2,2 -dipyridyl complexes

As shown earlier, A,A-dimethylaniline acts as an electron donor toward the electronically excited Ru(ll) tris(dipyridyl)complex (Bock et al. 1979). Nocera s group studied the effect of salt formation on the redox interaction between the ruthenium complex and the A/,At-dimethylaniline moiety. Two different salts, depicted in Scheme 5.26, were prepared and studied (Deng et al. 1997, Kirby et al. 1997, Roberts et al. 1997). 

Other coordination polyhedra based on bicapped dodecahedra, but having Dz symmetry, have been found for orthorhombic Phcn, Z =4) crystals of M(dip)2 (N03)3 (M=La, Tb and dip = 2,2 -dipyridyl) complexes (27(5, 277). Both La(III) and Tb(III) complexes have the same structure and this might be taken as evidence for the maintenance of the structure at least until Tb in the series. Sinha 218) have prepared the heavy lanthanide-bis-dipyridyl-trisnitrate complexes and the infrared studies 218, 219) showed no difference in the infrared spectra within the series, both ligands (dipyridyl and nitrate) being coordinated. 

Other imsymmetrical compounds include dipolar photochromic Zn(II) dipyridyl complexes 35 with nonlinear optical properties (08AG(E)577),... 

The coupling can be catalysed by the presence of Fe(III) or Co(ll) but is most efficiently induced by the dipyridyl complex of Ni(II) chloride, as described by Yamamoto et al.52). It is also efficiently promoted by l,4-dichoro-2-butene, as described by Taylor et al.53). The structures of these Yamamoto polyphenylenes are discussed in Sect. 3 at this point it is sufficient to note that they are yellow/brown infusible powders, apparently having a high degree of p-coupling but relatively short (10—12 rings) chain lengths. 

Frechet and coworkers recently described how living free radical polymerization can be used to make dendrigrafts. Either 2,2,6,6-tetramethylpiperidine oxide (TEMPO) modified polymerization or atom transfer radical polymerization (ATRP) can be used [96] (see Scheme 10). The method requires two alternating steps. In each polymerization step a copolymer is formed that contains some benzyl chloride functionality introduced by copolymerization with a small amount of p-(4-chloromethylbenzyloxymethyl) styrene. This unit is transformed into a TEMPO derivative. The TEMPO derivative initiates the polymerization of the next generation monomer or comonomer mixture. Alternatively, the chloromethyl groups on the polymer initiate an ATRP polymerization in the presence of CulCl or CuICl-4,4T dipyridyl complex. This was shown to be the case for styrene and n-butylmethacrylate. SEC shows clearly the increase in molecu-... 

Polymeric Catalysts such as porphirin-containing poly-(L-phenylalanine)-Fe(III) complex in the dehydrogenation of p-phenylenediamine (132), poly(L-lysine)-protoporphirin Fe(III)-4,4 -dipyridyl complex in the oxidation of cytochrome (133), poly(L-lysine)-Cu(II) complex in the hydrolysis of oligophosphate (134), and poly(L-lysine)-Cu(II) complex in the oxidation of 3,4-dioxyphenylalanine and in the hydrolysis of phenylalanine (135-137) have their own structures. 

Recently, Hart and Laming [371] have prepared 6is-dipyridyl complexes of rare earth containing chloride, nitrate and thiocyanate as anions. 

Sotomayor, M. D. P. T. Tanaka, A. A. Kubota, L. T., Development of an amperometric sensor for phenol compounds using a Nafion (R) membrane doped with copper dipyridyl complex as a biomimetic catalyst,./. Electroanal. Chem. 2002, 536, 71-81... 

Chemically modified electrodes resulting from the attachment of quinones, phenantroline, dipyridyl complexes, and N4 complexes, from the development of polymer-coated carbon materials, and from electrodes modified by enzymes have been specifically designed for the electrocatalytic reduction of molecular oxygen (OERR). Carbon materials with immobilized hydroquinone have also been utilized to accelerate the electrochemical oxidation of molecular hydrogen. 

