ELECTRON-PARAMAGNETIC-RESONANCE STUDY OF THE STRUCTURE OF C4 IN SOLID NE

The electron-paramagnetic-resonance spectrum of C4 in a neon matrix at approximately 4 K formed by the vacuum-ultraviolet photolysis of 1,3-butadiene has been investigated to determine if there is any evidence of the bending of the molecule, which had previously been indicated by the results of EPR and Fourier-transform infrared measurements made on C4 trapped in argon at 10-12 K. The observed spectra, which include C-13 hyperfine splitting and zero-field splitting data, confirm the splitting of the perpendicular xy1 and xy2 lines of triplet C4 into separate x and y components, which is indicative of the inequivalent axes of a bent molecule.