Abstract
The salicylidene Schiff bases of bis(2‐aminophenyl)diselenide and ‐ditelluride react with [ReOCl3(PPh3)2] or the arylimidorhenium(V) compounds [Re(NPhR)Cl3(PPh3)2] (R = H, F, CF3) 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 O2– or NPhR2– ligands. The reduction of the dichalcogenides and the formation of the chalcogenolato ligands occurs in situ by released PPh3 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.
Highlights
In contrast to the large number of alcoholato or thiolato complexes, organoselenolato and -tellurolato complexes of rhenium are rare
The salicylidene Schiff base of bis(2-aminophenyl)diselenide {HLSe}2 was prepared by a reaction of di(2-aminophenyl)diselenide with two equivalents of salicylaldehyde in boiling ethanol
Rhenium(V) complexes with tridentate selenolato- and tellurolato-substituted Schiff base ligands are formed during reactions of the corresponding dichalcogenides {HLSe}2 or {HLTe}2 with phosphine-containing rhenium(V) complexes such as [ReOCl3(PPh3)] or [Re(NAr)Cl3(PPh3)2] (Ar = Ph, PhF, PhCF3)
Summary
In contrast to the large number of alcoholato or thiolato complexes, organoselenolato and -tellurolato complexes of rhenium are rare. Reactions of [ReOCl3(PPh3)2] with {HLSe}2 give yields of [ReO(LSe)Cl(PPh3)] in the range of 70 %, when the reaction is performed at room temperature in moist CH2Cl2 under inert conditions. The reduction of disulfides and diselenides with phosphines with formation of phosphonium-chalcogenolate ion pairs or bis(organochalcogen)phosphoranes has been observed before.[34,35,36,37] In the reactions of the present study, the phosphonium species seems to have a remarkably high formation probability and is found as a fragment of high intensity in the ESI+ mass spectra taken from CH2Cl2 solutions of [ReO(LSe)Cl(PPh3)].
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