THE TERM SOLVATOCHROMISM DESCRIBES A CHANGE IN POSITION OR INTENSITY OF AN ABSORPTION OR EMISSION BAND OF A COMPOUND IN SOLUTION, WHEN THE POLARITY OF THE MEDIUM IS CHANGED. AMONG THE SOLVATOCHROMIC METAL COMPLEXES THE MIXED-CHELATE COPPER (II) COMPLEXES WITH B-DIKETONE AND DIAMINE LIGANDS HAVE RECEIVED GREAT ATTENTION [1-3].THESE COMPLEXES ARE VERY SOLUBLE IN A LARGE NUMBER OF ORGANIC SOLVENTS AND SHOW SOLVATOCHROMIC PROPERTY. IT WAS FOUND THAT D–D TRANSITION BAND OF THE COMPLEXES IS EXTREMELY INFLUENCED BY THE SOLVENT ATTACK, THE CONSTITUENT GROUPS IN THE DIKETONATE IONS, DIAMINE GROUPS AND THE COUNTER ION.IN THIS WORK WE PREPARED THE COMPLEXES [CU(PH-ACAC)(DIAMINE)]X (WHERE PH-ACAC IS 1-PHENYL- 1,3-BUTANEDIONE, DIAMINE IS N,N-DIMETHYL,N'-BENZYL-1,2-DIAMINOETHANE AND X = PF6 -, BF4 -), SHOWN IN FIG. 1. THE SYNTHESIZED COMPLEXES WERE CHARACTERIZED BY C.H.N ELEMENTAL ANALYSIS, MOLAR CONDUCTANCE, IR AND VISIBLE SPECTROSCOPY TECHNIQUES. THE INFLUENCE OF VARIOUS SOLVENT POLARITY AND COUNTER IONS ON THE LMAX VALUES OF THE D–D BANDS OF THE COMPLEXES HAVE BEEN INVESTIGATED BY MEANS OF VISIBLE SPECTROSCOPY. BOTH COMPLEXES DEMONSTRATED POSITIVE SOLVATOCHROMISM. A NUMBER OF EMPIRICAL SCALES ARE USED TO DESCRIBE THE SOLVENT POLARITY, SUCH AS DN, AN, ET(30), A, B AND P*. THE STEPWISE MULTIPLE LINEAR REGRESSION (SMLR) METHODPROVED THAT AMONG DIFFERENT SOLVENT PARAMETERS DN OF THE SOLVENT PLAYS THE MOST IMPORTANT ROLE IN THE SOLVATOCHROMISM OF THE COMPOUNDS.