Alan Cowley made many particularly important contributions to the chemistry of the main-group elements. His earliest work in this area was concerned with homoatomic ring and chain compounds, noteworthy achievements being the syntheses of the first three- and four-membered phosphorus and arsenic rings, respectively. His work on the static and dynamic stereochemistry of phosphorus compounds is also widely recognised and extends from mathematical formulations to experimental studies.
Subsequent work was concerned with multiply bonded compounds of the heavier main-group elements. Important contributions to this area include the syntheses of the first compounds with phosphorus–arsenic, phosphorus–antimony, and arsenic–arsenic double bonds, along with the demonstration that these and related species, such as phospha–alkenes and phosphine–imines, exhibit very interesting reaction chemistry and ligative behaviour.
Alan’s later work focused on the bis(imino)acenaphthene (BIAN) ligand with respect to its applications in catalytic, redox, and luminescent chemistry. Finally, the neglected semiconductor, boron arsenide, has been investigated from the standpoint of its photoelectrochemistry and thermal properties.