ic0262740_si_001.cif (160.96 kB)

Oxidation of Ni3(dpa)4Cl2 and Cu3(dpa)4Cl2:  Nickel−Nickel Bonding Interaction, but No Copper−Copper Bonds

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posted on 05.03.2003, 00:00 by John F. Berry, F. Albert Cotton, Lee M. Daniels, Carlos A. Murillo, Xiaoping Wang
Of the known trinuclear dipyridylamido complexes of the first-row transition metals, M3(dpa)4Cl2 (dpa is the anion of di(2-pyridyl)amine, M = Cr, Co, Ni, Cu), the one-electron-oxidation products of only Cr3(dpa)4Cl2 and Co3(dpa)4Cl2 have been isolated previously. Here we report one-electron-oxidation products of Ni3(dpa)4Cl2 (1) and Cu3(dpa)4Cl2 (3):  Ni3(dpa)4(PF6)3 (2) and [Cu3(dpa)4Cl2]SbCl6 (4). While there are no Ni−Ni bonds in 1, the Ni−Ni distances in 2 are 0.15 Å 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 [M3(dpa)4Cl2]n+ (n = 0, 1) compounds is presented and discussed.