ORGANOSILICON RINGS - STRUCTURES AND STRAIN ENERGIES

Geometries, strain energies, and electronic structures for 23 organosilicon compounds have been determined. The species studied were those for which silicon successively replaced carbon in cyclopropane, bicyclobutane, and [1.1.1]propellane and in propane, cyclobutane, and bicyclo[1.1.1] pentane. Wave functions constructed from the recently developed compact effective core potentials and using a split-valence, d-polarized basis set were employed. Accurate strain energies, validated by extensive comparison with existing experimental data and ab initio calculations, were obtained from a series of homodesmic reactions. When the compounds investigated are displayed in a periodic table format (increasing number of silicon replacements down a column, increasing number of fused rings across rows) many useful interrelationships and bonding patterns manifest themselves. In spite of their considerable complexity in structure and properties, it proves possible to understand them in terms of electronegativity arguments and a simple two-orbital, three-atom, molecular orbital model. Our results also predict several interesting new organosilicon compounds, and an analysis of their synthetic accessibility suggests that these new species should be realizable. © 1990, American Chemical Society. All rights reserved.