Formation Constants of Copper(I)−Olefin Complexes in Aqueous Solution

A simple kinetic method has been applied to measure the formation constants of aqueous copper(I) with fumaronitrile, dimethyl fumarate, and fumaric and maleic acids. At 0.14 M ionic strength, the values of β1 are (0.85 ± 0.02) × 103, (6.1 ± 0.1) × 103, (7.3 ± 0.1) × 103, and (2.2 ± 0.4) × 103 M-1, respectively. The values for the last two olefins are compared to previous results. Values of β1 for hydrogen maleate and β2 for fumaronitrile also have been determined. A reanalysis of much earlier work has been done, and all the results are discussed in terms of the effect of substituents on the olefin on the β1 values. The structure of bis(fumaronitrile)copper(I) nitrate also is reported. The nitrile is N-coordinated to copper(I), which has a distorted tetrahedral geometry, while the overall structure consists of macrocyclic Cu6(fumaronitrile)6 rings which extend in three dimensions.