Metal complexes of N-tosylamidoporphyrin: cis-acetato-N-tosylimido-meso-tetraphenylporphyrinatothallium(III) and trans-acetato-N-tosylimido-meso-tetraphenylporphyrinatogallium(III)

The crystal structures of acetato-N-tosylimido-meso-tetraphenylporphyrinatothallium(III), Tl(N-NTs-tpp)(OAc) (1), and acetato-N-tosylimido-meso-tetraphenylporphyrinatogallium(III), Ga(N-NTs-tpp)(OAc) (2), were determined. The coordination sphere around the Tl3+ ion is a distorted square-based pyramid in which the apical site is occupied by a chelating bidentate OAc- group, whereas for the Ga3+ ion, it is a distorted trigonal bipyramid with O(3), N(3), and N(5) lying in the equatorial plane. The porphyrin ring in the two complexes is distorted to a large extent. For the Tl3+ complex, the pyrrole ring bonded to the NTs ligand lies in a plane with a dihedral angle of 50.8 degrees with respect to the 3N plane, which contains the three pyrrole nitrogens bonded to Tl3+, but for the Ga3+ complex, this angle is found to be only 24.5 degrees. In the former complex, Tl3+ and N(5) are located on the same side at 1.18 and 1.29 A from its 3N plane, but in the latter one, Ga3+ and N(5) are located on different sides at -0.15 and 1.31 A from its 3N plane. The free energy of activation at the coalescence temperature Tc for the intermolecular acetate exchange process in 1 in CD2Cl2 solvent is found to be delta G++171 = 36.0 kJ/mol through 1H NMR temperature-dependent measurements. In the slow-exchange region, the methyl and carbonyl (CO) carbons of the OAc- group in 1 are separately located at delta 18.5 3J(Tl-13C) = 220 Hz] and 176.3 2J(Tl-13C) = 205 Hz] at -110 degrees C.