Remarkable Metal-Complexed Phosphorus Analogues of the Cyclopropenylcarbene–Cyclobutadiene Rearrangement

Abstract
In situ-generated metal carbonyl-complexed cyclopropenylphosphinidenes undergo a sequence of structural changes leading to phosphorus analogues of Pettit’s seminal (η4-cyclobutadiene)iron tricarbonyl complex via multiple valence isomers along the reaction pathway and the elimination of one molecule of carbon monoxide.