LAUSR

Abstract This article presents a comprehensive review of the structures of the known structurally characterized transition metal (M) pnictide (E = P, As) compounds. These compounds are being widely studied for a range of important applications including magnetic materials, magnetocaloric effects, electric conductivity, and superconductivity in addition to high catalytic activities for reactions such as hydrodesulfurization, hydrodenitrogenation, and water splitting. A number of the MxEy combinations are found in mineral form, including meteorites. There is tremendous diversity in this class of compounds, with examples from early to late transition metals being observed having metal to main group element ratios (M:E) ranging from 7.5:1 to 1:10. The review covers 231 M:E stoichiometries crystallizing in 289 different crystal lattices. Compounds with high phosphorus or arsenic content show interesting catenated structures ranging from simple En units (E = 2–4), pyramidal P(P)3 groups, and P6 rings to more complex branched chains, ribbons and 2-dimensional networks.