Molecular complexation of free base meso-tetraarylporphyrins with antimony(III) chloride in free solvent media

The reaction of meso-tetraarylporphyrins (H2t(Xp)p) with SbCl3 under free solvent conditions affords green complexes with a 1:1 H2t(X)pp:SbCl3 ratio. These complexes have dimeric structures with a (μ-Cl)2bridge. UV–VIS, 1H NMR and 13C NMR spectra data show that the porphyrin core of [(H2t(Xp)p)2Sb2Cl6], similar to 1:2 (donor:acceptor) molecular complexes of meso-tetraarylporphyrins and porphyrin diacid, is distorted, thus two nitrogen atoms of pyrrolenine in a side of the porphyrin plane act as electron donors to an antimony atom of SbCl3. Molecular complexation of meso-tetraarylporphyrins with SbCl3 produces a large downfield shift for the NH signal, although there is no hydrogen bonding present.

Mixing of meso-tetraarylporphyrins (H2t(Xp)p) and SbCl3 under free solvent conditions leads to the formation of [(H2t(Xp)p)2Sb2Cl6] complexes, where two nitrogen atoms of pyrrolenine in the porphyrin core act as electron donors to an antimony center, and so there is a (μ-Cl)2 bridge between two antimony atoms. The molecular complexes exhibit no hydrogen bonding but show a large downfield shift for the NH signals (∼3 ppm).Figure optionsDownload as PowerPoint slide