Structural reorganizations accompanying the nickel(II)–nickel(I) redox change in nickel complexes with the tripodal ligand MeC(CH2PPh2)3(triphos, L). X-Ray crystal structure of [NiL(I)]2[As6I8

Abstract

The stereodynamic aspects of the nickel(II)–nickel(I) conversion in complexes of the tridentate phosphine MeC(CH2PPh2)3, (triphos, L) have been analysed. The structural reorganization, which accompanies the redox change, is pointed out. The substantial electrochemical reversibility observed for the nickel(II)–nickel(I) reduction, being indicative of minor molecular rearrangement, is consistent with the simple elongation of the Ni–I bond distance in the nickel(I) with respect to the nickel(II) derivative [2.546(2)vs. 2.414(4)A]. The nickel(II) complexes [NiL(X)]Y (X = Cl, Br, or I, Y = ClO4) and [NiL(I)]2[As6I8] have been synthetized and characterized. A complete X-ray analysis has been carried out for [NiL(I)]2[As6I8]. a= 22.500(8), b= 19.092(5), c= 24.912(12)A, β= 109.29(4)°, space group C2/c, Z= 4. The X-ray results showed two very interesting features: the isolation of a tetrahedral nickel(II) complex with the unprecedented P3X donor atom set and the formation of the new polyanionic cluster species [As6I8]2–. An angular overlap model analysis was performed to rationalize the electronic spectra of the [NiL(X)]+ complexes (X = Cl, Br, or I).