Studies on adducts of rhodium(II) tetraacetate and rhodium(II) tetratrifluoroacetate with some amines in CDCl3 solution using 1H, 13C and 15N NMR

Abstract

1H, 13C and 15N NMR spectroscopy has been applied for investigation of amine adducts with rhodium(II) tetraacetate dimer and rhodium(II) tetratrifluoroacetate dimer in CDCl3 solution. Subsequent formation of two adducts, 1:1 and 2:1, was proved by NMR and VIS titration experiments, and by NMR measurements at reduced temperatures, from 233 to 273K. The adduct formation shift, defined as Δδ=δadduct−δligand and characterizing complexation reaction, varies from ca. 0 to +1.6ppm for 1H, from ca. −10 to +6ppm for 13C and from −4.4 to −39ppm for 15N NMR. Formation of N–Rh bond slows the inversiof on the nitrogen atom and generates, in the case of N-methyl-(1-phenylethyl)-amine, a nitrogenous chiral center in the molecule. VIS spectra of amine-dirhodium salt mixture contain two bands in the 532–597nm spectral range, assigned to 1:1- and 2:1-adducts.