NATURE OF THE CARBON PHOSPHORUS DOUBLE-BOND AND THE CARBON PHOSPHORUS TRIPLE BOND AS STUDIED BY SOLID-STATE NMR

The nature of the carbon-phosphorus double bond in 2,4,6-t-Bu3C6H2P=C(SiMe3)2 and the carbon-phosphorus triple bond in 2,4,6-t-Bu3C6H2C≡P has been studied by 13C and 31P solid-state NMR. Magic angle spinning and static cross-polarization experiments have been used to determine the principal elements of the 13C and 31P shielding tensors. In the 13C spectra, the presence of a dipolar coupling to the 31P nucleus permits assignment of the orientation of the 13C shielding tensors in the molecular frame. These shift tensors are compared to previous work on diphosphenes, disilenes, alkenes, and alkynes. It is found that the shift anisotropies for 31P and 13C in these multiply bonded environments are quite similar when the larger intrinsic chemical shift range for 31P is taken into account. © 1990, American Chemical Society. All rights reserved.