Chemistry:Disilicon carbide
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| Other names
1,3-disilaallene; Methanediylidenebis(silane)
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3D model (JSmol)
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PubChem CID
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CompTox Dashboard (EPA)
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Related compounds
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Tricarbon; Silicon dicarbide; Silicon carbide; SiC4 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Disilicon carbide is an unstable inorganic molecule with formula SiCSi or Si2C. It can exist as a dilute gas, or in a solid noble gas matrix. In nature it occurs in the envelope of super-giant carbon-rich stars.
Properties
The Si2C molecule is bent into a V shape. The angle Si-C-Si is 114.87°, and the C-Si bond lengths are 1.693 Å. This structure differs significantly from tricarbon C3 which is linear, and silicon dicarbide SiC2 which is a three-membered ring (triangle).[2] The molecule has C2v symmetry.[3]
When condensed with solid argon, it exhibits infrared absorption lines at 1188.9 and 658.2 cm−1.[3]
Disilicon carbide cations Si2C+ also exist.[4]
Early theoretical calculations of the shape of the molecule were wrong, and attempts to calculate the microwave spectrum were very sensitive to changes. Even zero-point energy causes an offset of 2 GHz. Because of nuclear spin statistics (both of carbon and silicon have their main isotopes with no spin in the nucleus), many of the rotation transitions are forbidden. Researchers also found that the lowest transition frequency was still too high for their apparatus to measure, so they use carbon-13 to increase the rotational inertia, and drop the line frequency by 10%, so that it could be measured.[5]
Production
When silicon carbide is heated to high temperature and evaporated, SiCSi is the most common molecule in the gas phase.[2]
In the lab, SiCSi can be made from silane and methane, diluted in neon, subject to an electric discharge.[2]
- 2 SiH
4 + CH
4 → SiCSi + 6 H
2
Another way to produce it is by laser ablation of solid silicon to make silicon gas, which in diluted methane, reacts to form disilicon carbide.[6]
- 2 Si + CH
4 → SiCSi + 2 H
2
Natural occurrence
Si2C has been discovered in the carbon-rich star RW Leo. In this star Si2C is ten times more abundant than C2Si.[7][8]
Other silicon-containing molecules found in carbon rich stars include SiO, SiH4, c-SiC2, SiS, SiC, C4Si, SiN, c-SiC3, SiCN, SiNC, and SiH3CN.[9]
SiCSi is likely an important component in the formation of silicon carbide grains, which are an significant part of pre-solar grains found in meteorites.[10]
References
- ↑ Informatics, NIST Office of Data and. "Disilicon carbide" (in en). https://webbook.nist.gov/cgi/cbook.cgi?ID=C12070041.
- ↑ 2.0 2.1 2.2 McCarthy, Michael C.; Baraban, Joshua H.; Changala, P. Bryan; Stanton, John F.; Martin-Drumel, Marie-Aline; Thorwirth, Sven; Gottlieb, Carl A.; Reilly, Neil J. (4 June 2015). "Discovery of a Missing Link: Detection and Structure of the Elusive Disilicon Carbide Cluster". The Journal of Physical Chemistry Letters 6 (11): 2107–2111. doi:10.1021/acs.jpclett.5b00770. PMID 26266510. Bibcode: 2015JPCL....6.2107M.
- ↑ 3.0 3.1 Kafafi, Zakya H.; Hauge, Robert H.; Fredin, Leif; Margrave, John L. (March 1983). "Infrared matrix isolation spectrum of the disilicon carbide (Si2C) molecule". The Journal of Physical Chemistry 87 (5): 797–800. doi:10.1021/j100228a020. Bibcode: 1983JPhCh..87..797K.
- ↑ Parent, Denise C. (August 1992). "Formation of silicon carbide cluster cations and their reaction with acetylene. Unusual behavior of the disilicon carbide ions". International Journal of Mass Spectrometry and Ion Processes 116 (3): 257–271. doi:10.1016/0168-1176(92)80044-2. Bibcode: 1992IJMSI.116..257P.
- ↑ Martin-Drumel, Marie-Aline; Baraban, Joshua H.; Changala, P. Bryan; Stanton, John F.; McCarthy, Michael C. (28 May 2019). "The Hunt for Elusive Molecules: Insights from Joint Theoretical and Experimental Investigations". Chemistry – A European Journal 25 (30): 7243–7258. doi:10.1002/chem.201805986. PMID 30673130. Bibcode: 2019ChEuJ..25.7243M. https://hal.science/hal-02066011.
- ↑ Witsch, Daniel; Lutter, Volker; Breier, Alexander A.; Yamada, Koichi M. T.; Fuchs, Guido W.; Gauss, Jürgen; Giesen, Thomas F. (16 May 2019). "Infrared Spectroscopy of Disilicon-Carbide, Si 2 C: The ν 3 Fundamental Band". The Journal of Physical Chemistry A 123 (19): 4168–4177. doi:10.1021/acs.jpca.9b01605. PMID 31008598. Bibcode: 2019JPCA..123.4168W.
- ↑ "The Discovery of the Molecule Si-C-Si in Space". https://www.cfa.harvard.edu/news/discovery-molecule-si-c-si-space.
- ↑ Cernicharo, J.; McCarthy, M. C.; Gottlieb, C. A.; Agúndez, M.; Prieto, L. Velilla; Baraban, J. H.; Changala, P. B.; Guélin, M. et al. (2 June 2015). "DISCOVERY OF SiCSi IN IRC+10216: A MISSING LINK BETWEEN GAS AND DUST CARRIERS OF Si–C BONDS". The Astrophysical Journal 806 (1): L3. doi:10.1088/2041-8205/806/1/L3. PMID 26722621.
- ↑ Sharma, M. K.; Chandra, S. (June 2022). "Disilicon Carbide (Si2C) in the Interstellar Medium". Astrophysics 65 (2): 266–277. doi:10.1007/s10511-022-09736-0.
- ↑ Chandra, Suresh; Denis-Alpizar, Otoniel (24 October 2024). "MASER and dasar lines of disilicon carbide (SiCSi) using accurate collisional rate coefficients". The European Physical Journal Plus 139 (10). doi:10.1140/epjp/s13360-024-05713-y. Bibcode: 2024EPJP..139..932C.
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