Two-Electron Oxidative Atom Transfer at a Homoleptic, Tetravalent Uranium Complex

A tetrahomoleptic, pseudotetrahedral U4+ imidophosphorane complex, [U­(NP­(pip)3)4], 1-U­(PN), is reported. This complex can be oxidized by two electrons with either mesityl azide or nitrous oxide. This two-electron atom/group transfer oxidation is the first example observed at a homoleptic, tetravalent uranium complex. The mesityl imido compound [U­(NMes)­(NP­(pip)3)4], 2-U­(PN)­NMes, exhibits a unique square pyramidal geometry in contrast to the expected trigonal bipyramidal geometry of the oxo complex [U­(O)­(NP­(pip)3)4], 2-U­(PN)­O. The bonding driving the structural dichotomy of these structures and the absence of a structurally observable inverse trans-influence in 2-U­(PN)­NMes were examined by DFT and natural bonding orbital analysis.