INELASTIC NEUTRON SCATTERING STUDIES OF DIHYDROGEN AND HYDRIDE LIGANDS IN TRANSITION METAL COMPLEXES. Juergen Eckert, MLNSC, Los Alamos National Laboratory, Los Alamos, NM 87545

Spectroscopic studies of dihydrogen and hydride ligands by inelastic neutron scattering (INS) have provided a great deal of insight in the nature of the chemical bonding of these ligands to the metal as well as important information on their local structure. In the case of the dihydrogen ligand INS can probe the hindered rotations of dihydrogen as well as metal-dihydrogen vibrational modes which have in conjunction with theoretical studies been crucial to understanding the bonding interactions of this novel ligand. This talk will cover three types of recent INS studies on hydrogen ligands: (1) the location of hydride ligands in metal clusters with large numbers of ancillary ligands by utilization of analysis of the hydride vibrational spectra; (2) information on metal-dihydrogen bonding interactions derived from extensive work on dihydrogen complexes, and the resulting implications for understanding the reaction coordinate for oxidative addition of hydrogen to the metal, and (3) some results on exchange reactions between dihydrogen and hydride ligands on the same metal.

This work has benefitted from the use of facilities at the Manuel Lujan Jr. Neutron Scattering Center, a National User Facility funded as such by the Department of Energy, Office of Basic Energy Sciences.