Interaction of Ca2+ and Mg2+ with Ionophores Studied by Using a Pair‐Potential Model Based on ab initio Calculations

Atom pair potentials are obtained from ab initio SCF‐LCAO‐MO calculations for model complexes of Mg2+ and Ca2+ with N, N‐dimethylacetamide, and malonamide. The SCF‐LCAO‐MO interaction energies for 271 complexes of Mg2+ and 271 complexes of Ca2+ with these amides were fitted with a simple analytical potential by a least‐square procedure. Interaction energies and optimal ion locations obtained by pair‐potential calculations are compared with values obtained by ab initio calculations for some related amides. The application of the atom pair potentials to the structure of the Mg2+‐complex [MgCl2 (C3H7ON)6] of N‐ethylacetamide is discussed.