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)