Esr Determination of the Stability Constants of Cobaloxime(ii)—pyridine Mixed Complexes in Methanol

The stability constants of the 1:1 and 1:2 mixed complexes of bis(dimethylglyoximato)cobalt(II) with pyridine have been determined between 41 and -30°C in methanol, by means of an iteration procedure based on changes in the solution esr spectra. At 24°C, K 1=175 and K 2=0.83 M−1. The thermodynamic parameters are δH1=δH2=−(3.9 ± 0.2) kcal/mol; δS1=−(2.8 ± 0.6), δS2=− (13.5 ± 0.8) cal/mol.K.