Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802021062/ob6184sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536802021062/ob6184Isup2.hkl |
CCDC reference: 202300
To a flame-dried flask were added (II) (100.1 mg, 0.5 mmol) and Co2(CO)8 (512.9 mg, 0.5 mmol) and CH2Cl2 (10 ml), and the mixture was stirred for 12 h at room temperature in the dark. After evaporation, hexane was added to the residual black solid and filtered through a thin layer of silica gel. After evaporation of the filtrate, dark purple crystals of (I) were obtained in 50–60% yield.
The H atoms were located from difference density maps and refined isotropically with restraints, C—H 0.968 (3)–1.079 (3) Å.
It has been recognized that 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene, (II), C16H8, has the most strained acetylenes (Destro et al., 1975). Although these triple bonds are quite reactive because of their great strain energy, only one example of a plutinum complex on the triple bonds has been reported so far (Shimada et al., 1997). We have advanced a new methodology for access to various acetylenes and succeeded in preparing a Co2(CO)6 complex of an acetylenic cyclophane (Orita et al., 2002). We have been intrigued by the structural features of Co2(CO)6 complexes of the most strained acetylene 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene, (II), and have carried out an investigation of the title compound, (I).
By X-ray analysis of the starting cyclophane (II), it has been revealed that the triple bonds adopt a bond length of 1.195 (2) Å and a bond angle of 155.3 (1)° (Destro et al., 1975). Coordination of the Co2(CO)6 moiety on the acetylene of (I) makes the C1—C2 bond length lengthen to 1.356 (2) Å and the bond angle C1—C2—C3 contract to 147.53 (16)°. In sharp contrast to these, the corresponding length and angle of the other side in (I) remain unchanged, exhibiting the same bond length [1.196 (2) Å] and angle [155.98 (18)°] as observed in (II). Interestingly, the lengths of the C1—C2, C2—C3 and C1—C16 bonds are almost the same as in the (η2-PhC≡ CPh)-Co2(CO)6 complex (Gregson et al., 1983). The bond angle C1—C2—C3 [147.53 (16)°] is somewhat larger than the corresponding angle [140.2 (9)°] in diphenylacetylene-Co2(CO)6. Two cobalt atoms Co1 and Co2 are located at the same distance from C1 and C2, but unsymmetrically folded out of the plane involving the eight-membered ring [Co1—C1—C2—C3 = 154.1 (4)° and Co2—C1—C2—C3 = -122.5 (4)°].
Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: TEXSAN (Rigaku, 1999); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: CrystalStructure (Molecular Structure Corporation/Rigaku Corporation, 2001).
[Co2(C16H8)(CO)6] | F(000) = 968.0 |
