2D-Coordination Polymers Constituted from Indium Halides and Dipyridyl N-Donor Ligands

Four indium-based, 2D coordination polymers (CP) were synthesized utilizing InCl3 and InI3 and the bidentate ligands 4,4'-bipyridine (bipy), 1,2-di(4-pyridyl)ethylene (bpe) and 1,2-di(4-pyridyl)ethane (bpa). The isoreticular networks (2)(infinity)[In2Cl6(bipy)] (1) and (2)(infinity)[In2Cl6(bpe)] (2) are constituted by chloride- and ligand-bridged octahedra with a honeycomb like (6,3)-net topology (hcb topology). In contrast, (2)(infinity)[(In4Cl12)(bpa)(3)] (3) consists of {In4Cl12N6} units, with each indium atom being coordinated by chloride anions and bpa ligands in an octahedral fashion. Bpa ligands connect indium atoms in two dimensions, forming a semi-regular uninodal 3-c net with the point symbol (4,8(2)), as present in the fes topology. In (2)(infinity)[(InI3)(2)(bpa)(3)] (4), indium is coordinated by three iodide and three bpa ligands in a meridional fashion. In contrast to (2)(infinity)[In2Cl6(bipy)] (1) and (2)(infinity) [In2Cl6(bpe)] (2), the indium-centered octahedra are linked by the bidentate linker only, but also a honeycomb-like, zigzag-shaped (6,3)-net with a hcb topology is formed. The CPs were investigated by SCXRD, PXRD, IR-spectroscopy, and with DTA/TG regarding their thermal properties.