Thenoyltrifluoroacetone complexes

The geometry of the nine-coordinate thorium atom in the thenoyltrifluoroacetonate complex, [Th CF3COCHCO-(2-C4H3S) 4 (n-CsHi7)3PO ], is a 4,4,4-tricapped trigonal prism (Figure 7).124... 

Similar to the Sr example, lanthanide extraction into ILs has been reported to yield different structures than when prepared with an organic solvent instead the IL. In ILs, the formation of anionic Nd(tta)4 or Eu(tta)4 (Htta = 2-thenoyltrifluoroacetone) complexes with no water coordinated to the metal center is preferred. In nonpolar organic solvents, hydrated, neutral complexes, M(tta)3(H20)M (n = 2 or 3) form [162],... 

When combined with solid-phase extraction, flow injection in flame AAS also enables on-line trace matrix separations to be performed. Here the matrix can be complexed and the complexes kept on the solid phase while trace elements pass on towards the atomizer. For the case of the trace analysis of Zr(>2, after dissolution it was thus possible to keep up to 4 pg of Zr as a TTA (thenoyltrifluoroacetone) complex on the column, while impurities such as Fe were eluted and determined with a high efficiency [133]. This opens up a new line of research on the use of on-line trace-matrix separations for any type of complex samples. 

Extraction with triphenylarsine oxide in CHCI3 followed by the reaction with Arsenazo III (after stripping of the analytes with 4 M HCl) makes a basis of the determination of Zr and Hf (and Ti) in minerals and alloys [1], Sequential liquid-liquid extraction and spectrophotometric determination of zirconium(IV) with calixarene hydroxamic acid and thiocyanate has been described [2]. Colorimetric determination of Zr and Hf with Xylenol Orange and a liquid-liquid extraction of thenoyltrifluoroacetone complexes using H2O-IBMK has been studied [3]. 

Binnemans s group found that a high quantum yield and an enhanced photostabiUty are achieved for a Eu " tetrakis(2-thenoyltrifluoroacetonate) complex dissolved in a weakly coordinating 1-hexyl-3-methylimidazolium ionic liquid... 

Thenoyltrifluoroacetone and carboxin and its derivatives specifically block Complex II, the succinate-UQ reductase. Antimycin, an antibiotic produced by Streptomyees griseus inhibits the UQ-cytochrome c reductase by blocking electron transfer between bn and coenzyme Q in the Q site. Myxothiazol inhibits the same complex by acting at the site. 

The reduction of pertechnetate with concentrated hydrochloric acid finally yields the tetravalent state, and no further reduction to the tervalent state takes place. Therefore, the tervalent technetium complex has usually been synthesized by the reduction of pertechnetate with an appropriate reductant in the presence of the desired ligand. Recently, the synthesis of tervalent technetium complexes with a new starting complex, hexakis(thiourea)technetium(III) chloride or chloropentakis(thiourea)technetium(III) chloride, has been developed. Thus, tris(P-diketonato)technetium(III) complexes (P-diketone acetylacetone, benzoyl-acetone, and 2-thenoyltrifluoroacetone) were synthesized by the ligand substitution reaction on refluxing [TcCl(tu)5]Cl2 with the desired P-diketone in methanol [28]. 

A broad range of metal centers have been used for the complexation of functional ligands, including beryllium [37], zinc, transition metals such as iridium [38], and the lanthanide metals introduced by Kido [39], especially europium and terbium. Common ligands are phenanthroline (phen), bathophenanthrolin (bath), 2-phenylpyridine (ppy), acetylacetonate (acac), dibenzoylmethanate (dbm), and 11 thenoyltrifluoroacetonate (TTFA). A frequently used complex is the volatile Eu(TTFA)3(phen), 66 [40]. 

Equation (4.41) is valid only when the complexes MA ° can be neglected in the aqueous phase. Comparing Eqs. (4.37b) and (4.41c), it is seen that no horizontal asymptote is obtained even at high concentrations of AT or HA and H. Thus, for very large distribution constant of the uncharged complex (i.e., >1000) a straight line with slope -z is experimentally observed, as in the case for the Cu(II)-thenoyltrifluoroacetone (HTTA) system (Appendix D 5g). 

