engleski

Late Transition Metal Complexes of Iminodiacetamide Ligands: Steric, Electronic and Counterion Effects on Stereochemistry

Iminodiacetamides (imda) are amide derivatives of the well-known complexone iminodiacetic acid. The flexible linking arms of these ligands permit a variety of coordination modes, such as meridional, trans-facial, and cis- facial.[1] All previously reported imda complexes except [Ni(H-imda)2](ClO4)2 are trans-facial ML complexes.[2, 3] In this communication, the factors favouring different stoichiometries and coordination modes of ML complexes of these ligands are discussed. To study these factors, the steric bulkiness of the substituent on the central nitrogen atom, and the electronic properties of the substituents on the phenyl rings were varied. Complexes of imda derivatives with late transition metals (Zn2+, Cu2+, Ni2+, Co2+ and Cd2+) were prepared and characterized. To test the effect of counterions, metal salts with anions of different coordinating ability were used (BF4-, ClO4-, NO3- and Cl-). The complexes were characterized in solid state (single crystal X-ray diffraction, IR, TG-DTA) and in solution (1H, 13C, 1D and 2D NMR, UV-Vis). Experimental results were compared to DFT calculations, determining the substituent effect on the relative stability of isomers. Our goal was to determine factors that enable the formation of cis-facial isomers, for future use in asymmetric catalysis. References: 1) Đ. Škalamera, E. Sanders, R. Vianello, A. Maršavelski, A. Pevec, I. Turel, S. I. Kirin, Dalton Trans., 2016 (45), 2845–2858. 2) M. Sekizaki, Acta Crystallogr., 1976 (32), 1568. 3) N. Smrečki, V. Stilinović, M. Merkaš, A. Lučić, B.M. Kukovec, Z. Popović, Aust. J. Chem. 2016 (69), 896–904. This work has been fully supported by Croatian Science Foundation under the project IP-2014-09-1461.

iminodiacetamide ; nitrogen ligands ; metal complexes ; stereochemistry

nije evidentirano