Terminal and Four-Coordinate Vanadium(IV) Phosphinidene Complexes. A Pseudo Jahn-Teller Effect of Second Order Stabilizing the V-P Multiple Bond

摘要

Examples of group 4 and 5 early-transition metal phosphinidenes include only a handful of complexes of Ti, Zr, Nb, and Ta. Recently, we reported a four-coordinate titanium complex containing a terminal phosphinidene functionality. Ti-phosphinidenes are expected to be unstable, because of the hard-soft contrast among these elements. The recent isolation of the first complex containing a Ti = P bond was in part accomplished by stabilizing kinetically this reactive functionality and by applying an α-hydrogen migration strategy using a nucleophilic alkylidene ligand. Inspired by this result, we applied an analogous strategy for preparing a family of four-coordinate complexes with a thus far unknown terminal V = P functionality. We have also determined that these radical species are stabilized not only kinetically but also via a pseudo Jahn-Teller effect of second order.