Further Evidence for the Plastic Crystalline Nature of l-Vinyl-o-Carborane

In the course of this investigation it has been shown that l-vinylo-carborane has two phases between the crystalline solid below − 65°C and the isotropic liquid above + 79°C. In phase I between + 11 and + 79°C, this waxy material has been shown to be isotropic with a face-centered cubic structure. In this phase the NMR resonance line width was a function of temperature and found to be of the order of 0.01 gauss, which is consistent with spherical rotation and diffusional motion of the molecular centers of gravity. The evidence presented here together with that previously reported provides convincing evidence of the plastic crystalline nature of phase I. In the range of − 65 to + 11°C, phase 11, I-vinyl-o-carborane has been shown to be birefringent and more crystalline like in nature.