Tetranuclear phosphide- and phosphinidene-bridged derivatives of the diphosphenyl complex [Mo2Cp2(μ-PCy2)(μ-κ2:κ2-P2Me)(CO)2]

Abstract

Reaction of the title complex with excess [Fe2(CO)9] at room temperature gave the tetranuclear derivative [Fe2Mo2Cp2(μ4-P)(μ-PCy2)(μ3-PMe)(CO)9], following from formal insertion of an Fe(CO)3 fragment in the P-P bond of the diphosphenyl ligand with formation of a new heterometallic bond (Mo-Fe = 2.935 (1) Å), and coordination of an Fe(CO)4 fragment through the lone electron pair of the resulting phosphide ligand (P-Fe = 2.359(2) Å). Reactions of the title complex with excess of the tetrahydrofuran (THF) adducts [MLn(THF)] (MLn = MnCp(CO)2, W(CO)5) led instead to tetranuclear diphosphenyl-bridged complexes [M2Mo2Cp2(μ-PCy2)(μ-κ2:κ1:κ1:κ1-P2Me)(CO)2L2n] displaying a Mo-Mo double bond (Mo-Mo = 2.760(2) Å when M = W), along with the phosphide- and phosphinidene-bridged complex [Mo2W2Cp2(μ3-P)(μ-PCy2)(μ3-PMe)(CO)10], with the latter displaying a Mo-Mo triple bond (Mo-Mo = 2.5542(4) Å) and a trigonal planar phosphide ligand. Reaction of the title complex with excess [Mo(CO)4(THF)2] also resulted in facile P-P bond cleavage of the diphosphenyl ligand to give [Mo4Cp2(μ4-P)(μ-PCy2)(μ3-PMe)(CO)9], a cluster built on a Mo3 triangular core bridged by phosphinidene and phosphide ligands, with the latter further coordinated to an exocyclic Mo(CO)5 fragment. The related Mo2W2 complex [Mo2W2Cp2(μ3-P)(μ-PCy2)(μ3-PMe)(CO)9] could be rationally synthesized upon reaction of the trinuclear cluster [Mo2WCp2(μ3-P)(μ-PCy2)(μ3-PMe)(CO)6] with the adduct [W(CO)5(THF)]. The title complex reacted photochemically with [M2(CO)10] (M = Mn, Re) to give the 66-electron tetranuclear derivatives [M2Mo2Cp2(μ4-P)(μ-PCy2)(μ3-PMe)(CO)9], after formation of a new Mo-M bond (Mo-Mn = 2.9988(7) Å, Mo-Re = 3.1003(4) Å) and cleavage of the diphosphenyl P-P bond. In contrast, its room-temperature reaction with [Co2(CO)8] gave the 64-electron square-planar cluster [Co2Mo2Cp2(μ4-P)(μ-PCy2)(μ4-PMe)(μ-CO)(CO)6] resulting from formation of two new Mo-Co bonds (Mo-Co = 2.8812(7) and 2.9067(7) Å) and facile P-P bond cleavage in the diphosphenyl ligand.