resumo
In an effort to capture fluoroanions by cationic cobalt(III) complex, two new cobalt(III) complex salts of composition [Co(phen)(3)](BF4)(3)center dot H2O (1) and [Co(phen)(3)](PF6)(3)center dot CH3COCH3 (2) have been synthesized by the reaction of tris(1,10-phenanthroline)cobalt(III)chloride with sodium salts of tetrafluorborate and hexafluorophosphate (1:3 molar ratio) in aqueous medium. Single crystals of 1 were obtained directly from the reaction mixture when the solution was allowed to evaporate slowly at room temperature and single crystals of 2 were obtained by recrystallizing the precipitated product from acetone and water solution by slow evaporation. The newly synthesized complex salts were characterized by elemental analyses, TGA spectroscopic studies (IR, UV/Visible, H-1, C-13, F-19 and B-11 NMR), Solubility product and conductance measurements. X-ray structure determination revealed ionic structures consisting of one [Co(phen)(3)](3+), three [BF4](-) ions and one lattice water molecule in complex salt 1, one [Co(phen)(3)](3+), three [PF6](-) anions and one acetone molecule as solvent of crystallization in complex salt 2. The three 1,10-phenanthroline ligands (each bidentate) coordinated to cobalt(Ill) showed distorted octahedral geometry around the central metal ion. Supramolecular hydrogen bonding networks between ionic groups [Co-phenCH(delta+)center dot center dot center dot F-anion(delta-)] by second sphere coordination have been observed that stabilize crystal lattice besides electrostatic forces of attraction. The structural studies suggest that [Co(phen)(3)](3+) is a promising anion receptor for the fluoroanions (BF4)(-) and (PF6)(-) in aqueous medium. (C) 2008 Elsevier B.V. All rights reserved.
palavras-chave
DOT-CENTER-DOT; CROWN-ETHER COMPLEXES; 2ND-SPHERE COORDINATION; ANION RECEPTOR; HYDROGEN-BOND; HEXAFLUOROPHOSPHATE SALTS; VIBRATIONAL-SPECTRA; IONIC LIQUIDS; TETRAFLUOROBORATE; RECOGNITION
categoria
Chemistry
autores
Sharma, RP; Singh, A; Brandao, P; Felix, V; Venugopalan, P
nossos autores
Paula Cristina Ferreira da Silva Brandão
Investigador Auxiliar
Vítor Félix
Professor Associado com Agregaçãoagradecimentos
The authors gratefully acknowledges the financial support of CSIR vide Grant no- 01(2020) 2005/EMR-II.