IR SPECTROSCOPY OF MATRIX-ISOLATED PROPARGYL RADICALS.

PAUL R. WINTER, G. BARNEY ELLISON, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309; JULIUSZ G. RADZISZEWSKI AND MARK R. NIMLOS, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401.

Organic radicals isolated in a rare gas (Ar or Ne) matrix at 10K can be prepared by UV photolysis of a suitable precursor. A precursor/rare gas mixture is deposited on a CsI window at 30K and cooled to 10K. The matrix is then irradiated with UV light for several hours to photodecompose the precursor. IR absorption spectra are recorded before, during, and after the photolysis using a Fourier transform spectrometer. We have prepared propargyl radical in the photodecomposition 1-butyn-3-nitrite (HCCCH2 CH2ONO) at 254 nm. \begincenter HCCCH2CH2ONO \longrightarrow HCCCH2CH2O + NO HCCCH2CH2O \longrightarrow HCCCH2 + CH2O \endcenter We have identified the propargyl radical, along with formaldehyde and nitric oxide, in the photoproducts of the butynnitrite decomposition and assigned many of the IR fundamentals of propargyl in the Ar matrix. \begincenter

nu1 3316 cm-1
nu2 3102 cm-1
nu3 1955 cm-1
nu4 1446 cm-1
nu5 1028 cm-1
nu6 656 cm-1
nu10 986 cm-1
nu11 638 cm-1

\endcenter We are currently working to produce the propargyl radical and dueterated isotopes from a variety of other precursors, including propargyl bromide (HCC-CH2-Br) and bromoallene (CH2=C=CHBr).