Bipyridyl complex

Methanol can be converted to a dye after oxidation to formaldehyde and subsequent reaction with chromatropic acid [148-25-4]. The dye formed can be deterruined photometrically. However, gc methods are more convenient. Ammonium formate [540-69-2] is converted thermally to formic acid and ammonia. The latter is trapped by formaldehyde, which makes it possible to titrate the residual acid by conventional methods. The water content can be determined by standard Kad Eischer titration. In order to determine iron, it has to be reduced to the iron(II) form and converted to its bipyridyl complex. This compound is red and can be determined photometrically. Contamination with iron and impurities with polymeric hydrocyanic acid are mainly responsible for the color number of the merchandized formamide (<20 APHA). Hydrocyanic acid is detected by converting it to a blue dye that is analyzed and deterruined photometrically. 

Organometallic compounds apart, oxidation states below - -2 are best represented by complexes with tris-bidentate nitrogen-donor ligands such as 2,2 -bipyridyl. Reduction by LiAlH4 in thf yields tris(bipyridyl) complexes in which the formal oxidation state of vanadium is -1-2 to —1. Magnetic moments are compatible with low-spin configurations of the metal but. 

Alkene complexes Ammine complexes Aqueous chemistry Arsine complexes Binary compounds Bipyridyl complexes Bond lengths acetylacetonate alkene complexes alkyl and aryl complexes ammine complexes aqua ion... 

Tris(bipyridyl) complexes structure, 1, 63 Tris(diketonate) complexes structure, 1,65 Trisdithiolencs metal complexes synthesis, 2, 597... 

In conforming to an expected linear free energy relationship, the Ce(lV) oxidation of various 1,10-phenanthroline and bipyridyl complexes of Ru(II) in 0.5 M sulphuric acid are consistent with the requirements of the Marcus treatment . The results for the oxidation of the 3- and 5-sulphonic-substituted ferroin complexes by Ce(IV) suggest that the ligand does not function as an electron mediator, and that the mechanism is outer-sphere in type. Second-order rate coefficients for the oxidation of Ru(phen)j, Ru(bipy)3, and Ru(terpy)3 are 5.8x10, 8,8 X 10, and 7.0 x 10 l.mole . sec, respectively, in 0.5 M H2SO4 at 25 °C a rapid-mixing device was employed. 

Examination by stopped-flow method of the autoxidation of the bipyridyl complex of Cu(I), Cu(bipy)2, shows that it is first-order both in O2 and in the complex, with k2 (25 °C) = (6.5 0.5)x 10 l.moIe . sec. No was incorporated from labelled water into the product H2O2, indicating the 0-0 bond remains intact during reduction. The authors favour a /wo-equivalent reduction on thermodyamic grounds, proposing a rate-determining formation of a Cu(I)-02 complex which reacts rapidly with a second Cu(I) species, viz. 

A stopped-flow examination of the reduction by the bipyridyl complex of Cu(I), Cu(bipy)2, reveals the kinetics... 

The reductions by ferrous ion and mono- and bis-bipyridyl complexes of Fe(II) are also simple second-order with (for the Fe reaction at zero ionic strength ). 2 = TO X 10 exp(—12.1 X 10 /Rr) l.mole . sec . This reaction generates an intermediate capable of oxidising ethanol but the effect is suppressed by addition of Cl , Br and acrylonitrile, the latter being polymerised. 

Table 1 Colors (established by bulk electrolysis in acetonitrile) of the ruthenium(II) tris-bipyridyl complexes of the ligands given below, in all accessible oxidation states.15...

The intense colors in 2,2/-bipyridyl complexes of iron(II), ruthenium(II), and osmium(II) are due to excitation of an electron from metal t2g orbitals to an empty, low-lying ir orbital of a conjugated 2,2 bipyridyl ligand. The photoexcitation of this MLCT excited state can lead to emission as the excited state collapses back to the ground state. However, not all complexes are... 

Luminescence spectroscopy is one of the most sensitive techniques for identification of impurities in dyes. The most commonly observed impurities in to-bipyridyl complexes of the type [RuL2X2] are the homoleptic tris-bipyridyl species [RuL3]2+. Since the emission quantum yields of the [RuL3]2+ complexes are significantly higher than those of the [RuL2X2] complexes, one can identify the homoleptic impurities at a level of less than 1%. This does depend, however, on the relative quantum yields, and position of the emission spectral maxima, for the complexes and impurities involved. 

Fig. 35. Self-assembled glycodendrimers around a Fe(II)-bipyridyl complex.267...

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