Intramolecular parameters, dependence

In order to define the relative reactivity of the M(II)Pc and M(II)P towards the 2-mercaptoethanol we considered two different reactivity indexes the electro-philicity (co) and the intermolecular hardness ( ad)- The first one is an intramolecular parameter, depending only on the electronic characteristic of the acceptor species, while the second one, defined in terms of both acceptor and donor properties, is an intermolecular parameter. As a consequence, the combined use of these two indexes should give a complete picture of the overall oxidation process. In Figure 12.2, the relative electrophilicity (A ) and intermolecular hardness (A tjDA) with respect to those of the analogous C0-N4 systems are reported. 

The rate of this intramolecular isomerization depends on the chain length, with the maximum in the case of a six-atomic transition state, i.e., when the tertiary C—H bond is in the (3-position with respect to the peroxyl group [13]. For the values of rate constants of intramolecular attack on the tertiary and secondary C—H bond, see Table 2.9. The parameters of peroxyl radical reactivity in reactions of intra- and intermolecular hydrogen atom abstraction are compared and discussed in Chapter 6. 

Thus we again assume a Lennard-Jones form, where now the well depth and range parameters depend on the solute s internal vibrational coordinates. Without loss of generality we can define these coordinates so that q = Q = 0 corresponds to the minimum in the intramolecular potential. The solute-solvent potential in Hb above is actually then

(r, 0, 0), where clearly e = e(0, 0) and a = cr(0, 0). The oscillator-bath interaction term is... 

In DAA the intramolecular wavefunctions depend on intermolecular coordinates R, as on a parameter and in the matrix elements involved in Eqn. (50) we can separate a matrix element at the electron-vibration intramolecular wavefunctions V R), and consequently, for both adiabatic and nonadiabatic intramolecular transitions the following equation holds ... 

C. Dependence of Collisional Relaxation Rates on Intramolecular Parameters.. . 363... 

Section III is devoted to a review and analysis of experimental data. Special attention will be given to the problems of the reversibility of the electronic relaxation and to the dependence of the electronic relaxation rates on the intramolecular parameters and on the properties of the collision partner. 

As shown in Section II, the rate constant of the collision-induced electronic relaxation (K/ or K /) depends on intramolecular parameters (s-/ coupling constant—and s-/ level spacing e /) as well, as on the strength of the external, collisional perturbation (expressed in (19) by the overall dephasing rate -y,/). The separation of both factors is not always self-evident. Nevertheless, for the simplicity sake we will first discuss the relation between the amount of the intramolecular s-I coupling (mixing) by assuming constant value of the intermolecular interaction. 

From our point of view, 8 depends not only on the Ca.a potential but also on the intramolecular parameters of the A excited species, relevant for a particular relaxation process. As discussed before [Section II.D.l (19)] we expect more complex relations between rotational and electronic relaxation rates than a simple proportionality supposed in (28). As a matter of fact neither in glyoxal nor in iodine can both processes be described by the same set of parameters. 

In this book, we discriminate it from the molecular theta temperature 0 defined in Chapter 1 based on the intramolecular interaction. depends on both intra- and intermolecular interaction. If the interaction between the statistical repeat units can be described by a single excluded volume parameter v in (1.71), these two are identical. In the perturbational calculation of the third virial coefficient, simple substitution of (1.71) cannot explain the observation of positive A3 > 0 at the 0 temperature. In such a case, the third cluster integral must be introduced in addition to the binary cluster integral v. 

Intramolecular concentration dependence The study of photophysical phenomena in homopolymers alone precludes variation of one of the most powerful parameters available to a photochemist, namely concentration. The local concentration experienced by the constituent chromophores of a pol3mier may be varied to some extent by altering the thermodynamic compatibility of the solvent and more dramatically by the use of copolymers containing the luminophore of interest and a spectroscopically inactive comonomer. 

Implementation of this extrapolation method requires appropriate concentration terms to be adopted to describe the intramolecular concentration dependence of the rate parameters A.. In this context it has been assumed that the variation in aromatic content in the copolymers dominates the variations in photophysical behaviour across the the range of aromatic compositions and that microcompositional terms derived from steady-state analysis of sufficient to characterize the de-... 

The problem with rotational contributions to intensities is dealt with by eliminating the rotational terms from both sides of the resulting linear equations. As a consequence, the parameters obtained are determined from purely vibrational distortions in the molecules. As noted in an early review Overend [16], subtraction of contributions to dipole moment derivatives arising from the compensatory molecular rotation present in particular modes of polar molecules is required to consider tire quantities obtained as purely intramolecular parameters that depend solely on the electronic structure of molecules. A satisfactory treatment of rotational contributions is implicit in the valence optical scheme. In contrast, in atomic polar tensors and bond charge tensors, due to the requirement that intensities are expressed on the basis of parameters referring to space-fixed Cartesian systems, a considerable amount of rotational intensity is introduced into the respective tensor elements, as shown by Person and Kubulat [86]. 

Table 10.4 lists the rate parameters for the elementary steps of the CO + NO reaction in the limit of zero coverage. Parameters such as those listed in Tab. 10.4 form the highly desirable input for modeling overall reaction mechanisms. In addition, elementary rate parameters can be compared to calculations on the basis of the theories outlined in Chapters 3 and 6. In this way the kinetic parameters of elementary reaction steps provide, through spectroscopy and computational chemistry, a link between the intramolecular properties of adsorbed reactants and their reactivity Statistical thermodynamics furnishes the theoretical framework to describe how equilibrium constants and reaction rate constants depend on the partition functions of vibration and rotation. Thus, spectroscopy studies of adsorbed reactants and intermediates provide the input for computing equilibrium constants, while calculations on the transition states of reaction pathways, starting from structurally, electronically and vibrationally well-characterized ground states, enable the prediction of kinetic parameters. 

Joachim C (1987) Ligand-length dependence of the intramolecular electron transfer through-bond coupling parameter. Chem Phys 116 339... 

A low field shift of proton signals of the OH-group in A-(salicylidenephenyl-amine-A-oxides H-12.7-13.6 ppm) indicates the presence of an intramolecular hydrogen bond. The value of this shift depends on the pK value of the parent phenol (400). While studying solvation effects of 11 NMR spectra in a-(2-hydroxy-l-phenyl)-A-(4-substituted-phenyl)nitrones, a Koppel-Palm three-parameter correlation was detected (401). 

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