Fluoro complexes solubility

Solvent extraction techniques are useful in the quantitative analysis of niobium. The fluoro complexes are amenable to extraction by a wide variety of ketones. Some of the water-insoluble complexes with organic precipitants are extractable by organic solvents and colorimetry is performed on the extract. An example is the extraction of the niobium—oxine complex with chloroform (41). The extraction of the niobium—pyrocatechol violet complex with tridodecylethylammonium bromide and the extraction of niobium—pyrocatechol—sparteine complex with chloroform are examples of extractions of water-soluble complexes. Colorimetry is performed on the extract (42,43). Colorimetry may also be performed directly on the water-soluble complex, eg, using ascorbic acid and 5-nitrosahcyhc acid (44,45). 

HF is weakly ionized (pH <3.2), and soluble alumino-fluoro complexes are formed resulting in the presence of aluminum ions in the treated water and lowering of the active sites. At near neutral pHs, the uptake of fluoride is maximum. Assuming that the pHpzc of AA is about 8-9 as reported in several literatures, then at near neutral pHs the active sites consist of = AI-OH (protonated) and = AI-OH (non-protonated) aluminol sites. The interaction between fluoride and the protonated aluminol sites leads to the formation of inner-sphere complexes and elimination of water. The reaction can be represented by... 

The acidopentamminecobalt(III) salts have characteristic colors dependent upon the atom coordinated, i.e., salts in which there is a cobalt-oxygen bond vary in color from pink to red the fluoro complex is pink the chloro, red the bromo, purple the iodo, olive green and the nitro, orange. The nitrate salts of most of these complexes are only slightly soluble in water. None of these compounds is soluble in nonpolar solvents. Solutions of the compounds may decompose after long standing, liberating ammonia and cobalt hydroxide. Rates of aquation and of hydrolysis... 

The reaction between either Cp2Mg or CpNa with [ScF3] leads to a complex mixture of three compounds an unidentified hexane-soluble species, a species characterised as [Cp3Sc] and a third toluene-soluble compound, identified as t ScF(Cp)2 3], which has been crystallographically characterised [Fig. 1] [5], The mixture was unaffected by variation of the ratio of the starting materials and, in solution, the fluoro complex exists as an equilibrium between the monomeric, dimeric and trimeric forms. 

The authors used test solutions consisting of Th(N03)4 or mixtures of Th(N03)4 and NaF to increase the solubility of CaF2(s). From the measured solubihty they could then determine the equilibrium constants for the fluoro complexes of Th(IV). The ionic strength of the solutions was not controlled and varied from about 0.1 to 5 M. No evidence is presented as to whether equilibrium is attained, or not. The number of data points on which the thorium fluoro complexes are based is very limited. The data reported by the authors correspond to average values of log, K = 5.92 and logj = 8.68 for the reactions Th" -t F ThF and Th" -i- 2F ThF respectively and for reasons stated above, these values are not accepted by this review. 

Fluorine species. The solubility of Po" hydroxide in HF rises with c(HF), and there may be fluoro complexes. 

Another variant of this type reaction has recently been utilized by Novartis to manufacture an intermediate for Prosulfuron (see Table 1.1). The synthetic scheme is shown by reaction 7.32. The soluble palladium-complex-catalyzed C-C coupling between a diazonium salt and a fluoro alkene gives the required intermediate. This is then converted to the final product by standard reactions of synthetic organic chemistry. 

The unexpectedly high solubility of K2[TcBr6] (in contrast to that of the fluoro and chloro complexes) in methanol appears to be due to partial substitution of Br by MeO . By the use of KOR, salts such as K2[Tc(OMe)6] and K2[Tc(0CH2CH20)3] may be isolated. These complexes show a f(TcO) IR absorption at 450-460 cm-1 (356). A crystal structure of 28, with the zwitterionic tripod ligand Me3N+C(CH20 )3, shows octahedral geometry with Tc-0 distances of 1.987(4)-2.005(4) A. Complex 28 is water soluble and stable at pH > 4 for over 24 hr (357). 

Due to the low solubility of cobalt(II) fluoride in most solvents, formation of cobalt fluoro N-donor complexes (which are the only low-valent cobalt fluorides which are reliably reported) features a variety of starting materials. A common theme that runs throughout this work has been the use of [Co(BF4)2] as the fluoride source, and the subsequent controlled decomposition to obtain a metal-bound fluoride. This has been done, for example, with tris- (3,5-dimethyl-pyrazol-l-yl)methyl amine (amtd) to give [M2(amtd)2F(BF4)3(EtOH)Y(H20)] (M = Co, Cu, Zn x = 0-1.5, y = 1-2). The cobalt complex has been structurally characterised by X-ray diffraction [Fig. 3] [57]. Similarly, the combination of [M(BF4)2] (M = Mn, Co, Ni), [M(N03)2], NH4(NCS) and 3,5-diethyl-1,2,4-triazole (detrH) produces... 

The silver-carbon bond in compounds containing a perfluoroalkyl group is considerably more stable than in non-fluorinated compounds. The synthesis can be accomplished by the nucleophilic addition of silver fluoride to fluoro-olefines. A typical example of this reaction is given in equation 9. The complexes are soluble in organic solvents and have been isolated as the 1 1 complexes with acetonitrile [RAg(CH3CN)]23. 

Above, the parameters necessary to solubilize important nitrogen ligands in fluorocarbon media have been established. In a concomitant manner, important metal complexes that are needed as precatalysts for many classical catalytic reactions require special attention with regard to fluorocarbon solubility, simply because of the polar and/or ionic nature of these complexes. Thus, we found in our experience that, in many cases, the counteranion also needed fluoro ponytails to ensure fluorocarbon solubility, even if the metal ion was coordinated to a fluorous-soluble ligand such as 1. Therefore, we [4, 5], and Pozzi et al. [6], have addressed this critical... 

Trifluoromethylation of Aryl Iodides. Complex 1 is an efficient trifluoromethylating reagent of iodoarenes. The reaction takes place at 80 °C, employing dimethylformamide (DMF) as the solvent, due to the good solubility of complex 1 in this solvent (eq 1). Remarkably, a large excess of the iodoarene is not necessary. Thus, a variety of aryl iodides (substituents include methyl, methoxy, chloro, fluoro, nitro, nitrile, trifluoromethyl in the para-position, as well as 2-iodopyridine) undergo trifluoromethylation in good yields (60-85%). 

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