Molecular models for WH6 under pressure

Abstract

At atmospheric pressure, some tungsten hydrides exist as discrete molecular complexes in low temperature matrices, but are very reactive and cannot be isolated in bulk at room temperature. Under pressure, one observes WH in experiment at room temperature, and calculations indicate several other stoichiometries are stable, all extended and not molecular. This work aims at constructing a bridge between discrete molecules and the pressurized extended structures, with the emblematic example of WH₆. The equilibrium structure, known as a distorted trigonal prismatic molecule, is likely to be a good acceptor. In numerical experiments, discrete WH₆ molecular complexes are allowed to interact with each other in their ground states at T = 0 K and P = 1 atm. They spontaneously rearrange to form 1D-chains, with the W centers adopting a tricapped trigonal prismatic environment. The electronic structure of these chains is examined and related to that of the monomer and extended solids.