Chemical-shift-tensor parameters retrieved from solid-effectively asymmetric s tensors have been reported, although with differing values of s ii . This undoubtedly reflects state NMR spectral data convey both structural and molecular implications, and efforts are continually devoted to the the difficulties in obtaining precise values of h for nearly axially symmetric s tensors (6, 10, 11), together with the development of techniques to gather such information from solid samples (1). Single-crystal methods are accurate but fact that homonuclear 31 P, 31 P coupling effects have been neglected in the previous works. Recently, Eichele and Wa-are sometimes limited by the requirement of samples of adequate shape and size. The most usual NMR technique for sylishen ( 12) have studied a powdered sample of NH 4 H 2 PO 4 using MAS NMR, concluding that the apparent asymmetry obtaining the principal components of the s tensor involves studying the distribution of side-band intensities from magic-of the s( 31 P) tensor is due to the presence of homonuclear P, P dipolar coupling. angle spinning (MAS) spectra of solid powders (2). Several methods have been discussed for the retrieval of chemical-We now consider the approximate relative values of the 31