Molecular-mechanical analysis of the structure of strained organic molecules. Communication 3. Substituted bicyclo[1.1.0]butanes

Abstract

1. The complex use of the MM/2 molecular mechanics method and quantum chemical calculations was proposed for the description of the structural and thermochemical characteristics of bicyclo [1.1.0]butane and its polycyclic derivatives, which have not previously been studied experimentally. 2. The structural and energetic consequences of substitution of different positions in the bicyclobutane molecule were analyzed, and the determining role of a change in the dihedral angle between the planes of the three-member rings and the degree of pyramidicalness of the inverted tetrahedral bridge carbon atoms was demonstrated. 3. A new variant of inclusion of the bicyclobutane fragment in the polycyclic backbone structure due to linkage of positions 1 and exo-2 by a polymethylene bridge was proposed, and the tetramethylene bridge formed in this six-member ring is optimum.