Detailed Spectroscopic, Thermodynamic, and Kinetic Characterization of Nickel(II) Complexes with 2,2‘-Bipyridine and 1,10-Phenanthroline Attained via Equilibrium-Restricted Factor Analysis

The molar absorptivity curves of the mono and bis nickel(II) complexes of 2,2‘-bipyridine and 1,10-phenanthroline have been deduced from the composite absorbance data of a series of equilibrium solutions in methanol using equilibrium-restricted factor analysis, a technique for extracting spectral and thermodynamic information for component species involved in solution equilibria. The solutions achieve equilibrium slowly (t 1/2 ≈ 100 min) as the amounts of the tris and methanolato complexes are initially in excess. The relative formation constants at 293 K have been determined with a high degree of accuracy, especially for the bipyridine complexes: log(K 1/K 2) = 0.340(4) and log(K 2/K 3) = 1.091(6). Solubility limitations compromised the accuracy of the thermodynamic results for the phenanthroline complexes.