LEWIS BASE ADDUCTS OF HALOGENORHENIUM(VII) OXIDES - O-17 NMR-SPECTROSCOPY STRUCTURAL ASPECTS AND CATALYSIS

Halogenorhenium(VII) oxides (XReO3, 1a-1e, X = F, Cl, Br, CN, SCN) rea ct with the bidentate Lewis base 4,4'-bis(tert-butyl)-2,2'-bipyridine to form soluble complexes of composition XReO3. L (2a-2e). These compl exes were characterized by O-17 NMR spectroscopy, mass spectroscopy, I R spectroscopy and elemental analysis. The single crystal X-ray struct ure of 2c (X = Br) was determined. The Re-Br bond distance is comparat ively long (265.30(8) pm) and probably partially ionic. Ln solution th e complexes do not exchange the Lewis base ligands or the oxygen ligan ds rapidly as happens for the closely related organorhenium( VB) triox ides. The O-17 NMR spectra of the halogeno complexes do not show tempe rature dependences. All complexes (2a-2e) show considerable catalytic activity in the oxidation of 2,3-dimethylnaphthalene. (C) 1998 Elsevie r Science S.A. All rights reserved.