Copper ethylene complexes

Copper olefin complexes are usually generated by the direct reaction of a Cu(l) source, the ligand, and the corresponding olefin. Copper ethylene complexes are of interest in view of their biochemical importance,98,98a-98e their applications in organic chemistry,99,99a,99b and industrial applications.100 100 Because of this, many copper alkene complexes have been reported, with different nuclearity, in compounds with one, two, or even three C=C units coordinated to a given copper center. 

Nickel atoms have also been allowed to react with C2H4 under cryogenic conditions (101,123). Depending on the metal-concentration conditions and the deposition temperature, either mononuclear species, Ni(C2H4) , n = 1-3(123), or multinuclear species, Ni2(C2H4) ,m = 1-2, and Ni3(CjH4)i, may be isolated. Unlike the copper complexes, these species are all colorless the mononuclear ethylene complexes each dis-... 

Copper(I) and silver(I) complexes are exceptions of the general trend in stability constants with electron-donating or attracting substituents. Thus most known 7i-complexes of silver and copper are less stable than their respective ethylene complexes (154 156). The steric hindrance introduced by the substituents seems to have a major effect in those systems. 

Copper chloride complexes can be used as catalysts in a number of organic reactions. Examples include the Wacker process, which is the oxidization of ethylene to acetaldehyde by oxygen and aqueous Cu and Pd precatalysts (or, alternatively using iron catalysts) plus the synthesis of acrylonitrile from acetylene and hydrogen cyanide using CuCl. Cuprous chloride has also been used as a desulfiuizmg and... 

No structurally characterized discrete Cu complexes are known. A few species have been observed in the gas phase, or at very low temperatnres nsing matrix-isolation techniques, including polynnclear copper species such as Cu2 and Cu3 and several copper-carbon monoxide and copper-ethylene species. There have also been reports of reactive species thonght to contain zerovalent copper, and several clnsters or other species where, arguably, some of the Cu is present in the Cn oxidation state. ... 

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