Gutman acceptor numbers

Thermal ruthenium-sulfur bond breaking in cis-[Ru"(bipy)2(pheno-thiazine)Cl] is markedly affected by the nature of the solvent, being faster in acetonitrile or in acetone than in methanol or in ethanol, and much slower in dimethyl sulfoxide or in dimethylformamide. Such bond breaking is readily photo-induced, particularly in acetone or dichloromethane. Relative quantum yields for photodissociation of cis-[Ru(CN)2(phen)2] in the presence of thiocyanate in a range of solvents correlate well with their Gutman acceptor numbers. The photoreaction is favored by solvents of high Solvent effects on photo-... 

Acidic/Basic Lewis acidity/basicity determines the solvent s abihty to demate or accept a pair of electrons to form a coordinate bond with solute and/or between solvent molecules. A scale for this acid/base pre ierty was proposed by Gutman (DN and AN -donor and acceptor number, reflectively) based on caleuimetric determination. The complete proton transfer reaction with femnatiem of protonated ions is determined by proton affinity, gas phase acidity, acid or base dissociation constants. Both concepts differ in terms of net chemicsd reactiem. 

The donor number (DN) is defined as the negative AH value for the solvation of SbCls by a donating solvent in 1,2-dichloroethane solution Gutman, V. The Donor-Acceptor Approach to Molecular Interactions, Plenum Press New York, 1978, Chapter 2. 

Gutman chose the reaction enthalpy of solvent with the reference acceptor (antimony pentachloride) to quantify Lewis-donor properties. The donor number, DN, is a dimensionless parameter obtained from negative values of reaction enthalpy. The data obtained from electrochemical and NMR studies were combined into one scale in which data are available for several hundred solvents. These data have a linear correlation with E according to the following equation ... 

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