Thermodynamic Study of the Interaction of Co(II)-Schiff Base Complexes with Phosphines

The equilibrium constants and the thermodynamic parameters for the interaction of CoLx (L1 = 5-OMe-salabza, L2 = salabza, L3 = 5-Br-salabza and L4 = 5-NO2-salabza) as acceptors, with phosphines (PBu3, PPh2Me) as donors in dichloromethane were studied. This was performed by using UV-Vis spectrophotometry titration for 1:1 adduct formation of the selected complexes at various temperatures (T = 283-298 K). The trend of the adduct formation of the Co(II) complexes with a given phosphine donor decreases as CoL1 > CoL2 > CoL3 > CoL4. The stability of the resulting adducts with different Co(II)-schiff base complexes found to decrease in the order PBu3 > PPh2Me