| Abstract
| - Structural, IR, and conductivity data demonstrate that H(CH3SO3)2- and H(CF3CO2)2- are more weakly coordinating than the parent anions CH3SO3- and CF3CO2-, respectively. Shown here are IR spectra of [Cu(CO)(CF3CO2)]2 (A, ν(CO) = 2123 cm-1) and [Cu(CO)(H(CF3CO2)2)]2 (B, ν(CO) = 2134 cm-1).
- The coordination or ion pairing of the hydrogen-bonded anions H(CF3CO2)2- and H(CH3SO3)2- to NEt4+, Li+,Cu+, and/or Cu2+ was investigated. The structure of {Cu2(H(CH3SO3)2)4}n consists of centrosymmetric dimericmoieties that contain two homoconjugated (CH3SO2O−H···OSO2CH3)- anions per Cu2+ ion, forming typicalJahn−Teller tetragonally elongated CuO6 coordination spheres. The oxygen atoms involved in the nearly linearO−H···O hydrogen bonds (O···O ∼ 2.62 Å) are not coordinated to the Cu2+ ions. The structure of Cu2(CO)2(H(CF3CO2)2)2 consists of pseudo-C2-symmetric dimers that contain one homoconjugated (CF3COO−H···OCOCF3)-anion per Cu+ ion, forming highly distorted tetrahedral Cu(CO)O3 coordination spheres. Three of the four oxygenatoms in each hydrogen-bonded H(CF3CO2)2- anion are coordinated to the Cu+ ions, including one of the oxygenatoms in each O−H···O hydrogen bond (O···O ∼ 2.62 Å). Infrared spectra (ν(CO) values) of Cu(CO)(CF3CO2)or Cu(CO)(CH3SO3) dissolved in acetonitrile or benzene, with and without added CF3COOH or CH3SO3H,respectively, demonstrate that HA2- anions involving carboxylates or sulfonates are more weakly coordinatingthan the parent anions RCO2- and RSO3-. Direct current conductivities of THF solutions of Li(CF3CO2) containingvarying concentrations of added CF3COOH further demonstrate that Li+ and NEt4+ ion pair much more weaklywith H(CF3CO2)2- than with CF3CO2-.
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