Bis bipyridyl

The reductions by ferrous ion and mono- and bis-bipyridyl complexes of Fe(II) are also simple second-order with (for the Fe reaction at zero ionic strength ). 2 = TO X 10 exp(—12.1 X 10 /Rr) l.mole . sec . This reaction generates an intermediate capable of oxidising ethanol but the effect is suppressed by addition of Cl , Br and acrylonitrile, the latter being polymerised. 

Bis(bipyridyl)nickel(0) has been prepared by metal-vapor methods and electrochemical data were obtained for it. In these low-valence states, a significant proportion of the electron density lies on the bipy ligand.2469 Also, the crystal and molecular structure of 4,6-dimethyl-2,2 -dipyr-idyldicarbonylnickel(O) (1021) has been determined. The coordination geometry about Ni is tetrahedral.2470... 

Stoddart and coworkers [112-115] cyclized bis(bipyridyl)s in the presence of crown ethers to obtain a [2]catenane at a yield of 70%. It is illustrated in Fig. 37. The high yield can be attributed to the 7i-donor-acceptor interaction between the ring and the axle. It was shown that one of the two intercrossed rings moves around the other. The group of Stoddart [116-118] reported [3-5] catenanes (see Fig. 38 for [3]catenane). The [5]catenane of Stoddart et al. [118] was named olympiadane , because it resembles the symbol logo of International Olympic Games, as seen in Fig. 39. 

Hatano et al.l39 found that the poly(L-lysine)-Cu(II) complex exerted asymmetrically selective catalysis on the hydrolysis of phenylalanine ester, whereas Cu ions and bis(bipyridyl)Cu had no catalytic activity. The great stability of the intermediate PLL-Cu complex with the D-ester was considered responsible for the catalytic activity. 

The organosulfinato complexes (RS02)Zn(0H2)2 react with bipy according to equation (6) (R = Ph or p-MeCeHt). In the case of the bis(bipyridyl) derivatives, both O-bonded and S-bonded linkage isomers are formed.678 The hydrated sulfinate also reacts with py to give the derivatives [(RS02)2Zn(py)] (R = Ph or p-MeCsFLt).679 The polymeric structures (99) and (100) are postulated for the two 1 1 complexes. 

The work was further extended to the replacement of CouL by Co11 bipyridyls171 (with H2A as reductant) and in this case, quantum yields of up to 0.13 were recorded. Under the conditions used ([Ru(bipy)3]2+/H2A/Co2+/bipy), the principle Co species in solution are the mono- and bis-bipyridyl derivatives and the mechanism is analogous to that proposed for ConL, involving an unstable Co111 hydride species some dihydrobipyridyl is also produced. Replacement of bipy by 4,4 -dimethyl-2,2 -bipyridyl (dmbp) increases the quantum yield, but substitution of Co2+ by Fe2+, Ni2+, Zn2+, Cu2+ or Mn2+ leads to a substantial drop in hydrogen yields. 

There was reported an interesting example in which copper(I) complexes of the bis(bipyridyl) ether 19a are chiral (C2-symmetry) and crystallize in form of their racemate.43 The additional attachment of two chiral (S)-2-methylbutyl ether groups leads to the chiral ligand 19b which consequently can form two diastereomeric copper(I) complexes, from which the complex with the left-handed prohelical [Cu,(bpy)2] substructure is found in 30% excess.44... 

Pseudo polyrotaxanes consist of low molecular weight rotaxanes which can assemble via non-covalent interactions. An illustrative example has recently been described by Stoddart, using a tetra-cationic bis(bipyridyl-phenyl)-cyclophane as macrocyclic ring component and phenylene-l,4-bis(oxy-oligoethyleneoxy)-co-carboxylic acid [385]. 

A novel Os and Ru bis(bipyridyl) containing an amide macrocyclic receptor has been shown to detect the presence of anions by both electrochemical and optical methodologies. Photophysical studies have clearly shown that the rate constants of the energy transfer process responsible for the quenching of the luminescent ruthenium excited state significantly decreases in the presence of chloride ions. ... 

Other metallocycles assembled from two ligand molecules and two metal atoms have been reported by Harding et aV Bimetallic [2+2] macrocycles from the bis(bipyridyl) derivatives 3-7 and nickel(II), copper(I), silver(I), zinc(II) and cad-mium(II) have been reported. Products of this type may have either chiral, helical... 

Figure 7.1 Strucure of di-zinc(II) metallocycle incorporating bis(bipyridyl) moieties linked by 2,1 -substituted pyrene groups ...

The preparation of bis(bipyridyl) (702) and bis(phenanthroline) cobalt(III) complexes (576) has been the subject of a number of papers. Interest centers on the possibility of cis-trans isomerism in these complexes, since it would seem that the close approach of the 6,6 -(bipyridyl) and 2,9-(phenanthroline) protons in the trans complex would make this stereochemistry unattractive for central ions such as co-balt(III), rhodium(III), or iridium(III). Cis complexes are well established, but a violet compound claimed to be anionic cobalt(II) species (21, 573, 591). 

Ruthenium(VIII) oxide is generated in situ during the reaction using another oxidizing agent, usually sodium metaperiodate, but sodium hypochlorite has also been used. Ruthenium sources are usually ruthenium(III) chloride or ruthenium(IV) oxide, preferably as hydrates, but w-bis(bipyridyl)dichlororuthenium dihydrate... 

The arylation reaction of primary and secondary amines has been investigated using nickel or palladium complexes as catalysts, and bromo- or chloroarenes as arylating agents. Among the complexes tested, the more efficient catalyst is the bis (bipyridyl) nickel (II) bromide, bipy2NiBr2, which affords for example high yields in the arylation of allylamine with /n-bromotrifluoromethylbenzene. The reduction of the haloarene, sometimes observed with the nickel complexes, becomes predominant with palladium catalysts whatever the complex used. 

Beer. P.D. Drew, M.G.B. Hesek. D. Shade. M. Szemes, F. Anion recognition properties of new upper-rim bis [rhenium bipyridyl. ruthenium(II) bis(bipyridyl), cobaltocenium] calix [4] arene receptors dictated by lower-rim substituents. Chern. Commun. 1996, 18, 2161. 

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