Synthesis, Spectroscopic And Epr Results And Crystal Structure Of Copper(Ii) Formato Derivatives With Pyrazine And Dimethylpyrazines

The complexes of copper formato with pyrazine and dimethylpyrazines: Cu(HCOO)(2)(pyrz) (1), Cu-2(HCOO)(4)(pyrz) (2), Cu-2(HCOO)(4)(2,3-Me2pyrz) (3), Cu-2(HCOO)(4)(2,5-Me(2)pyrz) (4), and Cu-2(HCOO)(4)(2,6-Me(2)pyrz)(2) (5) have been synthesized and characterized by chemical analysis and IR and electronic spectroscopies. The three-dimensional structure of compound I consists of -Cu-pyrz-Cu-pyrz- chains joined by bridging formate groups coordinated, in configuration syn-anti, to two copper atoms. The coordination around the copper atom is orthorhombic with two Cu-O distances of 2.374(1) angstrom, two Cu-O of 1.952 angstrom and two Cu-N of 2.080 angstrom. Compound 5 is formed by molecular dimers with the [Cu-2(mu-HCOO)(4)] unit, two copper atoms and four syn-syn fomate groups, and two ligands coordinated to the copper atoms in the axial positions. In compounds 2 and 3 chains Of [CU2(mu-HCOO)(4)] dimers with pyrz or 2,3-Me(2)pyrz as bridging ligands are formed.The EPR signal of I is orthorhombic (g = 2.23, 2.20 and 2.06). In the EPR spectra of 2 - 5 compounds the triplet (S = 1) signals are observed. The g(perpendicular to), g(parallel to) and D values are been calculated.