Quantitative Correlations Between Strain and Stability Differences

4 Quantitative Correlations Between Strain and Stability Differences 

Linear and non-linear correlations of structural parameters and strain energies with various molecular properties have been used for the design of new compounds with specific properties and for the interpretation of structures, spectra and stabilities 661. Quantitative structure-activity relationships (QSAR) have been used in drug design for over 30 years 2881 and extensions that include information on electronic features as a third dimension (the electron topological approach, ET) have been developed and tested 481 (see Section 2.3.5). Correlations that are used in the areas of electron transfer, ligand field properties, IR, NMR and EPR spectroscopy are discussed in various other Chapters. Here, we will concentrate on quantitative structure-property relationships (QSPR) that involve complex stabilities 124 289-2911. 

In order to get relative strain energies and to simplify the analysis La(III) is defined as a reference point, and Eq. 9.6 is the corresponding strain energy equation. The correlation of these computed strain energy data sets with corresponding, experimentally available thermodynamic data leads to the QSPR defined in Eq. 9.7. 

There are some major limitations to the prediction of metal ion selectivities by molecular mechanics calculations alone. This is due to a number of approximations inherent in the methods discussed above, and these restrict the reliability of the calculated stabilities. The main points are as follows. 

Second, Completely Revised and Enlarged Edition Peter Comba, Trevor W. Hambley copyright WILEY-VCH Verlag GmbH, 2001 

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Quantitative Correlations Between Strain and Stability Differences 123 9.4... 

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