Acta Phys. -Chim. Sin. ›› 1997, Vol. 13 ›› Issue (07): 659-662.doi: 10.3866/PKU.WHXB19970718

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Coordinating Properties of Nickel(II) tetra(4-N-benzylpyridyl) porphyrin in Aqueous Solution

Liu Zhi-Xian,Shi Shuang-Qun,Zhang Jian-Jun,Song Xin-Fang,Meng Min-Quan   

  1. Department of Chemistry,Center of Experiment,Department of Science and Research,Hebei Teachers' University,Shijiazhuang 050016
  • Received:1996-11-18 Revised:1997-02-28 Published:1997-07-15
  • Contact: Liu Zhi-Xian

Abstract:

Beer's law experiment, variable-temperature spectral experiment of UV-Vis absorption, 1H NMR, and measurement of magnetic moment were conducted for NiTMPyP in aqueous solution. It was found that Beer's law was obeyed in concentration range 8× 10-7-2×10-5.mol•dm-3.With the temperature increasing from 0 ℃ to 95 ℃, the isosbestic point appeared at 435 nm and the lowest downfield 1H NMR peak narrowed gradually and shifted to upfield. The magnetic moment is 2.07 BM in D2O at 30 ℃, but in the D2O-CD3COCD3 mixed solvent there was no evidence for the existance of paramagnetic species. These results show that NiTMPyP exists in aqueous solution as an equilibrium mixture of diamagnetic, four-coordinate nickel (Ⅱ) and paramagnetic, sir-coordinate nickel (Ⅱ) complexed by water molecules in the axial position. The thermodynamic parameters of the axial-coordinated reaction were △S?=-178.6 J•K-1•mol-1, △G298K?=-1.6 kJ•mol-1.

Key words: Nickel(II) porphyrin, Coordinate property, Absorption spectrum, 1H NMR spectrum, Beer's law