Synthesis, characterization and redox behaviour of benzoyldiazenido- and oxorhenium complexes bearing N,N- and S,S-type ligands

The reactions of [ReCl2{η2-N2C(O)Ph}(PPh3)2] (1) with 2-aminopyrimidine (H2Npyrm), 2,2′-bipyridine (bpy) and tetraethylthiuram disulfide (tds), in MeOH upon reflux, lead to the new η1-(benzoyldiazenido)rhenium(III) complexes [ReCl{η1-N2C(O)Ph}(HNpyrm)(PPh3)2] (2) and [ReCl2{η1-N2C(O)Ph}(bpy)(PPh3)] (3), and the known oxo(diethyldithiocarbamato)dirhenium(v) complex [Re2O2(μ-O){Et2NC(S)S}4] (4), respectively. The Et2NC(S)S ligands in 4 result from S–S bond rupture of tds molecules. The obtained compounds have been characterized by IR, 1H, 31P{1H} and 13C{1H} NMR spectroscopies, FAB+-MS, elemental and single-crystal X-ray diffraction (for 2 and 4) analyses. Complex 2 represents the first structurally characterized Re compound derived from 2-aminopyrimidine. Besides, the redox behaviour of 2–4 in CH2Cl2 solution has been studied by cyclic voltammetry, and the Lever electrochemical ligand parameter (EL) has been estimated, for the first time, for HNpyrm. The electrochemical results are discussed in terms of electronic properties of the Re centres and the ligands.

Graphical abstractη1-(Benzoyldiazenido)rhenium(III) and oxodirhenium(v) complexes have been prepared from reactions of the dichloro-η2-benzoylhydrazido precursor with 2-aminopyrimidine (H2Npyrm), 2,2′-bipyridine (bpy) and tetraethylthiuram disulfide (tds), and their redox behaviour has been studied.Figure optionsDownload full-size imageDownload as PowerPoint slide