Trifluoroacetate Complexes Research Articles

Synthesis and characterization of lanthanide trifluoroacetate complexes with 3-picoline- N-oxide

Complexes with composition Ln(F 3C-COO) 3·2(3-picNO)·ξH 2O 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 Nd 3+ 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 5D 0 → 7F 9 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.

Synthesis, properties and thermal study of 4-picoline- n-oxide (4-picNO) lanthanoid trifluoroacetate complexes

Complexes with general formula [Ln(CF 3 COO) 3 (4-picNO) 2 ] 2 (Ln=La-Er) were synthesized and characterized by microanalytical procedures, conductance measurements, IR spectra, electronic absorption spectra of the neodymium and emission spectra of the europium complex, and a TG study of the paraseodymium, neodymium, europium, holmium and erbium compounds

Synthesis and spectral characterization of dinuclear palladium(I) phenoxides and the crystal structure of Pd2(dppm)2(OCOCF3)2

Dinuclear palladium(I) phenoxide compounds Pd 2 (dppm) 2 (OAr) 2 (dppm=bis(diphenylphosphino)methane) and Pd 2 (dmpm) 2 -(OAr) 2 (dmpm=bis(dimethylphosphino)methane) have been synthesized from the corresponding dichloro compounds by metathesis with sodium or potassium aryloxides. The trifluoroacetate complex Pd 2 (dppm) 2 (OCOCF 3 ) 2 also undergoes ligand exchange to yield palladium(I) bisphenoxides. The reactions were followed by 31 P NMR spectroscopy

Complexes of lanthanoid salts with macrocyclic ligands. Part 25. Lanthanoid trifluoroacetate complexes with 12-crown-4, 15-crown-5, and 18-crown-6 ethers

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(CF 3CO 2) 3· (C 8He 16O 4), Ln = La, Ce, Pr; [Ln(CF 3CO 2) 3] 3· (C 8H 16O 4) 2, Ln = Pr, Eu, Er; [Ln(CF 3CO 2) 3] 2· (C 8H 16O 4), Ln = Pr, Nd, Sm; [Ln(CF 3CO 2) 3] 2· (C 10H 20O 5), Ln = LaEu; Ln(CF 3CO 2) 3·(C 12H 24O 6), Ln = LaEu; [Ln(CF 3CO 2) 3] 2·(C 12H 24O 6), 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 [Ln 2(CF 3CO 2) 3(OH)(C 10H 20O 5) 2] [Ln 2(CF 3CO 2) 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(CF 3CO 2) 3·3H 2O 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(CF 3CO 2) 3 generates an emission spectrum with broad bands and probably contains several, closely related polymeric species. The spectrum of [Eu(CF 3CO 2) 3] 2(C 10H 20O 5) is consistent with the presence of two chemically different sites for Eu(III); the emission bands are broad. The double salt AgEu(CF 3CO 2) 4·3CH 3CN has also been investigated; the observed transitions point to the presence of a species with idealized D 2 d symmetry. The emission spectrum of [Eu(CF 3CO 2) 3] 2(C 12H 24O 6) 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 β 1 is greater than 6 for both complexes; it is equal to 4.4 for the samarium 1:1 complex with 18-crown-6 ether.

ChemInform Abstract: Complexes of Lanthanoid Salts with Macrocyclic Ligands. Part 17. Synthesis and Crystal and Molecular Structure of a Hydroxide‐bridged Praseodymium Trifluoro‐acetate Complex with 15‐Crown‐5‐Ether, [Pr2(CF3CO2)3(OH)(C10H20O5)2][Pr2(CF3CO2)

Chemischer InformationsdienstVolume 16, Issue 37 Organoelement Compounds ChemInform Abstract: Complexes of Lanthanoid Salts with Macrocyclic Ligands. Part 17. Synthesis and Crystal and Molecular Structure of a Hydroxide-bridged Praseodymium Trifluoro-acetate Complex with 15-Crown-5-Ether, [Pr2(CF3CO2)3(OH)(C10H20O5)2][Pr2(CF3CO2)]. D. HARRISON, D. HARRISONSearch for more papers by this authorA. GIORGETTI, A. GIORGETTISearch for more papers by this authorJ.-C. G. + BUENZLI, J.-C. G. + BUENZLISearch for more papers by this author D. HARRISON, D. HARRISONSearch for more papers by this authorA. GIORGETTI, A. GIORGETTISearch for more papers by this authorJ.-C. G. + BUENZLI, J.-C. G. + BUENZLISearch for more papers by this author First published: September 17, 1985 https://doi.org/10.1002/chin.198537244Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume16, Issue37September 17, 1985 RelatedInformation

