Metal complexes of meso-tetra-(p-chlorophenyl)porphyrin and meso-tetra-(p-bromophenyl)porphyrin: Tl (p-Cl)(4)tpp (OAc) and In (p-X)(4)tpp (OAc) X=Cl, Br, tpp=5,10,15,20-tetraphenylporphyrinate

Abstract

The crystal structures of acetato-[meso-tetra(p-chlorophenyl)porphyrinato]thallium(III) Tl[(p-Cl)(4)tpp](OAc) (1), acetato-[mesotetra(p-chlorophenyl)porphyrinato]indium(III) In[(p-Cl)(4)tpp](OAc) (2) and acetato-[meso-tetra(p-bromophenyl)porphyrinato]indium(III) In[(p-Br)(4)tpp](OAc) (3) were determined. The coordination sphere around the Tl3+ ion in I is described as six-coordinate distorted square-based pyramid in which the apical site is occupied by a chelating bidentate OAc- group, whereas for the In3+ ion in 2 and 3, it is a five-coordinate regular square-based pyramid in which the unidentate OAc- ligand occupies the axial site. The plane of the four pyrrole nitrogen atoms [i.e. N(l)-N(4)] strongly bonded to Tl3+ (or In3+) is adopted as a reference plane 4N. The Tl3+ is moderately out of the 4N plane; its displacement of 0.69 Angstrom is in the same direction as that of the acetate oxygen for 1. The In3+ are located at 0.57 Angstrom from its 4N plane for 2 and 3. The free energy of activation at the coalescence temperature T-c for the intermolecular acetate exchange for I in CD2Cl2 is found to be DeltaG(200)(not equal) = 42.54 kJ mol(-1) whereas the intermolecular OAc- exchange for acetato-[meso-tetra(p-bromophenyl)porphyrinato]thallium(III) Tl[(p-Br)(4)tpp](OAc) (4) in CD2Cl2 is determined to be DeltaG(200)(not equal) = 42.46 U mol(-1) through H-1 NMR temperature-dependent measurements. Moreover, the two oxygen atoms of the acetato group for 2 and 3 are asymmetrically and chelating bidentately bound to the indium atom in CD2Cl2 (or CDCl3) solvent. (C) 2003 Elsevier Science Ltd. All rights reserved.