Complexes, spectrophotometric characterization

The oxidation can be followed spectrophotometrically (Figure 13). The spectra of the trans-dithiolato complexes are characterized by ab-... 

The reaction of superoxotitanium(IV) with a number of substrates has been monitored by stopped-flow techniques/ In 1 M perchloric acid, the oxidation of iodide and bromide proceeded with second-order ratde constants of 1.1 x 10 M s and 2M s respectively. It is proposed that the reduction of superoxotitanium(IV) proceeds by a one-electron mechanism. Based on proton dependences, the species TiO " is more reactive than the protonated form Ti02(0H)2. The chromium chelate, bis(2-ethyl-2-hydroxybutyrato)oxochro-mate(V), is reduced by iodide, generating a Cr(IV) intermediate. The reaction is considered to proceed through formation of an iodine atom (T) for which both Cr(V) and Cr(IV) compete. In aqueous solution, [Co(EDTA)] forms a tight ion pair with I . Upon irradiation of this ion pair at 313 nm, reduction of [Co(EDTA)] to [Co(EDTA)] occurs with oxidation of 1 to IJ. The results may be interpreted on the basis of a mechanism in which [Co(EDTA)] and V are the primary photoproducts where the latter subsequently disproportionate to I3 and 1 . The kinetics and mechanism of the oxidation of 1 by a number of tetraaza macrocyclic complexes of Ni(III) have been reported. Variations in rate constants and reaction pathways are attributable to structural differences in the macrocyclic ligands. Of interest is the fact that with some of the Ni(III) complexes, spectrophotometric evidence has been obtained for an inner-sphere process with characterization of the transient [Ni(III) L(I)] intermediates. Iodide has also been used as a reductant for a nickel(III) complex of R-2-methyl-1,4,7-triazacylononane. In contrast to the square-planar macrocycles, the octahedral... 

Berto S, Crea F, Daniele PG, De Stefano C, Prenesti E, Sammartano S (2012) Potentiometric and spectrophotometric characterization of UOj -citrate complexes in aqueous solution, at different concentrations, ionic strengths and supporting electrolytes. Radiochim Acta 100 13-28... 

V,iV -diphenylthiourea (H2L) has been reacted with Ni11 to give the neutral complex [Ni(HL)2], which has been characterized using spectroscopic and thermogravimetric analysis. In addition, the stability constants for [Ni(HL)]+ and [Ni(HL)2] have been determined spectrophotometrically.1013... 

Measurement of pH-dependent equilibria can also be used to identify coordination isomerization reactions in addition to stepwise dissociation, such as in the case of the iron(III) complex of exochelin MN (59). Here, a combination of spectrophotometric and potentiometric titration characterized multiple equilibria involving second-sphere protonation, coordination isomerization, and stepwise dechelation, and is illustrated in Fig. 8. 

Characterization of Enzyme-Substrate Complex by use of CM-Chitin (Carboxymethyl Chitin). CM-chitinwas prepared by carboxymethylation of chitin according to the method of Imoto, Hayashi and Funatsu (13). The ozonized lysozyme (1.3 mg) solutions at different pHs were neutralized with NaOH or HCl to pH 8.0 and the poured into the column (1.5 X 4 cm.) containing white cotton-like Cm-chitin ( 65 mg.), which was equilibrated with 0.1 M Tris-Cl buffer pH 8.0. Aliquots were eluted first with 0.1 M Tris-Cl pH 8.0 and then with 0.2 M HAc. The absorbance of the fractions was measured spectrophotometrically at 280 nm. 

The interaction of 2-pyridinecarbaldehyde with Cu(II) has been studied by potentiometric and spectrophotometric methods,522 and formation constants have been determined. The neutral deprotonated complex (167) was characterized in the solid state. 

Complexes of Tc(III) where O-atom transfer occurs by reacting [TcOC14] with several phosphine ligands in 4-picoline as solvent yield the mcr-[Cl3(pic)3Tc] and mer-[Cl3(pic)(PMe2Ph)2Tc] complexes. The products were characterized by x-ray diffraction and spectrophotometric methods [501]. 

Chemiluminescence detection in capillary electrophoresis (CE) has attracted much attention as a promising way to offer excellent analytical selectivity and sensitivity. Several reagents, such as luminol, acridinium, peroxyoxalate, and tris(2,29-bipyridine)ruthenium(II) complex have been utilized. Since chemiluminescence detection is approximately 102—106 times more sensitive than spectrophotometric and fluorometric detections, its combination with isoelectric focusing may result in a highly sensitive analytical tool for amphoteric compounds, e.g., proteins and peptides. A detector using luminol-H202 chemiluminescence has been characterized in a very simple and inexpensive setup, but only pressure-driven mobilization of the zones was effective. [68],... 

None have been properly characterized for osmium, though a 1 1 complex between 0s04 and P043- has been detected spectrophotometrically.667... 

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