Molecular Hydrogen Metal Complexes (Molecule of the Month for September 1997)
It has been recently discovered that the H2 molecule can coordinate to a metal atom without clevage of the H-H bond. The first such compound was [W(CO)3(H2)(P-i-Pr3)2] (ref. G. Kubas, Acc. Chem.Res., 21,120,1988), many other compounds of this type are now known. The significance of this discovery is that it provides an example of a species intermediate between molecular hydrogen and a dihydro complex.
Calculations indicate that the bonding consists of donation of electron density from the H-H bond into a vacant metal d orbital and a simultaneous back pi bonding from a different d orbital into the empty s* orbital of H2.
Formal Chemical Name (IUPAC)
Update by Karl Harrison
(Molecule of the Month for September 1997 )