Solvatochromic Properties of Heteroleptic Copper(II) Complexes Containing N,N,N',N'-Tetramethylethylenediamine and 2-Aacetylcyclopentanone Ligands

Three new heteroleptic copper(II) complexes, [(tmen)Cu(dike)H2O]X where tmen = N,N,N',N'-tetramethylethylenediamine, dike = 2-acetylcyclopentanone anion and X= ClO4- (1), Cl- (2) and Br- (3) are prepared and characterized by elemental analyses, molar conductance measurements and IR and UV-Vis spectroscopy techniques. The complex 1 is fairly soluble in various organic solvents and demonstrates distinctive solvatochromism. However, the solubility of complexes 2 and 3 is less than 1 and their color changes are limited to polar solvents. The influence of the solvent polarity and counter ions on the wave length maxima, max values of the d-d bands of the complexes have been investigated by visible spectroscopy. A multi-parametric equation has been utilized to explain the solvent effect on the d-d transition of [(tmen)Cu(dike H2O)]ClO4 using SPSS/PC software. The stepwise multiple linear regression (SMLR) method demonstrated that the donor power of the solvent plays the most important role in the observed negative solvatochromism of the compound.