SYNTHESIS OF OS3W ALKYLIDYNE AND ALKYLIDENE CLUSTERS BY SOLID-STATE PYROLYSIS - DIRECT C-O BOND-CLEAVAGE OF COORDINATED KETENYL LIGAND

The heterometallic tetranuclear ketenyl compound [Os3(CO)10(mu-H){C(O) CH2W(CO)3(eta-C5Me5)}] 1 possessing a pendant W(eta-C5Me5)(CO)3 substi tuent is prepared by condensation of [Os3(CO)10(NCMe)2] with the aldeh yde complex [W(eta-C5Me5)(CO)3(CH2CHO)]. Pyrolysis of 1 in the solid s tate at 185-degrees-C afforded four tetrahedral compounds [WOs3(eta-C5 Me5)(CO)9(mu-O)(mu3-CMe)] 2, [WOs3(eta-C5Me5)(CO)9(mu-O)(mu-H)(mu-CHMe )] 5, [WOs3(eta-C5Me5)(CO)11(mu3-CMe)] 3 and [WOs3(eta-C5Me5)(CO)11(mu 3-CH)] 4, demonstrating a unique example of C-0 bond scission for the ligated ketene fragment. Since treatment of 2 with H-2 in toluene also afforded 5 in moderate yield, it is highly probable that the latter i s produced via reaction with trace amounts of H-2 generated from the d ecomposition of 1. The molecular structures of 2 and 4 have been deter mined by single-crystal X-ray analysis.