INFRARED-SPECTRA OF MATRIX-ISOLATED AND SOLID ETHYLENE - FORMATION OF ETHYLENE DIMERS

Spectra of matrices with ethylene/argon ratios from 1/1 to 1/999 and a 1/24 ethylene/xenon matrix have been recorded in the temperature range 15-105 K. From relative i.r. intensities, frequency shifts and statistical calculations, the data are interpreted in terms of a monomer → dimer → aggregate → crystal scheme. It is proposed that the dimer, (C2H4)2, has D2d symmetry with a structure determined by quadruple hydrogen bonding and hydrogen-hydrogen repulsion. A method is described for calculation of the vibrational splitting due to interactions between the dimer molecular constituents. Solid ethylene has been studied between 15 and 85K. A transformation between two crystalline phases is characterized. © 1979.