A Neutron Diffraction Study of [OsClH_3(PPh_3)_3]: A Complex Containing a Highly 'Stretched' Dihydrogen Ligand

摘要

Oxidative addition of dihydrogen to a transition metal is one of the most important steps in many catalytic processes.Some years ago,Kubas and co-workers used neutron diffraction to show for the first time that H_2 could bind to a metal in a sideways fashion as eta~2-H_2,now called the non-classical dihydrogen ligand (I).Further insertion of the metal into the dihydrogen ligand,upon continuation of the oxida-tive addition process,weakens the H-H bond causing it to lengthen (II) and finally cleave to form two terminal hydride ligands (III).The weakening of the H-H bond (II) is considered to be an intermediate step along the pathway,and it is this step that has garnered a considerable amount of interest.