Crystal And Molecular Structure Stabilized By Weak Interaction In Unique 3,5-Diiodo-L-Tyrosinato Copper(Ii) Complex - Synthesis, Experimental And Theoretical Studies

The ternary Cu(II)/amino-acid/diamine systems have large positive logK values than binary Cu/amino systems, suggesting stabilization due to the effective stacking interaction between aromatic diamine and the aromatic side group of the amino acid. Thus, a hybrid 3,5-diiodo-L-tyrosinato copper(II) complex with an aromatic diamine, of formula [Cu(L-I2TyrO-)(H2O)(phen)]center dot 2H2O (1) was characterized in depth by using X-ray, TG/DTG, DSC, FTIR, Raman, Q-band EPR, NIR-Vis-UV, magnetic methods and the theoretical calculations. The crystal structure is stabilized by weak pi center dot center dot center dot pi stacking, metal center dot center dot center dot pi and intraand intermolecular pi center dot center dot center dot I non-covalent interactions. The computed interaction energies of Cg(1)center dot center dot center dot Cg(2), Cg(3)center dot center dot center dot I and Cg(1)center dot center dot center dot Cu ranging from 0.69 kcal/mol--2.20 kcal/ mol. The weak interactions shift the bands assigned as nu(C-I) to higher frequency in the FT-IR spectrum. The g tensor is axial with g|| (2.239) > g perpendicular to (2.057) indicating that the unpaired electron residues in the dx2-y2 orbital. The exchange pathway occurs in the zig-zag chain with d(Cu center dot center dot center dot Cu) = 9.429 angstrom.