Interplay between the geometric and electronic structures: different ground states and geometries for the 3 d and 5 d TM doped MSnn (n = 6–8) clusters

Abstract The global lowest energy structures of the Sc/Ti/V/Cr/Mn and La/Hf/Ta/W/Re doped clusters MSn n (n = 6–8) are determined. The ground states of the 3 d TM (transition metal) doped clusters have high spin multiplicities (2 to 6), but the 5 d TM doped clusters (except for HfSn 8 ) have low spin multiplicities of 1 or 2. With increasing the numbers of the d electrons and the differences in the multiplicities of the corresponding clusters, the geometries of the 3 d and 5 d TM doped clusters become different significantly. The TM atoms in most of these clusters are exohedrally doped, but the W, Re atoms in Sn 6,7 and Re in Sn 8 are endohedrally doped. W@Sn 6 has an octahedral structure with symmetry O h , and it is the smallest TM endohedrally doped cluster ever reported. The density of states and molecular orbitals show that the 3 d orbitals of the TM generally keep localized but the 5 d orbitals interact strongly with the superatomic orbitals formed by the Sn n frame. As the result, the 5 d TM doped clusters have larger binding energies. While the electron counting rules are generally regarded as the basic rules for understanding the superatoms, the results in this study demonstrate that the geometric structure and the electronic structure interplay strongly and the corresponding clusters with isoelectronic compositions or dopants from the same group may be quite different.