Photoelectron spectroscopy of the allenyl ion CH/sub 2/=C=CH/sup -/

Journal Article · Wed May 18 04:00:00 EDT 1983 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00348a008· OSTI ID:5750107

Oakes, J M; Ellison, G B

We have studied the photodetachment spectra of CH/sub 2/=C=CH/sup -/, CD/sub 2/=C=CH/sup -/, and CH/sub 2/=C=CD/sup -/ using deuterium-labelled methylacetylenes and allene and pricussors. By comparing the photoelectron spectra of these selectively labeled species, we conclude that the ion has an allenyl (rather than propargyl) structure. The electron affinities (EA) of a set of propargyl radicals are as follows: EA(CH/sub 2/C=CH) = 0.893 +- 0.025 eV, EA(CD/sub 2/C=CH) = 0.907 +- 0.023 eV, and EA(CH/sub 2/C=CD) = 0.88 +- 0.15 eV. A single active vibration is observed in the photoelectron spectra of CH/sub 2/=C=CH/sup -/ and CD/sub 2/=C=CH/sup -/. This mode has a frequency of 510 cm/sup -1/ and is assigned as an out-of-plane bend of the acetylenic hydrogen of the propargyl radical (either CH/sub 2/C=CH or CD/sub 2/C=CH). The gas-phase acidity of allene and methylacetylene are reported as ..delta..H/sup 0//sub acid/ (H-CH/sub 2/CCH) = 382.3 +- 1.2 kcal/mol and ..delta..H/sup 0//sub acid/ (H-CH=C=CH/sub 2/) = 380.7 +- 1.2 kcal/mol. The ..delta..H/sub f//sup 0//sub 298/ (CH/sub 2/=C=CH) is 59.4 +- 1.2 kcal/mol.

• Research Organization: Univ. of Colorado, Boulder
• DOE Contract Number: AC02-80ER10722
• OSTI ID: 5750107
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:10; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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AFFINITY
ALKYNES
ALLENE
DATA
DEUTERIUM
DIENES
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN ISOTOPES
INFORMATION
IONIZATION
ISOTOPE EFFECTS
ISOTOPES
ISOTOPIC EXCHANGE
LABELLING
LIGHT NUCLEI
MASS SPECTRA
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXYGEN
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
POLYENES
RADICALS
SAMPLE PREPARATION
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS