Magnetic, spectroscopic and X-ray crystallographic structural studies on copper(II) complexes of tridentate NNS Schiff base ligands formed from 2-acetylpyrazine and S-methyl- and S-benzyldithiocarbazates

摘要: New copper(II) complexes of general empirical formula, [Cu(NNS)X] (NNS = anionic forms the 2-acetylpyrazine Schiff bases S-methyl- and S-benzyldithiocarbazate, Hapsme Hapsbz) X Cl, Br, NCS NO have been synthesized characterized. X-ray crystal structures free ligand, Hapsbz complexes, [Cu(apsbz)(NO)], [Cu(apsme)(NCS)] [Cu(apsme)Cl] determined. In solid state, base, remains in its thione tautomeric form with sulfur atom trans to azomethine nitrogen atom. diffraction shows that [Cu(apsbz)(NO)] complex is a novel coordination polymer which one atoms pyrazine ring bridges two adjacent ions. The base coordinated ion iminothiolate via thiolate atom, atoms, overall geometry each copper being close square-pyramid. [Cu(apsme)X] (X NCS, Cl) are dimers adopts five-coordinate near square-pyramidal an NS environment. coordinates as uninegatively charged tridentate ligand chelating pyridine atoms. A unidentate thiocayanate or chloride bridging from second completes sphere. Room temperature μ values for state range 1.70-2.0 typical uncoupled weakly coupled Cu(II) centres. Variable susceptibility studies show chain displays weak ferromagnetic coupling across bridges, while S-bridged dinuclear compounds display either antiferromagnetic relates subtle differences. EPR frozen DMF solutions give rather similar g all indicative Cu (d) ground orbitals on centers.