Diphenoxo-bridged dinuclear nickel(II) complex of a dinucleating macrocycle with N(amine)(6)O-2 metal-binding sites: synthesis, X-ray crystal structure and electrochemistry

The complex Ni2L(ClO4)(2) was obtained by the reaction of Ni(ClO4)(2) and t he macrocyclic ligand H2L, where L2- is the dinucleating macrocycle with tw o 2,6-di(aminomethyl)-4-methyl phenolate entities combined by the same two lateral chains -(CH2)(2)-NH-(CH2)(2)-, at the amino nitrogens. The crystal structure of complex Ni2L(ClO4)(2) was determined by X-ray diffraction. The macrocycle adopts a twisted configuration and the geometry about each nick el atom is square pyramidal with the N3O2 donor sets of the macrocycle. The nickel-nickel separation bridged by the two phenolic oxygens is 3.092 Angs trom and the Ni-O-Ni angle is 100.7(2)degrees. The two Ni-O (phenolate) bon d lengths are 2.001(3) and 2.016(3) Angstrom, respectively. The three Ni-N bond distances are 2.055(4), 2.960(5) and 2.063(4) Angstrom. The cyclic vol tammogram of the complex shows two reversible one electron oxidation steps (E-1/2 = 0.835, 1.05 V, versus SCE,Pt/MeCN) with the formation of Ni(II)-Ni (III) and Ni(III)-Ni(III) species. (C) 1999 Elsevier Science S.A. All right s reserved.