One Step Forward to "Stapled" Bis(phthalocyanine) Metal Complexes: Synthesis, Characterization, and Redox Properties of Bis(phthalocyaninato)niobium(IV). X-ray Crystal Structure of the Monoelectronically Oxidized Species [Pc2Nb](I3)(I2)0.5(ClNP)3.5 (ClNP = 1-Chloronaphtalene)

Bis(phthalocyaninato)niobium(IV) has been prepared and isolated as a monosolvate, [Pc2Nb]. CINP (CINP = 1-chloronaphthalene). It is a light-brown, stable-to-air Nb(IV) (d(1)) paramagnetic sandwich-like species, which, upon oxidation by It under mild conditions, undergoes a metal-centered monoelectronic oxidation to give the diamagnetic Nb(V) (d(0)) [PC2Nb](+) fragment, with formation of saltlike species of formula [Pc2Nb](I-3)(I-2)0.5(CINP)(3.5) (I). The structure of I has been elucidated by single-crystal X-ray work. Crystals are triclinic: formula C64H32N16Nb . I-3 . 0.5I(2) . 3.5C(10)H(7)Cl, M = 2194.8, a = 17.702(3) Angstrom, b = 18.708(3) Angstrom, c = 13.504(2)Angstrom, V = 4267.5(13) Angstrom(3), alpha = 106.00(2)degrees, beta = 93.39(2)degrees, gamma = 83.26(1)degrees, Z = 2, space group P (1) over bar. The structure of the [Pc2Nb](+) fragment, "stapled" by two inter-ligand C-C sigma bonds (C11A-C11B and C31A-C31B = 1.574(15) Angstrom), together with its color and UV-visible spectral behavior, allows a straightforward assignment of the same "stapled" structure to the unoxidized [Pc2Nb]. The present niobium sandwiched materials reiterate the peculiar structural findings shown only by the previously reported [Pc2Ti].