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 [Pc<sub>2</sub>Nb](I<sub>3</sub>)(I<sub>2</sub>)<sub>0.5</sub>(ClNP)<sub>3.5</sub> (ClNP = 1-Chloronaphthalene)

Bis(phthalocyaninato)niobium(IV) has been prepared and isolated as a monosolvate, [Pc<sub>2</sub>Nb]·ClNP (ClNP = 1-chloronaphthalene). It is a light-brown, stable-to-air Nb(IV) (d<sup>1</sup>) paramagnetic sandwich-like species, which, upon oxidation by I<sub>2</sub> under mild conditions, undergoes a metal-centered monoelectronic oxidation to give the diamagnetic Nb(V) (d<sup>0</sup>) [Pc<sub>2</sub>Nb]<sup>+</sup> fragment, with formation of saltlike species of formula [Pc<sub>2</sub>Nb](I<sub>3</sub>)(I<sub>2</sub>)0.5(ClNP)<sub>3.5</sub> (<b>I</b>). The structure of <b>I</b> has been elucidated by single-crystal X-ray work. Crystals are triclinic:  formula C<sub>64</sub>H<sub>32</sub>N<sub>16</sub>Nb·I<sub>3</sub>·0.5I<sub>2</sub>·3.5C<sub>10</sub>H<sub>7</sub>Cl, <i>M</i> = 2194.8, <i>a</i> = 17.702(3) Å, <i>b</i> = 18.708(3) Å, <i>c</i> = 13.504(2) Å, <i>V</i> = 4267.5(13) Å<sup>3</sup>, α = 106.00(2)°, β = 93.39(2)°, γ = 83.26(1)°, <i>Z</i> = 2, space group <i>P</i>1̄. The structure of the [Pc<sub>2</sub>Nb]<sup>+</sup> fragment, “stapled” by two inter-ligand C−C σ bonds (C11A−C11B and C31A−C31B = 1.574(15) Å), together with its color and UV−visible spectral behavior, allows a straightforward assignment of the same “stapled” structure to the unoxidized [Pc<sub>2</sub>Nb]. The present niobium sandwiched materials reiterate the peculiar structural findings shown only by the previously reported [Pc<sub>2</sub>Ti].