Synthesis and molecular structure of two six-membered Ru3C3 rings existing in boat- and chairlike configurations formed by insertion of C9H6 units into metal-metal bonds of [RU(3)(CO)(12)]

The reaction of diazoindene (C9H6N2) with [Ru-3(CO)(12)] in THF leads to the formation of the clusters [Ru-3(CO)(10)(eta(5):eta(1)-C9H6)] (1), by the insertion of a C9H6 moiety into a Ru-Ru bond, [Ru-3(CO)(8)(eta(5)-C9H6)(2)] (2), a trinuclear complex with an open Ru-3 unit containing the 1,1'-bis(indenylidene) ligand, and two metallacyclic ruthenium trimers of formula [Ru-3(CO)(6)-(eta(5):eta(1)-C9H6)(3)] (3 and 4). The cyclic trimers have stable chair- and twist-boat-like configurations similar to the boat-chair isomerism of cyclohexane. Both complexes are configurational rather than conformational isomers, because the boat-to-chair ring flip is hampered by the rigid nature of the Ru3C3 metallacycle. The structures of 2-4 have been established by X-ray crystallography.