A Mixed-Valent and High-Spin Vanadium Phosphide

High Resolution Image Download MS PowerPoint Slide Accessing high-spin configurations of transition metal phosphides defines a dividing line that prevents common properties of solid-state materials from being replicated within multiple-bonded molecular analogs. Here, we report the synthesis of a V III phosphaethynolate complex, [(pyrNdipp) 2 V(PCO)] ( 2 ) in a halide metathesis with Na(OCP). Exposure of 2 to Lewis-basic ligands induces a one-electron reductive elimination of the PCO – moiety, generating V II complexes [(pyrNdipp) 2 V(L) 2 ] (L = THF, DMAP; 3 THF, 3 DMAP ). When 2 is instead photolyzed, a cascade of reduction, decarbonylation, and multiple-bond formation steps affords a high-spin and mixed-valent vanadium phosphide, [(pyrNdipp) 2 V═P═V(pyrNdipp) 2 ] ( 4 ) comprising formal [V 2 III, IV ] nodes. Structural characterization coupled with vibrational, UV–visible, and X-ray spectroscopic studies reveals an S 4 symmetrical [V═P═V] centered architecture conforming to a fully delocalized, mixed-valency description. Theoretical studies demonstrate that 4 evades spin-pairing by leveraging the weak ligand-field splitting at the vanadium nodes, leading to a high-spin, S T = 3/2 ground state of this multiple-bonded, weakly Jahn–Teller distorted system.