fac-[Re(CO)3L] Complexes Containing Tridentate Monoanionic Ligands (L−) Having a Terminal Amido and Two Amine Ligating Groups

fac-[Re(CO)3L]+ Complexes with N−CH2−CH2−X−CH2−CH2−N Tridentate Ligands. Synthetic, X-ray Crystallographic, and NMR Spectroscopic Investigations

“…We have also examined related complexes with elaborated dien ligands linked with CO in place of SO 2 . 18 Our results showed that facially coordinated sulfonamido ligands have different chirality in each chelate ring more frequently than they have the same chirality, in agreement with the pca reports. 20,21 In contrast, the two chelate rings in the Re analogue of [ 99m -Tc(CO) 3 (LANH)] agents (LANH 2 ) lanthionine, a natural dicysteine-derived dipeptide linked through a common sulfur and exhibiting tridentate NSN binding) were found to have the same chirality.…”

“…11,17 The location in space of the chelate ring atoms is a key factor in designing fac-[ 99m Tc(CO) 3 L] agents because these atoms act as a fulcrum for the pendant groups. In turn, the position of the pendant group has a significant effect on the overall shape of the agent 18 and hence on its biological activity. For diethylenetriamine-type ligands bound to a metal center in a tridentate fashion, the pucker of the two fivemembered chelate rings can have either δ or λ chirality (Chart 1), leading to four possible combinations of chelate ring chirality, δλ, λδ, λλ, and δδ.…”