PUB - Publikationen an der Universität Bielefeld

The title compound phosphabutatriene possesses two energetically closely spaced frontier orbitals, as in methylene-phosphane and in phosphaallene. They are built up from the pi system or the sigma orbital of phosphorus by interaction with neighboring pi bonds. The extension of these frontier orbitals over all (heavy) atoms makes self-dimerization to different cyclobutane derivatives feasible. Substituent effects on the ordering of sigma and pi are analyzed. Vibrational analyses indicate P = C vibrations of low intensity which decrease with increasing length of the heterocumulene chain. The analysis is extended to the two next higher homologs, which are hitherto experimentally unknown.