Both the phosphorus chemical shift (CS) tensor and the Hg-199-P-31 spin-spin coupling tensor have been determined for the 1:1 mercury(II) phosphine complex HgPCy(3)(NO3)(2) (Cy = cyclohexyl) (1) using single-crystal P-31 NMR spectroscopy. The phosphorus CS is found to be anisotropic with a span of approximately 90 ppm. The orientation of the principal axis system of the phosphorus CS tensor has been assigned in the molecular reference frame and is found to conform with the local site symmetry at the phosphorus atom. These results represent the first determination of the complete phosphorus CS tensor in a metal-phosphine complex. The orientation dependence of the Hg-199-P-31 spin-spin coupling has been monitored as a function of crystal orientation in the external magnetic field from which the traceless part of the Hg-199-P-31 J tensor has been determined. A significant anisotropy, on the order of 5400 Hz, is found to exist, indicating the participation of non-Fermi contact mechanisms in the electron mediated transmission of nuclear spin information between Hg-199 and P-31 in 1. An X-ray crystallographic structure determination has also been performed for 1, revealing the presence of a polymeric chain structure in contrast to the dimeric species found previously. Crystals of 1 were found to belong to the monoclinic space group P2(1)/c with Z = 4 and unit cell dimensions a = 10.360(2) Angstrom, b = 10.247(1) Angstrom, c = 21.005(4) Angstrom, beta = 97.73(2)degrees. The structure was refined using least-squares techniques to a final R-factor of 0.0365 based on 3070 independent reflections.