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Hexacoordinated transition metal bpa and imda complexes

Transition metal complexes with coordination number 6 can exhibit octahedral or trigonal prismatic geometry. The distinction between the geometries can be made based on several angular parameters: θ, ρ and ω. Continuing our recent research on tridentate ligands (L) with two identical terminal coordination sites like bis(2-picolyl)amine (L = bpa), we now extend our attention to phenyl iminodiacetamides (L = imda). In this communication we present hexacoordinated ML2 complexes with different central metal cations, M = Zn2+, Co2+, Ni2+, Cd2+. Crystal structures of several ML2 complexes determined by X-ray diffraction on single crystals will be compared with structures calculated by M05-2X/LanL2DZ method. In addition, the calculated energies for the different isomers will be discussed (mer-, cis- or trans-). Starting from the unsubstituted ligand, various electron donating or withdrawing substituents will be added to bpa or imda systems in order to evaluate their influence on the geometry and energetics of the studied complexes. Our goal is to identify the factors governing the stabilization of cis-isomers which could be used as catalysts in asymmetric reactions.

asymmetric reactions ; X-ray diffraction ; computational studies

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