Electron paramagnetic resonance (EPR) studies of the rhenium(II) complex Re(eta(5)-Cp)(BDI) (1; BDI = N,N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-beta-diketiminate) have revealed that this species reversibly binds N-2 in solution: flash frozen toluene solutions of 1 disclose entirely different EPR spectra at 10 K when prepared under N-2 versus Ar atmospheres. This observation was additionally verified by the synthesis of stable CO and 2,6-xylylisocyanide (XylNC) adducts of 1, which display EPR features akin to those observed in the putative N-2 complex. While we found that 1 displays an extremely large g(max) value of 3.99, the binding of an additional ligand leads to substantial decreases in this value, displaying g(max) values of ca. 2.4. Following the generation of isotopically enriched N-15(2) and (CO)-C-13 adducts of 1, HYSCORE experiments allowed for the measurement of the corresponding hyperfine couplings associated with spin delocalization onto the electron-accepting ligands in these species, which proved to be small. A cumulative assessment of the EPR data, when combined with insights provided by near-infrared (NIR) spectroscopy and time-dependent density functional theory (TDDFT) calculations, indicated that while the binding of electron acceptors to 1 does lead to decreases in g(max) in relative accord with the field strength (i.e., pi-acidity) of the variable ligand, the magnitude of these decreases is primarily due to the changes in electronic structure at the Re center.