Mr = 486.17 | Dx = 1.742 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.7107 Å |
a = 16.2876 (8) Å | Cell parameters from 8782 reflections |
b = 7.4552 (4) Å | θ = 4.0–27.5° |
c = 17.1415 (5) Å | µ = 1.83 mm−1 |
β = 117.075 (3)° | T = 93 K |
V = 1853.34 (15) Å3 | Cubic, black |
Z = 4 | 0.30 × 0.30 × 0.20 mm |
Rigaku RAXIS-IV diffractometer | 3763 reflections with F2 > 2σ(F2) |
Detector resolution: 10.00 pixels mm-1 | Rint = 0.037 |
ω scans | θmax = 27.5° |
Absorption correction: multi-scan (Higashi, 1995) | h = −21→21 |
Tmin = 0.471, Tmax = 0.694 | k = −9→9 |
14932 measured reflections | l = −21→21 |
4379 independent reflections |
Refinement on F2 | All H-atom parameters refined |
R[F2 > 2σ(F2)] = 0.031 | w = 1/[0.002Fo2 + 1.000σ2(Fo)]/(4Fo2) |
wR(F2) = 0.090 | (Δ/σ)max < 0.001 |
S = 0.99 | Δρmax = 0.59 e Å−3 |
4090 reflections | Δρmin = −0.90 e Å−3 |
279 parameters |
[Co2(C16H8)(CO)6] | V = 1853.34 (15) Å3 |
Mr = 486.17 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 16.2876 (8) Å | µ = 1.83 mm−1 |
b = 7.4552 (4) Å | T = 93 K |
c = 17.1415 (5) Å | 0.30 × 0.30 × 0.20 mm |
β = 117.075 (3)° |
Rigaku RAXIS-IV diffractometer | 4379 independent reflections |
Absorption correction: multi-scan (Higashi, 1995) | 3763 reflections with F2 > 2σ(F2) |
Tmin = 0.471, Tmax = 0.694 | Rint = 0.037 |
14932 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 279 parameters |
wR(F2) = 0.090 | All H-atom parameters refined |
S = 0.99 | Δρmax = 0.59 e Å−3 |
4090 reflections | Δρmin = −0.90 e Å−3 |
Refinement. Refinement using reflections with F2 > -10.0 σ(F2). The weighted R-factor (wR) and goodness of fit (S) are based on F2. R-factor (gt) are based on F. The threshold expression of F2 > 2.0 σ(F2) is used only for calculating R-factor (gt). |
x | y | z | Uiso*/Ueq | ||
Co1 | 0.38094 (2) | 0.17146 (3) | 0.28606 (1) | 0.01106 (7) | |
Co2 | 0.26158 (2) | 0.35769 (3) | 0.17228 (1) | 0.01072 (7) | |
O2 | 0.4392 (1) | 0.4646 (2) | 0.41524 (9) | 0.0329 (4) | |
O4 | 0.3628 (1) | 0.4352 (2) | 0.06964 (9) | 0.0255 (4) | |
O5 | 0.06619 (9) | 0.3703 (2) | 0.04409 (9) | 0.0220 (3) | |
O1 | 0.4323 (1) | −0.1258 (2) | 0.41238 (9) | 0.0247 (4) | |
O6 | 0.2603 (1) | 0.6809 (2) | 0.27254 (9) | 0.0250 (4) | |
O3 | 0.5318 (1) | 0.1777 (2) | 0.23545 (9) | 0.0252 (4) | |
C13 | 0.0564 (1) | 0.1268 (3) | 0.3466 (1) | 0.0164 (4) | |
C21 | 0.1428 (1) | 0.3695 (2) | 0.0920 (1) | 0.0152 (4) | |
C20 | 0.3230 (1) | 0.4129 (3) | 0.1085 (1) | 0.0165 (4) | |
C8 | 0.1662 (1) | −0.1107 (2) | 0.0582 (1) | 0.0130 (4) | |
C10 | 0.0846 (1) | −0.0361 (3) | 0.1521 (1) | 0.0152 (4) | |
C1 | 0.2469 (1) | 0.1542 (2) | 0.2383 (1) | 0.0116 (4) | |
C2 | 0.2736 (1) | 0.0918 (2) | 0.1791 (1) | 0.0113 (4) | |
C19 | 0.4738 (1) | 0.1737 (2) | 0.2548 (1) | 0.0160 (4) | |
