CoHn (n = 1–3): Classical and non-classical cobalt polyhydride

UB3LYP calculations with the TZVP, DGDZVP and 6-31+G(2d,p) basis sets have been used to explore the potential energy surfaces of CoHn (n = 1–3). A hydrogen rearrangement process with a low activation energy was found in the H–Co⋯H–H complex. This process requires elongation of the H–H bond and a concomitant shortening of the distance between the hydride and the vicinal hydrogen of the H2 ligand. In addition, we present a classification of cobalt–hydrogen interactions in the CoHn complexes based on topological parameters of the charge density.