3,3 -Bipyridine, theoretical studies

There has been much interest in the predominant conformation of the bipyridines. Theoretical studies of the molecular structure of 2,2 -bipyridine suggest that the conformation with the nitrogen atoms transoid to one another is more stable than the cisoid In 3,3 -bipyridine,... 

Experimental and theoretical studies of the behavior of 2,2 -, 2,3 -, 3,3 -, and 4,4 -bipyridines in paper and thin-layer chromato-graphy and of 2,2 - and 4,4 -bipyridines in linear-elution adsorp-tion, - gas, and gas-liquid chromatography have been de-... 

Diquat (75) and some of its relatives have been included in theoretical studies of redox equi-libria. Further studies of the polarography of diquaternary salts of 2,2 -bipyridine, including work in nonaqueous systems, have been... 

There is some debate as to whether the localized- or trapped-valence description of the Taube-Creutz ion is correct or whether a delocalized picture is more appropriate. A theoretical study indicates that it is a delocalized, Class III system." Meyer and co-workers have summarized the structural and spectroscopic evidence and placed it between Class II and Class III. The trapped-valence model seems correct" for the complex in which the bridging ligand is 4,4 -bipyridine, since the two pyridine rings are not planar and therefore are not in 11 conjugation. 

The Raman spectra of 2,2 -bipyridine ° and 4,4 -bipyridine - have been studied. The experimental data agree with theoretical calculations. The resonance Raman spectrum of the radical anion of 2,2 -bipyridine has also been investigated. The Raman and IR spectra of 2,2 -bipyridine, using polarized light, have been obtained and assignments have been made. ... 

In related model complex studies, Isied and coworkers, have examined photo-induced (or pulse-radiolytically initiated) electron-transfer processes in which a polypyridine-ruthenium(II) complex is linked by means of a 4-carboxylato,4 -methyl,2,2 -bipyridine ligand and a polyproline chain to a [Co(NH3)5] + or [(-NH-py)Ru (NH3)5] acceptor. Chains composed of from zero to six cis-prolines have been examined. The apparent distance dependence of the electron-transfer rate constant, corrected for variations in the solvent reorganizational energy, seems to exhibit two types of distance dependence, 0.7-1A for short chains and /3 a0.3 A for long chains. A very detailed theoretical analysis of electron transfer in the complexes with four proline linkers has indicated that the electronic coupling is sensitive to conformational variations within the proline chain. ... 

One of the first systems investigated concerned the redox reaction between Co(terpy)2 and Co(bpy)3 in different solvents, where terpy = 2,2 6, 2"-terpyridine, and bpy = 2,2 -bipyridine (20). Because of the similar charge on these species, K for ion-pair formation in terms of an outer-sphere mechanism is very small, and the observed AV is a composite quantity. The reported activation volumes for the investigated solvents are -9.4 (H2O), -13.8 (HCONH2), and -5.1 (CH3CN) cm mol . Theoretical calculations based on the Marcus-Hush relationships resulted in a A value of -7.3 cm mol" for the reaction in water, which is indeed close to the experimental value (20). A series of reactions were studied where it was possible to resolve K and /cet, that is, A V(K) and A V (fcEx)- In this case, oppositely charged reaction partners were selected, as indicated in the following scheme (21-23) ... 

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