Terpyridine, reaction with metal ions

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 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 ... 

We also realized viscosity oscillations of a polymer solution based on different mechanisms [26]. It is known that a terpyridine ligand binds or dissociates with a Ru metal ion depending on the redox states of the Ru metal ion [29]. Generally, when the Ru metal ion is in the reduced Ru(II) state, the Ru(II) metal ion forms bis-complexes with terpyridine (Ru(terpy)2). However, when the Ru metal ion is in the oxidized Ru(III) state, the Ru(in) metal ion forms a monocomplex with terpyridine (Ru(terpy)) (Fig. 11.7). Therefore, supramolecular block copolymers have been made by using Ru(terpy)2 as a junction point [29], If the Ru-terpyridine complex acts as a catalyst of the BZ reaction, the redox oscillation may cause periodical binding/dissociation of the Ru-terpyridine complex. Recently, a theoretical computational simulation in the case that the Ru-terpyridine complex acts as a reversible crosslinking point of polymer network during the BZ reaction has been reported by Balazs et al. [30]. The... 

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]. 

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