Interstellar hide and go seek: C₃H₄O. There and back (again)

Abstract

The molecular species C3H4O represents a striking example of an astrochemical conundrum.

Theoretical Appraisal of Cyclopropenone: Aggregation and Complexes with Water

“…22 As noted, primarily CPN (c-C 3 H 2 O), and isomers of a related molecular species C 3 H 4 O, were identified concomitantly in a cold, starless cloud in the SagittariusB2(N) region of the ISM, and also in other cold, dark clouds. 14 As for C 3 H 4 O, a species with two extra hydrogens, only trans-acrolein (CH 2 CHCHO) is definitely identifiable as pointed out by Field-Theodore and Taylor, 14 who proposed further that its methylketene (CH 3 CHCO) isomer should be a promising candidate as well, for being merely 1.9 kJ mol −1 higher in energy, albeit having hitherto eluded its detection. Fitzpatrick and Fanning 25 theoretically established that CPD, CPN, and dimethyl-CPN form stable adducts with borane and transfluoroborane, and characterized their attributes, such as structure, dipole moment, population charges, and thus forth.…”

“…Cyclopropenone (HCCOCH, or c-C 3 H 2 O, herein abbreviated “CPN”), − is another simple exotic carbene that possesses an intrinsic C 2v symmetry, which manifests in the Sagittarius B2 ( N ) region of the ISM. CPN has been theoretically, as well as experimentally investigated upon, along with its derivatives, over the past seven decades. − In particular, CPN plays its role as a tracer in nonequilibrium chemistry when interstellar acetylene and carbon-monoxide ices react under a cosmic shower . While CPN marks its presence in natural sources across the universe, some of its derivatives have demonstrated a wide range of biological activities and prominent medicinal qualities.…”

Dramatic effect of the nature of R on the intrinsic acidity and basicity of potential astrochemical R–C≡COH and R–C≡CSH compounds

“…Indeed, mainly along the last decade, a lot of information on the reactivity of many potential astrochemical compounds came from high-level ab initio calculations [1][2][3][4][5][6][7][8]. In a similar way, it was possible to determine the structure of new or potential astrochemical compounds [9][10][11][12] or predict their existence and/ or their spectroscopic properties [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], or to explore their behavior in water or ice [27][28][29]. A fairly complete set of data on different astrochemical compounds have been compiled 2 years ago [30].…”

Reassignment of the Photoelectron Spectrum of Methylketene Using a Hybrid Model of Harmonic and Anharmonic Oscillators to Compute Franck–Condon Factors

“…Since the first astronomical observation of ketene (H 2 CCO) in the interstellar medium, the search of methylketene (MK) in space followed . MK is regarded as a promising interstellar molecule to be detected because its energy is computed to be only slightly higher than trans -acrolein, the most stable isomer of C 3 H 4 O. − Given that trans -acrolein has been observed in some interstellar mediums, − it is anticipated that MK can also be detected. This line of thinking is consistent with the minimum energy principle based on thermodynamics, which describes that the abundance ratios of isomers in space are related to their energy differences. − Consequently, the more stable the isomer is, the more likely it is to be observed in the interstellar medium.…”

“…The unsuccessful hunt for MK in space has been interpreted by some research studies. For instance, based on computed potential energy surfaces, Field-Theodore and Taylor proposed that the lack of MK in interstellar space is owing to high activation energies and unfavorable kinetics . Based on photoionization experiments, Derbali et al proposed that MK might be hydrogenated or photoionized in the interstellar environment such that its abundance it too low to be detected .…”