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When determining the stability constants for ternary complexes, M p A q B r it is common practice the fix the values for the corresponding binary complexes M p′ A q′ and M p′′ B q′′, at values which have been determined in separate experiments. Use of such constraints reduces the number of parameters to be determined, but may result ...
If the correction factor is greater than one, the reaction displays an asymmetric amplification, also known as a positive non-linear effect. Under the ML 2 model, a (+)-NLE infers a less reactive heterochiral catalyst. In this case, the equilibrium constant K also increases as the correction factor increases.
Matrix isolation is an experimental technique used in chemistry and physics. It generally involves a material being trapped within an unreactive matrix. A host matrix is a continuous solid phase in which guest particles (atoms, molecules, ions, etc.) are embedded. The guest is said to be isolated within the host matrix.
The extra constant factor introduced in the denominator was introduced because, unlike the discrete form, the continuous form shown above is not dimensionless. As stated in the previous section, to make it into a dimensionless quantity, we must divide it by h 3 N (where h is usually taken to be the Planck constant).
C is an overcounting correction factor, often used for particle systems where identical particles are able to change place with each other. [note 4] F provides a normalizing factor and is also the characteristic state function, the free energy. Again, the value of F is determined by demanding that ρ is a normalized probability density function:
There are two main kinds of complex: compounds formed by the interaction of a metal ion with a ligand and supramolecular complexes, such as host–guest complexes and complexes of anions. The stability constant(s) provide(s) the information required to calculate the concentration(s) of the complex(es) in solution.
The polar sensitivity factor ρ* can be obtained by plotting the ratio of the measured reaction rates (k s) compared to the reference reaction versus the σ* values for the substituents. This plot will give a straight line with a slope equal to ρ*. Similar to the Hammett ρ value:
In some cases, true host-guest reversibility is observed, in other cases, the encapsulated guest cannot escape. [13] Molecular encapsulation of a nitrobenzene bound within a hemicarcerand. [14] An important implication of encapsulation (and host-guest chemistry in general) is that the guest behaves differently from the way it would when in ...