REACTIONS OF TETRANUCLEAR RHODIUM TRIRUTHENIUM CLUSTERS WITH DI-PHOSPHINES AND TRI-PHOSPHINES AND WITH ALKYNES

The compound [RhRu3(mu-H)2(mu-CO)(CO)9(cp)] 1 (cp = eta(5)-C5H5) and an equimolar amount of diphosphine Ph2P(CH2)nPPh2 [n = 1 (dppm), 2 (dppe) or 3 (dppp)] react at ambient temperature principally with cleavage of the heteronuclear cluster to form several homonuclear rhodium and ruthenium products. Isolated ruthenium clusters are simple phosphine derivatives of [Ru3(CO)12] or [Ru4(mu-H)4(CO)12], including [Ru3(mu-diphos)2(CO)8] (diphos = dppm or dppe), [Ru3(mu-diphos)(CO)10] and [{Ru3(mu-diphos)(CO)9}2(mu-diphos)] (diphos = dppe or dppp), and [Ru4(mu-H)4(CO)10(dppp)]. Reaction of 1 with the triphosphine MeC(CH2PPh2)3 affords hydrido-clusters [Ru3(mu-H)H(mu-triphos)(CO)8] and [Ru3(mu-H){mu-PPhCH2CMe(CH2PPh2)2}(CO)8] 12, the latter formed by elimination of benzene under very mild reaction conditions. The solid-state structure of cluster 12 has been determined by X-ray crystallographic analysis [monosolvate with dichloromethane, monoclinic, space group P2(1)/n, a = 19.549(3), b = 14.2462(21), c = 16.429(4) angstrom, beta = 90.271(18)-degrees, Z = 4, R = 0.051, R' = 0.060] and the geometrical non-rigidity of this asymmetric molecule in solution is revealed by variable-temperature P-31 NMR spectroscopy. Reactions of cluster 1 with alkynes, RC = Cr (R = Ph or Et), give heteronuclear products, including isomers of [RhRu3(C2R2)(CO)9(cp)] and trimetallic clusters [RhRu2(C2R2)(CO)n(cp)] (R = Et, n = 7; R = Ph, n = 8); from reaction of [RhRu3(mu-H)4(CO)9(eta(5)-C5Me5)] with PhC = CPh a related tetranuclear cluster [RhRu3(C2R2)(CO)9(eta(5)-C5Me5)] is formed. A new, octahedral heteronuclear cluster [Rh2Ru4(mu-H)2(CO)12(cp)2] is also reported.