Hydrogen atom addition to d8 complexes of nickel, palladium and platinum

Abstract

Dilute solutions of Ni(CN) 2 - 4 and Pt(CN) 2 - 4 in methanol-water glasses at 77 K give, on exposure to ionizing radiation EPR spectra, assigned to H.M(CN) 2 - 4 derivatives. The very large 1 H hyperfine splittings show that the unpaired electron must be in an M.H σ * orbital. The initial species are the electron adducts, M(CN) 3 - 4 , but on annealing, features for these protonated anions grow in. However, the palladium complex gives a different derivative, with relatively small 1 H hyperfine splitting. This is thought to be the result of a rearrangement putting the excess electron into the d-manifold of the metal, so that the ligand becomes a normal hydride ligand. So far as I know, these metal hydrides are unique in transition metal chemistry.