Linear free energy relationship modelling for predicting metal-ligand stability constants by thermodynamic radii

The thermodynamic radii of 15 metal ions Ag⁺, Al³⁺, Am³⁺, Ba²⁺, Be²⁺, Fe³⁺, Ga³⁺, Hg²⁺, In³⁺, K⁺, Li⁺, Na⁺, NpO₂⁺, Sr²⁺, and UO₂²⁺ were calculated by linear free energy relationship modelling using 8269 experimental stability constants (log<i>K</i>) of ML complexes of 42 metal ions (M) and 1990 diverse organic ligands (L) in water. The predictive performance of relationships on the base of the thermodynamic radii was estimated on 5272 combinations of ligands and metal ion pairs of external test sets. Squared determination coefficient (Rdet2) and root mean squared error (<i>RMSE</i>) of log<i>K</i> predictions are 0.801 and 2.4 for combined data of the test sets, respectively. The corresponding performances for the 3003 combinations of training data are Rdet2 0.921 and <i>RMSE</i> 1.7.