Multiple Bonds between Main-Group Elements and Transition Metais. 77.¹ Condensation Reactions of Methyltrioxorhenium(VII) with Catechols and Aromatic Thiols

The title compound methyltrioxorhenium(VII) reacts with catechols to yield complexes of the formula CH₃Re(O)₂(l,2-O₂C₆R₄) (〈2〉) that are fully characterized as pyridine adducte 3. Conducting these reactions in the presence of nucleophiles, e.g., halides, gives the hexacoordinate anions [CH₃Re(O)2(l,2-O₂C₆R₄)(X)]⁻ of compounds 4a-c (X = C1, Br, I) in high yields. Based upon spectroscopic data, the oxo ligands occupy cis positions and the halide ligand occupies trans positions with respect to the methyl group of these novel five-membered d⁰ rhenacycles. The rhenium(V) species “CH₃ReO₂^”, prepared in situ from 1 by reduction with (polymer bound) triphenylphosphane, reacts with phenanthrenequinone in the presence of pyridine to give the neutral hexacoordinate complex CH₃Re(O)₂(9,10-O₂C₁₄H₈)(NC₅H5) (5), with the quinone ligand being present in the reduced form as catecholate while the rhenium is in the oxidation state VII. Reaction of 1 with thiophenol gives initially the rhenium(VII) complex CH₃ReO(SC₆H₅)₄ (6), which upon heating undergoes intramolecular elimination of diphenyl disulfide, C₆H₅SSC₆H₅, to give the dinuclear rhenium(V) complex [CH₃ReO(μ-SC₆H5)(SC₆H₅)]2 (7; X-ray diffraction study). Condensation of 1 with benzene-1,2-dithiol gives the rhenium(VII) complex CH₃ReO(1,2-S₂C₆H₄)₂ (8).