Synthesis, spectroscopic and structural characterization of some novel adducts of copper(II) salts with unidentate nitrogen bases

Syntheses, spectroscopic characterization and single crystal X-ray studies are reported for a number of complexes of copper(II) salts with simple monodentate nitrogen bases. The 1:4 adduct of copper(II) sulfate with 3,5-dimethylpyridine (m2py) CuSO4·4m2py, takes the form [(O3SO)Cu(m2py)4], the Cu–O vector of the square–pyramidal coordination environment being disposed on the 4-axis in tetragonal space group P4/n. The complex CuCO3·Cu(NCS)2·4py is a linear polymer, taking the form ⋯O·Cu(py)2·O·C{O·Cu(py)2(NCS)2}·O·Cu(py)2⋯ (etc.), all atoms lying in the mirror plane of space group Pnma, excepting the pair of ‘py’ (pyridine) ligands disposed to either side. In Cu(OH)I·3/4I2·2py·1/2MeCN ≡ [{(py)2Cu(OH)}4](I3)3I·2MeCN a novel cubanoid tetranuclear cation is found (2-symmetry). The EPR spectra of the above compounds show a trend in the anisotropy of the g-values that correlates well with the crystal structures. Obtained only in small quantities but supported by single crystal X-ray studies are the adduct of Cu(OH)Cl with pyrrolidine (pyrr), Cu(OH)Cl:pyrr (1:3), which takes the centrosymmetric binuclear form [(pyrr)3Cu(μ-OH)2Cu(pyrr)3]Cl2, the copper atom being disposed in a distorted trigonal bipyramidal array, and the adduct 3CuCl2·CuO·4quin, [Cu4Cl6O(quin)4]Cl2, which contains the familiar Cu4Cl6O core with monodentate quinuclidine (quin) attached to the copper atoms; this compound crystallizes in the cubic space group 4 ¯ 3 m .