The present paper deals with magnetic interactions, solvatochromism and DFT calculation in two new end-on cyanato-bridged dinuclear copper(II) complexes with the formula [L(OCN)Cu(μN,N-OCN)]2, 1-2, where L1 = N,N-dimethyl,-N'-benzyl-ethylenediamine (1) and L2 = N,N-diethyl,-N'-benzyl-ethylenediamine (2). Both complexes were characterized on the basis of physicochemical and spectroscopic methods. X-ray crystallography of complex 2 showed dinuclear nature with terminal and bridging cyanato. Each copper atom achieved a distorted square-pyramidal environment that built up by five nitrogen atoms, two N-bonded cyanato ligands that link two copper ions in an end-on fashion, another act as an N-bonded terminal ligand and two nitrogen atoms of the diamine cleating ligand. The interaction between two metal ions was investigated by magnetic measurement from 2 to 300 K. The variable temperature magnetic susceptibility data showed weak ferromagnetic interaction with J values 1.8 cm-1 for 1 and 7.7 cm-1 for 2. DFT computational results buttressed the experimental observations. The positive solvatochromic behaviors of the compounds were investigated in some organic solvents. The spectral shifts of these solutes were correlated with Kamlet and Taft parameters (α, β and π*) using linear solvation energy relationships (LSEC). The multi-parametric analysis indicates that both polarity/polarizability parameters (π*) and hydrogen bond donating ability (β) of the solvents play important role in the absorption maxima of the compounds.
