COMPLEXES WITH FUNCTIONAL PHOSPHINES .17. SYNTHESIS AND CHARACTERIZATION OF RUTHENIUM CLUSTERS WITH KETOPHOSPHINE LIGANDS - CRYSTAL-STRUCTURE OF THE CLUSTER [RU3(MU-H)(MU-ETA-1(O)-ETA-2(P,O)-O(=CPH)=CHPPH2)(CO)9] CONTAINING A BRIDGING PHOSPHINOENOLATE LIGAND

Reactions of the ketophosphine Ph2PCH2C(O)Ph (P-O) with [Ru3(CO)12] afford the derivatives [Ru3(CO)11(P-O)] (1) and [Ru3(CO)10(P-O)2] (4). In the presence of triphenylphosphiniminium acetate (PPN)(OAc), the former leads to the labile [Ru3(CO)10{mu-(P) O)}] (2), in which the functional phosphine acts as a (P, O) bridging ligand, whereas thermal activation of either 1 or 4 results in PC-H bond cleavage and formation of [Ru3(mu-H)[mu-eta(1)(O):eta(2)(P,O)-O(...CPh)...CHPPh2}(CO)9] (3) whose crystal structure reveals an unprecedented bonding mode for the phosphinoenolate ligand, its oxygen atom bridging the Ru(1)-Ru(2) edge. Protonation of this complex occurs selectively at the enolato-carbon and [Ru3(mu-H){mu-Ph2PCH2C(O)Ph}(CO)10]BF4 (5) and [Ru3(mu-H){mu-Ph2PCH2C(O)-Ph}2(CO)8]BF4 (7) were characterized in which the P O ligand(s) bridge between two Ru centres.