CHARACTERIZATION OF A NOVEL TRIPLY BONDED IMINOPHOSPHENIUM CATION BY N-15 AND P-31 SOLID-STATE NMR-SPECTROSCOPY

The first stable compound containing a nitrogen-phosphorus triple bond, [2,4,6-tri-t-Bu-C6H2N = P]+[AlCl4]- (1), has been investigated by N-15 and P-31 solid-state NMR spectroscopy. Analysis of dipolar chemical shift NMR spectra for static powdered samples of 1 has provided the three principal components of the N-15 and P-31 chemical shift tensors and allowed the determination of their orientations in the molecular frame of reference. Both chemical shift tensors are slightly nonaxially symmetric with N-15 and P-31 chemical shift anisotropies of 421 +/- 4 ppm and 581 +/- 4 ppm, respectively. The most shielded principal component of both chemical shift tensors is oriented along the N,P bond axis. Comparison of the observed N-15 and P-31 chemical shift tensors for 1 with experimental and theoretical results for related compounds suggests that the electronic environment surrounding the N,P moiety of 1 is similar to other systems containing a formal triple bond.