4,4 -Dimethyl-2,2 -bipyridyl

Pyridine is converted by a modified Raney nickel catalyst into 2,2 -bipyridyl, and the reaction has been extended to many substituted pyridines and quinolines. 2-Substituted pyridines give the 6,6 -bipyridyls. 3-Methylpyridine gives 5,5 -dimethyl-2,2 -bipyridyl, but none of the other isomers. 

Scheme 19 Catalytic activation of glycosyl acceptors by Ph2SnCl2. DMBPY denotes 5,5- -dimethyl-2,2 -bipyridyl...

Uranium, pentakis(dimethyl sulfoxide)dioxy-stereochemistry, I, 74 Uranium, pentakis(urea)dioxy-stereochemistry, 1,74 Uranium, tetrakis(bipyridyl)-stereochemistry, I, 94 structure, 1, 24... 

The element symbols within each formula are arranged according to a modified Hill system in which the order is metal(s), C, H and then any remaining symbols arranged alphabetically. Compounds containing two (or more) different metals appear twice (or more), being listed under each metal. Common ligand abbreviations which appear in the text have also been used in the index. These include acac (acetylacetone), bipy (2,2 -bipyridyl), diars [o-phenylenebis(dimethyl-arsine)], dien (diethylenetriamine), etc. 

The reductive coupling of allyl halides to 1,5-hexadiene at glassy C electrodes was catalyzed by tris(2, 2,-bipyridyl)cobalt(II) and tris(4,4 -dimethyl-2, 2/-bipyridyl)cobalt(II) in aqueous solutions of 0.1 M sodium dodecylsulfate (SDS) or 0.1 M cetyltrimethylammonium bromide (CTAB).48 An organocobalt(I) intermediate was observed by its separate voltammetric reduction peak in each system studied. This intermediate undergoes an internal redox reaction to form 1,5-hexadiene... 

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... 

Homochiral pyridyl, bipyridyl, and phosphino derivatives of 2,2-dimethyl-1,3-dioxolane (113)-(115) were prepared from T-(+)-tartrate. These compounds were assessed in metal-catalyzed asymmetric hydroformylation of styrene enantioselectivity was generally low.342... 

In a very special system, the photoelectrochemical regeneration of NAD(P)+ has been performed and applied to the oxidation of the model system cyclohexanol using the enzymes HLADH and TBADH. In this case, tris(2,2 -bipyridyl)ruthenium(II) is photochemically excited by visible light [43]. The excited Ru(II) complex acts as electron donor for AT,AT -dimethyl-4,4 -bipyridinium sulfate (MV2+) forming tris(2,2 -bipyridyl)ruthenium(III) and the MV-cation radical. The Ru(III) complex oxidizes NAD(P)H effectively thus... 

Paraquat (1,1 dimethyl, 4,4 bipyridyl) is a nonselective contact herbicide. It is used almost exclusively as a dichloride salt and usually is formulated to contain surfactants. Both its herbicidal and toxicological properties are dependent on the ability of the parent cation to undergo a single electron addition, to form a free radical that reacts with molecular oxygen to reform the cation and concomitantly produce a superoxide anion. This oxygen radical may directly or indirectly cause cell death. Diquat, l,T-ethylene-2,2 -dipyridylium, is a charged quaternary ammonium compound often found as the dibromide salt. The structure of diquat dibromide and that of the closely related herbicide paraquat can be seen in Fig. 4.5. 

Methyl Viologen Dichloride see N,V -dimethyl-4,4 -bipyridyl dichloride). 

Interesting complexes have been prepared from the chiral ligands derived from 3,3 -dimethyl-2,2 -bipyridyl Af,JV -dioxide (216,217).955,956 A number of diastereomeric tris complexes were isolated. These could be interconverted photochemically. 

The nature of the other recorded bipy complexes, and of those with 4,4 -dimethyl-2,2 -bipyridyl, ThX4-1.5Ci2H12N2 (X = Cl or N03) is unknown. 

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. 

Abbreviations arene, i/6-benzene or substituted benzene derivative bipy, 2,2 -bipyridyl Bu, Bu", Bu, iso-, n-, or rerf-butyl COD, 1,5-cyclo-octadiene Cp, /5-C5H5 DAD, dimethyl-acetylene dicarboxylate dam, 1,2-bis(diphenylarsino)methane DBA, dibenzylideneacetone DMF, A. A -dimethylformamide dpe, l,2-bis(diphenylphosphino)ethane dpen, os-l,2-bis(di-phenylphosphino)ethylene dpm, 1,2-bis(diphenylphosphino)methane ESR, electron spin resonance F6-acac, hexafluoroacetylacetone FN, fumaronitrile MA, maleic anhydride Me, methyl MLCT, metal ligand charge transfer phen, 1,10-phenanthroline Pr , Pr", iso- or n-propyl py, pyridine RT, room temperature TCNE, tetracyanoethylene tetraphos, (Ph2PCH2CH2)jP THF, tctrahydrofuran Xylyl, 2,6-Me2C6H3. 

A sensor for organic chloride-containing compounds was constructed by immobilization of luminol or tris (2,2 bipyridyl) ruthenium (III) between a PMT and a poly (tetrafluoro) ethylene (PTFE) membrane [15], through which a stream of air was sampled by diffusion. A heated Pt filament incorporated in the gas line leading to the CL cell was used to oxidize the analytes prior to diffusion across the PTFE membrane. Detection limits for CC14, CHC13, and CH2C12 were 1.2-4 ppm. A similar device could also be used for the determination of hydrazine and its monomethyl and dimethyl derivatives or NH3 vapor. The detection limit for hydrazine was only 0.42 ppb [16]. 

In many cases ligands are abbreviated by giving a substituent and its location followed by the ligand abbreviation (e.g., 4,4 -Me-bpy would be 4,4 -dimethyl-2,2 -bipyridyl). In tables collecting complexes of one ligand type only the substituent is given. Ligand structures appear in Fig. 1. 

Nakamaru, K. (1982) Synthesis, luminescence quantum yields, and lifetimes of trischelated ruthenium(II) mixed-ligand complexes including 3,3 -dimethyl-2,2 -bipyridyl, Bull. Chem. Soc. Jpn. 55, 2697-2705. 

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