Thorium(IV) and Uranium(IV) Phosphaazaallenes

The synthesis of tetravalent thorium and uranium complexes with the phosphaazaallene moiety, [N(Bu-t)C=P(C6H5)](2-), is described. The reaction of the bis(phosphido) complexes, (C5Me5)(2)An[P(C6H5)(SiMe3)](2), An = Th, U, with two equivalents of (BuNC)-Bu-t produces (C5Me5)(2)An((CNBu)-Bu-t)[eta(2)-(N,C)-N(Bu-t)C=P(C6H5)] with concomitant formation of P(SiMe3)(2)(C6H5) via silyl migration. These complexes are characterized by NMR and IR spectroscopy, as well as structurally determined using X-ray crystallography.