Inorganic Compounds Containing the Trifluoroacetate Group

The interaction of carboxylic acids with aluminium oxides: journeying from a basic understanding of alumina nanoparticles to water treatment for industrial and humanitarian applications

Carboxylic acids are found to react with aluminium oxides via a topotactic reaction such that the carboxylate acts as a bridging ligand. This reaction allows for carboxylate-functionalized alumina nanoparticles to be prepared directly from boehmite (AlOOH). Understanding the structural relationship between molecular and surface species allows for the rationalization/prediction of suitable alternative ligands as well as alternative oxide surfaces. The identity of the carboxylate substituent controls the pH stability of a nanoparticle as well as the porosity and processability of ceramics prepared by thermolysis. Through the choice of functional groups on the carboxylic acid the properties of the alumina surface or alumina nanoparticle can be tailored. For example, the solubility/miscibility of nanoparticles can be tuned to the solvent/matrix, and the wettability to be varied from hydrophobic to super hydrophilic. The choice Zwitter ionic substituents on alumina micro-/ultra-filtration membranes are found to enhance the flux and limit fouling while allowing for the facile separation of organic compounds from water. Examples are presented of purification of frac and flow-back water from oil well production as well as providing drinking water from contaminated sources in underdeveloped regions.

Synthesis and Reactivity of Haloacetato Derivatives of Iron(II) Including the Crystal and the Molecular Structure of [Fe(CF3COOH)2(μ-CF3COO)2]n

The syntheses of haloacetates of iron(II) and their reactivity are described. The compound Fe(CF3COO)2, 1, crystallizes from CF3COOH/(CF3CO)2O solution as the polynuclear [Fe(CF3COO)2(CF3COOH)2]n, 2, which contains bridging trifluoroacetates and monodentate trifluoroacetic acid groups. Fe(CF3COO)2(DMF)x, as obtained from Fe(CO)5 and CF3COOH/(CF3CO)2O in DMF, reacts with dioxygen at room temperature to give two micro3-oxo compounds, namely, [Fe3(micro3-O)(CF3COO)6(DMF)3], 3, a Fe(II)-Fe(III)-Fe(III) derivative, and [Fe4(micro3-O)2(micro2-CF3COO)6(CF3COO)2(DMF)4], 4, containing Fe(III) atoms only, which have been characterized by X-ray diffraction methods. Iron(II) chloro- and bromoacetates can be isolated by exchange reactions of iron(II) acetate with chloro- and bromo-substituted acetic acids in moderate to good yields. The stability of iron(II) haloacetates decreases on increasing the atomic weight and the number of halogens on the alpha-carbon atom. The species Fe(CX3COO)2 (X = Cl, 7; Br, 8), in THF solution, slowly convert into [Fe3(micro3-O)(CCl3COO)6(THF)3], 11, or [Fe3(micro3-O)(CBr3COO)6(THF)3][FeBr4], 10, respectively. Likewise, when iron(II) acetate (or trifluoroacetate) is left for several hours in the presence of a variety of haloacetic acids in THF, selective formation of different species, depending on the nature of the starting compound and of the acid employed, is observed. The formation of these products is the result of C-X bond activation (X = Cl, Br) and haloacetato decomposition, which occurs with concomitant oxidation at the metal centers. Carboxylic acid degradation species (CH2XCOOH, CX4, CX3H, CX2H2, X = Cl, Br) have been observed by GC-MS.