Weak C-H…F-C interactions in carboxylate anion binding: Synthesis, spectroscopic and X-ray structural studies of [Co(phen)2CO3]2 (C7H3O2FCl)Cl·11H2O and [Co(phen)2CO3](C7H3NO4Cl)·6H2O

Abstract

Two new complex salts containing 2,5-substituted benzoate ions, [Co(phen)2CO3]2(C7H3O2FCl)Cl·11H2O (1) and [Co(phen)2CO3](C7H3NO4Cl)·6H2O (2) (where phen = 1,10-phenanthroline, C7H3O2FCl = 2-chloro-5-fluorobenzoate (cfbz) and C7H3NO4Cl = 2-chloro-5-nitrobenzoate(cnbz)) were synthesized by reacting carbonatobis(1,10-phenanthroline)cobalt(III) chloride with appropriate salts in aqueous medium. A detailed packing analysis has been undertaken to delineate the role of second sphere C-H…F and C-H…O interactions amid other heteroatom interactions. The complex salts have been characterized by elemental analyses, spectroscopic studies (IR, UV/Visible, multinuclear NMR), conductance and solubility product measurements. Single crystal X-ray structure determination revealed ionic structures of both the complex salts having discrete ions along with lattice water molecules. Crystal lattice is stabilized by a variety of hydrogen bonding interactions, i.e. O-H…O, C-H…O and C-H…F involving second sphere coordination besides π-π interaction. Furthermore, packing analyses reveal that C-H…F interactions can manifest even in the presence of a large number of heteroatom interactions.