C9 | 0.1057 (1) | −0.0845 (3) | 0.0972 (1) | 0.0150 (4) | |
C7 | 0.1446 (1) | −0.2097 (3) | −0.0181 (1) | 0.0166 (4) | |
C11 | 0.0975 (1) | 0.0473 (2) | 0.2323 (1) | 0.0134 (4) | |
C15 | 0.2018 (1) | 0.2259 (2) | 0.3560 (1) | 0.0148 (4) | |
C14 | 0.1388 (1) | 0.2193 (3) | 0.3901 (1) | 0.0162 (4) | |
C5 | 0.2963 (1) | −0.1492 (2) | −0.0041 (1) | 0.0180 (4) | |
C18 | 0.4177 (1) | 0.3489 (3) | 0.3670 (1) | 0.0193 (4) | |
C12 | 0.0349 (1) | 0.0417 (3) | 0.2675 (1) | 0.0160 (4) | |
C17 | 0.4127 (1) | −0.0156 (3) | 0.3617 (1) | 0.0160 (4) | |
C22 | 0.2628 (1) | 0.5587 (3) | 0.2340 (1) | 0.0163 (4) | |
C4 | 0.3178 (1) | −0.0486 (3) | 0.0712 (1) | 0.0156 (4) | |
C16 | 0.1823 (1) | 0.1403 (2) | 0.2763 (1) | 0.0120 (4) | |
C3 | 0.2536 (1) | −0.0267 (2) | 0.1038 (1) | 0.0125 (4) | |
C6 | 0.2098 (1) | −0.2296 (3) | −0.0489 (1) | 0.0186 (4) | |
H1 | 0.3759 (1) | 0.0145 (3) | 0.1015 (1) | 0.020 (1)* | |
H2 | 0.3342 (1) | −0.1761 (2) | −0.0376 (1) | 0.024 (1)* | |
H3 | 0.1951 (1) | −0.2961 (3) | −0.1023 (1) | 0.024 (1)* | |
H4 | 0.0783 (1) | −0.2749 (3) | −0.0496 (1) | 0.021 (1)* | |
H5 | −0.0218 (1) | −0.0267 (3) | 0.2361 (1) | 0.020 (1)* | |
H6 | 0.0133 (1) | 0.1271 (3) | 0.3774 (1) | 0.022 (1)* | |
H7 | 0.1524 (1) | 0.2889 (3) | 0.4422 (1) | 0.021 (1)* | |
H8 | 0.2589 (1) | 0.2967 (2) | 0.3870 (1) | 0.018 (1)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Co1 | 0.0072 (1) | 0.0128 (1) | 0.0118 (1) | −0.00002 (8) | 0.0032 (1) | −0.00026 (8) |
Co2 | 0.0078 (1) | 0.0120 (1) | 0.0118 (1) | −0.00017 (8) | 0.0040 (1) | 0.00012 (7) |
O2 | 0.0311 (8) | 0.0277 (8) | 0.0236 (7) | 0.0039 (7) | −0.0019 (6) | −0.0111 (6) |
O4 | 0.0192 (7) | 0.0349 (8) | 0.0274 (7) | 0.0008 (6) | 0.0150 (6) | 0.0073 (6) |
O5 | 0.0110 (7) | 0.0286 (8) | 0.0222 (6) | 0.0025 (5) | 0.0040 (5) | 0.0040 (5) |
O1 | 0.0238 (8) | 0.0236 (7) | 0.0245 (7) | −0.0008 (6) | 0.0091 (6) | 0.0066 (6) |
O6 | 0.0272 (8) | 0.0195 (7) | 0.0243 (7) | 0.0030 (6) | 0.0082 (6) | −0.0046 (6) |
O3 | 0.0159 (7) | 0.0336 (9) | 0.0305 (7) | 0.0027 (6) | 0.0144 (6) | 0.0059 (6) |
C13 | 0.0163 (9) | 0.0187 (9) | 0.0187 (8) | 0.0030 (7) | 0.0119 (7) | 0.0021 (7) |
C21 | 0.0162 (9) | 0.0163 (9) | 0.0156 (8) | 0.0017 (7) | 0.0095 (7) | 0.0010 (6) |
C20 | 0.0128 (8) | 0.0159 (8) | 0.0166 (7) | 0.0011 (7) | 0.0029 (6) | 0.0028 (6) |
C8 | 0.0124 (8) | 0.0130 (8) | 0.0154 (7) | −0.0011 (6) | 0.0080 (6) | 0.0000 (6) |
C10 | 0.0092 (8) | 0.0204 (9) | 0.0160 (7) | −0.0046 (7) | 0.0059 (6) | −0.0028 (7) |
C1 | 0.0082 (8) | 0.0127 (8) | 0.0127 (7) | 0.0002 (6) | 0.0036 (6) | 0.0010 (5) |
C2 | 0.0072 (7) | 0.0131 (8) | 0.0124 (7) | −0.0013 (6) | 0.0032 (6) | −0.0001 (6) |
C19 | 0.0117 (8) | 0.0157 (9) | 0.0170 (8) | 0.0010 (6) | 0.0035 (6) | 0.0027 (6) |
