NMR relaxation times were measured for the acetylene carbon and hydrogen nuclei in the coupled two-spin system H5C6-C=C-13-H. For the experiments reported here, 0.15 and 0.30 M solutions of phenylacetylene in pure d-8-toluene and in 50/50 mixtures of fully deuterated toluene/methanol and toluene/2-propanol were studied. The values obtained at 7.0 T between 163 and 189 K for the carbon-hydrogen bond distance, r(CH), corrected for vibrational averaging and the carbon and proton chemical shift anisotropies (Delta delta), are 109.1 +/- 1.0 pm, -159.6 +/- 7.2 ppm, and -13.7 +/- 0.3 ppm, respectively. Within experimental error, these parameters are independent of temperature, magnetic field strength, and solvent. The temperature dependence of the C-13 isotropic chemical shift (which can be measured more precisely than the Delta delta value) is approximately -0.017 ppm/K; it is not linear and can be described (in units of ppm) by the quadratic equation delta(iso) = (5.608 X 10(-5)) T-2 -0.0410T + 82.30, where T is the temperature in degrees Kelvin and delta(iso) is the isotropic chemical shift relative to TMS. In terms of the components of the proton and carbon chemical shift tensors (relative to TMS), we obtain : delta(parallel to)(H) = -6.31 ppm, delta(perpendicular to)(H) = 7.39 ppm, delta(parallel to)(C) = -27.76 ppm, and delta(perpendicular to)(C) = 131.84 ppm (delta(iso)(H) = 2.82 ppm and delta(iso)(C) = 78.64 ppm in a 50/50 toluene/methanol mixture). Using the Redfield formalism, simultaneous information about the two CSA values, the bond distance, the correlation time, and the intermolecular interactions can be obtained at a single fixed temperature and a single magnetic field value while observing a single nucleus. The relative contributions of the dipolar, CSA, and intermolecular interactions depend on different components of the spectral density function and are, consequently, temperature (i.e., correlation time) dependent.