Related Experiment Video
Updated: Jul 22, 2025

Microwave-assisted Intramolecular Dehydrogenative Diels-Alder Reactions for the Synthesis of Functionalized Naphthalenes/Solvatochromic Dyes
Published on: April 1, 2013
Microwave Spectrum and Novel Molecular Structure of (Z)-1-Chloro-3,3,3-trifluoropropene-Acetylene
Helen O Leung1, Mark D Marshall1, Seohyun Hong1
1Department of Chemistry, Amherst College, P.O. Box 5000, Amherst, Massachusetts 01002-5000, United States.
Abstract:
The gas-phase heterodimer formed between (Z)-1-chloro-3,3,3-trifluoropropene and acetylene is investigated using quantum chemistry calculations and observed via chirped-pulse Fourier transform microwave (FTMW) spectroscopy. Subsequent analysis of higher resolution spectra, including those using a sample enriched in H13C13CH, obtained with a Balle-Flygare FTMW spectrometer reveals a novel structure, as predicted by theory, for the complex, in which the acetylene functions as the gas-phase (Lewis) base and the halopropene as the acid. In the equilibrium structure, the acetylene molecule is located perpendicular to the symmetry plane of (Z)-1-chloro-3,3,3-trifluoropropene with the triple bond interacting with the two olefinic hydrogens. Mapped electrostatic potential surfaces suggest that this structure results from a reduction in the nucleophilicity of the halogen atoms as compared to previously studied acetylene halo-olefin complexes and a concomitant increase in the electrophilicity of the hydrogen atoms.
Related Concept Videos
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group...
Mass Spectrometry: Cycloalkane Fragmentation
For example, cyclohexane molecular ions have a mass-to-charge ratio (m/z) of 84, which tends to produce a stronger signal than linear alkanes like hexane. This stability comes from...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...

