Gutmann’s donor number

Donor strengths, taken from ref. 207b, based upon the solvent effect on the symmetric stretching frequency of the soft Lewis acid HgBr2. Gutmann s donor number taken from ref 207b, based upon AHr for the process of coordination of an isolated solvent molecule to the moderately hard SbCL molecule in dichioroethane. ° Bulk donor number calculated as described in ref 209 from the solvent effect on the adsorption spectrum of VO(acac)2. Taken from ref 58, based on the NMR chemical shift of triethylphosphine oxide in the respective pure solvent. Taken from ref 61, based on the solvatochromic shift of a pyridinium-A-phenoxide betaine dye. 

One of them is Gutmann s donor number, DN, (Gutman and Vychera 1966) defined as the negative of the standard molar heat of reaction (expressed in kcal mol 1, 1 cal = 4.184 J) of the solvent with antimony pentachloride to give the 1 1 complex, when both are in dilute solution in the inert diluent 1,2-dichloroethane. This quantity needs to be determined calorimetrically, as was done for a considerable number of solvents at that time (Gutman and Vychera 1966). There are several problems with the DN scale. One is the fact that calorimetric equipment... 

A series of silanol and silylamine chemical shifts were obtained in various solvents. (83) The silanols are found to be highly dependent (>5ppm shifts) upon solvent basicity with the more basic solvents causing low frequency shifts. This shielding effect is found to give an excellent linear correlation with Gutmann s donor number (DM) (130) which is a measure of the electron pair donor ability of the solvent. Figure 23 shows the correlation for five of the compounds examined. It... 

The Gutmann s Donor Number (DN) was proposed [Gutmann, 1978] as a quantitative empirical parameter for solvent nueleophilicity. For most solvents it was found to correlate well with the p scale. 

Gutmann s donor number Linear Solvation Energy Relationships (0 hydrogen-bond parameters)... 

Tfaeie have been a number of attempts to develop solvent parameter scales that could be used to correlate ttiermodynamic and kinetic results in terms of these patametois. Gutmann s Donor Numbers, discussed previously, are sometimes used as a solvent property scale. Kamlet and Taft and co-workers developed the solvatochromic parameters, Uj, B, and n that are related to the hydrogen bonding acidity, basicity and polarity, respectively, of the solvent. Correlations with these parameters also use the square of tte Hildebrand solubility parameter, (5, that gives the solvent cohesive energy density. Parameters for some common solvents are collected in Table 3.6. 

Donating solvents such as hexamethylphos-phoramide or dimethylpropylurea give rise to upheld shifts which have been interpreted as caused by the formation of pentacoordinated complexes. The solvents shifts seem to follow Gutmann s donor number for solvents. 

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