Rationalising and Predicting the Structure and Bonding of Bare and Ligated Transition Metal Clusters and Nanoparticles
During the last 50 years, experimental chemists have forged thousands of molecular ligated transition metal clusters and particles with an enormous variety of complicated and/or unexpected structures and compositions. Theoretical models and rules have greatly assisted these developments by explaining the stability and shape of the clusters and particles. However, research is now extending towards the investigation of larger ligated or bare species at (or approaching) the nanoscale, where electron-counting rules and models mainly based on the closed-shell principle can lose their relevance and are often replaced (or accompanied) by increasingly powerful computational tools. We examine these qualitative and quantitative computational tools from a historical perspective and with a view to their future application in the theoretical and experimental study of bare and molecular ligated transition metal clusters and particles. Case studies are discussed to illustrate how computational rationalisation and, to a lesser extent, prediction of large transition metal cluster and particle structures has developed into a sophisticated and successful field of research.