Structure and bonding of the noble gas-metal carbonyl complexes M(CO)₅-Ng (M = Cr, Mo, W and Ng = Ar, Kr, Xe)

Quantum mechanical ab initio calculations at the MP2 and CCSD(T) level of theory using effective core potentials for the heavy atoms as well as density functional calculations using various gradient corrections are reported for the noble gas-transition metal pentacarbonyl complexes M(CO)₅-Ng (M = Cr, Mo, W and Ng = Ar, Kr, Xe). The optimized geometries show increasing metal-noble gas distances in the order Ar < Kr < Xe and Cr < W < Mo. The theoretically predicted M-Ng bond energies are very close to experimentally observed data. The nature of the interactions between the unsatured 16 e^- fragments M(CO)₅ and the noble gases is investigated using the topological analysis of the electron density distribution and by a detailed analysis of the bond energies. Excitation energies are predicted using time-dependent density functional theory in good agreement with experimental measurements.