Self-Assembly and X-Ray Crystal Structures of Novel Sn(IV)Porphyrin Phenolates

A series of complexes of the type Sn(TTP)L₂] have been prepared by the condensation of Sn(TTP)OH₂] (TTP = meso-tetratolylporphyrin) with a range of substituted phenols. The resulting complexes were characterised using ¹H NMR and single crystal X-ray diffraction techniques. In each case, the condensation of the phenols with the Sn(IV)porphyrin in CDCl₃ solution is slow (h) but essentially quantitative. The slow kinetics of the formation of the diaxial phenolate complexes allows for the identification, by ¹H NMR spectroscopy, of three independent complexes within this process, namely an outer-sphere (H-bonded) complex as well as two independent phenolate complexes. The rate of condensation is in the order phenol 4-methoxyphenol > 4-nitrophenol and suggests a steric rather than pKa dependency.