PHYSICAL-PROPERTIES OF METAL CLUSTER COMPOUNDS .1. MAGNETIC MEASUREMENTS ON HIGH-NUCLEARITY NICKEL AND PLATINUM CARBONYL CLUSTERS

Metal-carbonyl cluster compounds are composed of macromolecules that consist of a core of metal atoms coordinated by a "shell" of CO ligands. We present susceptibility and high-field magnetization measurements on various high-nuclearity platinum and nickel clusters. The compounds display very unusual low-temperature magnetic behaviour, which we ascribe to quantum-size-effects arising from the discreteness of the electronic energy levels due to the small dimensions of the metal clusters (10-40 atoms). We compare our results with predictions from molecular orbital calculations.