BONDING IN THE MONOCHLORIDES AND DICHLORIDES OF IRON AND COBALT

The geometries, ground and low-lying excited states of FeCl2, CoCl2, F eCl and CoCl have been studied using local density functional calculat ions within the linear combination of Gaussian-type orbitals framework . The ground state of FeCl2 is predicted to be (5) Delta(g) and that o f CoCl2 to be (4) Sigma(g)(-). These ground states and the predicted o rder of the excited states require reassignments of the electronic spe ctra of these molecules. Cellular ligand-field analyses have been perf ormed resulting in excellent agreement with the experimental transitio n energies. The ground states of FeCl and CoCl are predicted to be (6) Delta and (3) Sigma(-) respectively. The dissociation energies of the se species have been determined and a comparison of the bonding in the se electronically related molecules is presented. These lead to the pr ediction that the second chloride is bonded more strongly than the fir st in the dichlorides.