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 K 1 between the 4‐pyridyl phthalocyanine 2 and the porphyrinatocobalt(II) complexes (1.1–1.2 × 10 4 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)