SYNTHESIS AND MOLECULAR-STRUCTURE OF 2 6-MEMBERED RU3C3 RINGS EXISTING IN BOAT-LIKE AND CHAIR-LIKE 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)(e ta(5)-C9H6)(2)] (2), a trinuclear complex with an open Ru-3 unit conta ining the 1,1'-bis(indenylidene) ligand, and two metallacyclic rutheni um 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 configurati ons similar to the boat-chair isomerism of cyclohexane. Both complexes are configurational rather than conformational isomers, because the b oat-to-chair ring flip is hampered by the rigid nature of the Ru3C3 me tallacycle. The structures of 2-4 have been established by X-ray cryst allography.