The adsorption of tris(1,10-phenanthroline)metal(II) ([M(phen)3]2+) by a clay is studied with Monte Carlo simulations. A two-dimensional sheet of linked [SiO4]4- and [AlO4]5- tetrahedra is used for the model tetrahedral sheet of a clay. The thermal distributions of the configurations are obtained using a Metropolis algorithm at 300 K. The binding states are compared when the racemic or enantiomeric pairs of the chelates are intercalated between two sheets separated at 11 Å. The intermolecular distance rM,M, at the minimum free energy is smaller for the racemic pair (9.2 Å) than for the enantiomeric pair (11.4Å). The racemic pair has a mean binding energy 0.0114 au (29.9 kJ/mol) lower than the enantiomeric pair. It is, therefore, concluded that the racemic pair of [M(phen)3]2+ forms a more compact and stable pair than does the enantiomeric pair. The conclusions support the recent experimental findings as to the racemic adsorption of [M(phen)3]2+ (M = Ni, Fe, and Ru) by montmorillonite. © 1992 American Chemical Society.