ELECTRON-PARAMAGNETIC RESONANCE-SPECTRA AND STRUCTURES OF CU[C2H4], CU[C2H4]2, AND CU[C2H4]3 IN HYDROCARBON MATRICES

Two mononuclear π-complexes, Cu[C2H4] and Cu[C2H4]2, have been positively identified by EPR spectroscopy from reaction of Cu atoms and ethylene at 77 K in inert hydrocarbon matrices on a rotating cryostat. The spectra of these copper(0) complexes are consistent with dative bonding for both species and with a C2v structure for Cu[C2H4] and a D2h structure for Cu[C2H4]2. Spectra of Cu[13CH2CH2] and Cu[13CH2CH2]2 are consistent with these assignments. A third complex is formed in both adamantane and cyclohexane that could be Cu[C2H4]2 with a structure other than D2h but is more likely to be the mononuclear trisligand complex Cu[C2H4]3 with a D3h structure. In the absence of a well-resolved isotropic spectrum of Cu[13CH2CH2]3, this assignment must however be taken as tentative.