Pathways of cluster growth: infra-red multi-photon dissociation spectroscopy of a series of Re–Si clusters, [ReSin]+, n = 3–9

Abstract

Infra-red multiple-photon dissociation spectroscopy on Xe-tagged Re/Si clusters, [ReSi_n]⁺, n = 3–9, reveals intense absorption features around 400 cm⁻¹, along with, in some cases, additional bands in the 250–350 cm⁻¹ window. A survey of the potential energy surface using density functional theory in conjunction with particle swarm optimisation indicates a growth pattern based on a growing network of Si atoms wrapped around the Re centre: the Si_n units can be viewed as fragments of a putative 16-vertex Frank–Kasper polyhedron. The structural evolution for the [ReSi_n]⁺ series differs significantly from the iso-electronic Mn series studied previously, where the metal ion is typically bound externally to the surface of a growing 3-dimensional Si_n cluster, the differences reflecting the greater accessibility of 5d vs. 3d electron density.