.84 (12) | C9—C1—C1' | 114.12 (12) |
C2'—C1'—C1 | 113.52 (12) | C2—C1—C1' | 113.77 (13) |
C3'—C2'—C1' | 109.81 (15) | C3—C2—C1 | 109.85 (14) |
C2'—C3'—C4' | 110.95 (16) | C2—C3—C4 | 111.15 (15) |
C9'—C4'—C3' | 107.61 (14) | C9—C4—C3 | 107.14 (14) |
C4'—C9'—C1' | 109.08 (14) | C4—C9—C1 | 109.48 (13) |
Late transition metal complexes have been shown to be active catalysts for hydrogenations, hydroformylations, isomerizations or cycloadditions (Eisen et al., 1991; Leitner, 1995; Castellanos-Páez et al., 1997; Zhu et al., 1998; Witulski et al., 1999; Beller et al., 1999). In comparison to their analogous cyclopentadienyl complexes the more electrophilic transition metal complexes with indenyl ligands often show enhanced reactivities (Kakkar et al., 1992). This was attributed to the ability of indenyl complexes to undergo ring slippage of the five-membered indenyl ring coordinated to the metal from a η5– to a η3-coordination mode (Trost & Kulawiec, 1993). Currently only one X-ray structure of a neutral bis(indenyl) complex of cobalt has been described (Westcott et al., 1990).
Bis(indene) compounds are potential precursors for the synthesis of dibenzfulvenes (Lustenberger et al., 1979), bis(indane) compounds (Grindley et al., 1996) or bimetallic complexes (Arce et al., 1999) and can generally be conveniently synthesized by oxidative coupling of the corresponding indenyl salts (Escher et al., 1987). Due to two asymmetric centers at the bridging carbon atoms three stereoisomers occur of which two form a pair of enantiomers, with (1R,1'R) or (1S,1'S) configurations at their stereogenic centers. Currently only two crystal structures of bis(indene) compounds have been reported (Lustenberger et al., 1979; Maouche et al., 1985).
In the course of our investigations regarding the synthesis of indenyl-transition metal complexes (Halterman et al., 2000; Schumann, Stenzel, Dechert, Girgsdies & Halterman et al., 2001), we isolated bis(2,4,7-trimethylindenyl)cobalt(II), (I), and rac-1,1'-bis(2,4,7-trimethylindene), (II), as side products in the formation of dicarbonyl(2,4,7-trimethylindenyl)cobalt(I) in the presence of 1 eq. iodine, starting from 1 eq. octacarbonyldicobalt(0) and 2 eq. (2,4,7-trimethylindenyl)lithium (Figures 1 and 2). \sch
Chromatographic separation of the crude mixture in an inert atmosphere with n-hexane as eluent followed by crystallization from n-hexane, resulted in the isolation of the pure compound (I) and the diastereomerically pure compound (II). The pure crystalline compound (I) and its solutions are sensitive to air and moisture while (II) is stable under these conditions. The high thermal stability of (I) and (II) can be shown by mass spectrometry as the molecular ions form the peaks of highest intensity. Compounds (I) and (II) are soluble in polar solvents such as THF, pyridine and diethyl ether as well as in aromatic solvents such as benzene or toluene, and non-polar solvents such as n-hexane.
Compound (II) can be obtained independently by reacting stoichiometric amounts of (2,4,7-trimethylindenyl)lithium with iodine in THF at 338 K without the presence of the cobalt complex. In the absence of iodine, however, no product is formed. Under the reported reaction conditions the corresponding diastereomeric meso-compound (1R,1'S)-1,1'-bis(2,4,7-trimethylindene) is formed in approximately 20% yield, as determined by 1H NMR spectroscopy of the crude reaction mixture.
