The first noncluster vanadium(IV) coordination polymers: Solvothermal syntheses, crystal structure, and ion exchange

Two isostructural vanadium(IV) coordination polymers [VO(dod)(2)]X-2 [X = Cl, Br; dod = 1,4-diazoniabicyclo[2,2,2] octane-1,4-diacetate (C10H16N2O4)] have been synthesized solvothermally and determined by single-crystal X-ray analysis. Both of them crystallize in the tetragonal space group P4/ncc (no. 130), with cell parameters a = 15.702(5), c = 9.745(5) Angstrom, V = 2403(2) Angstrom (3), Z = 4 for 1 and a = 15.916(5), c = 9.820(4) Angstrom, V = 2488(2) Angstrom (3), Z = 4 for 2. In both complexes, each vanadium atom adopts a (VO5)-O-IV square-pyramidal environment, being coordinated by four oxygen atoms [V-O = 1.978(2) Angstrom for 1 and 1.969(3) Angstrom for 2] from four dod ligands and a terminal oxygen atom [V = O = 1.580(5) Angstrom for 1 and 1.572(7) Angstrom for 2]. The bis-monodentate dod ligands bridge vanadium atoms to furnish two-dimensional double wave-like layers of (4,4) topological type. Along the c-axis direction, there are square channels constructed from side-sharing saddle-shaped rings. The microporous material I shows chloride-to-sulfate exchange properties in aqueous media. (C) 2001 Academic Press.