Benzynechromium tricarbonyl. Further synthetic studies

Article abstract of DOI:10.1016/s0020-1693(96)05252-8

The thermolysis of Ru₃(CO)₁₁[Ph₂PC₆H ₅Cr(CO)₃] affords two isomers of the benzyne derivative Ru₃(CO)₇(C₆H₄) [PPhC₆H₅Cr(CO)₃]₂ ((5) and (6)). The crystal structure of 5, previously determined, shows the phenyl groups are trans to the Ru₃-triangle; in 6 they are probably cis and on the same side of the Ru₃-triangle as the benzyne moiety. Os₃(CO)₁₁[Ph₂PC₆H ₅Cr(CO)₃] decomposes on heating to afford a benzyne derivative of a less common class Os₃(CO)₉(C₆H₄)[PC₆H ₅Cr(CO)₃] (7), and an electron deficient molecule Os₃(CO)₈(PhPC₆H₄)[Ph ₂PC₆H₅Cr(CO)₃] (8), in which the PhPC₆H₄ moiety acts as a four-electron donor. The isopropylphosphine derivatives M₃(CO)₁₁[Prⁱ₂PC₆H ₅Cr(CO)₃] (M=Ru, Os), also undergo thermolysis to afford HRu₃(CO)₈[C₆H₄Cr(CO) ₃](PPrⁱ₂) (10), Ru(CO)₃[Prⁱ₂PC₆H ₅Cr(CO)₃]₂ (11), H₂Os₃(CO)₈[PrⁱPC₆H ₄Cr(CO)₃] (12) and H₂Os₃(CO)₈[PrⁱPC₆H ₄Cr(CO)₃] [Prⁱ₂PC₆H₅-Cr(CO)₃] (13). Complex 10 is probably a benzynechromium tricarbonyl derivative with a Cr-Ru bond. The phosphines are trans in complex 11, a derivative of Ru(CO)₅. The structures of complexes 12 and 13 are closely related and the orthometalated [PC₆H₄Cr(CO)₃] moiety is acting as a four-electron donor to the cluster. Crystal data: for 8 (C₄₁H₂₄CrO₁₁Os₃P ₂·CH₂Cl₂): monoclinic, a = 13.039(3), b = 18.001(2), c = 20.125(2) A?, β = 108.42(1)°, Z=4, space group P2₁/n; for 11 (C₃₃H₃₈Cr₂O₉P₂Ru): monoclinic, a = 15.390(1), b = 10.241(2), c = 23.490(1) A?, β = 96.686(6)°, Z=4, space group P2₁/a; for 12 (C₂₁H₁₃CrO₁₂Os₃P): orthorhombic, a = 14.695(2), b = 16.696(2), c = 11.186(1) A?, Z = 4, space group P2₁2₁2₁; for 13 (C₃₅H₃₂Cr₂O₁₄Os₃P ₂·2CH₂Cl₂): monoclinic, a = 11.536(2), b = 18.354(4), c = 23.176(3) A?, β = 98.43(2)°, Z = 4, space group P2₁/n. The structures were solved by Patterson methods and were refined by full-matrix least-squares procedures to R = 0.057, 0.031, 0.030 and 0.032 (R_w = 0.065, 0.030, 0.028 and 0.030) for 6320, 6103, 3529 and 6042 reflections with I ≥ 3σ (I), respectively.