Fig. 4.21 Distribution constants, Ky)c, for uncharged metal complexes MA vs. distribution constants for the corresponding undissociated acid ligand HA solid circles Zn(II), solid triangles Co(III). Variation with ligand composition HFA hexafluoroace-tylacetone, TFA trifluoroacetylacetone, AA acetylacetone, FTA 2-furoyltrifluoroacetone, TTA 2-thenoyltrifluoroacetone, PTA pivaloyltrifluoroacetone, BFA benzoyltrifluoroace-tone, BZA benzoylacetone. (From Ref. 36.)... 

We can now make sensible guesses as to the order of rate constant for water replacement from coordination complexes of the metals tabulated. (With the formation of fused rings these relationships may no longer apply. Consider, for example, the slow reactions of metal ions with porphyrine derivatives (20) or with tetrasulfonated phthalocyanine, where the rate determining step in the incorporation of metal ion is the dissociation of the pyrrole N-H bond (164).) The reason for many earlier (mostly qualitative) observations on the behavior of complex ions can now be understood. The relative reaction rates of cations with the anion of thenoyltrifluoroacetone (113) and metal-aqua water exchange data from NMR studies (69) are much as expected. The rapid exchange of CN " with Hg(CN)4 2 or Zn(CN)4-2 or the very slow Hg(CN)+, Hg+2 isotopic exchange can be understood, when the dissociative rate constants are estimated. Reactions of the type M+a + L b = ML+(a "b) can be justifiably assumed rapid in the proposed mechanisms for the redox reactions of iron(III) with iodide (47) or thiosulfate (93) ions or when copper(II) reacts with cyanide ions (9). Finally relations between kinetic and thermodynamic parameters are shown by a variety of complex ions since the dissociation rate constant dominates the thermodynamic stability constant of the complex (127). A recently observed linear relation between the rate constant for dissociation of nickel complexes with a variety of pyridine bases and the acidity constant of the base arises from the constancy of the formation rate constant for these complexes (87). 

Studies of vanadyl diketonate complexes VO(dik)2L (L = heterocyclic amine) continue. The stability constants of VCKdik L1 (L1 = 4-methylpyridinelV-oxide) fall in the series dik = thenoyltrifluoroacetone (tta) > trifluoroacetone (tfa) > dbm > bzac > acac > dpm whereas the pKa s of the diketones fall in the series dbm > bzac > acac > tta > tfa.409 The i.r. spectra of the complexes in solution show two... 

Recently, the formation of the dinuclear Eu(II) complex at the toluene-water interface was found out by a time-resolved total reflection fluorometry. When bathophenanthroline sulfate (bps) was added to the extraction system of Eu(III) with 2-thenoyltrifluoroacetone (Htta), a double component luminescence decay profile was observed and it showed the presence of dinuclear complex at the interface [27]. The observed life times x — 22 and 203 ps were attributed to the dinuclear complex Eu2(tta)2(bps)2 and the mononuclear complex Eu(tta)2bps. The shorter lifetime of the dinuclear complex than x = 98 ps for an aqua-Eu(III) ion suggested a charge transfer deactivation in the dinuclear complex. 

Attempts to obtain thermodynamic data for solvent extraction of Bk(III) by thenoyltrifluoroacetone in benzene and for complexation of Bk(III) by hydroxide and citrate ions were unsuccessful (202). The high extractability and complexability of the easily accessible tetrava-lent state of berkelium probably accounts for the difficulty encountered in this work. 

Like with trivalent actinides vide infra), 2-thenoyltrifluoroacetone (HTTA) is also effective at complexing with tetravalent actinides. Extractant dependency studies have shown than Th displays a 1 4 extraction stoichiometry (Thrextractant) with HTTA. ... 

The extraction of by a synergistic mixture of 2-thenoyltrifluoroacetone (HTTA) and tributylphosphate (TBP) from nitric acid media into benzene has been studied. Previous literature reports have described the synergistically extracted species as U02(N03)(TTA) TBP. However, Patil et have used extraction studies to show that the nitrate anion is not present in the extracted complex. Rather, the only species involved in the synergistic extraction is UO2-(TTA)2 TBP. ... 

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