C9 | 0.0103 (8) | 0.0176 (9) | 0.0154 (7) | −0.0044 (7) | 0.0045 (6) | −0.0024 (6) |
C7 | 0.0172 (9) | 0.0179 (9) | 0.0159 (8) | −0.0042 (7) | 0.0085 (6) | −0.0032 (6) |
C11 | 0.0109 (8) | 0.0144 (8) | 0.0159 (7) | 0.0001 (6) | 0.0069 (6) | −0.0001 (6) |
C15 | 0.0150 (8) | 0.0159 (8) | 0.0141 (7) | −0.0003 (7) | 0.0071 (6) | −0.0015 (6) |
C14 | 0.0204 (9) | 0.0160 (9) | 0.0153 (7) | 0.0014 (7) | 0.0107 (7) | −0.0002 (6) |
C5 | 0.022 (1) | 0.0184 (9) | 0.0191 (8) | 0.0009 (7) | 0.0140 (7) | −0.0013 (6) |
C18 | 0.0133 (9) | 0.022 (1) | 0.0171 (8) | 0.0028 (7) | 0.0017 (7) | 0.0012 (7) |
C12 | 0.0128 (8) | 0.0185 (9) | 0.0188 (8) | −0.0010 (7) | 0.0091 (6) | −0.0011 (7) |
C17 | 0.0109 (8) | 0.0195 (9) | 0.0169 (7) | −0.0012 (7) | 0.0056 (6) | −0.0025 (7) |
C22 | 0.0117 (8) | 0.0195 (9) | 0.0144 (7) | 0.0004 (7) | 0.0030 (6) | 0.0018 (6) |
C4 | 0.0125 (8) | 0.0175 (8) | 0.0191 (7) | −0.0008 (7) | 0.0090 (6) | −0.0010 (6) |
C16 | 0.0115 (8) | 0.0132 (8) | 0.0119 (7) | 0.0012 (6) | 0.0059 (6) | 0.0013 (6) |
C3 | 0.0120 (8) | 0.0119 (8) | 0.0144 (7) | 0.0006 (6) | 0.0067 (6) | −0.0001 (6) |
C6 | 0.0240 (9) | 0.0177 (9) | 0.0180 (8) | −0.0022 (7) | 0.0131 (7) | −0.0034 (7) |
Co1—Co2 | 2.4616 (3) | C13—C12 | 1.390 (2) |
Co1—C1 | 1.9564 (17) | C13—H6 | 1.053 (4) |
Co1—C2 | 1.9626 (16) | C8—C7 | 1.401 (2) |
C1—C2 | 1.356 (2) | C8—C3 | 1.420 (2) |
C2—C3 | 1.474 (2) | C10—C11 | 1.434 (2) |
C8—C9 | 1.434 (2) | C1—C16 | 1.471 (2) |
C9—C10 | 1.196 (2) | C7—C6 | 1.391 (2) |
Co1—C19 | 1.8196 (19) | C7—H4 | 1.079 (3) |
Co1—C18 | 1.8101 (19) | C11—C12 | 1.401 (2) |
Co1—C17 | 1.8122 (18) | C11—C16 | 1.417 (2) |
Co2—C21 | 1.7942 (19) | C15—C14 | 1.394 (2) |
Co2—C20 | 1.8331 (18) | C15—C16 | 1.408 (2) |
Co2—C1 | 1.9719 (16) | C15—H8 | 0.989 (3) |
Co2—C2 | 1.9903 (18) | C14—H7 | 0.968 (3) |
Co2—C22 | 1.8297 (18) | C5—C4 | 1.392 (2) |
O2—C18 | 1.135 (2) | C5—C6 | 1.396 (3) |
O4—C20 | 1.133 (2) | C5—H2 | 1.036 (3) |
O5—C21 | 1.140 (2) | C12—H5 | 0.975 (3) |
O1—C17 | 1.131 (2) | C4—C3 | 1.400 (2) |
O6—C22 | 1.136 (2) | C4—H1 | 0.970 (3) |
O3—C19 | 1.135 (2) | C6—H3 | 0.970 (3) |
C13—C14 | 1.386 (3) | ||
C1—C2—C3 | 147.53 (16) | Co1—C1—C2 | 70.0 (1) |
C2—C3—C8 | 120.83 (14) | Co2—C1—C2 | 70.7 (1) |
C3—C8—C9 | 114.39 (14) | Co1—C1—C16 | 134.95 (12) |
C8—C9—C10 | 155.98 (18) | Co2—C1—C16 | 127.31 (12) |
Co2—Co1—C1 | 51.48 (5) | C2—C1—C16 | 147.67 (16) |
Co2—Co1—C2 | 51.99 (5) | Co1—C2—Co2 | 77.03 (6) |
C1—Co1—C2 | 40.49 (6) | Co1—C2—C1 | 69.5 (1) |
Co2—Co1—C19 | 102.93 (6) | Co2—C2—C1 | 69.3 (1) |
C1—Co1—C19 | 142.76 (7) | Co1—C2—C3 | 138.38 (12) |
C2—Co1—C19 | 103.51 (7) | Co2—C2—C3 | 124.67 (11) |
Co2—Co1—C18 | 93.52 (6) | Co1—C19—O3 | 178.97 (16) |
C1—Co1—C18 | 106.57 (8) | C8—C7—C6 | 119.97 (16) |
C2—Co1—C18 | 141.27 (8) | C8—C7—H4 | 118.2 (1) |
