Vibrational spectra of trifluoroacetates

doi:10.1016/0584-8539(73)80060-1

Spectrochimica Acta Part A: Molecular Spectroscopy

Volume 29, Issue 12, December 1973, Pages 2017-2024

Spectrochimica Acta ...

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Abstract

Infrared and Raman spectra of CsI(O₂CCF₃)₄ and Cs₃I(O₂CCF₃)₆ are reported and compared to those of the free trifluoroacetate anion and covalent trifluoroacetyl compounds. The bonding of the trifluoroacetate group in [I(O₂CCF₃)₄]⁻ is best interpreted as being covalent with strong ionic contributions. The vibrational spectrum of the free trifluoroacetate ion is reassigned.

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Citation Excerpt :
The FTIR spectra of dried gel at different temperatures are shown in Fig. 2. The vibration peaks of CF3COO− agree well with that in literature [16]. Below 210 °C, the O–H vibration at ∼ 3500 cm−1 originated from absorbed water.
Preferentially (002) oriented ZnO films were prepared on Si (111) substrates at relatively low temperature by trifluoroacetate metalorganic deposition (TFA-MOD) method. The growth process, structure and photoluminescence properties were studied by thermogravimetric analysis, Fourier transform infrared absorption, X-ray diffraction, X-ray photoelectron spectra and photoluminescence. The green photoluminescence is enhanced remarkably and becomes visible by naked eyes with the formation of zinc silicate after 900 °C annealing. Furthermore, the oxygen partial pressure of annealing ambient also affects the green photoluminescence evidently. Our results support that oxygen antisite defect in ZnO is responsible for the green emission and a small amount of Zn₂SiO₄ can enhance the green emission.
Ab initio calculations of the structure, vibrational spectra, and thermodynamic properties of silver trifluoroacetates
2002, Journal of Molecular Structure
The structure and properties of monomeric and dimeric silver trifluoroacetates were calculated at different levels of approximation, from RHF with the 3-21G basis set for all atoms to MP2 with the SBKJC and Stutrgart RSC relativistic effective core potentials for silver and the 6-311G (df) basis set for the other atoms. The monomer was found to exist as two conformers in the gas phase, in a more stable conformer, the Ag atom formed coordination bonds with two carboxyl oxygens, and a less stable conformer contained O–Ag–F bridges and the CO double bond. The CF₃ group freely rotated in the monomer without Ag–F bonds and experienced hindered rotations in the dimer. The theoretically predicted vibrational spectrum of the dimer and the thermodynamic functions of the dimerization reaction were consistent with the available experimental data.
Preparation and properties of complexes between rare earth trifluoroacetates and hexamethylphosphoramide (HMPA)
2000, Journal of Alloys and Compounds
Complexes of composition [Ln(TFA)₃(HMPA)₃] (Ln=La, Nd, Eu, Gd, Dy, Ho and Er, TFA=trifluoroacetate) were prepared and characterized by complexometric analyses with EDTA and CHN microanalytical procedures. IR spectra show that HMPA’s are linked to the central ions through the PO oxygen and that the trifluoroacetate ions are also coordinated. The visible absorption spectrum of the neodymium compound in a silicone mull, at room temperature, allows us to calculate the nephelauxetic parameter β=0.990, the covalent factor b^1/2=0.070 and Sinha’s parameter δ=1.01. They are suggestive of an essentially electrostatic interaction between lanthanide and ligands. The emission spectra of the europium complex at room temperature and at 77 K were also determined. Thermogravimetry show that HMPA molecules are totally evaporated at ca. 260°C and that the residues are the corresponding rare earth oxyfluorides.
Synthesis and characterization of lanthanide trifluoroacetate complexes with 3-picoline-N-oxide
1992, Journal of Alloys and Compounds
