Magnetic Properties and UV-Visible Spectroscopic Studies of Metal Cluster Compounds

Abstract

Molecular metal cluster compounds have been known for many years; the essential features of the structure of Fe2 (CO) 9 were recognised during the 1930’s [1]. The first crystallographic characterisation of a metal-metal bond unsupported by bridging ligands was achieved more than thirty years ago [2]. With the development of single-crystal X-ray diffraction as a powerful routine method, very many metal cluster compounds were structurally characterised, including many with interstitial main group atoms. The larger metal carbonyl clusters were found to resemble fragments of bulk metallic lattices (fee, hep, etc.) [3]. During the same time, it became apparent from theoretical and experimental (electron microscopy) studies that small, ligand-free metal particles could have geometries not available to continuous three-dimensional lattices: icosahedral, polytetrahedral, etc. [4, 5, 6, 7, 8]. Examples of these types of geometry were also then found among molecular cluster compounds, notably the extensive series of gold clusters based on icosahedral geometry [9].