First observation of alkyne radical anions by electron spin resonance spectroscopy: Hexyne/ n -hexane mixed crystals

Journal Article · Fri Mar 01 04:00:00 EST 1991 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.460659· OSTI ID:6255284

Matsuura, K; Muto, H ^[1]

---

1. Government Industrial Research Institute, Nagoya, Hirate-cho, Kita-ku, Nagoya, 462, Japan (JP)

The radical anions of alkynes have been first observed by electron spin resonance spectroscopy following alkene anions previously studied. Hexyne radical anions were formed in 1-, 2-, or 3-hexyne/{ital n}--hexane mixed crystals irradiated at 4.2 or 77 K. The characters of the anions were as follows; (a) the {alpha}-proton hyperfine coupling is very large ({similar to}4.5 mT for the 1-hexyne anion), (b) the {beta}-proton couplings are very small ({similar to}1.0 mT for C--H{sub {beta}} proton with the conformational angle of 0{degree}), and (c) the radicals show a negative {ital g} shift (2.0014). From these observations, it was found that the anions have a nonlinear(bent) molecule structure in the anticonfiguration ({ital trans} C--C{equivalent to}C--C) with the bend angle {similar to}60{degree}, and that the unpaired electron orbital is approximately composed of the anticombination of the {ital sp}{sub 2} hybrid orbitals of the C{equivalent to}C carbon atoms. A discussion based on complete neglect of differential overlap (CNDO) molecular orbital (MO) calculations was given for the observed negative {ital g} shift, which was shown to be characteristic of the alkyne anions which have a high-lying unpaired electron orbital and an antibonding 2{ital p}--2{ital p} {pi} carbon orbital just above it on the upper energy side.

• OSTI ID: 6255284
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 94:5; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ALKANES
ALKYNES
ANIONS
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
CRYSTALS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
HYDROCARBONS
IONIZING RADIATIONS
IONS
MAGNETIC RESONANCE
MOLECULAR CRYSTALS
ORGANIC COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
RESONANCE
STRUCTURAL CHEMICAL ANALYSIS
X RADIATION