Advances in the chemistry of metal–metal quadruple bonds 2015–2020

This chapter focuses on the advances made in the chemistry of metal–metal quadruply bonded complexes over the last 5 years and is split into three main themes: electron transfer, reactivity and coordination chemistry. The question of electron (de)localisation is examined through the study of ground-state mixed valence complexes and their photo-excited state dynamics. Fundamental studies of metal–metal bonding allow the exploration of new modes of reactivity and low-coordinate compounds which are finding use in catalysis. Additionally, coordination chemistry allows the tuning of molecular properties and this can have profound effects on the electronic structures of functional molecular materials.