| dc.description | The nuclear magnetic resonance line shapes of solid compounds are used to gain new and fundamental information on several chemical systems. Analysis of the $\sp{31}$P nmr line shapes of several metal-phosphorus systems is used to characterize the anisotropic nature of the $\sp{31}$P chemical shielding and metal-phosphorus indirect spin-spin coupling. This work has revealed that substantial anisotropies exist in the indirect spin-spin coupling between $\sp{31}$P and $\sp{199}$Hg or $\sp{195}$Pt. In the mercury(II) phosphines, (HgPR$\sb3$(NO$\sb3)\sb2\rbrack\sb2$, these anisotropies are quite large, of the order of 5 kHz, for couplings that possess isotropic values of approximately 10 kHz. Although the isotropic $\sp{31}$P-$\sp{199}$Hg indirect spin-spin couplings are larger in the mercury(II) phosphonates, HgP(O)(OEt)$\sb2$X, this study indicates that the anisotropies in these couplings are much smaller. In the square-planar platinum(II) bisphosphine complexes, Pt(PR$\sb3)\sb2$Cl$\sb2$, the $\sp{31}$P-$\sp{195}$Pt indirect couplings are found to possess anisotropies in the indirect spin-spin couplings of at least 1 to 2 kHz, although a dependence of these values on the geometry of the complex cannot be determined. These findings are significant as they demonstrate that the indirect spin-spin coupling between $\sp{31}$P and some metal nuclei is not dominated by the Fermi contact mechanism, as has been commonly assumed. The nmr line shapes of half-integer spin quadrupolar nuclei are found to be sensitive to the relative orientation of the chemical shielding and quadrupolar interactions, and a method to interpret such line shapes is proposed. This is used to simulate the $\sp{133}$Cs nmr powder spectra of Cs$\sb2$CrO$\sb4$ at four magnetic fields, as these interactions are not aligned in this compound. | en_US |
