Two New Coordination Polymers with UO22+ Units and Fluorinated Aromatic Carboxylate Linkers

Abstract

A new coordination polymer, namely 2∞[(UVIO2)2(L)(DMA)3] (1) (C2/c, Z = 8) with L = 4-monofluorobiphenyl-3,3',5,5'-tetracarboxylate (4-mF-BPTC4–) was synthesized by solvothermal reaction in DMA (N,N'-dimethylacetamide). Its crystal structure was solved and refined from single-crystal X-ray diffraction data. It contains two different types of UO22+ units, which are connected by fluorinated tetracarboxylate ligands to form a layered structural motif. Three DMA molecules are coordinated to one UO22+ unit (CN = 7), whereas the other is solely coordinated by oxygen atoms of the tetracarboxylate linkers (CN = 8). The layers are held together by van der Waals interactions, which do not include any hydrogen bonds. An isostructural coordination polymer is formed with L' = 4,4'-difluorobiphenyl-3,3',5,5'-tetracarboxylate (4,4'-dF-BPTC4–), as confirmed by XRPD (X-ray powder diffraction), IR/Raman spectroscopy and elemental analysis. The DSC/TG analyses of both compounds show that they are stable up to approx. 300 °C in an inert argon atmosphere.