C19—Co1—C18 | 100.97 (9) | C6—C7—H4 | 121.76 (11) |
Co2—Co1—C17 | 150.05 (6) | C10—C11—C12 | 125.57 (15) |
C1—Co1—C17 | 98.60 (7) | C10—C11—C16 | 113.79 (14) |
C2—Co1—C17 | 106.17 (7) | C12—C11—C16 | 120.64 (14) |
C19—Co1—C17 | 102.29 (8) | C14—C15—C16 | 120.47 (16) |
C18—Co1—C17 | 97.28 (8) | C14—C15—H8 | 119.1 (1) |
Co1—Co2—C21 | 145.29 (6) | C16—C15—H8 | 120.4 (1) |
Co1—Co2—C20 | 98.65 (5) | C13—C14—C15 | 120.63 (15) |
C21—Co2—C20 | 102.85 (7) | C13—C14—H7 | 121.5 (1) |
Co1—Co2—C1 | 50.92 (5) | C15—C14—H7 | 117.7 (1) |
C21—Co2—C1 | 96.17 (7) | C4—C5—C6 | 120.37 (16) |
C20—Co2—C1 | 139.19 (8) | C4—C5—H2 | 130.96 (11) |
Co1—Co2—C2 | 50.98 (4) | C6—C5—H2 | 108.6 (1) |
C21—Co2—C2 | 97.86 (7) | Co1—C18—O2 | 177.44 (16) |
C20—Co2—C2 | 101.11 (7) | C13—C12—C11 | 119.78 (16) |
C1—Co2—C2 | 40.02 (6) | C13—C12—H5 | 122.18 (11) |
Co1—Co2—C22 | 101.95 (5) | C11—C12—H5 | 118.0 (1) |
C21—Co2—C22 | 97.31 (8) | Co1—C17—O1 | 176.04 (16) |
C20—Co2—C22 | 107.23 (8) | Co2—C22—O6 | 177.16 (17) |
C1—Co2—C22 | 105.67 (7) | C5—C4—C3 | 120.95 (16) |
C2—Co2—C22 | 143.79 (7) | C5—C4—H1 | 122.04 (11) |
C14—C13—C12 | 120.26 (16) | C3—C4—H1 | 116.9 (1) |
C14—C13—H6 | 115.6 (1) | C1—C16—C11 | 121.30 (14) |
C12—C13—H6 | 124.09 (11) | C1—C16—C15 | 120.44 (15) |
Co2—C21—O5 | 175.95 (16) | C11—C16—C15 | 118.21 (15) |
Co2—C20—O4 | 175.37 (17) | C8—C3—C4 | 118.17 (14) |
C9—C8—C7 | 125.03 (16) | C2—C3—C4 | 120.83 (15) |
C7—C8—C3 | 120.59 (15) | C7—C6—C5 | 119.95 (16) |
C9—C10—C11 | 156.41 (18) | C7—C6—H3 | 120.6 (1) |
Co1—C1—Co2 | 77.60 (6) | C5—C6—H3 | 119.4 (1) |
C1—C2—C3—C8 | 11.0 (6) | Co1—C1—C2—C3 | 154.1 (4) |
C3—C8—C9—C10 | −7.2 (7) | Co2—C1—C2—C3 | −122.5 (4) |
C16—C1—C2—C3 | 7.9 (7) | Co1—C1—C16—C15 | 33.3 (3) |
C8—C9—C10—C11 | 3.0 (10) | Co2—C1—C16—C15 | −79.0 (2) |
Experimental details
Crystal data | |
Chemical formula | [Co2(C16H8)(CO)6] |
Mr | 486.17 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 93 |
a, b, c (Å) | 16.2876 (8), 7.4552 (4), 17.1415 (5) |
β (°) | 117.075 (3) |
V (Å3) | 1853.34 (15) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.83 |
Crystal size (mm) | 0.30 × 0.30 × 0.20 |
Data collection | |
Diffractometer | Rigaku RAXIS-IV |
Absorption correction | Multi-scan (Higashi, 1995) |
Tmin, Tmax | 0.471, 0.694 |
No. of measured, independent and observed [F2 > 2σ(F2)] reflections | 14932, 4379, 3763 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.090, 0.99 |
No. of reflections | 4090 |
No. of parameters | 279 |
No. of restraints | ? |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.59, −0.90 |
Computer programs: PROCESS-AUTO (Rigaku, 1998), PROCESS-AUTO, TEXSAN (Rigaku, 1999), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), CrystalStructure (Molecular Structure Corporation/Rigaku Corporation, 2001).
