Two-Electron Reduction of a Vanadium(V) Nitride by CO To Release Cyanate and Open a Coordination Site

Abstract

We report herein that the terminal nitride complex Na[NV(N[t-Bu]Ar)(3)] (Na[1-VN], Ar = 3,5-Me(2)C(6)H(3)) reacts with CO over the course of 24 h to generate V(N[t-Bu]Ar)(3) (1-V) and sodium cyanate in an isolated yield of 77%. The reaction products were identified using a combination of NMR and IR spectroscopy, and cyanate formation was further confirmed by performing a (13)C labeling experiment. In addition, we report on the synthesis and structural characterization of the isocyanate complex (OCN)V(N[t-Bu]Ar)(3) (1-V(NCO)) to compare its redox chemistry with that of (OCN)Nb(N[t-Bu]Ar)(3) (1-Nb(NCO)). Electrochemical studies of 1-Nb(NCO) and 1-V(NCO) revealed large differences in the M(5+)/M(4+) and M(4+)/M(3+) reduction potentials. Complex 1-V(NCO) displays two redox events in the cyclic voltammogram: a quasireversible event -0.11 V vs Fc/Fc(+) and a reversible event at -1.56 V vs Fc/Fc(+). Complex 1-Nb(NCO) displays two redox events as well: a quasireversible event at -1.1 V and an irreversible event at -2.9 V vs Fc/Fc(+).