Reactivity of dirhenium and triruthenium carbonyls toward a biphosphole ligand: M–M, P–P and C–H bonds cleavage

Abstract : The reaction of [Re2(CO)8(CH3CN)2] with bis(2-thienyl)biphosphole in refluxing n-octane affords the complex [Re(CO)3(η5-PC16H14S2)] (1) where cleavage of the Re–Re and P–P bonds occurs; its molecular structure confirms the formation of a rhenium mononuclear compound with a η5-coordinated phospholyl unit and three carbonyl groups oriented in a tripod. On the other hand, bis(2-thienyl)biphosphole reacts with [Ru3(CO)12] in refluxing cyclohexane to affording two new compounds [Ru3(CO)9(μ:η1:η5-PC16H13S2)] (2) and [Ru4(CO)13(μ:η1-PC16H14S2)2] (3). Spectroscopic data and theoretical studies of 2 suggest the formation of an open Ru3 cluster with two metal–metal bonds bridged by a (η1:η5-PC16H13S2) unit and a C-H bond activation of one of the thienyl substituents. X-ray structure of 3 reveals a novel tetranuclear ruthenium cluster containing 13 terminal carbonyl ligands and two phospholyl units coordinated as μ-phosphide.