CHLOROPHOSPHAETHENYL PHOSPHONIUM IONS BY CHLORIDE ABSTRACTION FROM DICHLOROPHOSPHANYL YLIDES

Dichlorophosphanyl ylides readily lose a chloride ion to Lewis acidic metal chlorides. In the cations so generated, a considerable part of t he phosphenium charge is transferred to the phosphonium center leading to a chlorophosphaalkene structure. This is demonstrated by NMR data ns well as by an X-ray structure analysis. The residual phosphenium ch arge becomes visible in weak but definite contacts with the GaCl4- ani ons that expand the coordination sphere of the P(III) atom from psi-tr igonal two-coordination to psi-trigonal bipyramidal (psi-TBP) tetra-co ordination. (C) 1996 John Wiley & Sons, Inc.