Molecular hydride carbonyl clusters and nanoclusters

This minireview outlines the actual status of the chemistry of hydride metal carbonyl clusters (MCCs) by means of pertinent examples, without being comprehensive. After a brief introduction to the topic, the major synthetic routes for the introduction of hydride ligands in MCCs are described, with particular focus on the different typologies of reagents that can be employed. The structures of hydride MCCs and the different coordination modes of hydride ligands are, then presented, based on single-crystal X-ray and neutron diffraction data available. Some general considerations on ¹H NMR studies of hydride MCCs are described, including fluxionality and the problems of detecting hydrides in larger MCCs. Moreover, electrochemical studies of hydride MCCs are summarized, focusing on electrochemistry as an indirect tool for determining the hydride nature of large MCCs, and tuning the redox potentials of MCCs by protonation/deprotonation reactions. Applications of hydride MCCs in catalysis and electrocatalysis are only briefly described at the end of this minireview, since this topic has been recently reviewed.