MULTIPLE BONDS BETWEEN TRANSITION-METALS AND MAIN-GROUP ELEMENTS .74. 5-MEMBERED RHENACYCLES THROUGH CONDENSATION-REACTIONS OF METHYLTRIOXORHENIUM(VII) WITH BIDENTATE LIGANDS - X-RAY CRYSTAL-STRUCTURES OF 8-OXYQUINOLINATO AND CATECHOLATO COMPLEXES

Methyltrioxorhenium(VII), CH3ReO3 (1), undergoes condensation reactions with aromatic bidentate ligands of type HO···X (X = N, NH2, OH) to yield products with strongly ligand-dependent structures. Mild conditions are characteristic of these condensation reactions. Thus, reactions of 1 with catechols 1,2-(HO)2C6H2RR’-3,4 in the presence of pyridine give compounds 2a–c of general formula CH3Re(O)2-(1,2-O2C6H2RR’-3,4)(NC5H5) in high yields. The single-crystal X-ray diffraction study of the parent catecholato derivative 2a (R = R’ = H) reveals an octahedral ligand sphere around the rhenium atom, with cis oxo ligands and the pyridine in trans position with respect to the methyl group. Treatment of 2a with anhydrous hydrogen chloride yields the ionic complex 3a of formula [C5H6NH]+[CH3Re(O)2(1,2-O2C6H4)Cl]−, resulting from nucleophilic replacement of the pyridine ligand by a chloride ion. Reaction of 1 with the heterobifunctional ligand 2-aminophenol yields the bis-substituted amidophenolato derivative CH3Re-(O)[1,2-O(HN)C6H4]2 (4). While the bis(thiophenolato) analogue of 4 could not be isolated, the pyridine adduct of the mono(amidothiophenolato) derivative CH3Re(O)2[1,2-O(HN)C6H4](C5H6N) (5) is easily obtainable. Smooth reaction of 1 with 1 equiv of the chelating ligand 8-hydroxyquinoline results in the formation of the binuclear compound (μ-O)[CH3Re(O)2(8-oxyquinolinato)]2 (6) in 90% yield. According to a single-crystal X-ray study, the centrosymmetric molecule consists of two corner-sharing distorted octahedra with a (linear) bridging oxo ligand. Most of the novel oxorhenium(VII) condensation products hydrolyze to the respective precursor compounds. The aliphatic analogues of this type of condensation products could not be isolated. © 1990, American Chemical Society. All rights reserved.