A mechanistic study of the C–P bond cleavage reaction of 1,2-(PH2)2-C6H4 with nBuLi/Sb(NMe2)3

Abstract

In situ ³¹P NMR spectroscopic studies of the reaction of the primary diphosphine 1,2-(PH₂)₂-C₆H₄ with the mixed-metal base system ⁿBuLi/Sb(NMe₂)₃, combined with X-ray structural investigations, strongly support a mechanism involving a series of deprotonation steps followed by antimony-mediated reductive C–P bond cleavage. The central intermediate in this reaction is the tetraphosphide dianion [C₆H₄P₂]₂²⁻ ([4]) from which the final products, the 1,2,3-triphospholide anion [C₆H₄P₃]⁻ (3) and [PhPHLi] (8·Li), are evolved. An EPR spectrocopic study suggests that homolytic C–P bond cleavage is likely to be involved in this final step.