Benzynechromium tricarbonyl. Further synthetic studies

{The thermolysis of Ru-3(CO)(11)[Ph(2)PC(6)H(5)Cr(CO)(3)] affords two isomers of the benzyne derivative Ru-3(CO)(7)(C6H4)[PPhC(6)H(5)Cr(CO)(3)](2) ((5) and (6)). The crystal structure of 5, previously determined, shows the phenyl groups are trans to the Ru-3-triangle; in 6 they are probably cis and on the same side of the Ru-3-triangle as the benzyne moiety. Os-3(CO)(11)[Ph(2)PC(6)H(5)Cr(CO)(3)] decomposes on heating to afford a benzyne derivative of a less common class Os-3(CO)(9)(C6H4)[PC6H5Cr(CO)(3)] (7), and an electron deficient molecule Os-3(CO)(8)(PhPC(6)H(4))[Ph(2)PC(6)H(5)Cr(CO)(3)] (8), in which the PhPC(6)H(4) moiety acts as a four-electron donor. The isopropylphosphine derivatives M(3)(CO)(11)[(Pr2PC6H5Cr)-P-i(CO)(3)] (M=Ru, Os), also undergo thermolysis to afford HRu3(CO)(8)[C6H4Cr(CO)(3)](PPr2i) (10), Ru(CO)(3)[(Pr2PC6H5Cr)-P-i(CO)(3)](2) (11), H2Os3(CO)(8)[(PrPC6H4Cr)-P-i(CO)(3)] (12) and H2Os3(CO)(8)[(PrPC6H4Cr)-P-i(CO)(3)][(Pr2PC6H5Cr)-P-i(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 (C41H24CrO11Os3P2 . CH2Cl2): monoclinic