The Polarographic Determination of the Formation Constants of the Oxalate Complexes of Copper(ii) and Cadmium(ii) in Light and Heavy Water

Abstract

Formation Constants of Copper and Cadmium Oxalate Complexes 249 oritly formed in a one-step process since the slope of tho formation curve is quite steep up to n -2. The third step is displaced considerably from the first two and is weaker. Formation constants for PJhG-Cu an; listed in Table I together with values for glycine and substituted glycines. The 2:1 PEG -Cu complex is weaker than the gl.ycine-Cu complex and comparable with the , -diethylglye.ine-Cu complex. Basolo and Chon21 concluded that the progressive decline in stability between the substituted glycines and copper as the alkyl substituents became larger was indicative of steric (24) F, Basolo and Y. T, Chen, J. Am. Chem. Soc., 76, 953 (1954).hindrance. Agreement between the log JC2 values for the PEG-Cu and , -diefhylglycine. -Cu systems is consistent with the planarity requirement for the first four Cu(TT) coordination positions where steric hindrance makes for a lowered stability constant.The observation of a 3-step reaction indicating -fold Cu(lf) coordination is in agreement with the spectroscopic data presented earlier.

Solvation of Ions

“…From the values obtained polarographically for the formation constants of the oxalate complexes of Cu(II) and Cd(II) in light and heavy water at 25.00±0.05°C and an ionic strength of 1.00 with NaN0 3 , it was concluded [321] that light water is more strongly solvating than heavy water.…”