Knowledge Bank

Infrared spectra have been obtained from 33 to $4000cm-1$ for 1, 2- and 1, 3- dimethylenecyclobutane in the gaseous and the solid ($-196\circ C$) states. Raman spectra have been measured for the solids at low temperature, and also for the liquids so that depolarizations could be obtained. The vibrational data for 1, 3-dimethylenecyclobutane show that it is planar and has molecular symmetry $D\pm$. Frequencies can be assigned to 33 of the 34 spectroscopically active fundamentals. Identifying the correct molecular point group for 1, 2-dimethylenecyelobutane is some what more difficult because of its lower symmetry, but the data conform quite well to $C2$.