Crystalline dihydrogen complexes. Intramolecular and intermolecular interactions and dynamic behavior

The molecular and crystal structure of complexes containing the 'non-classical' eta(2)-H-2 ligand have been examined. The solid-state dynamical behavior of the ligand has been investigated by atom-atom potential energy barrier calculations, and the results compared with the available spectroscopical and theoretical information. Electronic barriers to reorientation have also been evaluated by molecular orbital extended Huckel calculations in the cases of [Ru(eta(2)-H-2)(C5Me5)(dppm)][BF4] and of [OsCl(eta(2)-H-2)(H(2)bim)(P-Pr-i(3))(2)]Cl. The existence of hydrogen-bonding interactions involving the eta(2)-H-2 ligand has also been analyzed. (C) 1998 Elsevier Science S.A. All rights reserved.