Remarkable linear correlation, often preserving the generic form of the inclined W for various properties like M—N stretching frequencies of the 2,2 -dipyridyl complexes, lattice parameters of M203, MOBr, molecular volume(V/Z) for the trigonal glycolate complexes of the lanthanides with their L-values has already been observed (55). We would like to show here a few more correlation of the miscellaneous properties of the lanthanides with their L-values. 

The M—N stretching frequencies for the M(en)4(C104)3 complexes (87) exhibit a Unear variation within the four segments (tetrads) and the plot resemble an inclined W (Fig. 47), like that in the dipyridyl complexes (55). Furthermore, the M—N frequencies for the tris-complex, M(en)3(C104)3, where M = Gd to Ho also show a linear variation with their L-values and shifted from the plot for the tetrakis complex (Fig. 47). The linear relationship of the log Kx and the — AHX values of the tetrakis complexes has already been shown in Fig. 28. 

The above compensating reactions are attractive because of the success of similar schemes in the halide catalysis, but proof in this case is more difficult. Thus it was possible to show in the halide systems that halogen and halide are present simultaneously. Evidence for the presence of ferrous ion in the ferric catalysis would support a similar interpretation. Manchot and Lehmann (44) claimed to have proved that ferrous ion is formed from ferric ion in the presence of peroxide since the addition of <, < -dipyridyl to the mixture resulted in the slow formation of the red ferrous tris-dipyridyl ion Fe(Dipy)3++. However, later work (65,66), which will be discussed when these systems are considered in more detail (IV,6), indicates that the ferrous complex ion may be formed by reduction not of the ferric ion, but of a ferric dipyridyl complex. Similar conclusions on the presence of ferrous ion were drawn by Simon and Haufe (67) from the observation that on addition of ferri-cyanide to the system Prussian blue is formed. This again is ambiguous, since peroxide is known to reduce ferricyanide to ferrocyanide and the latter with ferric ion will of course give Prussian blue (53). 

The dipyridyl complex [Cr(dipy)3]+ yields (206, 408) s.h.f. structure from interaction with the six equivalent nitrogen atoms. No proton splittings are seen, presumably these are lost in the linewidth. 

With simple tris(dipyridyl) complexes of ruthenium(II) and their derivatives, a battery of luminescence techniques have been developed for studying the interactions and dynamics of metal complexes on DNA. Most of these methods depend on and exploit the rich photophysics and photochemistry of dipyridyl(bpy) complexes of ruthenium(II) characterized by inorganic chemists. 

Two recent examples of papain bioconjugation with formation of potential hybrid catalysts are shown in Figs. 6 and 7, featuring a manganese salen catalyst and dipyridyl complexes of copper, palladium, and rhodium, respectively [53, 58]. 

Fig. 7 Papain-based bioconjugation involving Cu-, Pd-, and Rh-dipyridyl complexes [53, 58]...

If the same statistical weight is given to aU configurations of encounter complexes (MA, H2P), X may be as low as lO". On the other hand, if the positions indicated in Fig. 3 were favoured by particular site interactions, x could increase beyond one. Viewing at an optimum path, replacement of water by different ligands could contribute to faster insertion of a metal by increasing x. [The fact that dipyridyl complexes of Cu2+ and Ni2+ are formed more slowly than corresponding acetato complexes may be due, in part, to <(ac ) >x(dip)]. 

The oxidation of Ti " by Fe" and the reaction between TF" and Sn" have been studied using flow and potential-time dependences. An investigation has also been made of the Ag -Ce " reaction. Polarographic studies of planar Schiff base complexes of Co , Ni", and Cu have shown well-defined oxidation waves and in some chelates the two-electron oxidation Co" Co " is postulated. Kinetic studies have also been made on the oxidation of cobalt(ii) dipyridyl complexes by copper(n) and iron(m) perchlorates in anhydrous acetonitrile. Solvent effects have also been investigated in redox reactions of tetrahalogenoplatinum(iv) complexes of the type PtLaX4. ... 

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