Reactions of Ru5(μ5-C2)(μ-SMe)2(μ-PPh2)2(CO)11 with C2(SiMe3)2:: formation of butatrienylidene complexes and related chemistry.: X-ray crystal structures of Ru5{μ5-CC[C2(SiMe3)]C(SiMe3)C(SiMe3)} (μ3-SMe)(μ-PPh2)2(CO)10, Ru5(μ5-CCCCH2)(μ3-SMe)(μ-SMe)(μ-PPh2)2(CO)10 and Ru5(μ5-CCCCH2)(μ-SMe)2(μ-PPh2)2(CO)11

The reaction between the dicarbon-containing complex Ru-5(mu(5)-C-2)(mu-SMe)(2)(mu-PPh2)(2)(CO)(11) (1) and C-2(SiMe3)(2) afforded two isomers of Ru-5{mu(5)-CCCCH(SiMe3)}(mu(3)-SMe)(mu-SMe)(mu-Phh(2))(2)(CO)(10) (2a,b). A minor product from this reaction was Ru-5{mu(5)-CC[C-2(SiMe3)]C(SiMe3)C(SiMe3)} (mu(3)-SMe)(mu-PPh2)(2)(CO)(10) (3) in which an SMe ligand is lost from 1. The major products from reactions of 1 with HC equivalent to Bu' were analogues of 2a,b, namely Ru-5(mu(5)-CCCCHBu)(mu(3)-SMe)(mu-SMe)(mu-PPh2)(2)(CO)(10) (6a,b). Treatment of 2 with KOH results in desilylation and formation of the first structurally characterised butatrienylidene complex Ru-5(mu(5)-CCCCH2) (mu(3)-SMe)(mu-SMe)(mu-PPh2)(2)(CO)(10) (4). Carbonylation (80 degrees C, 1.5 h) afforded Ru-5(mu(5)-CCCCH2) (mu-SMe)(2)(mu-PPh2)(2)(CO)(10) (5). The molecular structures of 3, 4 and 5 were determined by single-crystal X-ray studies. In 3 and 4, the Ru-5 core has an open envelope conformation; in 5, one Ru-Ru bond of the flap has been cleaved. Two molecules of alkyne have become attached to the same carbon atom of the C-2 unit in 3, with concomitant loss of (MeS + SiMe3). In 4 and 5, the organic ligand is butatrienylidene, formed by formal 'end-to-end' coupling of the C-2 moiety with the vinylidene :C=CII(SiMe3); the unsaturated carbene ligand is attached to the cluster by three of its four carbon atoms. (C) 1999 Elsevier Science s.A. All rights reserved.