Relationships among structure and spectroscopic properties in tetrahedrally distorted copper(II) (−)-sparteine dichloride

The 1:1 mixed crystalline Cu(C15H26N2)Cl2·Zn(C15H26N2)Cl2, 2, and the host lattice material, Zn(C15H26N2)Cl2, 3, were newly prepared and characterized, and the X-ray crystallographic structures of 2 and 3 determined. Further distortion around the Cu(II) center of Cu(C15H26N2)Cl2, 1, was achieved by introducing 1 into the corresponding diamagnetic Zn(II) host lattice. In the 1:1 mixed crystalline, the dihedral angle between the CuN2 and the CuCl2 planes in the Cu(C15H26N2)Cl2 units increased by ∼11° more than that in the neat 1. The ESR and the optical spectral data in solution and solid states were collected for 1 and 2, and the results correlated with the degree of the distortion around the Cu(II) center. The A∥ values of the ESR spectra and the ligand-field transitions are quite sensitive toward the small change in the dihedral angle between the CuCl2 and the CuN2 planes of the Cu(C15H26N2)Cl2 unit.