102631-28-7Relevant articles and documents
Studies of copper(I) olefin complexes. Formation constants of copper olefin complexes with 2,2′-bipyridine, 1,10-phenanthroline, and their derivatives
Munakata, Megumu,Kitagawa, Susumu,Kosome, Shigeru,Asahara, Akio
, p. 2622 - 2627 (2008/10/08)
Twenty-five new copper(I) olefin complexes, [Cu(biL)(olefin)]+ (biL = the derivatives of 2,2′-bipyridine and 1,10-phenanthroline (phen); olefin = ethylene and derivatives), were synthesized, and the formation constants were determined spectrophotometrically in 0.3 and 0.5 M acetonitrile/ethanol. The influence of substitutents of the biL and olefin on the formation constants and the 1H NMR of the olefinic protons of coordinated ethylene was investigated. The formation constant for the copper ethylene complex (Cu(biL)+ + C2H4 ? [Cu(biL)(C2H4)]+) was found to increase with increasing pKa of biL; electron-donating substituents such as methyl on biL stabilize the ethylene complexes, whereas electron-withdrawing substituents such as Cl destabilize it. 1H NMR resonances of the olefinic protons of [Cu(biL)(C2H4)]+ move upfield as the pKa value of biL increases, indicating an increase in the electron density around the olefinic protons. These findings demonstrate that the σ donation from biL to copper(I) is enhanced as the basicity of biL increases and the resulting electron-rich copper(I) enhances π back-donation in the copper(I)-ethylene bonding. The formation constants of [Cu(phen)(olefin)]+ at 25°C vary from 0.1 to 18 M-1, although they are not as sensitive to the substituent groups on the double bond of the olefin as those of nickel(0) olefin complexes. There is no simple correlation of the formation constant with the Hammett σ, as is distinct from nickel(0) and silver(I) olefin complexes.
