Tricarbon monosulfide explained

Tricarbon monosulfide (C₃S) or tricarbon sulfur is a reactive molecular substance that has been detected in outer space. Tricarbon monosulfide is a heterocumulene or thiocumulene, consisting of a straight chain of three carbon atoms and a terminal sulfur atom.^[1]

Properties

The dipole moment of tricarbon monosulfide is 3.704 debye. The bond lengths are 1.275 Å, for terminal C=C bond, 1.292 Å for internal bond, and 1.535 Å for the C=S bond. The similar bond lengths between the carbon atoms indicate they each have a double bond nature.^[1] The rotational constants for ¹²C¹²C¹²C³²S are B₀ = 2890.38000 MHz and D₀ = 0.00022416.

There is a characteristic infrared absorption band at 2047.5 cm⁻¹ due to stretching of a C=C bond.

Formation

Along with the related dicarbon monosulfide (CCS), tricarbon monosulfide was made by a glow discharge though carbon disulfide vapour in helium. Microwave emission lines from rotational transitions matched up with previously unknown molecular lines from the Taurus molecular cloud 1.^{[2] [3]} Maximal concentrations occurred with a carbon disulfide pressure of 0.02 torr.

In molecular clouds, the formation mechanism is speculated to be CCS + CH → CCCS + H.^[4]

On dust grains, in space the formation mechanism is theorised to be: CCC + H₂S → C₃•HSH → CCCS + H₂ when irradiated with visible or UV light. THis reaction has been reproduced in a solid argon matrix.^[5]

Natural occurrence

Tricarbon monosulfide has been detected in molecular clouds in space, such as the Taurus molecular cloud^[1] and the Kleinmann–Low Nebula. The ratio of tricarbon monoxide to tricarbon monosulfide reflects the ratio of sulfur to oxygen in the cloud. The ratio of concentration of sulfur to oxygen analogues follows the same pattern.^[1] The clouds can be cold and dark, or warm.^[6] CCCS has also been found in the stellar envelope of carbon-rich AGB stars, including in IRC+10216.^[7]

Notes and References

1. Etim . E. E. . Onudibia . M. E. . Asuquo . J. E. . Ukafia . O. P. . Andrew . C. . Ushie . O. A. . Interstellar C₃S: Different Dipole Moment, Different Column Density, Same Astronomical Source . FUW Trends in Science & Technology Journal . April 2017 . 2 . 1B . 574–577 .
2. Saito . Shuji . Kawaguchi . Kentarou . Yamamoto . Satoshi . Ohishi . Masatoshi . Suzuki . Hiriko . Kaifu . Norio . Laboratory detection and astronomical identification of a new free radical, CCS(³Σ^-) . Astrophysical Journal . 15 June 1987 . 317 . L115–L118 . 1987ApJ...317L.115S . 10.1086/184923. free .
3. Saito . Shuji . Kawaguchi . Kentarou . Yamamoto . Satoshi . Ohishi . Masatoshi . Suzuki . Hiriko . Kaifu . Norio . Laboratory detection of a new carbon-chain molecule C3S and its astronomical identification . Astrophysical Journal . 15 June 1987 . 317 . 2 . L119–L121 . 1987ApJ...317L.119Y . 10.1086/184924.
4. Sakai . Nami . Ikeda . Masafumi . Morita . Masaru . Sakai . Takeshi . Takano . Shuro . Osamura . Yoshihiro . Yamamoto . Satoshi . Production Pathways of CCS and CCCS Inferred from Their ¹³C Isotopic Species . The Astrophysical Journal . 10 July 2007 . 663 . 2 . 1174–1179 . 10.1086/518595 . 2007ApJ...663.1174S . free.
5. Roehr . Nathan P. . Szczepanski . Jan . Fu . Yi . Polfer . Nicolas C. . Vala . Martin . Reaction of the C₃(X¹Σ_g⁺) carbon cluster with H₂S(X¹A₁), hydrogen sulfide: Photon-induced formation of C₃S, tricarbon sulfur . The Journal of Chemical Physics . 26 November 2014 . 141 . 20 . 204310 . 10.1063/1.4901891 . 25429945 . 0021-9606 . 2014JChPh.141t4310R.
6. Tercero . B. . Cernicharo . J. . Pardo . J. R. . Goicoechea . J. R. . A line confusion limited millimeter survey of Orion-KL I. Sulfur carbon chains . Astronomy and Astrophysics . 17 August 2010 . 517 . A96 . 10.1051/0004-6361/200913501 . 2010A&A...517A..96T . 1004.2711 . 119251515.
7. 1993ApJ...417L..37B . C₃S and C₅S in IRC +10216 . Astrophysical Journal Letters . 417 . L37 . Bell . M. B. . Avery . L. W. . Feldman . P. A. . 1993 . 10.1086/187088.