Abstract: The EPR spectra and magnetic properties of a new binucleacr copper (Ⅱ)complex (DMF)₂]·4DMF are given. Threegroups of lines were observed at 77K and room temperature. Taking account of the magnetic moment and result drived from SCC-EHMO calculation of quantum chemistry, two groups of lines in the EPR spectrum were assigned to the binuc-lear copper (Ⅱ) ions, and the other one was assigned to the triplet state. At room temperature, paramagnetic properties of the compound in solid state are mainly from unpaired electron of tfe triplet state,and at frozen temperature they in solution state depend on the binuclear copper (Ⅱ) ions.
The complex has the following characteristics in electronic structure:rather weak interaction between the two copper (Ⅱ); less residual valence on the two copper (Ⅱ) which are bonded to bridging ligands and terminal ligands. The electronic spin concentration on the binuclear copper (Ⅱ) ions of the complex is~3-4% of that on the mononuclear copper (Ⅱ) compounds, so that the intensities of the two groups of lines drived from the copper (Ⅱ) are rather weak.The levels in the front of molecular orbital are nearly degenerated and electrons become triplet state excited by heat. Thus, a group of lines of triplet state was produced. Therefore, we come to the conclusion that the compound is a new type of binuclear copper (Ⅱ) cluster of triplet state with self-"magnetic dilution".

Key words: Triplet, Magnetic exchange interaction parameter, Residual valence state, Electronic spin concentration, Self-“magntic dilution”, Effect electtonic spin, Effect magnetic moment, Averaged valence state