engleski

Substituent Influence on the Solution State Structure of Iminodiacetamide Complexes with Late Transition Metals

Tridentate ligands, such as iminodiacetamide (imda) derivatives and transition metals are known to form complexes of ML and ML2 stoichiometry. In hexacoordinated ML2 complexes, depending on the orientation of the ligands, mer, trans-fac and Δ- or Λ-cis-fac geometrical isomers are possible. Our aim is to study substituent effects on the stereochemistry of imda complexes, as model complexes for catalysts in enantioselective reactions. In the solid state we observed mainly trans-fac isomers, while the cis-fac isomer was obtained only for R, R' = H. In acetonitrile solution, NMR spectroscopy reveled formation of trans-fac isomers at room temperature (R' = iPr) or at 0°C (R' = Bn). The substituent on the central amine nitrogen was also found to influence the N-M bond strength, which was studied with variable temperature NMR. The relative stabilities of the isomers depending on the ligand substituent were determined using DFT calculations.

tridentate ligands ; transition metals ; geometrical isomers

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