Cyclopropenylidene chemistry in the interstellar medium Athena R. Flint, C. Zachary Palmer, Alexandria G. Watrous, Brent R. Westbrook, Blake N. Rogers, Dev J. Patel and Ryan C. Fortenberry Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi,38677-1848, USA A series of functionalized cyclopropenylidenes and functionalized cyclopropenes are quantum chemically investigated for their potential to form in the cold ISM. Cyclopropenylidene is one of the most prevalent molecules in the interstellar medium (ISM) and other cosmic environments. However, for many years after its initial detection, little was known about the kinds of chemistry in which it might participate. The detection of cyclopropenone in 2006 1 and ethynyl cyclopropenylidene in 2021, 2 and subsequent computational analysis of their formation pathways, 3,4 highlight cyclopropenylidene as an important precursor of molecules both known and unknown in the ISM. To supplement results in the literature and build a greater knowledge of the possibilites of cyclopropenylidene chemistry, chemically accurate CCSD(T)-F12/cc-pVTZ-F12 (F12-TZ) calculations are used to locate chemically viable formation pathways for various cyclopropenylidene derivatives. Four currently undetected monosubstituted cyclopropenylidenes ( c -C 3 HX, X=CN, OH, NH 2 , F), 5 three disubstituted cyclopropenylidenes ( c -C 3 XX', X or X' = C 2 H, CN), 6 and four functionalized cyclopropenes ( c -C 3 H 2 X, X=NH, CH 2 , S, CC) 7 are presented as possible cosmic chemical species. c -C 3 HCN is a likely candidate for detection due to its greatly exothermic reaction pathway (-16.10 kcal mol -1 ) and large dipole moment (3.06 D). However, a small dipole moment (0.08 D) and lack of intense vibrational modes renders c -C 3 (CN) 2 likely undetectable despite favorable formation. Other disubstituted cyclopropenylidenes have favorable spectroscopic profiles for detection. c -C 3 H 2 S and c -C 3 H 2 NH have reaction profiles largely favorable for formation when considering the possibility of competing reaction products. The formation of c -C 3 H 2 CH 2 is barriered, but such a barrier may be surmountable in circumstellar environments where a radio line for that species has been tentatively detected. 8 References
1. Hollis J. M. et al. 2006, ApJ,642,933 2. Cernicharo J. et al. 2021, A&A,649,L15 3. Ahmadvand S. 2018, PhD thesis, University of Nevada, Reno, NV 4. Fortenberry R. C. 2021, ApJ, 921, 132 5. Flint A. R. and Fortenberry R. C. 2022, ApJ, 938, 15 6. Flint A. R. et al. 2023, A&A, 671, A95 7. Flint A. R., Rogers B. N. and Fortenberry R. C. 2023, MNRAS (submitted) 8. Rojas-García O. S. et al. 2022, ApJSS, 262, 13
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