A fully flexible, quantitative model based on Allinger’s MM2 force field has been developed to predict diastereoinduction in intramolecular nickel-catalyzed [4 + 4] cycloadditions. The position of all atoms are optimized with a force field consisting of MM2 parameters for normal atoms and new parameters for atoms attached to the metal. The new parameters for MM2 were derived from crystallographic data augmented by ab initio calculations where experimental data were lacking. Application of this new force field to a number of test complexes demonstrates that the method can be used to predict molecular structures for these systems and that the pi-allyl parameters are transferable to other square-planar metal complexes. Initial modeling studies on the conformational preferences of species relevant to nickel-catalyzed cyclodimerizations are presented. Molecular mechanics calculations on various proposed organonickel species suggest that stereoselectivity can be reproduced by consideration of the energies of stereoisomeric anti-eta1,eta3-bis-allylic nickel phosphine complexes. Predictions of new stereoselectivities are made for several systems.