The reactivity of cyanogen towards compounds containing active hydrogens at carbon atoms. Part 3. Synthesis of bis[1-cyano-2-(1-iminoethyl)butane-1,3-dionato]copper(II) from cyanogen and bis(acetylacetonato)copper(II): kinetics, thermodynamics and X-ray crystal structure

Abstract

The complex [Cu(acac)₂](acac = acetylacetonate) reacts with C₂N₂ under ambient conditions in dichloroethane to give in high yield a compound of stoicheiometry [Cu(acacC₂N₂)₂]. An X-ray single-crystal analysis revealed that this is bis[1-cyano-2-(1-iminoethyl)butane-1,3-dionato]copper(II), apparently derived from bis[3-(cyanoiminomethyl)pentane-2,4-dionato]copper(II) formed upon insertion of C₂N₂ into the methine C–H bonds in [Cu(acac)₂]. The kinetics of the cyanation process reveal that it occurs in two distinct steps, which display similar second-order rate constants. The kinetic and thermodynamic role of the complex [Cu(acac)₂] is discussed.