Molecular structure and crystal structure generation for [Fe3(CO)12]

Abstract

The electronic structure of [Fe₃(CO)₁₂] has been investigated by means of extended-Hückel calculations and compared to that of [Ru₃(CO)₁₂], showing that the bridged structure, observed in the solid state, arises because of electronic reasons, namely a weaker metal–metal repulsion in the case of the lighter cluster. This is associated with the bridge-formation process and becomes determining for the energetic balance in compounds of heavier metals. The possible existence of crystal structures which are alternative to the observed disordered one known for [Fe₃(CO)₁₂] has been explored by means of the atom–atom pairwise potential-energy method. Alternative ordered molecular arrangements have been generated and compared with the experimental crystal structure in terms of packing efficiency and cohesive energy.