A traditional synthetic method, and a new structural motif, for molybdenum-gold clusters: synthesis and solid-state structure of Au8{Mo(CO)5}4(PPh3)4.

The neutral cluster [Au8Mo4(CO)20(PPh3)4] was synthesized in low yield from [AuCl(PPh3)] and [Mo2(CO)10]2- in acetonitrile at room temperature. The cluster was characterized by X-ray analysis, IR, and 31P NMR spectroscopy. Its solid-state structure consists of four Au(3)Mo tetrahedral units, fused by four Au atoms in a ring.

Synthesis and structural characterization of the [[Rh(5)(CO)(14)]-(H(2)N(CH(2))(4)NH(2))-[Rh(5)(CO)(14)])](2-) and [Rh(5)(CO)(13)(H(2)N(CH(2))(2)NH(2))](-) anions (as [PPh(4)](+) salts): an unprecedented example of carbonyl substitution by alkylamines in a homoleptic metal carbonyl cluster anion.

The substitution of one or two carbonyls by many different primary and secondary alkylamines and -diamines has been established for the first time in a homoleptic carbonyl cluster anion, the trigonal bipyramidal [Rh(5)(CO)(15)](-). Two derivatives, the bis-monosubstituted [[Rh(5)(CO)(14)]-(H(2)N(CH(2))(4)NH(2))-[Rh(5)(CO)(14)]](2-) dianion (1) and the disubstituted chelated [Rh(5)(CO)(13)(H(2)N(CH(2))(2)NH(2))](-) monoanion (2), have been structurally characterized, both in the solid state (as [PPh(4)](+) salts) and in solution, revealing that the sites of the substitution are the cluster apexes. (13)C NMR spectra of 2 revealed localized fluxionality of the CO ligands over the temperature range 298-183 K.

Mixed Ruthenium-Rhodium Carbonyl Cluster Complexes. Synthesis of the Anions [Ru(3)Rh(CO)(13)](-) and [RuRh(3)(CO)(12)](-) and Crystal Structures of Their [N(PPh(3))(2)](+) Salts(1).

The new anion [Ru(3)Rh(CO)(13)](-) (1) has been obtained by reaction of [Rh(CO)(4)](-) ([N(PPh(3))(2)](+) or [PPh(4)](+) salt) with Ru(3)(CO)(12); [RuRh(3)(CO)(12)](-) (2) has been derived by oxidative degradation of [RuRh(4)(CO)(12)](2-). Their salts, [N(PPh(3))(2)][Ru(3)Rh(CO)(13)] (I) and [N(PPh(3))(2)][RuRh(3)(CO)(12)] (II), were characterized by single-crystal X-ray diffraction. Data for I: space group P&onemacr;, a = 9.