Synthesis, spectroscopy and magnetism of new mu-thiocyanato polynuclear copper(II)-chromium(III) complexes

New heteropolynuclear complexes with general formula [Cu(diamine)(2)](3)[Cr (NCS)(6)](2). nH(2)O, where diamine = N,N'-dimethylethylenediamine (1,2-dme n), N,N-dimethylethylenediamine (1,1-dmen), N,N'-diethylethylenediamine (1, 2-deen), N,N-diethylethylenediamine (1,1-deen), 1,3-diaminopropane (tn) wer e obtained by reactions of [Cr(NCS)(6)](3-) with the corresponding cationic Cu(II) complexes: [Cu(diamine)(2)](2+) and characterized by spectroscopic methods and magnetic measurements. The formation of end-to-end thiocyanato bridges between tetragonal Cu(II) and pseudo-octahedral Cr(IH) is evident f rom IR and UV-VIS spectra by appearance of new components of v(CN) band and shifts in the absorption maxima assigned to copper d-d transitions in comp arison with corresponding mononuclear complexes. The EPR spectra measured a t room temperature on solid samples show broad, symmetric signal at g=2.02- 2.03. Variable-temperature magnetic susceptibility measurements reveal the presence of weak antiferromagnetic interactions in [Cu(1,1-deen)(2)](3)[Cr( NCS)(6)](2).H2O and [Cu(tn)(2)](3)[Cr(NCS)(6)](2). 2H(2)O.