A computational study on mixed-ligand N2P3 donor-set iron(II) and ruthenium(II) classical and non-classical hydrides

Iron and ruthenium classical and non-classical hydrides of the type [MH(N-N)P-3](+) and [M(eta(2) -H-2)(N-N)P-3](2+) (M = Fe, Ru; N-N = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen); P = phosphites) were reported in 2004 together with an evaluation of the pseudo-aqueous pK(a) values of the eta(2)-H-2 complexes. The non-classical hydrides, even if doubly charged, showed a relatively low acidity, their pK(a) values ranging between -5.4 and -4.3. Moreover, ruthenium(II) derivatives showed to be more acidic than the corresponding iron(II) complexes. Information about the structural and electronic proprieties of complexes of this type, which allowed to better understand the role of both the metal centres and the ancillary ligands in the acidity of the co-ordinated hydrogen molecule, was obtained on the basis of DFT B3LYP calculations. (C) 2007 Elsevier Ltd. All rights reserved.