Crystal structures and spectroscopic properties of copper(II) pseudohalide complexes with two sparteine epimers, having a CuN4 chromophore

Abstract

Tetrahedrally distorted copper(II) sparteine pseudohalide complexes having a CuN4 chromophore were prepared and characterized by various spectroscopic techniques and X-ray crystallography. Among them, the crystal structures of copper(II) isothiocyanate complexes with two sparteine epimers, (-)-l-sparteine (Sp) and (-)-α-isosparteine (α-Sp), were determined. The NSp-Cu-NSp plane in copper(II) (-)-l-sparteine isothiocyanate [Cu(Sp)(NCS)2] and copper(II) (-)-α-isosparteine isothiocyanate [Cu(α-Sp)(NCS)2] is twisted by 58.2(6)° and 52.2(9)°, respectively, from the NNCS-Cu-NNCS plane. Based on the values of the dihedral angles and tilted distances of these two complexes, the geometry around Cu(II) in Cu(α-Sp)(NCS)2 is more distorted from the perfect tetrahedron than that in Cu(Sp)(NCS)2. For copper(II) sparteine pseudohalide (NCS- and N3 -) complexes having a CuN4 chromophore, the EPR and the optical spectral data were collected. The results of X-ray crystallography and ESR spectroscopy are in a good agreement with the assumption that the degree of distortion from planarity to tetrahedron will reduce the A

value of four-coordinate copper(II) sparteine pseudohalide complexes. © 2009 Elsevier Ltd. All rights reserved.