Structural information from the J-coupled multiplet of a (CH 3) 3PAlCl 3 coordination complex on zeolite Y

Abstract

The influence of the dipolar interaction on the magic-angle spinning (MAS) sideband intensity has been illustrated through the 31P MAS-NMR of a (CH 3) 3PAlCl 3 coordination complex which was stabilized on a dehydrated NaHY zeolite. The dramatic change of the J coupling multiplet pattern in each spinning sideband with rotation frequency served as a direct and convenient approach in determining the dipolar coupling constant and the orientation between the dipolar tensor and the chemical-shift tensor. The hextet splitting which results from the coupling of the phosphorus nuclei with the spin- 5 2 aluminum nuclei includes detailed lineshape features which make the simulation unique. From the analysis, the AlP internuclear distance is found to equal 2.51 Å, and the orientation between chemical-shift anisotropy and dipolar interaction in the complex is found to be coincident. This approach will be useful in interpreting the dipolar coupling interaction for isolated dipolar pairs which occur, for example, when the probe molecule (CH 3) 3P interacts with Lewis acid sites in zeolites.