Copper(II)-diethylenetriamine complexes with monodentate N-donor ligands : crystal and molecular structure of diethylenetriamine 2-cyanoguanidine copper(II) nitrate

Mixed ligand copper(II) complexes, [Cu(dien)(cnge)X2·nH20] (X =NO3−, N02− or 0.5SO42−), containing diethylenetriamine (dien) and cyanoguanidine (cnge), have been prepared and characterized. Similar complexes, [Cu(dien)(ImH)X2·nH20] (X = Cl−, N03−, N02− or 0.5SO242−), containing diethylenetriamine (dien) and imidazole (ImH), were prepared for comparison. Under identical reaction conditions, the corresponding pyridine complexes could not be isolated, the copper(II)-lien complexes, [Cu(dien)X2·nH20] (X = Br−, Cl−, N03−, N02− or 0.5SO42−) being formed. The structure of [Cu(dien)(cnge)(ONO2)2] (5) has been determined by single-crystal X-ray diffraction methods. It comprises discrete molecular units based on a tetragonally elongated octahedral copper(II) coordination sphere with equatorially bound dien (average y Cu---N = 2.004 A) and cnge (Cu---N = 1.945 A) and axially bound of cnge on coordination to copper(II) in Marked shifts (∼25 cm−) to higher frequency in the νas,(NCN) band of cnge on coordination to copper(II) in 5 and related complexes are shown to be consistent with strongly bound cnge, as evidenced by short CuN distances and near linear CuNC bond angles. FAB-MS studies gave comparable patterns for all complexes, inferring structural types similar to that for [Cu(dien)(cnge)(ONO2)2].