N-(2-Mercaptoethyl)picolylamine (MEPAH) was studied as a potentially biologically relevant ligand for the "fac-[M(CO)(3)](+)" core (M = Re, Tc-99, Tc-99m). To this end, the complex Re(CO)(3)(MEPA) as synthesized. The reaction of MEPAH with fac-[Re(CO)(3)(MeCN)(3)](+) took place over the course of seconds, showing the high affinity possessed by this ligand for the "fac-[Re(CO)(3)](+") core. A single-crystal X-ray diffraction study was performed confirming the nature of Re(COMMEPA), a rare mononuclear rhenium(l) thiolate complex. Additional exploration into derivatization of the ligand backbone has afforded the analogous N-ethyl complex, Re-(CO)(MEPA-NEt). The high affinity of the ligand for the metal coupled with the ease of its derivatization implies that utilization of this ligand system for the purposes of Tc-99m-radiopharmaceutical development is promising.