2,2 -Bipyridine, complexes with

Fig. 2 Catalytic hydrolysis of an unactivated aliphatic ester by a Cll(II) bipyridine complex with two attached CDs. (From Ref. [15].)...

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

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. 

Hevia E, Perez J, Riera V, Miguel D, Kassel S, Rheingold A. New synthetic routes to cationic rhenium tricarbonyl bipyridine complexes with labile Ugands. Inorg Chem. 

Mukaiyama aldol reactions, whereby trimethylsilyl enol ethers react with aldehydes in aqueous solution to form -ketoalcohols, have been promoted by new chiral lanthanide-containing complexes and a chiral Fe(II)-bipyridine complex with 0 outstanding diastereo- and enantio-selectivities. Factors controlling the diastereoselec-tivity of Lewis-acid-catalysed Mukaiyama reactions have been studied using DFT to reveal the transition-state influences of substituents on the enol carbon, the a-carbon of the silyl ether, and the aldehyde. The relative steric effects of the Lewis acid and 0 trimethyl silyl groups and the influence of E/Z isomerism on the aldol transition state were explored. Catalytic asymmetric Mukaiyama aldol reaction of difluoroenoxysilanes with /-unsaturated a-ketoesters has been reported for the first time and studied extensively. ... 

Interestingly, the rate constants for Diels-Alder reaction of the ternary complexes with 3.9 are remarkably similar. Only with 2,2 -bipyridine and 1,10-phenanthroline as ligands, a significant change in reactivity is observed. It might well be that the inability of these complexes to adopt a planar geometry hampers the interaction between the copper ion and the dienophile, resulting in a decrease of the rate of the catalysed Diels-Alder reaction. 

Copper(I) tends towards a tetrahedral coordination geometry in complexes. With 2,2 -bipyr-idine as a chelate ligand a distorted tetrahedral coordination with almost orthogonal ligands results. 2,2 -Bipyridine oligomers with flexible 6,6 -links therefore form double helices with two 2,2 -bipyridine units per copper(I) ion (J. M. Lehn, 1987,1988). J. M. Lehn (1990 U. Koert, 1990) has also prepared such helicates with nucleosides, e.g., thymidine, covalently attached to suitable spacers to obtain water-soluble double helix complexes, so-called inverted DNA , with internal positive charges and external nucleic bases. Cooperative effects lead preferentially to two identical strands in these helicates when copper(I) ions are added to a mixture of two different homooligomers. 

Coordination Compounds. A large number of indium complexes with nitrogen ligands have been isolated, particularly where Ir is in the +3 oxidation state. Examples of ammine complexes include pr(NH3)3] " [24669-15-6], prCl(NH3)] " [29589-09-1], and / j -pr(03SCF3)2(en)2]" [90065-94-4], Compounds of A/-heterocychc ligands include trans- [xCX py)][ [24952-67-8], Pr(bipy)3] " [16788-86-6], and an unusual C-metalated bipyridine complex, Pr(bipy)2(C, N-bipy)] [87137-18-6]. Isolation of this latter complex produced some confusion regarding the chemical and physical properties of Pr(bipy)3]3+ (167). 

Chiral carbenoid complexes with 2,2 -bipyridine ligands for asymmetric synthesis 98YGK764. 

There are more examples of a second type in which the chirality of the metal center is the result of the coordination of polydentate ligands. The easiest case is that of octahedral complexes with at least two achiral bidentate ligands coordinated to the metal ion. The prototype complex with chirality exclusively at the metal site is the octahedral tris-diimine ruthenium complex [Ru(diimine)3 with diimine = bipyridine or phenanthroline. As shown in Fig. 2 such a complex can exist in two enantiomeric forms named A and A [6,7]. The bidentate ligands are achiral and the stereoisomery results from the hehcal chirality of the coordination and the propeller shape of the complex. The absolute configuration is related to the handness of the hehx formed by the hgands when rotated... 

Sanna, G., Pilo, M.I., Minghetti, G., Cinellu, M.A., Spano, N. and Seeber, R. (2000) Electrochemical properties of gold(III) complexes with 2,2 -bipyridine and oxygen ligands. Inorganica Chimica Acta, 310, 34. 

Ru 2,2 -bipyridine complexes can form a large number of colored compounds upon successive reduction, with the formal Ru oxidation state from +2 to -4. In the case of highly reduced complexes, proper representation of the electrochromic reaction is actually the reduction of the hgand, not that of the metal center. 

Kenausis G, Taylor C, Katakis I, Heller A. 1996. Wiring of glucose oxidase and lactate oxidase within a hydrogel made with poly(vinyl pyridine) complexed with [Os(4,4 -dimethoxy-2,2 -bipyridine)2Cl]. J Chem Soc Faraday Trans 92 4131-4136. 

Cationic ferrocene complexes with one, two, and four cationic [B(R)bpy] (bpy = 2,2,-bipyridine) acceptors such as 66 show absorption at Amax = 496-540 nm with the contribution of charge transfer between the ferrocene unit and the B(R)bpy substituent(s) (165). This is confirmed by the EPR spectrum of the monoreduced neutral species, which features a line shape indicating a considerable admixture of the ligand and metal orbitals. Preparation and physical properties of the related polymer, 67, have also been reported (166). 

Second only to sulfur-based systems, nitrogen complexes are relatively well represented in the structural literature with 41 complexes reported. Of these, 25 are with I2 as the electron acceptor, 11 are with the interhalogen IC1, three are with Br2, and two are with IBr. As expected, in every case the halogen bond forms between the nitrogen and the softest halogen atom, i.e., iodine, in all of the complexes except those with dibromine. Most N I2 complexes, and all N Br2, N IBr, and N IC1 complexes are simple adducts, mode A. Exceptions for the diiodine complexes include bridging mode (B) observed for diazines, such as pyrazine [86], tetramethylpyrazine [86], phenazine, and quinoxaline [87], and for 9-chloroacridine [89] and the 1 1 complex of diiodine with hexamethylenetetramine [144] and amphoteric bridging mode (BA) observed for 2,2 -bipyridine [85], acridine [89], 9-chloroacridine [89], and 2,3,5,6-tetra-2/-pyridylpyrazine [91]. The occurrence of both B and BA complexes with 9-chloroacridine, and of B and A complexes and an... 

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