Complexes with composition Ln(F₃C-COO)₃·2(3-picNO)·ξH₂O were synthesized. According to X-ray powder patterns and IR data five series of isomorphous compounds were detected: LaNd; SmEu; Gd>Tm, Y; Ho, Er, Tb; Dy, Yb, Lu. They behave as nonelectrolytes in methanol. IR spectra show a shift of νNO to lower frequencies, as compared with the free ligand, as a result of coordination through the oxygen. The bands attributed to the anions indicate two modes of coordination. The neodymium spectrum at 77 K shows that the central ion is not involved in a cubic site. Electrostatic bonds between Nd³⁺ and ligands were evidenced by the nephelauxetic, Sinha's parameters and covalent factor from the room temperature spectrum. Using the electronic emission spectrum, at 77 K, it was possible to conclude that europium ions present two different symmetry sites, since a splitting of the ⁵D₀ → ⁷F₉ band was observed. The complex species are probably polymeric or at least dimeric, and europium ions are involved in two different sites, but with the same C_3ν symmetry.
Complexes of lanthanoid salts with macrocyclic ligands. Part 25. Lanthanoid trifluoroacetate complexes with 12-crown-4, 15-crown-5, and 18-crown-6 ethers
1985, Inorganica Chimica Acta
The lanthanoid trifluoroacetates, Ln(TFA)₃, react with 12-crown-4, 15-crown-5, and 18-crown-6 ethers to give complexes with various metal:ligand ratios, 1:1, 3:2, and 2:1. The following complexes have been isolated and characterized: Ln(CF₃CO₂)₃· (C₈He₁₆O₄), Ln = La, Ce, Pr; [Ln(CF₃CO₂)₃]₃· (C₈H₁₆O₄)₂, Ln = Pr, Eu, Er; [Ln(CF₃CO₂)₃]₂· (C₈H₁₆O₄), Ln = Pr, Nd, Sm; [Ln(CF₃CO₂)₃]₂· (C₁₀H₂₀O₅), Ln = LaEu; Ln(CF₃CO₂)₃·(C₁₂H₂₄O₆), Ln = LaEu; [Ln(CF₃CO₂)₃]₂·(C₁₂H₂₄O₆), Ln = Y, EuEr, Yb. Thermogravimetric data show that the 2:1 complexes are usually thermally more stable. The 2:1 complexes with the 15-membered polyether undergo a slow hydrolysis in the presence of traces of water, which yields the hydroxo complex [Ln₂(CF₃CO₂)₃(OH)(C₁₀H₂₀O₅)₂] [Ln₂(CF₃CO₂)₈]. The vibrational spectra confirm the coordination of the coronands; the Δν_as(CCO) shifts are not large, which point to a moderate interaction between the polyethers and the metal ions. Magnetic susceptibilities and X-ray powder diagrams have been measured.
High-resolution excitation and emission spectra have been analysed for the europium-containing compounds. The spectrum of Eu(CF₃CO₂)₃·3H₂O indicates the presence of a single species with low symmetry, in agreement with the crystal structure data for the isostructural Pr-salt. The anhydrous salt Eu(CF₃CO₂)₃ generates an emission spectrum with broad bands and probably contains several, closely related polymeric species. The spectrum of [Eu(CF₃CO₂)₃]₂(C₁₀H₂₀O₅) is consistent with the presence of two chemically different sites for Eu(III); the emission bands are broad. The double salt AgEu(CF₃CO₂)₄·3CH₃CN has also been investigated; the observed transitions point to the presence of a species with idealized D_2d symmetry. The emission spectrum of [Eu(CF₃CO₂)₃]₂(C₁₂H₂₄O₆) displays sharp bands and reveals the presence of two different sites for the metal ion with efficient energy transfers between them. One of the species may have a relatively high symmetry.
In solution, all the complexes are non-electrolytes in acetonitrile and propylene carbonate and close to 1:1 electrolytes in methanol. Some dissociation occurs in acetonitrile for the 2:1 complexes with 18-crown-6 ether. On the other hand, ¹H NMR spectra of the lanthanum 1:1 complexes with 12- crown-4 and 18-crown-6 ethers indicate no dissociation of the complexed polyether. Log β₁ is greater than 6 for both complexes; it is equal to 4.4 for the samarium 1:1 complex with 18-crown-6 ether.

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Vibrational spectra of trifluoroacetates

Abstract

J. Fluorine Chem.

Spectrochim. Acta

Spectrochim. Acta

J. Mol. Struct.

Spectrochim. Acta

J. Fluorine Chem.

Inorg. Chim. Acta

Inorg. Chem.

Inorg. Chem.

Inorg. Chem.