Crystal structure of catena-poly[bis(glycol-1 k²O,O')-(μ₂- tetrafluoroterephthalato)zinc(II)], Zn(C₈F₄O₄)(C₂H₆O₂)₂

Abstract

Source of materialBy placing aCH 3 OH solution (10 ml) of tetrafluoroterephthalic acid (tfbdc, 23.8 mg, 0.1 mmol) at the bottom of astraight glass tube and then carefully added abuffer of glycol (10 ml), above which aC H 3 OH solution (10 ml) containing ZnCl 2 (13.6 mg, 0.1 . mmol) was placed in this tube. The resulting slow diffusion of solvents across the boundary layer results in excellent colorless block-shaped crystals growing there over aperiod of two weeks. Experimental detailsHatoms bound to methylene carbon atoms were assigned to calculated positions with d(C-H) =0.97 Å and refined using ariding model, with U iso (H) =1 .2 U eq (C). Hydroxyl Ha toms were positioned geometrically with d(O-H) =0.84 Å and U iso (H) = 1.5 U eq(O). DiscussionThe design and synthesis of metal-organic frameworks constructed from transition metal ions and 1, In the asymmetric unit, one Zn II ion lying on an inversion center [at (0 0 ½)] is coordinated by six oxygen atoms in anearly ideal octahedral configuration. The Zn II ion is chelated by four Oatoms from two glycol molecules in the equatorial plane and two axial O atoms from two centrosymmetric tetrafluoroterephthalate (tfbdc) ligands. Because of the steric hindrance of the fluorine atoms located at the ortho positions of carboxylate, the rotation angle of tetrafluorined phenyl ring relative to carboxylate is 47.3(2)°, which is quite similar to that of arecent reported Mn-tfbdc polymer [8]. Each tfbdc anion bridges two Zn II centers in ab ismonodentate fashion to afford alinear chain along the [1 1 1]with adjacent Zn···Zn separation of 11.503(1) Å.Within the polymeric chain, one hydroxyl of the glycol molecule is involved in the strong intramolecular O4-H4···O2 i bond (i = -x,-y+2,-z+1)t o the uncoordinated O2 atom of tfbdc moiety. Moreover, intermolecular O3-H3···O1ii bonds (ii = x-1,y,z)connect adjoining chains into atwo-dimensional network.