Preparation of Cu en

Prepare the nitrate of the copper complex as in Sec. 17.6.1. Dissolve 2.7 g mercury(II) chloride in 35 cm and add to the solution 3.3 g KI and 3.4 g NH4 SCN. After dissolving the solids, add 15 cm ethanol and carefully bring to the boil on an electric water bath. Using the copper complex prepared as above (Sec. 17.6.1), add the concentrated solution to the mercury complex solution with vigorous stirring until precipitation seems complete. Cool in an ice/water bath to complete the precipitation and continue as in 17.6.1. 

Analytical methods for this complex and the cadmium complex are given in the reference. 

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