Scientists Create Rare High-Spin Vanadium Compound with Potential Magnetic Applications
Researchers have synthesized a mixed-valent vanadium phosphide that maintains unpaired electrons at high temperatures—a property typically impossible in molecular systems. The discovery could unlock new magnetic materials for electronics and computing devices where conventional compounds fail.
Originaltitel: A Mixed-Valent and High-Spin Vanadium Phosphide
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 VIII phosphaethynolate complex, [(pyrNdipp)2V(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 VII complexes [(pyrNdipp)2V(L)2] (L = THF, DMAP; 3THF, 3DMAP). 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)2V═P═V(pyrNdipp)2] (4) comprising formal [V2III, IV] nodes. Structural characterization coupled with vibrational, UV–visible, and X-ray spectroscopic studies reveals an S4 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, ST = 3/2 ground state of this multiple-bonded, weakly Jahn–Teller distorted system.