A new binuclear Cr(III) citrate anion: Synthesis, characterization and crystal structure of [Cr(CO(NH2)2)6]2[Cr2(CO(NH2)2)2(C6H4O7)2]3

The new anion [Cr2(CO(NH2)2)2(C6H4O7)2]2 − has been isolated in the complex [Cr(CO(NH2)2)6]2[Cr2(CO(NH2)2)2(C6H4O7)2]3. The crystals of this complex were obtained by a one-pot synthetic method using 1:1 molar ratio of hexaureachromium(III) chloride and trisodium citrate in aqueous medium. It was characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction analysis. The compound crystallizes in space group R‾3 of the trigonal system with three formula units in a cell of dimensions a = b = 24.7461(4) Å, c = 13.7204(3) Å and γ = 120°. The crystal structure comprises the columns consisting of [Cr(CO(NH2)2)6]3 + cations surrounded by a cylinder of complex anions, [Cr2(CO(NH2)2)2(C6H4O7)2]2 − which are packed in a honeycomb-like manner. This supramolecular architecture is formed and stabilized by inter- and intramolecular NH⋯O hydrogen bonds.

Graphical abstractA new anion [Cr2(CO(NH2)2)2(C6H4O7)2]2− has been isolated by using the one-pot synthetic method. The crystal structure comprises the columns consisting of [Cr(CO(NH2)2)6]3+ cations surrounded by a cylinder of [Cr2(CO(NH2)2)2(C6H4O7)2]2– anions. Such columns are packed in a distinctive honeycomb-like pattern. This supramolecular architecture is stabilized by inter- and intramolecular NH…O hydrogen bonds.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new anion, [Cr2(CO(NH2)2)2(C6H4O7)2]2– has been isolated by a one-pot synthesis. ► Crystal structure reveals the presence of both inter and intramolecular H-bonds. ► Crystals are packed in a distinct honeycomb like pattern.