The molecular structure of 1 (Figure 3) exhibits a cobalt(II) atom coordinated in η5-fashion to two 2,4,7-trimethylindenyl ligands. The indenyl planes in (I) are parallel to each other as the position of the cobalt atom lies on an inversion centre. As the cobalt atom lies on an inversion centre the main axes of the indenyl ligands form a rotation angle (RA) of exactly 180°. This is the first example of a bis(indenyl)cobalt compound where this is observed. In the less sterically hindered bis(η5-indenyl)cobalt(II) (Westcott et al., 1990) a nearly eclipsed conformation of the indenyl ligands (RA = 10.4°) is found, whereas in the more sterically hindered bis(η5-heptamethylindenyl)cobalt(III) hexafluorophosphate (O'Hare et al., 1993) a nearly perpendicular conformation (RA = 89°) occurs. Rotation angles of 9.1 and 151.3° have been observed for bis(η5-indenyl)iron(II) and bis(η5-heptamethylindenyl)iron(II), respectively, the latter increased angle was attributed to orbital effects (Crossley et al.,1989). In (+)-bis(η5-2-menthylindenyl)iron(II) a rotation angle of 134° has been ascribed to additional sterical interactions of the terpene units with the indenyl ligands (Schumann, Stenzel, Dechert & Halterman et al., 2001). A completely staggered indenyl ligand conformation, similar to that found in 1 has been observed for bis(η5-heptamethylindenyl)chromium(II), with the metal atom also situated on a crystallographic inversion centre (O'Hare et al., 1993).
The average bond length of carbon atoms in both five-membered rings to the metal is 2.119 (2) Å. These lengths correlate well with the average Co—C bond lengths of 2.077 (8) Å in bis(η5-heptamethylindenyl)cobalt(III) hexafluorophosphate (O'Hare et al., 1993) and 2.121 (4) Å observed in bis(η5-indenyl)cobalt(II) (Westcott et al., 1990). The five-membered rings of the indenyl systems are not equally bound to the cobalt atom but resemble an unsymmetrical η5-coordination with slip distortions (Δ M—C) of 0.153 Å [Δ M—C = difference in the average metal to carbon distances: 0.5(M—C4 + M—C9)–0.5(M—C1 + M—C3)] and ring slippage towards C2 of 0.157 Å [ring slippage = distance from the normal of the least-squares ring plane defined by C1, C2, C3, C4, C9 to the metal atom and the centroid of the five membered ring]. This tendency towards a slight η3-coordination, accounts for a hinge angle (HA) of 7.4° [HA = angle between normals to the least-squares planes defined by C1, C2, C3 and C1, C9, C4, C3] as well as a fold angle (FA) of 6.3° [FA = angle between normals to the least-squares planes defined by C1, C2, C3 and C4, C5, C6, C7, C8, C9]. Similiar values of Δ M—C = 0.119 Å, 0.074 Å, 0.043 Å and 0.030 Å, HA = 7.6, 4.5, 2.2 and 2.5° as well as FA = 6.0, 4.8, 1.0 and 4.4° are found in the 19 valence-electron complexes bis(η5-indenyl)cobalt(II), bis(η5-heptamethylindenyl)cobalt(III) hexafluorophosphate and the 18 valence-electron complexes bis(η5-indenyl)iron(II) and bis(η5-heptamethylindenyl)iron(II), respectively. Significantly increased distortions of Δ M—C = 0.418 Å, HA = 13.9° and FA = 13.1° are found in the 20 valence-electron complex bis(η5-indenyl)nickel(II) (Westcott et al., 1990) to avoid 20 valence-electron counts.
The molecular structure of the (1R,1'R) stereoisomer of (II) is shown in Figure 4. Bond length and angles compare well with those found in of meso-1,1'-bis (indenyl) (Lustenberger et al., 1979) and rac-1,1'-bis(1,3-dimethylindene) (Maouche et al., 1985). The tetrahedral geometries of the stereogenic centers (C1 and C1') are slightly distorted due to steric constraints as a result of the opposing 2,4,7-trimethylindenyl fragment [C2—C1—C1' = 113.77 (13)° and C2'-C1'-C1 = 113.52 (12)°]. Both 2,4,7-trimethylindenyl ring fragments are close to planarity with the largest deviations from their least squares planes being 0.066 (1) and 0.057 (1) Å towards the opposing indenyl fragments for C1 and C1' respectively. The C1—C1' bond length is 1.572 (2) Å. The length of the double bonds between C2 and C3 and C2' and C3' [1.340 (2) and 1.335 (2) Å] are not affected by the coupling of the two indenyl fragments. The least squares planes through the 2,4,7-trimethylindenyl rings lie at an angle of 56.62 (3)° to one another. The C2—C1—C1'-C2' torsion angle is 48.0 (2)°.
In the unit cell molecules of (II) pack along the a axis in zigzag chains of alternating (1R,1'R) and (1S,1'S) stereoisomers as a result of π- and geometrical stacking effects (Figure 5). The parallel planes through the indenyl moieties are 3.62 and 3.69 Å apart.