Inductive constants

In the presence of aprotonic organic solvents, both aromatic and aliphatic amines interact with 4-nitrophenyldiazonium in the same way. The first stage yields fast in corresponding triazenes. At the second stage, irrespective of initial amine nature, triazenes interact with an excess of diazo reagent and fonu l,3-bis(4-nitrophenyl)-triazene. Triazenes of aliphatic amines transform fast as well. In case of aromatic amines, the second stage yield depends on the inductive constants of substituents in an azo component. 

Originally the constant for the field/inductive effect was called the inductive constant ((jj). The field (through-space) contribution is, however, clearly larger than the inductive effect proper, i. e., the through-bond contribution. 

Inductive constants 510, 511 Inductive effects 391, 392 Infrared spectroscopy 515 of sulphones 110 of sulphoxides 118, 119 of three-membered ring sulphones and sulphoxides, 393, 394... 

Deuterium substitution rednces the electron affinity of organic snbstrates. The reduced electron affinity of deuterinm-snbstitnted analogs is due to the larger electron-donating effect of deuterium when compared to hydrogen. Its inductive constant is small bnt negative (-0.0011). The deuterium electron donor effect develops in organic ion-radicals also. 

A study of the selectivity of lariat aza[15] crown-5 (3.133) and BiBLE (bi-brachial lariat ether) diaza[18] crown-6 derived ligands (3.134) containing variously substituted arene rings showed that the Ag+ complex stability decreased as a function of the electron-withdrawing ability of the substituents, R, as measured by the substituents Taft o° inductive constant (a parameter measuring the electron-withdrawing... 

Substituent Hammett constants Inductive constants Taft constants a Swain-Lupton constants ... 

The inductive effect of an inorganic, organic or organometallic substituent, Y, is characterized quantitatively by several widespread constants, such as a and others (a, a, F etc.)34,57. The relationship ai(Y) = ct (Y) = F(Y) = 0.45electronic interactions. The most important independent mechanisms of polarization of bonds between the substituent Y and the reaction centre are the field and the inductive interactions. The contribution of each mechanism depends on the type of substituent Y29. 

At present the molecular structures of about condensed rings with a common Si<-N bond have been determined (Table 8). The Si... N distance in these molecules varies within wide range (from 200 to 290 pm) but always remains less than the sum of van der Waals radii of silicon and nitrogen. The length of the Si<-N bond in Si-substituted silatranes XS OCH CH ljN is related linearly to the Taft inductive constant o of the substituent lsi N = 220 — 6.3 a (r = 0.947) and has a more complicated relationship with its electronegativity Ijj = 302.1... 

The Ei parameters correlate with the Taft s inductive or constants of the substituents (Table 44) [347]. As a consequence, one can observe a correlation between the redox potential E values and the sum of the inductive constants for all the substituents (Figs. 44-51). 

Taft s inductive constants for substituents are rather obvious forms of the correlation constants for macrobicyclic systems, since they are determined for structurally similar organic compounds, namely, bicyclic esters of the type... 

The E values depend on the electron density on the encapsulated metal ion and on donor atoms, and as a result, correlate a sum of the inductive constants of apical substituents. The slope of three linear correlation regressions for Ns-sarcophaginates (including a sepulchrate) and for sarta.cn and capten (higher potentials) and absar (lower potentials) ligand complexes is the same hence, in each group the E values are governed by an inductive effect. 

A good agreement between the Oi values and Hammet s constants is observed in some cases (Fig. 56). For sepulchrate and sarcophaginate cobalt(III)/cobalt(II) pairs with apical amino, methyl, and chlorine substituents, the Log/en values correlate with inductive constants of these substituents (Fig. 56). 

Within the limits of the topic under discussion, the electronic effects of heteroaromatic groups can be described quantitatively by a set of various a constants. The most fundamental of these are the inductive constant a, and the... 

The ff constants for the 4,6-dimethyl-s-triazinyl group were evaluated by two independent methods (1) from the pK values of m- and p-(4,6-dimethyl-2-triazinyl)benzoic acids (series 10) and (2) from the spectra of 4,6-dimethyl-2-(m-/p-fluorophenyl)triazines (series 9) in various solvents (74JOC2591). That the ff] values in alcoholic media and in DMSO are very close can be accounted for by the low protophilicity of heterocyclic nitrogen atoms of the triazine ring and by their small steric accessibility in the presence of two methyl groups in the ring. At the same time, the polarity of the medium exerts an appreciable effect on the value of the inductive constants (see Table XIII). 

Charton inductive constants - electronic substituent constants (O inductive electronic constants)... 

The constant values k (Table E-4) are defined according to the Swain-Lupton - field-inductive constant f, i.e. they represent the relative field effect of an atom or a group. 

Electronic substituent constants representing the polar effect exerted by the substituent on the active site of a molecule. Different reaction series and data derived from various statistical procedures have led to several proposals for inductive constants only the most popular are considered in the following. 

The Roberts-Moreland inductive constant o is based on the dissociation constants K of 4-substituted bicyclo[2,2,2]octane-l-carboxylic acids in 50 % ethanol by volume at 25°C defined as ... 

An Additive Model of Inductive Effect was recently proposed to estimate the a inductive constant of substituents on the basis of the fundamental characteristics of the constituent atoms [Cherkasov et al, 1998a Cherkasov and Jonsson, 1998b] ... 

The Taft-Lewis inductive constant Oj was proposed [Taft and Lewis, 1958] to measure the inductive effect in aliphatic series on a scale for direct comparison with aromatic o values, derived from the o constant as ... 

---