HYDROGEN BONDS IN ORGANOMETALLIC CHEMISTRY: DIRECT AND INDIRECT PARTICIPATION OF TRANSITION METAL CENTERS. Lee Brammer, Department of Chemistry, University of Missouri-St. Louis, 8001 Natural Bridge Rd., St. Louis, MO 63121-4499, USA

Hydrogen bonds in which transition metal centers participate directly in either the acceptor (XHM, XHHM) or donor (MHX, M(H2)X) role have been the subject of definitive study only in recent years. Such interactions are important in the protonation/ deprotonation reactions of metal centers and metal hydride species. Discussion of such hydrogen bonds will draw examples from both our own work and that of other groups. Structure and bonding aspects of such hydrogen bonds will be presented from an experimental (crystallographic and spectroscopic) and theoretical viewpoint.

It has also begun to be recognized that interligand hydrogen bonding is of great importance in the way many organometallic molecules interact with each other. Some examples of soft CHX interactions will be discussed with emphasis on X = halogen. The indirect effect on these hydrogen bonds of the transition metal centers to which the ligands are coordinated will be discussed.