Chemistry of CS- and SCNPh-adducts of the pyramidal phosphinidene-bridged complex [MoCp(μ-κ:κ,η-PCH)(CO)(η-HMes*)(PMe)].

The title complex reacted readily with CS and SCNPh to give the phosphinidene-cumulene adducts [MoCp{μ-κ:κ,η-P(CS)CH}(CO)(η-HMes*)(PMe)] and [MoCp{μ-κ:κ,η-P(C(NPh)S)CH}(CO)(η-HMes*)(PMe)] respectively (Mes* = 2,4,6-CHBu), as a result of the formal insertion of the C[double bond, length as m-dash]S bond of the heterocumulene into the metallocene Mo-P bond of the phosphinidene complex. The newly formed species bear a pyramidal P atom with a lone electron pair involved in fast inversion, and displayed strong nucleophilicity which enabled easy addition at the P site of carbon-based electrophiles and chalcogen atoms, while the uncoordinated S and N atoms were also competitive nucleophilic sites in these complexes. These air-sensitive materials readily added an O molecule in the solid state, to give the corresponding derivatives [MoCp{μ-κ:κ,η-OP(O)(C(X)S)CH}(CO)(η-HMes*)(PMe)] (X = S, NPh), and the CS adduct reacted selectively with S in solution to give the sulfide derivative [MoCp{μ-κ:κ,η-P(S)(CS)CH}(CO)(η-HMes*)(PMe)], which was stabilized through methylation, thus yielding the cationic complex [MoCp{μ-κ:κ,η-P(S)(C(SMe)S)CH}(CO)(η-HMes*)(PMe)]. The CS adduct could be methylated selectively at either the P or C[double bond, length as m-dash]S sites, depending on the reagent used, to give respectively the cationic complexes [MoCp{μ-κ:κ,η-PMe(CS)CH}(CO)(η-HMes*)(PMe)] or [MoCp{μ-κ:κ,η-P(C(SMe)S)CH}(CO)(η-HMes*)(PMe)]. Further methylation could be accomplished through reaction with [MeO]BF to give the dipositive cation [MoCp{μ-κ:κ,η-PMe(C(SMe)S)CH}(CO)(η-HMes*)(PMe)]. In contrast, the SCNPh adduct was only methylated at the P site to yield the phosphanylthioformamidato complex [MoCp{μ-κ:κ,η-PMe(C(NPh)S)CH}(CO)(η-HMes*)(PMe)], but was readily protonated at the N site upon reaction with (NH)PF, to give the phosphanylthioformamide-like derivative [MoCp{μ-κ:κ,η-P(C(NHPh)S)CH}(CO)(η-HMes*)(PMe)]. In the presence of Na(BAr'), this adduct was even able to displace chloride from the solvent (dichloromethane) to give the corresponding chloromethyl derivative [MoCp{μ-κ:κ,η-P(CHCl)(C(NPh)S)CH}(CO)(η-HMes*)(PMe)]. The structures of the new complexes were analyzed using spectroscopic, diffractometric and, in some cases, density functional theory methods.