Ni(II) complexes of stereo-isomeric hexazamacrocyclic ligands derived from 2,6-diacetylpyridine

The nitrate and perchlorate Ni(II) complexes of the stereo-isomeric hexazamacrocyclic ligands L1 (3,6,14,17,23,24-hexaazatricyclo[17.3.1.18,12]tetracosa-1(23),8,10,12(24),19,21-hexaene,2,7,13,18-tetramethyl) and L2 (3,7,15,19,25,26-hexaazatricyclo[19.3.1.19,13]hexacosa-1(25),9,11,13(26),21,23-hexaene,2,8,14,20-tetramethyl) derived from 2,6-diacetylpyridine have been synthesized and characterized by microanalysis, LSI-MS, conductivity measurements, IR, UV–Vis spectroscopy and magnetic studies. Crystal structures of L1·2H2O as well as of the complexes [NiL1](ClO4)2[NiL1](ClO4)2 and [NiL2](NO3)2[NiL2](NO3)2 have been determined. The X-ray studies show the presence of mononuclear endomacrocyclic complexes with the metal ion coordinated to all the nitrogen donor atoms from the macrocyclic framework in a N6 core. The geometry around the metal ions can be described as distorted octahedral. The nitrate and perchlorate anions do not coordinate to the metal ions, but they are involved in intermolecular interactions through hydrogen bonds to the amine groups of the macrocyclic ligands.

A new series of nitrate and perchlorate Ni(II) complexes of the stereo-isomeric hexazamacrocyclic ligands L1 and L2 derived from 2,6-diacetylpyridine were synthesized by reaction of the ligand and the appropriate salt in refluxing acetonitrile. The reactions gave analytically pure products that were characterized by elemental analysis, LSI-MS, conductivity measurements, IR, UV–Vis spectroscopy and magnetic studies.Crystal structures of L1·2H2O as well as of the complexes [NiL1](ClO4)2 and [NiL2](NO3)2 have also been determined. The X-ray studies show the presence of mononuclear endomacrocyclic complexes with the metal ion coordinated to all the nitrogen donor atoms from the macrocyclic framework in a N6 core. The geometry around the metal ions can be described as distorted octahedral. The nitrate and perchlorate anions do not coordinate to the metal ions, but they are involved in intermolecular interactions through hydrogen bonds to the amine groups of the macrocyclic ligands.Figure optionsDownload as PowerPoint slide