3,3 -Dimethyl-2,2 -bipyridyl, structure

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

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... 

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. 

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. 

Scheme 1. Molecular structure of AR25 [chemical name cis-bis(2,2 -bipyridyl-4,4 -dicarboxylic acid)(5,6-dimethyl-1,10-phen-anthroline)bis(isothiocyanato)ruthenium(II)].

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