title: Oxidation of Ni3(dpa)4Cl2 and Cu3(dpa)4Cl2: nickel-nickel bonding interaction, but no copper-copper bonds.
abstract: Of the known trinuclear dipyridylamido complexes of the first-row transition metals, M(3)(dpa)(4)Cl(2) (dpa is the anion of di(2-pyridyl)amine, M = Cr, Co, Ni, Cu), the one-electron-oxidation products of only Cr(3)(dpa)(4)Cl(2) and Co(3)(dpa)(4)Cl(2) have been isolated previously. Here we report one-electron-oxidation products of Ni(3)(dpa)(4)Cl(2) (1) and Cu(3)(dpa)(4)Cl(2) (3): Ni(3)(dpa)(4)(PF(6))(3) (2) and [Cu(3)(dpa)(4)Cl(2)]SbCl(6) (4). While there are no Ni-Ni bonds in 1, the Ni-Ni distances in 2 are 0.15 A shorter than those in 1, very suggestive of metal-metal bonding interactions. In contrast, the oxidation of 3 to 4 is accompanied by a lengthening of the Cu-Cu distances, as expected for an increase in electrostatic charge between positively charged nonbonded metal ions, which is further evidence against Cu-Cu bonding in either 3 or 4. A qualitative model of the electronic structures of all [M(3)(dpa)(4)Cl(2)](n+) (n = 0, 1) compounds is presented and discussed.
authors.affiliation: Department of Chemistry and Laboratory for Molecular Structure and Bonding, PO Box 30012, Texas A&M University, College Station, Texas 77842-3012, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Berry
authors.forename: F Albert
authors.initials: FA
authors.lastname: Cotton
authors.forename: Lee M
authors.initials: LM
authors.lastname: Daniels
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Murillo
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang