Coordination Polymers of Zinc, Nickel(II), and Manganese Trifluoroacetates with 1,4-Dioxane

The reactions of zinc, nickel(II), and manganese(II) acetate hydrates with excess trifluoroacetic acid in boiling 1,4-dioxane give coordination polymers (CPs): {[Zn3(µ-OH2)2(µ-OOCCF3)4(OOCCF3)2(OH2)2] [µ-O(CH2CH2)2O)]·3O(CH2CH2)2O}n (1, 81% yield), {[Ni2(µ-OH2)(µ-OOCCF3)2(OOCCF3)2 (OH2)2(O(CH2CH2)2O)]2[µ-O(CH2CH2)2O)]·5O(CH2CH2)2O}n (2, 89% yield), and {[Mn2(µ-OOCCF3)3(OOCCF3)(OH2)][µ-O(CH2CH2)O]2}n (4, 79% yield). According to X-ray diffraction data, the CP structure is determined by the nature of the transition metal. In polymer 1, the trinuclear Zn3(µ-OH2)2(µ-OOCCF3)4(OOCCF3)2(OH2)2 moieties (Zn···Zn, 3.6490(3) Å) are linked by bridging dioxane molecules to give zigzag-like 1D-CP, while the hydrogen atoms of coordinated water molecules form 2D-CP via intermolecular hydrogen bonds (HBs) with oxygen atoms of solvation solvent molecules. In CP 2, two binuclear Ni2(µ-OH2)(µ-OOCCF3)2(OOCCF3)2(OH2)2(O(CH2CH2)2O moieties (Ni···Ni, 3.5388(13) Å) in the tetranuclear Ni4 complex are linked by a bridging dioxane molecule, while the terminal and solvation solvent molecules form intermolecular HBs with the hydrogen atoms of the peripheral water molecules, thus giving 2D-CP. In the case of most electron-deficient Mn(II) ion, each metal atom in the binuclear complex Mn2(µ-OOCCF3)3(OOCCF3)(OH2) (Mn···Mn, 4.2487(5) Å) is bound to two bridging dioxane molecules to give 2D-CP, the dimensionality of which increases to 3D via the formation of intermolecular HBs between the terminal water molecule and the oxygen atom of the terminal and bridging carboxylate anion. It was also shown that in a similar reaction of Ni(OOCMe)2(OH2)4 with 2 moles of HOOCCF3 at room temperature, only anion exchange takes place, resulting in the polymer {Ni(OOCCF3)2(OH2)4⋅[O(CH2CH2)2O]}n (3). Apart from X-ray diffraction, the CPs were studied by chemical analysis and IR spectroscopy.