Laboratory Studies on the Infrared Absorptions of Hydrogenated Carbon‐Silicon Clusters: Directing the Identification of Organometallic SiCH_xSpecies toward IRC +10216

Abstract

Silicon-bearing species of the molecular formula SiCH x (x ¼ 1 6) are plausible candidates for organometallic molecules that might be present in the circumstellar envelope of IRC +10216. Combining matrix-isolation laboratory experiments with computed vibrational spectra of these molecules, we have observed several fundamentals of the new silicon-containing radicals SiCH 3 and SiCH 5 , in addition to the well-known SiCH 4 and SiCH 6 species, via infrared spectroscopy. These bands can now be used to search for hydrogen-deficient silicon-carbon-carrying molecules in the circumstellar envelope of the carbon star IRC +10216; the column densities of these species will yield valuable clues to the formation of silicon carbide molecules (SiC), together with their aggregates and partially hydrogenated clusters in the interstellar medium.

The UMIST database for astrochemistry 2006

“…The curves calculated using the latest RATE06 rate coefficients are labelled "RATE06" and "RATE06-dipole" for the non-dipole and dipole versions respectively. The curve labelled "RATE99" uses the rate coefficients for the radiative association of CH Notes: c-C 3 H = 2.4D; HCCCCH = 0D; H 2 C 3 H(propargyl) = 0.14D; H 2 CCCC = 4.1D from Oswald & Botschwina (1995); HCSi from Smith et al (2001); HCS from Ochsenfeld et al (1999); HS 2 from Zhuo et al (1994); CCP from El-Yazal et al (1997); CCl from Largo et al (2001); H 2 SiO from Ma & Schaeffer (1994); CH 2 CN from Gutsev & Adamowicz (1995); SiCH 3 from Kaiser & Osamura (2005); C 3 P from del Rio et al (1996); C 4 P from Yu et al (2005); C 4 S from Pascoli & Lavendry (1998); C 5 N from Botschwina (1996); CnH 2 , n = 5-9, from Maluendes & McLean (1992). …”

A Combined Experimental and Theoretical Study on the Formation of the 2-Methyl-1-silacycloprop-2-enylidene Molecule via the Crossed Beam Reactions of the Silylidyne Radical (SiH; X2Π) with Methylacetylene (CH3CCH; X1A1) and D4-Methylacetylene (CD3CCD; X1A1)

“…90,[92][93][94] Therefore, it is crucial to systematically explore the chemical dynamics of neutral-neutral reactions involving silicon-bearing reaction partners such as the silylidyne radical (SiH; X 2 Π) with hydrocarbon molecules leading to the formation of simple organosilicon molecules (SiC x H y , x≤6, y≤6) under single collision conditions. [95][96][97][98] These organosilicon molecules have also attracted great interest from the physical organic chemistry community due to the distinct chemical bonding of silicon versus its isovalent carbon counterpart. [99][100][101][102][103] Studies utilizing the crossed molecular beam approach involving isovalent 32 and silaisocyano products (HCCNSi, silaisocyanoacetylene; C 2 H 3 NSi, silaisocyanoethylene) 32 ( Figure 2).…”

Quantum scattering study of the abstraction reaction of H atoms from tetramethylsilane

“…Since their detection in the interstellar medium (ISM) [1], both in the gas phase of molecular clouds [2] and in the circumstellar envelope (CSE) of carbon-rich stars [2][3][4][5][6][7], silicon carbide molecules and grains have been the subject of a growing scientific interest [8][9][10]. MacKay and Charnley [7] reported silicon bearing species (SiC, SiC 2 , SiC 4 , SiH 2 and SiH 4 ) observed in the CSE of the carbon-rich star IRC +10216 (Cw Leo) at the temperature of 2200 K and larger silicon bearing species are expected to be present in the Universe [9].…”