CYANIDE COMPLEXES OF ZINC(II) AND CADMIUM(II) IN 3-M NACL MEDIUM

A detailed re-investigation of the complexation of zinc(II) and cadmium(II) ions by cyanide at high pH values has been made in aqueous 3 M NaCl medium at 25°C using glass electrode potentiometry. Both metal ion systems gave clear evidence for the formation of ternary hydroxocyano complexes although only the Zn(ll) species could be characterised quantitatively due to the lack of quantitative information for the Cd(II)-OH- complexes in this medium. A detailed computational analysis using the ESTA suite of programs has been made, including an assessment of the effects of error propagation in these highly correlated systems by Monte Carlo simulation. Formation constants are derived for the binary H+-, Zn(II)-, and Cd(II)-CN- systems and ternary Zn(II)CN--OH- system. For both metal ions a maximum coordination number of four was found even for the ternary systems. The absence of higher coordination number complexes was confirmed by FTIR and 13C NMR spectroscopy. © 1990, Taylor & Francis Group, LLC. All rights reserved.