New 2D and 3D Coordination Polymers by Dehydration of 1∞[MII(tF‐BDC)(H2O)4] (MII = Zn2+, Co2+, Ni2+ and tF‐BDC2– = Tetrafluoroterephthalate)

Abstract

By dehydration of the known coordination polymers 1∞[MII(tF‐BDC)(H2O)4] (MII = Co2+, Zn2+ and tF‐BDC2– = tetrafluoroterephthalate) the homoleptic anhydrous coordination networks 3∞[MII(tF‐BDC)] were obtained as polycrystalline powders. Their crystal structures (C2/c, Z = 4) were solved and refined by means of synchrotron powder diffraction data. These structures are characterized by [MIIO4] tetrahedra, which are connected by the tF‐BDC2– linkers to form a 3D non‐porous coordination network. The dehydration leads to a change from a [MIIO6] octahedral coordination in the hydrate to a tetrahedral coordination sphere in the anhydrous compound. For the cobalt compounds this leads to a color change from pale rose to deep blue upon heating and dehydration, which was analyzed by means of UV/Vis/NIR spectroscopy and measurements of the magnetic susceptibilities. In contrast, 1∞[NiII(tF‐BDC)(H2O)4] can only partly be dehydrated to form 2∞[NiII(tF‐BDC)(H2O)2] (P1, Z = 1) with retention of the octahedral [NiIIO6] coordination in both compounds. At higher temperatures the tF‐BDC2– linker starts to decompose, before a complete dehydration can take place.