| Abstract
| - This work describes the syntheses and characterization of t two novel metal complexes: a cisoid six-coordinate, bridged thallium(III) porphyrin complex, Tl(N−NTs−tpp)(OAc) (1) with an TlIII−NTs−N linkage, and a transoid five-coordinate, bridged gallium(III) porphyrin complex, Ga(N−NTs−tpp)(OAc) (2) with a GaIII−NTs−N linkage. The X-ray crystals of 1 and 2 are also reported. Compound 1 is a distorted square-based pyramid in which the apical site is occupied by a chelating bidentate OAc- group, whereas compound 2 is a distorted trigonal bipyramid.
- 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 siteis occupied by a chelating bidentate OAc- group, whereas for the Ga3+ ion, it is a distorted trigonal bipyramidwith O(3), N(3), and N(5) lying in the equatorial plane. The porphyrin ring in the two complexes is distorted toa large extent. For the Tl3+ complex, the pyrrole ring bonded to the NTs ligand lies in a plane with a dihedralangle of 50.8° with respect to the 3N plane, which contains the three pyrrole nitrogens bonded to Tl3+, but forthe Ga3+ complex, this angle is found to be only 24.5°. In the former complex, Tl3+ and N(5) are located on thesame side at 1.18 and 1.29 Å from its 3N plane, but in the latter one, Ga3+ and N(5) are located on different sidesat −0.15 and 1.31 Å from its 3N plane. The free energy of activation at the coalescence temperature Tc for theintermolecular acetate exchange process in 1 in CD2Cl2 solvent is found to be ΔG⧧171 = 36.0 kJ/mol through 1HNMR temperature-dependent measurements. In the slow-exchange region, the methyl and carbonyl (CO) carbonsof the OAc- group in 1 are separately located at δ 18.5 [3J(Tl−13C) = 220 Hz] and 176.3 [2J(Tl−13C) = 205 Hz]at −110 °C.
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