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-Me₂C₆H₃) 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 ¹³C 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 M⁵⁺/M⁴⁺ and M⁴⁺/M³⁺ 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⁺.