Metal core rearrangements in hetero-bimetallic nona-osmium carbonyl clusters;: the crystal and molecular structures of [Os9(CO)24{Au(PCy3)}2] and [Os9(CO)23(Au2DPPE)]

The reaction of the nona-osmium cluster dianion [(Ph3P)(2)N](2)[Os-9(CO)(24)] with the electrophilic gold reagents "AuPR3+" and "Au2L2+" (where R = Ph (2a, 3a), Cy (2b, 3b) and L = bis-(diphenylphosphino)methane (DPPM) (la) or 1,2-bis-(diphenyl)ethane (DPPE) (lb)) has been studied. The monogold fragment reacts to give both the mono-and di-substituted products [(Ph3P)(2)N][Os-9(CO)(24){Au(PR3)}] and [Os-9(CO)(24){Au(PR3)}(2)]. The structure of the latter cluster (R = Cy (2b)) has been determined by a single crystal X-ray diffraction analysis and a major rearrangement of the metal core geometry was found to have occurred on coordination of the gold fragments. In contrast, reaction with the digold reagent "Au2L2+" results in the isolation of only one product of formulation [Os-9(CO)(23)(Au2L)], where coordination of the heteroatom moiety has been accompanied with the loss of a carbonyl ligand. From a single crystal X-ray diffraction analysis (L = DPPE (lb)) this compound was shown to have retained its original cluster geometry, with the gold atoms coordinated in close proximity to each other. (C) 1998 Elsevier Science S.A.