Anharmonic Vibrational Analysis for the Propadienylidene Molecule (H2C═C═C:).
Qunyan Wu1, Qiang Hao1, Jeremiah J Wilke1
1Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
Singlet propadienylidene (vinylidenecarbene) vibrational frequencies were accurately calculated using advanced computational methods. These theoretical results closely match experimental data, aiding in the understanding of this interstellar molecule.
Area of Science:
- Astrochemistry
- Computational Chemistry
- Molecular Spectroscopy
Background:
- Singlet propadienylidene (vinylidenecarbene) was identified in interstellar space.
- Accurate theoretical data is crucial for interpreting experimental observations of this molecule.
Purpose of the Study:
- To determine an accurate quartic force field for singlet propadienylidene (3S).
- To calculate fundamental vibrational frequencies and related spectroscopic constants for 3S and its isotopologues.
Main Methods:
- Ab initio coupled-cluster (CC) calculations with single and double excitations and perturbative triple excitations [CCSD(T)] method.
- Correlation-consistent core-valence quadruple-ζ (cc-pCVQZ) basis set.
- Vibrational second-order perturbation theory (VPT2) for spectroscopic property determination.
Main Results:
- Theoretical zero-point vibration corrected rotational constants (B0) agree with experimental values within 0.3%.
- Isotopic shifts of rotational and vibrational frequencies show excellent agreement with experimental data.
- A mean absolute deviation of only 2.6 cm(-1) was found between theoretical anharmonic and experimental fundamental vibrational frequencies for most modes.
Conclusions:
- The calculated spectroscopic properties provide a reliable theoretical benchmark for singlet propadienylidene.
- The study validates the computational approach for studying interstellar carbene species.
- A discrepancy in the CH2 symmetric stretch suggests a potential re-evaluation of experimental assignments.
More Related Videos
09:35Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
08:54Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid
Published on: January 25, 2020
Related Concept Videos
01:24π Molecular Orbitals of 1,3-Butadiene
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
01:18Aromatic Hydrocarbon Anions: Structural Overview
Due to the absence of continuous...
01:18π Molecular Orbitals of the Allyl Cation and Anion
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
01:24IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds