Terpyridine nickel

The crude 2,2 -bipyridine obtained from the reaction of pyridine and degassed Raney nickel was found to contain 1.5% of 2 6, 2"-terpyridine, but no 2,2 2, 2" 6 ",2 "-quaterpyridine could be detected. Moreover, experiments with 2,2 -bipyridine and Raney nickel have failed to yield quaterpyridine, and the amount of terpyridine formed in experiments with mixtures of pyridine and 2,2 -bipyridine was found to be no higher than in the reaction with pyridine itself. " ... 

From the dimensions of the lattice of W-6 Raney nickel, it seems that the formation of 2,2 6, 2"-terpyridine would be expected when one molecule of 2,2 -bipyridine and one molecule of pyridine are... 

Phenylmethylsilanediol, synthesis, 42 155 Phenylsilanetriol, monosodium salts, 42 169 4 -Phenyl-2,2 6, 2 -terpyridine bis nickel complex, 30 74 molecular structure, 30 74 PhjtfluorenyllSiOH, 42 197 (Ph(Me2N)C-=Nli], 37 59-65 orientation of imino ligand, 37 61-63 (PhMe SiljCSiH OH, 42 244-245, 248 (PhMe SiljCsiMeHlOH), 42 191 Phosphaalkenes acyclic, 33 338-353 butadienes, 33 346-349 cumulenes, 33 352... 

Dale Margerum Ralph Wilkins has mentioned the interesting effect of terpyridine on the subsequent substitution reaction of the nickel complex. I would like to discuss this point—namely the effect of coordination of other ligands on the rate of substitution of the remaining coordinated water. However, before proceeding we should first focus attention on the main point of this paper-which is that a tremendous amount of kinetic data for the rate of formation of all kinds of metal complexes can be correlated with the rate of water substitution of the simple aquo metal ion. This also means that dissociation rate constants of metal complexes can be predicted from the stability constants of the complexes and the rate constant of water exchange. The data from the paper are so convincing that we can proceed to other points of discussion. 

The submitters report that 4 -(methylthio)-2,2 6, 2 -terpyridine also can be conveniently reduced to 2, 2" 6, 2 -terpyridine with Raney nickel in ethanol. The checkers found, however, that this procedure invariably gave product contaminated with 4 -ethoxy-2,2 6 ,2 -terpyridine. Raney nickel which was exhaustively washed with water to remove base still gave 15% of this byproduct. 

Fig. 8. The crystal and molecular structure of 4 -phenyl-2,2 6, 2"-terpyridine (a) and its bis complex with nickel(II) (b) 129).

Although there have been numerous reports of nickel(II), palladium(II), and platinum(II) complexes of 2,2 6, 2"-terpyridine, complexes in higher oxidation states are all but unknown. Morgan and Burstall described the... 

The solution properties of the 1 1 complexes of nickel(II) with 2,2 6, 2"-terpyridine are poorly characterized this is particularly unfortunate, since the nickel(II)-2,2 6, 2"-terpyridine system has been widely studied in investigations into the binding of 2,2 6, 2"-terpyridine to metal ions. The rate of the reaction ... 

A radical species may also be generated by reduction of an electron-deficient compound and a classical entry to 4,4 -bipyridines is the reduction of a pyridine by sodium and subsequent rearomatization. Figure 8a illustrates the use of such a reduction in order to prepare the precursor of a sodium-ion molecular switch [30], A more general route, derived from the ancient copper-catalyzed Ullmann coupling, is the metal-induced dimerization of an aryl halide. The key step is a reductive elimination within the coordination sphere of the metal. A nickel(O) complex, in stoichiometric quantities, is usually selected for this purpose. Constable and Ward have used such a reaction to prepare a bis-terpyridine from an interesting synthon, which would have otherwise required a more specialized strategy with dedicated intermediates (Figure 8b) [31]. 

Rate parameters for the reaction of nickel(II) with pyridine, bipyridine, phenanthroline, and terpyridine are available [118] for dimethyl-sulphoxide and acetonitrile solvents along with similar data for terpyridine in methanol and ethylene glycol (Table 12). To test whether or not substitution is normal in type, ligand substitution rate coefficients (fej) are compared with the respective solvent exchange rates (fes) by means of a ratio R defined as... 

Bis(oxazoline)pyridine (Pybox) and terpyridine (terpy) belong to the family of tridentate ligands that are often excluded from the discussions on pincer chemistry. However, recent studies have shown that in some cases they are redox-active [52, 53] and exhibit properties closely resembling those of pincer ligands. Thus, cross-coupling reactions catalyzed by nickel complexes containing these ligands are also discussed in this chapter. 

The use of cyclic voltammetry has already been mentioned in the characterizations of nickel(II) complexes with nitrogen- and phosphorus-donor ligands and of ruthenium(II) terpyridine bipyridine complexes with a phosphorus(III) ligand.Similarly, it has been used in the characterization of bis(diphenylphosphinomethyl)amino ligands and their Ni(II) and Pd(II) complexes. " A novel electrochemical sensor for detection of Dimethoate insecticide, and other similar organophosphates (OPs), based on a thin film-imprinted polymer, has been produced using electrodeposition of silver nanoparticles and electropolymerisation controlled by cyclic voltammetry scans " and more details are given later under sensors and biosensors. 

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