3D supramolecular networks of Co(II)/Fe(II) using the croconate dianion and a bipyridyl spacer: Synthesis, crystal structure and thermal study

Three new supramolecular networks of cobalt(II) and iron(II), {[Co(4,4′-bipy)(H2O)4] · (C5O5) · (H2O)2}n (1), {[Fe(4,4′-bipy)(H2O)4] · (C5O5) · (H2O)2}n (2) and {[Co2(bpds)2(C5O5)2(H2O)4] · (H2O)3}n (3) [4,4′-bipy = 4,4′-bipyridyl, bpds = 4,4′-bipyridyl disulfide, C5O52-=croconate dianion] have been synthesized and characterized by X-ray single crystal structure determination and thermogravimetric analysis. All of these coordination networks feature 1D polymers. Complexes 1 and 2 have a comparable structure based on metal centers coordinated by four water molecules and bridged by 4,4′-bipy ligands to give rise to a linear chain. Crystal packing shows a 3D supramolecular architecture through H-bonding occurring between lattice croconate dianions and water molecules. Conversely complex 3 is formed by Co(C5O5)(H2O)2 units connected by bridging bpds resulting a polymer with a zig zag arrangement. The metal coordination sphere comprises of two chelating oxygens from the croconate dianion, two water molecules and two bpds nitrogens located in cis positions. The coordinated water and lattice water molecules undergo H-bonding to form a 3D supramolecular network.

Graphical abstract3D supramolecular networks, {[Co(4,4′-bipy)(H2O)4] · (C5O5) · (H2O)2}n (1), {[Fe(4,4′-bipy)(H2O)4] · (C5O5) · (H2O)2}n (2) and {[Co2(bpds)2(C5O5)2(H2O)4] · (H2O)3}n (3) [4,4′-bipy = 4,4′-dipyridyl, bpds = 4,4′-bipyridyl disulfide, C5O52-=croconate dianion] have been synthesized and characterized by X-ray single crystal structure determination and thermogravimetric analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide