The reactivity of a bis(methylene)phosphane anion

A bis(methylene)phosphane anion, i.e. a heteroallene-type molecule, was obtained from the desilylation of the corresponding bis(silyl)methyl-substituted phosphaalkene. Spectroscopic and single-crystal X-ray diffraction analyses of this bis(methylene)–phosphane anion revealed that the central phosphorus atom features a cumulative C=P=C π-bond with adjacent sp2-hybridized carbon atoms. On the consideration of its polar bonding situation, its reactivity toward electrophiles was examined. The reaction with MeI gave a 1:1 mixture of a methylated phosphaalkene and bis(methylene)-λ5-phosphane, while several new phosphaalkene-substituted chlorometallylenes were also synthesized and characterized.