Copper complexes crystal-field calculations

The conditional stability constants (log K<.) obtained for copper with humic compounds extracted from soils and natural waters are invariably greater than those for other transition metals (see Table IV). This is expected from the enhanced levels of crystal field stabilisation energy which result fi-om the splitting of the 3d electronic orbitals on Cu by an octahedral field (Mackay and Mackay, 1969). The divei ence in the values of log Kc shown in Table IV, may, in part, have arisen from intrinsic variations in the copper-binding properties of the various humic samples. However, these deviations may also be explained in terms of the different experimental conditions employed (pH, ionic strength, temperature, for example) and the assumptions made in the calculations. For example, an increase in the pH will enhance the availability of dissociated binding sites (see Section 6) which are then free to participate in further complexation of copper and... 

---