Conformational study of Co(II), Ni(II), and Cr(III) complexes of the edta-type: Crystal structure of 1D polymeric trans(O)-Ba[Co(1,3-pddadp)] · 8H2O complex stabilized by infinite water tapes |
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Authors: | S Grubiši? DD Radanovi? U Rychlewska B War?ajtis NS Draškovi? MI Djuran SR Niketi? |
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Institution: | 1. Center for Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Njegoševa 12, P.O. Box 815, 11001 Belgrade, Serbia;2. Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland;3. Department of Chemistry, Faculty of Science, University of Kragujevac, R. Domanovi?a 12, P.O. Box 60, 34000 Kragujevac, Serbia;4. Department of Chemistry, Faculty of Science, University of Belgrade, Studentski trg 16, P.O. Box 158, 11001 Belgrade, Serbia |
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Abstract: | The trans(O6) isomer of the BaCo(1,3-pddadp)] · 8H2O complex (where 1,3-pddadp represents hexadentate 1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate ion) has been prepared and characterized by X-ray crystallography. In the crystal structure the complex cations and anions are bridged by carboxylate oxygen atoms from the in-plane coordinated glycinate rings (G-rings) of Co(1,3-pddadp)]2− and by the barium-coordinated water molecules, thus forming 1D polymeric chains, separated by infinite water tapes hydrogen bonded to the Co(1,3-pddadp)]2− carboxylate oxygens from the out-of-plane β-alaninate rings (R-rings). Conformational analysis of the three possible geometrical isomers: trans(O5), trans(O5O6), and trans(O6) of the Co(1,3-pddadp)]2− complex, with ligand acting as hexadentate, as well as of the corresponding complexes of Ni(II) and Cr(III) has been performed using the consistent force field (CFF) method, with the parameters developed previously for edta-type complexes of chromium(III) and supplemented with new parameters for cobalt(II) and nickel(II). The energy-minimized structure of the trans(O5O6) isomer represents the global minimum for the M(1,3-pddadp)]n− (M = Co(II), Ni(II), and Cr(III)) species. The occurrence of the least energetically favored trans(O6) isomer in a crystal and the exceptional conformation of the axially oriented β-alaninate rings can be accounted for by the stabilizing role of the infinite tapes of planar cyclic water pentamers and hexamers which act as a “glue” to reinforce the coordination polymeric chains. |
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Keywords: | Co(II) Ni(II) and Cr(III) complexes Hexadentate chelates Molecular mechanics (MM) One-dimensional Co(II)/Ba(II) coordination polymers Infinite water tapes |
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