Ligand field spectra of the 3d transition metals in molten cesium, sodium, potassium/trifluoroacetate

Results are reported of electronic absorption spectroscopic studies that were carried out to investigate the ligand field properties of 3d transition metals in molten alkali-metal trifluoroacetates. The purpose of these studies was to examine the nature of transition-metal trifluoroacetate complexes in a medium free of other ligands and to explore the solvent properties of molten trifluoroacetates relative to other glassy and molten salts and to water. 12 references, 2 figures, 1 table.

Thermal study of rare-earth trifluoroacetate complexes with thioxane-oxide

Thermal study of rare-earth trifluoroacetate complexes with thioxane-oxide

Trifluoroacetate complexes of cobalt(II), nickel(II), and copper(II) with pyridine-type ligands. Part 5. Dynamic nuclear magnetic resonance studies of cis–trans isomerism

Dynamic 1H n.m.r. studies of complexes of general type [ML2(O2CR)2][M = CoII or NiII; L = 3Me-py, 4Me-py, or 4Et-py (py = pyridine); R = CF3, CF2H, CFH2, C2F5, or C3F7] have yielded accurate energies for the cis–trans interconversion of these complexes. For cobalt(II) complexes ΔG‡ values lie in the range 47–60 kJ mol–1, whereas for nickel(II) complexes values are substantially higher being 67–71 kJ mol–1 for trifluoroacetate complexes. Data for ΔS‡ imply that the mechanisms of the isomerisation are dependent on the carboxylate ligand O2CR and become more dissociative in nature in the order R = CF3 < CF2H < CFH2 < C2F5 < C3F7, this order also applying to the relative magnitudes of ΔH‡ values. Isomerism in the related [ML4(O2CR)2] complexes, where the O2CR ligands are unidentate, is shown to be a much more facile, dissociative process, detectable amounts of two additional species thought to be cis- and trans-[ML2(O2CR)2] also being present.

Metal-metal bonded complexes of the early transition metals. 2. Synthesis of quadruply bonded tungsten(II) trifluoroacetate complexes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal-metal bonded complexes of the early transition metals. 2. Synthesis of quadruply bonded tungsten(II) trifluoroacetate complexesA. P. Sattelberger, K. W. McLaughlin, and John C. HuffmanCite this: J. Am. Chem. Soc. 1981, 103, 10, 2880–2882Publication Date (Print):May 1, 1981Publication History Published online1 May 2002Published inissue 1 May 1981https://doi.org/10.1021/ja00400a073RIGHTS & PERMISSIONSArticle Views386Altmetric-Citations42LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (476 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Activation of molecular oxygen and selective oxidation of olefins catalyzed by group VIII transition metal complexes

Abstract

Preparation and characterization of cyclic polyolefin copper(I) trifluoroacetate complexes

A series of polyolefin copper(I) trifluoroacetate complexes has been prepared with the following empirical formulae: Cu(O 2CCF 3)((Z.E.E)-1,5,9-cyclododecatriene): Cu(O 2CCF 3)(endo-dicyclopentadiene): Cu(O 2CCF 3) (1,5-cyclooctadiene); Cu 2(O 2CCF 3) 2(1,5-cyclooctadiene): Cu 2(O 2CCF 3) 2(1,3,5,7-cyclooctatetraene): Cu 4(O 2CCF 3) 4(1,3,5,7-cyclooctatetraene); and Cu 3(O 2CCF 3) 3(1,3,5-cycloheptatriene). These complexes are soluble in polar organic solvents and have been characterized in solution by 1H and 13C NMR and molecular weight studies. Although the polyolefins are labile in solution, the NMR studies have shown which double bonds are coordinated to copper for the olefins with non-equivalent double bonds and how many of the equivalent double bonds are coordinated for the more symmetric olefins. In all cases only one double bond is bound to each copper. For all of the complexes studied, the molecular weights are highly concentration dependent. increasing at higher concentrations. For the cyclododecatriene complex. the molecular weight levels at 660 in benzene, the molecular weight corresponding to a dimer. Similarly, the Cu 2(O 2CCF 3) 2(1,3,5,7-cyclooctatetraene) complex levels of at a dimer at high concentration in THF. The other complexes which are less soluble show molecular weights between that of a monomer and dimer.

