BOND - VALENCE STUDY OF COPPER(II) NIFLUMATES

Fedor Valach, Miroslav Tokarcik

Department of Chemical Physics, Faculty of Chemical Technology, Slovak University of Technology, SK-812 37 Bratislava, Slovak Republic, E-mail: valach@cvtstu.cvt.stuba.sk

Keywods: fenamate, copper(II) niflumate, 3-pyridylmethanol, bond-valence, crystal structure

Bond - valence sums distribution of niflumic acid anion in the structures of niflumic acid, C₁₃H₉F₃N₂O₂ 1 and 1:1 complex of (2 - 3 - (Trifluoromethyl)phenylamino - 3 - pyridine-carboxylic acid (niflumic acid) with ethanolamine, C₁₉H₂₀F₃N₃O₃ 2, was calculated by program VALMAP 2.0 3. The preferred coordination of niflumate ligand to the copper cation through one carboxylic oxygen atom was predicted. The crystal and molecular structure of copper(II) complex of niflumate ligand with 3-pyridylmethanol as neutral ligand confirmed the predicted bonding. Almost square-planar trans coordination of the Cu atom is formed by two carboxylic atoms from two niflumic ligands (nif) and two nitrogen atoms from two 3-pyridylmethanol ligands (3-pyMe). Cu-O and Cu-N bonds are 1.946(3) (2) and 2.038(3)A (2) long. Using the earlier developed formulae 4 for bond valence calculation the calculated Cu(II)-O bond length connecting the Cu (nif)₂(3-pyMe)₂ units into infinit chains is 2.61 (2)A . Observed values of these bond lengths are 2.573(3) (2)A [5].

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