[en] Investigations in the technetium-99 m chemistry [1] are stimulated by the search for new radiopharmaceuticals for nuclear medical applications. To understand the coordination mode of technetium with various complexing agents, macroscopic studies of technetium coordination chemistry are often performed in the milligram level using the low energy β-emitting radionuclide radionuclide ⁹⁹Tc, which has a much longer half life (t_1/2 = 2.12 x 10⁵ years) than ^99mTc (6 hours). Investigations of rhenium coordination chemistry are done in conjunction with Tc studies because Re possesses chemical properties similar to those of Tc. For some chemical tasks, Re provides a non-radioactive alternative to work with Tc radioisotopes. In addition, ¹⁸⁶Re and ¹⁸⁸Re are of great interest to nuclear medicine as they possess nuclear properties favorable for use in therapeutic radiopharmaceuticals. Our investigations of Tc and Re coordination chemistry are toward this goal. A large series of technetium and rhenium complexes resulting from this studies have been characterized by X-ray crystal structure determinations. (orig.)