Rhenium(V) Complexes with Selenolato‐ and Tellurolato‐Substituted Schiff Bases – Released PPh 3 as a Facile Reductant

The salicylidene Schiff bases of bis(2‐aminophenyl)diselenide and ‐ditelluride react with [ReOCl 3 (PPh 3 ) 2 ] or the arylimidorhenium(V) compounds [Re(NPhR)Cl 3 (PPh 3 ) 2 ] (R = H, F, CF 3 ) with formation of rhenium(V) complexes with tridentate {O,N,Se/Te} chalcogenolato ligands. The ligands adopt a facial coordination mode with the oxygen donors trans to the multiply bonded O 2– or NPhR 2– ligands. The reduction of the dichalcogenides and the formation of the chalcogenolato ligands occurs in situ by released PPh 3 ligands. The absence of additional reducing agents provides good yields of products with rhenium in the high formal oxidation state “+5”. A mechanism for the dichalcogenide reduction is proposed on the basis of the experimental results. In accordance with the proposed mechanism, best yields are obtained with a strict exclusion of oxygen, but in the presence of water.