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

Article abstract of DOI:10.1016/j.molstruc.2005.03.035

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 273 K. The adduct formation shift, defined as Δδ= δ_adduct-δ_ligand and characterizing complexation reaction, varies from ca. 0 to +1.6 ppm for ¹H, from ca. -10 to +6 ppm for ¹³C and from -4.4 to -39 ppm 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 532-597 nm spectral range, assigned to 1:1- and 2:1-adducts.