VIBRATIONAL-SPECTRA AND ASSIGNMENT FOR TRANS-3,4-DICHLOROCYCLOBUTENE - REVISED ASSIGNMENT FOR THE CIS ISOMER

A complete assignment of the vibrational fundamentals of trans-3,4-dichlorocyclobutene has been derived from infrared and Raman spectra. These frequencies are: (a) 3107, 2985, 1555, 1283, 1248, 1163, 1126, 1010, 920, 821, 452, 228 and 134 cm-1; (b) 3087, 2998, 1291, 1220, 1171, 956, 889, 782, 606, 327 and 246 cm-1. A long-path, gas-phase infrared spectrum is reported for the cis isomer. After some revisions in the previous assignment of the fundamentals of the cis isomer, notably lowering the ring puckering frequency from 381 to 145 cm-1, good correlations exist between the frequencies for the two isomers and with pertinent modes in cyclobutene itself.