Genetic algorithm optimization of a molecular mechanics force field for technetium

A new force field was developed using genetic algorithms (GAs) to optimize molecular mechanics (MM) parameters. The GA-MM approach was applied to the study of technetium (Tc) complexes with coordination numbers of 5 or 6 and formal oxidation states of +3 to +6 on the metal. Both soft and hard donor ligands, coordinated through dative, single, and multiple bonds to Tc, were studied. The new GA-MM force field was tested for the prediction of metric parameters (bond lengths, bond angles and dihedral angles) and overall geometry in reference to X-ray crystallographic data. Despite the chemical diversity found in technetium coordination chemistry, good modeling was achieved in a fraction of the time of higher-level, quantum-based methods, with considerably less computational resources. The GA-MM approach is general enough to be applicable to other d-block metals.