Rhenium and technetium complexes with tridentate N-[(N″,N″- dialkylamino)(thiocarbonyl)]-N′-substituted benzamidine ligands

Article abstract of DOI:10.1021/ic702344s

N-[(Dialkylamino)(thiocarbonyl)]benzimidoyl chlorides react with functionalized amines such as 2-aminophenol, 2-methylaminopyridine, and 2-aminobenzoic acid in clean and high-yield procedures with the formation of the novel tridentate N-[(N″,N″-dialkylamino)(thiocarbonyl)]-N′- substituted benzamidine ligands H₂L¹, HL², and H₂L³. By starting from (NBu₄)[MOCl₄] (M = Re, Tc) or [ReOCl₃(PPh₃)₂] and H ₂L¹, a series of oxorhenium(V) and oxotechnetium(V) complexes of the composition [MOCl(L¹)] were synthesized and characterized by spectroscopic methods and X-ray crystallography. The monomeric, five-coordinate compounds are air-stable and bind (L¹)^2- tridentate in the equatorial coordination sphere. Dimeric products of the compositions [{ReOCl(L²)}₂O] and [ReOCl(L ³)]₂ were isolated during reactions with HL² and H₂L³. While dimerization in [{ReOCl(L ²)}₂O] is established via an oxo bridge, the metal atoms in [ReOCl(L³)]₂ are connected by the carboxylic group of the ligand, and the product represents the first example of a high-oxidation state rhenium complex displaying such a bonding feature.