Knowledge Bank

Close examination of the mid-infrared spectrum of methylencyclobutane has yielded combination bands which involve the ring puckering vibration. These data have been interpreted using a two parameter potential function; $V(x)=a(x4+bx2)$, where x is the ring puckering coordinate. The coefficients a and b were determined by an iterative least squares treatment using the computer program of Ueda and $Shimanouchi.1$ The barrier at the planar conformation derived from these data $(165\pm 10cm-1)$ is in good agreement with that determined by other workers from the vibrational dependence of the rotational constants in the microwave spectrum $(160\pm 50cm-1).2$