6- -2,2 -bipyridine complexing agents

The bipyridines are dibasic, and the two acid dissociation constants Ki and K2, for all the bipyridines have been determined. Typical values are recorded in Table I. There has been considerable interest in the first dissociation constants Ki of 2,2 -bipyridine and substituted 2,2 -bipyridines because of their use as metal complexing agents. In general, the order of relative basic strengths of derivatives of 2,2 -bipyridine is as expected. Electron-attracting substituents reduce the basicity, whereas electron-donating substituents increase the basicity of the molecule. " The dissociation constants of several substituted bipyridines correlate well with the Hammet equation. 2,2 -Bipyridines with an electron-donating substituent at position 4 are monoprotonated at N-1 and not at... 

On the other hand, Takacs and coworkers added organometallic reducing agents to the reaction mixture and promoted the formation of low-valent iron(O) bipyridine complexes. The mechanism of the low-valent iron-catalyzed Alder-ene reaction involves coordination of the two starting materials within the ligand sphere of the iron, which makes the Woodward-Hoffmann rules for such reactions obsolete [11]. Thereby, the scope of the reactions was broadened so that alkenes and 1,3-dienes could also be used as educts in a formal [4 + 4]-cycloisomerization (Scheme 9.3) [12]. Intriguingly, the diastereoselectivity of the cydopentane products can be influenced by either the application of the 2Z-isomer 3 or the 2 E-isomer 4. Especially the E-isomers 4 gave almost exclusive cis selectivity [13]. 

Figure 23F-3 Functional groups formed on a metal or carbon surface by oxidation. Often, linking agents such as orgaonsilanes are bonded to the functionalized surface. Reactive components, such as ferrocenes, viologens, and metal bipyridine complexes, are then attached to form the modified surfaces shown in Figure 23F-4. (From A. J. Bard, Integrated Chemical Systems. New York Wiley, 1994. This material is used by permission of John Wiley Sons, Inc.)...

Adsorptive stripping voitammetry has also been applied to the determination of a variety of inorganic cations at very low concentrations. In these applications, the cations are generally complexed with surface active complexing agents, such as dimethylglyoxime, catechol, and bipyridine. Detection limits in the 10 to 10 " M range have been reported. 

Cl oxidation has been observed with many other DNA oxidizing agents such as y-radiolysis, neocarzinostatin, Mn-TMPyP (4,5,7), copper complexes of benzosulfonamides (40), Cu-kanamycin (41), or for copper complexed to guanine of DNA (42), but it was not associated to direct strand-cleavage events except for metal complexes like Cu(3-Clip-Phen) (43), or Ru(terpyridine)(bipyridine) complexes (44). 

A RHODIUM(III) BIPYRIDINE COMPLEX WITH FORMATE AS A REDUCING AGENT... 

Atom transfer radical polymerizations (ATRP) were reported simultaneously by two groups (1) Matyjaszewski et al. [218] and (2) Sawamoto and coworkers [226]. Matyjaszewski et al. utilized a Cu/bipyridine complex as a halogen transfer agent that functions between dormant and active polymer chains. Formation of polymers with predetermined molecular weight of up to ps 10 [5]... 

Ruthenium tris-2,2 -bipyridine complexes are known to play an active role as photochemical redox agents in the solar energy conversion The corresponding amphiphilic complex 96 does not polymerize, presumably due to sterical reasons. The Ru ions are octahedrally coordinated by the three 2,2 -bipyridine ligands, which causes a very bulky size of the head group. As a consequence, the distances between adjacent diyne units likely become too large for a solid-state 1,4-addition... 

Several substitutes for cobalt based drying agents are under development. Most of these are based on either manganese or vanadium salts. Manganese -bipyridine complexes have been especially promoted as alternatives. ... 

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