Aqueous trifluoroacetic acid as a medium for organic reactions. I. Acidity functions and the identity of the manganese(VII) species found in powerfully acidic media

The HR acidity function has been determined for the trifluoroacetic acid–water system, and extended beyond 100% acid by the addition of trifluoroacetic anhydride, to 99.5 wt.% anhydride. The existing H0 acidity function is corrected and extended to 100% trifluoroacetic acid, confirming Eaborn's observation that H0 attains a minimum value at approximately 97% acid. Comparison of the acidity functions shows that although trifluoroacetic acid is only weakly protonating, it is a strongly protonating-dehydrating medium. Changes in the uv–visible spectrum of potassium permanganate produced by changing acid concentration are used to calculate the degree of further ionization of the permanganate ion; the correlation of this with the HR acidity function further suggests the presence of the permanganyl cation, MnO3+, or its trifluoroacetate complex or ester, MnO3•O2CCF3, in these solutions. A cryoscopic investigation into the mode of ionization of permanganate in trifluoroacetic acid reveals that extensive ion-pair formation occurs in this solvent. Although this effect prevents an unequivocal determination of the number of solute particles being made the results are consistent with the presence of a permanganyl species in solution.

Solution Studies of the Dynamic Stereochemistry of Palladium(II) Carboxylate Complexes

A series of dimeric tertiary phosphine carboxylate complexes of palladium(II) of the general types [(PR3)Pd(O2CR)2]2 and [(PR3)Pd(O2CR)(O2CR)]2 have been synthesized and struc-turally characterized. The dynamic stereochemistry of the complexes where PR3 = Me2PhP has been investigated using variable temperature n.m.r. techniques. Exchange of the stereochemically nonequivalent methyl groups of the coordinated Me2PhP ligand occurs via a solvent assisted process involving ring opening of the "Pd2(OCO)2" bridged structure. For the trifluoroacetate complexes solution equilibria between monomer and dimer are readily apparent at low temperatures in the 19F n.m.r. The observed equilibrium constants are a function of the solvent and the size of the PR3 ligand. The reaction of [(PMe2Ph)Pd(O2CCF3)2]2 with excess AgO2CCF3 gives an unusual crystalline complex of stoichiometry Ag[(PMe2Ph)Pd(O2CCF3)3]. A quantitative measure of the ability of a coordinated carboxylate to stabilize intermediate species via chelation has been obtained from a variable temperature n.m.r. study of [(Π-2-methylallyl)Pd(O2CR)(Me2PhP)] (R=CH3, CH2Cl, CHCl2, CCl3, CF3, CMe3, CPh3, CH2Ph).

Trifluoroacetate complexes of cobalt(II), nickel(II), and copper(II) with pyridine-type ligands. Part III. Nuclear magnetic resonance studies of cobalt(II) complexes in solution

Complexes of cobalt(II) trifluoroacetate with pyridine and alkylpyridine ligands of stoicheiometries ML4T2 and ML2T2 have been investigated in solution by 1H and 19F n.m.r. spectroscopy. In deuteriochloroform solution, cis–trans isomeric equilibria were detected for both series of complexes. Rapid cis–trans exchange occurred at ambient temperatures but became slow on the n.m.r. time scale below ca. 0 °C for ML2T2 complexes and below ca. –50 °C for ML4T2 complexes. In the ML4T2 series, intermediate species were detected between ca. 0 °C and ca. –40 °C. In hexadeuterioacetone solution, a number of polymeric species were detected. Some evidence has also been obtained for a rapid intramolecular scrambling of ligands occurring in these complexes even at temperatures below –60 °C.

