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

Department of Chemistry, DeMontfort University, Leicester, LE 1 9BH, U.K

Manuscript received 10 October 2000

Dilute solutions of \(Ni(CN)_4^2-\) and \(Pt(CN)_4^2-\) in methanol-water glasses at 77 K give, on exposure to ionizing radiation EPR spectra, assigned to H-M(CN)\(_4^{2-}\), derivatives. The very large ¹H hyperfine splittings show that the unpaired electron must be in an M-H σ* orbital. The initial species are the electron adducts, M(CN)\(_4^{3-}\), but on annealing, features for these proto­nated anions grow in. However, the palladium complex gives a different derivative, with relatively small ¹H 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.