Equilibrium structure and fundamental frequencies of allene

Abstract

The r_e structure of allene is revised on the basis of high-level quantum chemical calculations (CCSD(T)/cc-pVQZ and CCSD(T)/cc-pCVQZ) as well as ia analysis of experimental rotational constants for C₃H₄, C₃D₄ and H₂C₃D₂ employing vibrational corrections obtained from quantum chemical calculations (SDQ-MBPT(4)/cc-pVTZ). For the equilibrium geometry a least-squares fit to the corrected rotational constants yields r(C–H) = 1.081 Å, r(C–C) = 1.307 Å, α(HCH) = 118.35° in satisfactory agreement with a previous, though less precise r_e structure based on gas-phase electron diffraction data. In addition, computed harmonic and fundamental frequencies are reported and compared to experimental values.