Inmaculada Amor

Aurophilic Self-Assembly of a Mo4Au2 Phosphinidene Complex with an Unprecedented H-Shaped Planar Metal Core

The isomers [Mo2Cp2(mu-kappa(1):kappa(1),eta(6)-PR*)(CO)2] (1) and [Mo2Cp(mu-kappa(1):kappa(1),eta(5)-PC5H4)(CO)2(eta(6)-HR*)] (2) (Cp = eta(5)-C5H5; R* = 2,4,6-C6H2(t)Bu3) react with [AuCl(THT)] and with the cation [Au(THT)2](+) (THT = tetrahydrothiophene) to give phosphinidene-bridged Mo2Au complexes resulting from the addition of an AuCl or Au(THT)(+) electrophile to their multiple P-Mo bonds. Removal of the Cl(-) or THT ligand from these derivatives causes a dimerization of the trinuclear structures to give the cationic derivative [{AuMo2Cp(mu3-kappa(1):kappa(1):kappa(1),eta(5)-PC5H4)(CO)2(eta(6)-HR*)}2](2+), which displays a novel H-shaped metal core held by strong Mo-Au dative bonds [2.768(1) A] and an aurophilic interaction [Au-Au = 3.022(1) A].

A thiophosphinidene complex as a vehicle in phosphinidene transmetalation: easy formation and cleavage of a P-S bond.

A method for the generation of transition metal-phosphorus multiple bonds has been developed using the reactions of a novel thiophosphinidene-bridged dimolybdenum complex with different metal carbonyls. The overall process could be considered as a transmetalation of the phosphinidene ligand involving the activation of P-S and P-Mo bonds.

Sn–H bond additions to asymmetric trigonal phosphinidene-bridged dimolybdenum complexes

The reactions between organotin hydrides HSnR3 (R = Bu, Ph) and the asymmetric trigonal phosphinidene-bridged complexes [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(CO)2(η6-HMes*)] (1), [Mo2Cp2(μ-PH)(CO)2(η6-HMes*)] (2), and [Mo2Cp2(μ-PMe)(CO)2(η6-HMes*)] (3) were examined, and found to be strongly dependent on the parent complex (Mes* = 2,4,6-C6H2tBu3). Compound 1 reacted with HSnR3 upon moderate heating (353–363 K), to give the corresponding derivatives [Mo2Cp{μ-κ1:κ1,η5-P(H)C5H4}(SnR3)(CO)2(η6-HMes*)], following from a formal 1,2-addition of the Sn–H bond across the Mo–P double bond of the parent complex, with specific formation of Sn–Mo and H–P bonds. Complex 2 reacted analogously, but much faster, to yield the corresponding phosphanyl-bridged derivatives [Mo2Cp2(μ-PH2)(SnR3)(CO)2(η6-HMes*)] at room temperature. However, these products progressively degraded to the corresponding mononuclear phosphine complexes trans-[MoCp(SnR3)(CO)2(PH3)] in the presence of trace amounts of water. The methylphosphinidene-bridged complex 3 (Mo–P = 2.550(3) and 2.281(3) A) was prepared upon reaction of MeLi with the phosphide-bridged complex [Mo2Cp2(μ-P)(CO)2(η6-HMes*)](BAr′4), (Ar′ = 3,5-C6H3(CF3)2). Its reaction with HSnR3 proceeded at room temperature with H–Sn bond addition now accompanied by spontaneous dehydrogenation, to yield the corresponding cyclopentadienylidene–phosphanyl derivatives [Mo2Cp{μ-κ1:κ1,η5-P(Me)C5H4}(SnR3)(CO)2(η6-HMes*)]. The structures of the new complexes were analyzed using spectroscopic, diffractometric and, in some cases, density functional theory methods. The Sn–H bond cleavages leading to the complexes eventually isolated in these reactions were proposed to be initiated by σ-bond coordination of the organotin reagent, via its Sn–H bond, to the metal atom of the MoCp(CO)2 fragment in the parent compounds, this being followed by a H-shift to the P atom of the bridging phosphinidene ligand.