ANISOTROPIC INDIRECT SPIN SPIN COUPLING IN THE SOLID-STATE - EXPERIMENTAL-EVIDENCE OF NONCONTACT CONTRIBUTIONS TO 1J-P31,HG-199

Anisotropies in the P-31 chemical shift tensor and the for a series of mercury phosphines, [HgPR3(NO3)2]2, have been determined from their P-31 solid-state NMR line shapes. The principal components of the P-31 chemical shift tensor vary over a total range of 125 ppm for the different mercury phosphines, but the component that is along or nearest to the P-Hg bond is relatively invariant. The indirect spin-spin coupling tensor involving P-31 and Hg-199, 1J(P-31, Hg-199), exhibits considerable anisotropy, of greater than 5 kHz in most cases. These results indicate that mechanisms other than the contact term are in part responsible for the transfer of nuclear-spin information between P-31 and Hg-199 in these compounds.