Tetraphosphabenzenes Obtained via a Triphosphacyclobutadiene Intermediate

Abstract

An acyl triphosphirene ligand transfers an O atom to Nb to liberate the putative triphosphacyclobutadiene intermediate [RCP3{W(CO)5}2], which engages in [2+4]-cycloaddition reactions with an organic diene and a phosphaalkyne (see scheme; P orange, O red, W violet, C white). The latter reaction yields the Dewar isomer of a tetraphosphabenzene, which can be converted to a tetraphosphabenzvalene containing a Z-diphosphene.