engleski

The Effects of Steric Aliphatic-Aliphatic Interactions in the Coordination Polymer of Bis(N, N-diethylglycinato)copper(II): Experimental Evidence and Theoretical Modeling

New coordination polymer catena-poly[(N, N-diethylglycinato-kO, kN)copper(II)-m-[N, N-diethylglycinato-kO1, kN:O2]] has been obtained by single-crystal X-ray diffraction. The copper(II) was surrounded with two amino N and two carboxyl O atoms in trans position in the coordination plane. Discrete polymeric chains were produced by axial coordinative bonding between copper(II) and carbonyl oxygen atom from adjacent asymmetric unit. Molecular mechanics (MM) force field developed to study the properties of copper(II) amino acid complexes reproduced well intermolecular aliphatic-aliphatic interactions between ethyl chains and C-H...O hydrogen bonding. The relative unit cell volume reproduction was 0.3%. Theoretical conformational analysis showed that experimentally obtained conformer was not the most stable in vacuo. The calculations of the unit cell packings and intermolecular interactions for a series of conformers elucidated the reasons that governed the experimentally obtained conformer to appear in the real crystal structure. MM results suggest that intermolecular aliphatic-aliphatic interactions between ethyl groups affected a conformational change concurrent with the change in the copper(II) coordination sphere upon crystallization.

amino acid; copper; X-ray diffraction; force field; conformational analysis; crystal lattice effects; intermolecular interactions

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