Axial Coordination of Porphyrinatocobalt(II) Complexes with Bis(pyridinolato)silicon(IV) Phthalocyanines

Treatment of dichlorosilicon(IV) phthalocyanine with 3‐ or 4‐hydroxypyridine in the presence of pyridine in toluene gave the corresponding bis(pyridinolato)silicon(IV) phthalocyanine complexes SiPc(3‐OPy)2 (1) or SiPc(4‐OPy)2 (2), respectively, which were spectroscopically and structurally characterized. As shown by electronic absorption spectroscopy, these compounds axially bind to meso‐tetraphenylporphyrinatocobalt(II) [Co(TPP) (3)] and meso‐tetrakis(3,5‐di‐tert‐butylphenyl)porphyrinatocobalt(II) [Co(TBPP) (4)] with the two pyridyl ligands forming the corresponding mixed phthalocyanine–porphyrin triads. The binding constants K1 between the 4‐pyridyl phthalocyanine 2 and the porphyrinatocobalt(II) complexes (1.1–1.2 × 104 M–1) are about threefold higher than those for the 3‐pyridyl counterpart 1. The heterodyads 2·3 and 2·4 were isolated by column chromatography and characterized by mass and absorption spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)