The Xe-129 NMR line shapes of xenon adsorbed in the nanochannels of the (+/-)-[Co(en)(3)]Cl-3 ionic crystal have been calculated by grand canonical Monte Carlo (GCMC) simulations. The results of our GCMC simulations illustrate their utility in predicting Xe-129 NMR chemical shifts in systems containing a transition metal. In particular, the nanochannels of (+/-)-[Co(en)(3)]Cl-3 provide a simple, yet interesting, model system that serves as a building block toward understanding xenon chemical shifts in more complex porous materials containing transition metals. Using only the Xe-C and Xe-H potentials and shielding response functions derived from the Xe@CH4 van der Waals complex to model the interior of the channel, the GCMC simulations correctly predict the Xe-129 NMR line shapes observed experimentally (Ueda, T.; Eguchi, T.; Nakamura, N.; Wasylishen, R.E. J. Phys. Chem. B 2003, 107, 180-185). At low xenon loading, the simulated Xe-129 NMR line shape is axially symmetric with chemical-shift tensor components delta(parallel to)=379 ppm and delta(perpendicular to)=274 ppm. Although the simulated isotropic chemical shift, delta(iso)=309 ppm, is overestimated, the anisotropy of the chemical-shift tensor is correctly predicted. The simulations provide an explanation for the observed trend in the Xe-129 NMR line shapes as a function of the overhead xenon pressure: delta(perpendicular to) increased from 274 to 292 ppm, while delta(parallel to) changed by only 3 ppm over the entire xenon loading range. The overestimation of the isotropic chemical shifts is explained based upon the results of quantum mechanical Xe-129 shielding calculations of xenon interacting with an isolated (+/-)-[Co(en)(3)]Cl-3 molecule. The xenon chemical shift is shown to be reduced by about 12% going from the Xe@[Co(en)(3)]Cl-3 van der Waals complex to the Xe@C2H6 fragment.