2,2-Bipyridyl ligand

The versatility of cyanide and bipyridyl ligands has been used to stabilize low oxidation states. By using potassium in liquid ammonia, K3Ti (CN)6 is reduced to K2Ti (CN)4 and TiBt3 - - KCN to K4Ti°(CN)4. With ZrBt3 and M CN (M = K, Rb) in liquid ammonia, ammonolysis occurs and zerovalent Zr is produced ... 

The bipyridyl ligand, with 80 %, gives the best catalyst, probably because it affords the best balance between the a-donor and rt-acceptor characters which favours respectively the oxidative addition of the aryl bromide and the reductive elimination of the aryl ether at the nickel center. 

No cases of cis/trans isomerism have yet been reported among organo-cobalt(III) complexes, even among compounds not covered by this review. Complexes such as [R2Co(bipy)2] all have the cis configuration steric hindrance would be greatly increased by the coplanarity of the two bipyridyl ligands in the trans isomer 123). 

Wilson and Lyle [36] recently reported the synthesis and use of a new C2-symmetric 2,2 -bipyridyl ligand that answered these steric demands, since, associated to copper(I)salts, high diastereoselectivities and enantioselectivities trans/cis = 80/20 and 82% ee) could be achieved in the benchmark... 

Casini, A., Cinellu, M.A., Minghetti, G., Gabbiani, C., Coronnello, M., Mini, E. and Messori, L. (2006) Structural and solution chemistry, antiproliferative effects, and DNA and protein binding properties of a series of dinudear gold(l II) compounds with bipyridyl ligands. Journal of Medicinal Chemistry, 49, 5524. 

A CT transition which is very similar to the -> MMCT transition has been observed by Vogler et al. [55] for complexes [M(2,2 -bipyridyl)X3] with X = Cl, Br, I and M = Sb, Bi. These authors report MLCT transitions involving the promotion of an electron from the lone pair to the n orbital of the bipyridyl ligand. For example, for M = Sb and X = Br they observe an orange color for the complex due to an absorption band with a maximum at 435 nm. In the complexes considered by us the transition is to an antibonding n orbital (with pronounced d character) on the filled-shell transition-metal complex ion. 

Verga, D. Richter, S. N. Palumbo, M. Gandolfi, R. Freccero, M. Bipyridyl ligands as photoactivatable mono- and bis-alkylating agents capable of DNA cross-linking. Org. Biomol. Chem. 2007, 5, 233-235. 

Cul, 12mol% of 2,2 -dipyridyl, in lOvol of xylene diglyme (9 1) at 140°C with azeotropic removal of the water as it was formed. The azeotropic removal of water helped alleviate the problem of solids coating the reaction vessel walls, which led to stalling of the reaction. The reaction was complete in less than lOh, typically with 96% assay yield and 92% isolated yield for 49 after aqueous work-up and subsequent crystallization [14b-d]. It was noteworthy that this catalytic system composed of the copper(I) salt with bipyridyl ligand was recently reported to be applicable to a wide range of Ullmann-type ether formations [14d]. 

Oxidative electropolymerization has been described for iron(II) and ruthenium(II) complexes containing amino-20 and pendant aniline-21 substituted 2,2 -bipyridyl ligands, and amino- and... 

The intense colors in 2,2/-bipyridyl complexes of iron(II), ruthenium(II), and osmium(II) are due to excitation of an electron from metal t2g orbitals to an empty, low-lying ir orbital of a conjugated 2,2 bipyridyl ligand. The photoexcitation of this MLCT excited state can lead to emission as the excited state collapses back to the ground state. However, not all complexes are... 

A diorganogold(m) complex with the aryl substituent attached to a bipyridyl ligand was found to undergo unexpected reductive elimination of the hydrocarbon upon treatment with Ph3P which involves C-C coupling (Equation (32)).121... 

Ruj1,111 11]0/ 1 11 11]- (E j2 T Interestingly, with increase of the tt-electron accepting capability in 2,2/-bipyridyl ligands, redox potentials are progressively anodic-shifted in the order 31 —> 32 —> 33 —> 34 [8]. The stabilization against... 

Reaction of triruthenium precursor 2 with one equivalent of bis(2,2 -bipyridyl) ligand gave monomeric species 38 or 39 with ort/iometallated bpyC=Cbpy or bpyC=C-C=Cbpy, respectively [30]. The dimeric species 40 or 41 is then... 

There are two levels of self-assembly in the formation of tetra-, penta-and hexa-nuclear products from the poly-bipyridyls (L) 20 and 21 and iron(II) salts FeCl2, FeBr2 or FeS04 - the products are anion-dependent. The coordination of three bpy units, from different ligand molecules, to the Fe2+ centers produces a helical structure interaction of these helical strands with anions results in further molecular organization to form the final toroidal product. The discussion draws parallels between the helical and toroidal structures here and secondary and tertiary structure in biological systems (482). Thermodynamic and kinetic intermediates have been characterized in the self-assembly of a di-iron triple stranded helicate with bis(2,2/-bipyridyl) ligands (483). 

The coordinated 2,2 -bipyridyl ligands are inert to photosubstitution in aqueous solution. 

Tetramethyl- or tetraphenyl- (cyclobutadiene)nickel dihalides undergo reductive ligand substitution with nitrogen donor ligands such as 2,2 -bipyridine or 1,4-diaza-1,3-dienes with the addition of sodium metal237. The 2,2/-bipyridyl ligand is readily displaced and reaction of this complex with a variety of olefins and alkynes leads to cycloaddition reactions with the cyclobutadiene ligand. 

Telfer, S. G. Yang, X.-J. Williams, A. F. Complexes of 5,5 -aminoacido-substituted 2,2 -bipyridyl ligands Control of diastereoselectivity with a pH switch and a chloride-responsive combinatorial library. J. Chem. Soc. Dalton Trans. 2004, 699-705. 

In nonbiological applications, mixed ruthenium complexes of bipyridyl ligands and substituted pteridine diones have been used as components of photovoltaic cells <2002JPH167>. When fabricated into sol-gel processed titanium oxide electrodes, these complexes achieved photocurrent conversion efficiency in the range 20 8%. 

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