Co1—Co2 | 2.4616 (3) | Co2—C20 | 1.8331 (18) |
Co1—C1 | 1.9564 (17) | Co2—C1 | 1.9719 (16) |
Co1—C2 | 1.9626 (16) | Co2—C2 | 1.9903 (18) |
C1—C2 | 1.356 (2) | Co2—C22 | 1.8297 (18) |
C2—C3 | 1.474 (2) | O2—C18 | 1.135 (2) |
C8—C9 | 1.434 (2) | O1—C17 | 1.131 (2) |
C9—C10 | 1.196 (2) | O3—C19 | 1.135 (2) |
Co1—C19 | 1.8196 (19) | C8—C3 | 1.420 (2) |
Co1—C18 | 1.8101 (19) | C10—C11 | 1.434 (2) |
Co1—C17 | 1.8122 (18) | C1—C16 | 1.471 (2) |
Co2—C21 | 1.7942 (19) | C11—C16 | 1.417 (2) |
C1—C2—C3 | 147.53 (16) | Co2—C1—C2 | 70.7 (1) |
C2—C3—C8 | 120.83 (14) | Co1—C1—C16 | 134.95 (12) |
C3—C8—C9 | 114.39 (14) | Co2—C1—C16 | 127.31 (12) |
C8—C9—C10 | 155.98 (18) | C2—C1—C16 | 147.67 (16) |
Co1—Co2—C1 | 50.92 (5) | C10—C11—C16 | 113.79 (14) |
C7—C8—C3 | 120.59 (15) | C1—C16—C11 | 121.30 (14) |
C9—C10—C11 | 156.41 (18) | C8—C3—C4 | 118.17 (14) |
Co1—C1—C2 | 70.0 (1) | ||
C1—C2—C3—C8 | 11.0 (6) | Co1—C1—C2—C3 | 154.1 (4) |
C3—C8—C9—C10 | −7.2 (7) | Co2—C1—C2—C3 | −122.5 (4) |
C16—C1—C2—C3 | 7.9 (7) | Co1—C1—C16—C15 | 33.3 (3) |
C8—C9—C10—C11 | 3.0 (10) | Co2—C1—C16—C15 | −79.0 (2) |
It has been recognized that 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene, (II), C16H8, has the most strained acetylenes (Destro et al., 1975). Although these triple bonds are quite reactive because of their great strain energy, only one example of a plutinum complex on the triple bonds has been reported so far (Shimada et al., 1997). We have advanced a new methodology for access to various acetylenes and succeeded in preparing a Co2(CO)6 complex of an acetylenic cyclophane (Orita et al., 2002). We have been intrigued by the structural features of Co2(CO)6 complexes of the most strained acetylene 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene, (II), and have carried out an investigation of the title compound, (I).
By X-ray analysis of the starting cyclophane (II), it has been revealed that the triple bonds adopt a bond length of 1.195 (2) Å and a bond angle of 155.3 (1)° (Destro et al., 1975). Coordination of the Co2(CO)6 moiety on the acetylene of (I) makes the C1—C2 bond length lengthen to 1.356 (2) Å and the bond angle C1—C2—C3 contract to 147.53 (16)°. In sharp contrast to these, the corresponding length and angle of the other side in (I) remain unchanged, exhibiting the same bond length [1.196 (2) Å] and angle [155.98 (18)°] as observed in (II). Interestingly, the lengths of the C1—C2, C2—C3 and C1—C16 bonds are almost the same as in the (η2-PhC≡ CPh)-Co2(CO)6 complex (Gregson et al., 1983). The bond angle C1—C2—C3 [147.53 (16)°] is somewhat larger than the corresponding angle [140.2 (9)°] in diphenylacetylene-Co2(CO)6. Two cobalt atoms Co1 and Co2 are located at the same distance from C1 and C2, but unsymmetrically folded out of the plane involving the eight-membered ring [Co1—C1—C2—C3 = 154.1 (4)° and Co2—C1—C2—C3 = -122.5 (4)°].