Technetium (V) and rhenium (V) complexes of 2,3-bis(mercaptoacetamido)propanoate. Chelate ring stereochemistry and influence on chemical and biological properties

Monoxo complexes of technetium(V) and rhenium(V) with 2,3-bis(mercaptoacetamido)propanoate (map) have been synthesized. The complexes with general formula (Ph{sub 4}X)(MO(map)) (where X = As, P; M = Tc, Re) were characterized by IR, visible-UV spectra, and negative ion fast atom bombardment spectroscopy. The chelate ring epimers were separated by HPLC (semipreparative reverse-phase C{sub 18}) isolated and crystallized as salts of (Ph{sub 4}X)(MO(map)). The structures of the two epimers (syn and anti) of technetium and one of the epimers (syn) of the rhenium complexes were determined by single-crystal X-ray analyses. All three complexes crystallize in the space group P2{sub 1}/c and have four formula units in the unit cell. In all of the three complexes, the metal (Tc, Re) is coordinated to one oxygen (yl) atom, two sulfur (thiolate) atoms, and two nitrogen atoms (amide) in a distorted square-pyramidal geometry. The position trans to the oxygen (yl) atom is vacant.