Structural change and hydrophobic interaction as related to unusual stability constants of copper(II) complexes with 2,2′-bipyridyl and substituted 1,10-phenanthrolines

Unusual values of K, and K-2 for the formation of complexes CuL2 with L = 2,2'-bipyridyl (bpy) and substituted 1,10-phenanthrolines (phen) have been discussed in relation to the structural change from CuL to CuL2 and the hydrophobic interaction between the coordinated ligands. The free energy for the structural change from the distorted octahedral CuL2 to the trigonal bipyramidal CuL2 has been estimated to be 0.80 (-4.5 kJ mol(-1)) for L = bpy and 0.47 (-2.7 kJ mol(-1)) for L = phen.