Transformation of 1,1′-biphosphirane-M(CO)5 (M = Mo, Cr, W) complexes: Possible mechanisms and reactivity of active intermediates

Abstract

The possible mechanisms of transformations of biphosphirane-M(CO)5 (M = Mo, Cr) complexes have been investigated by performing a combined density functional theory (DFT) and experimental study. According to calculated results, these kinds of reactions contain three possible pathways, including two pathways (i.e. the concerted and stepwise pathways) leading to 3,4-dihydro-1,2-diphosphete intermediate and one stepwise pathway leading to diphosphorus intermediate. Computational results reveal that both stepwise pathways are more energetically favorable than the concerted pathway in kinetics, and both two intermediates could be obtained in the experiments. Then we systematically studied the electrophilicity of two intermediates with coordination of different M(CO)5 (M = Mo, Cr, W). Further molecular electrostatic potential (MEP) demonstrates that two phosphorus atoms in the active intermediates can work as electrophilic sites. The obtained insights should be useful for rational design on novel reactions involving two active intermediates in future.