Are cumulenones kinked? A systematic high-level ab initio study of H2CCCO, H2CCCCO and H2CCCCCO

Abstract

The cumulenones, propadienone (H2C=C=C=O), butatrienone (H2C=C=C=C=O) and pentatetraenone (H2C=C=C=C=C=O) have been systematically investigated with high-quality ab initio methods. At our highest levels of theory, the equilibrium structures of all three cumulenones show significant bending in the heavy-atom chain. Although the barrier to linearity of the carbon chain is significant for propadienone (approximately 5 kJ mol-1), the calculated barriers for butatrienone and pentatetraenone are very small (less than 0.5 kJ mol-1). Calculated spectroscopic properties of the cumulenones are in good agreement with available experimental data. Show more