The universal force field approach is used to investigate the steric demand in nitrogen molecule cleavage by three-coordinate molybdenum complexes MoL3 of different ligand types L (L = NH2, NMe2, N(mesityl)(tert-butyl), O(tert-butyl), Me, tert-butyl, neopentyl). Calculated geometries of the intermediates L3Mo-N-2-MoL3, of the products L3MoN, and of the undersirable side product dimers L3MoMoL3 are presented. The primary role of ligand sterics appears to be the prevention of dimerization of MoL3 monomers.