The translational diffusion constant of a paramagnetic species, dichlorobis(eta-cyclopentadienyl)vanadium (V(eta(5)-C5H5)(2)Cl-2), abbreviated as Cp(2)VCl(2), in chloroform was measured at room temperature (25 +/- 1 degrees C) by a capillary diffusion method. Using the Stokes-Einstein equation for translational diffusion, the diffusion coefficient and the molecular hydrodynamic radius of Cp(2)VCl(2) in chloroform were found to be 5.20 x 10(-6) cm(2)/s and 5.86 Angstrom, respectively. An analysis of the temperature dependent ESR line widths of Cp(2)VCl(2) in toluene in the motional-narrowing region was carried out using the four sets of the magnetic parameters available in the literature. It was found that only those by Peterson and Dahl could explain our line width data. Our analysis suggests that Cp(2)VCl(2) exhibits anisotropic rotational diffusion with N = 2.7 +/- 0.7 at an axis z’ = Y, where N is the ratio of R(parallel to)/R(perpendicular to), R(parallel to) is the rotational diffusion constant along the molecular Z axis, and R(perpendicular to) is the rotational diffusion constant perpendicular to the molecular Z axis. This value is consistent with the N value obtained from the Stokes-Einstein model (N = 3.3) and the allowed-values equation, AVE, with rho(X) = 3.02 rho(Y) - 7.18. The AVE is not consistent with isotropic reorientation and only consistent with axial symmetry if rho(X) = 1, rho(Y) = 2.71. In addition, the rotational correlation times as a function of temperature were determined from the line width data. The anisotropic interaction parameter kappa, which is a measure of the anisotropy of intermolecular interactions, was found to be 0.044. The kappa value showed that Cp(2)VCl(2) in toluene is more slip than VOAA in toluene, which is more stick (its kappa is 0.58). Therefore, it seems that the kappa value decreases with decreasing solute corrugation. The stickiness factor (S) was calculated for Cp(2)VCl(2) in toluene and was found to be close to the slip limit (S approximate to 0), indicating that there is no tendency for the solvent (toluene) to stick at the surface of the diffusing Cp(2)VCl(2) particles.