Trifluoroacetate complexes of cobalt(II), nickel(II), and copper(II) with pyridine-type ligands. Part IV. Nuclear magnetic resonance studies of nickel(II) complexes and theoretical treatment of spin-density distributions in cobalt(II) and nickel(II) complexes

1 H and 19F N.m.r. studies have been carried out on complexes of nickel(II) trifluoroacetate with pyridine and alkylpyridine ligands (L), having stoicheiometries NiL4T2 and NiL2T2. cis- and trans-Isomers of these complexes have been detected, although in some cases the chemical-shift distinction is very small. cis–trans-Interconversion is slow on the n.m.r. time scale at temperatures < ca. 60 °C, in contrast to corresponding CoII complexes. EHMO Calculations have been carried out to determine the conformational preferences of the free ligands and to explain the measured n.m.r. isotropic shifts in both the CoII and NiII series. The results indicate that the contact shifts are dominated by a σ-delocalisation mechanism but that π-spin polarisation is important particularly for the alkyl-substituent shifts. Limitations of the EHMO method are discussed.

Trifluoroacetate complexes of cobalt(II), nickel(II), and copper(II) with pyridine-type ligands. Part II. Preparation, vibrational and electronic spectral properties of cobalt(II) and nickel(II) complexes

Pyridine, β- and γ-picoline, and β- and γ-ethylpyridine complexes of cobalt(II) and nickel(II) trifluoroacetates have been prepared and fully characterised by spectroscopic methods. All the complexes in the solid state were octahedral and of stoicheiometry MLxT2, where L = pyridine-type ligand, T = CF3CO2 and x= 2 or 4, with the CF3CO2 group being either mono- or bi-dentate. Definitive distinction between these two modes of co-ordination was sought by vibrational and electronic spectroscopy.

Radiochromatographic, conductometric and high-frequency titration studies on the thiourea complexes of palladium(II) and platinum(II)

Palladium(II) and platinum(II) complexes of thiourea, MTuX 2, MTu 2X 2, MTu 4X 2 (X = Cl,Br,I) and MTu 4A 2 (A = ClO 4,BF 4,CF 3COO), were prepared. Palladium(II) iodide gives a Pd 3Tu 3I 4Cl 2 complex. The complexes PdTuX 2, PdTu 2X 2, PdTu 4X 2 (X = Cl,Br), PdTuA 2, PdTu 2A 2, PdTu 4A 2 (A = ClO 4, BF 4, CF 3COO), PdTu 3(BF 4) 2 and PtTuX 2, PtTu 2X 2, PtTu 4X 2 (X = Cl,Br,I) were identified by high-frequency titration in aqueous solution. Molar conductivities showed that MTuX 2 and MTu 2X 2 are non-electrolytes. In methanol, MTu 4A 2 (A = ClO 4,BF 4, CF 3COO) and PtTu 4X 2 (X = Cl,Br,I) complexes behave as uni-bivalent electrolytes, while PdTu 4X 2 (X = Cl,Br,I) complexes show a reduced conductivity. The conductivities of the halide and trifluoroacetate complexes are even lower in dimethylformamide and show a partial interaction of the anion with the complex. The elution of the complexes with ketones containing an aqueous solution of the sodium salt and with alcohols containing an aqueous solution of the free acid show that in both cases the only species which migrates in compact spots is the very stable (MTu 4] 2+ ion, with very high R F values in the ketone mixture and very low values in the alcohol mixtures.

Trifluoroacetate complexes of cobalt(II), nickel(II), and copper(II) with pyridine-type ligands. Part I. Metal(II) trifluoroacetates and copper(II) complexes

Complexes of the general type CuLx(CF3CO2)2, where x= 2 or 4, L = pyridine, mono-and di-substituted pyridines, quinoline, or isoquinoline, have been prepared and characterised by spectroscopic methods. The complexes are six-co-ordinate with the trifluoroacetate group involved in either mono-or bi-dentate attachment to the copper; this distinction has been made by i.r. studies. Thermal decomposition studies were carried out on these complexes. The resulting complexes were of the general stoicheiometry [CuLx(CF3CO2)2]n where x= 2, 1, or ½ and n= 1, 2, or perhaps 4.