C3H2 interstellar

The radio detection of a small molecule formed of three carbons and two hydrogens by Thaddeus et al. [1] in 1985 came as a surprize to all astrochemists cyclopropenylidene C3H2, last bom to the small world of detected interstellar species was soon to become famous, though competition is high in this world where exotism is common. 

C3H2 a puzzling interstellar molecule F. PauzatandD. Talbi... 

As far as acyclic allene hydrocarbon intermediates are concerned, these begin with a C3H2 species, 254, about which there has been considerable discussion since it has also been detected in radioastronomy studies to belong to the (growing) number of organic compounds present in interstellar and circumstellar space [105]. 

Ochsenfeld, C. Kaiser, R.L Lee, Y.T. Suits, A.G. Head-Gordon, M. A coupled-cluster ab initio study of triplet C3H2 and the neutral-neutral reaction to interstellar C3H. J. Chem. Phys. 1997, 106, 4141-4151. 

Vrtilek, J.M. Gottlieb, C.A. Thaddeus, P. Laboratory and astronomical spectroscopy of C3H2, the first interstellar organic ring. Astrophys. J. 1987, 314, 110-125,. 

Takahashi, J. Yamashita, K. Ab initio studies on the interstellar molecules C3H2 and C3H and the mechanism for the neutral-neutral reaction C(V)-HC2H2. J. Chem. Phys. 1996, 104, 6613-6627. 

The species labeled (y/) have been observed in interstellar molecular clouds. The four products of dissociative recombination (17.21,17.22a,b) are all observed. The cyclic C3H2 is a very abundant interstellar species. 

The rotational spectrum has been calculated accuratly by ab-initio methods [2], and has been measured in the laboratory with high precision [3,4], so that the radio detection of C3H2 can be done without ambiguity, encouraging its search in different environments as dense dark clouds [5], diffuse interstellar medium [6] or HII regions [7]. 

The exciting discoveries of Interstellar hydrocarbon ring molecules have been very recent. Cyclopropenylidene, C-C3H2, appears to be widely distributed in the Interstellar medium millimetre-wave transitions of C-C3H2 have recently been identified in emission in several cold molecular dust clouds and in absorption in the direction of the galactic center (4). The detection of the related cyclic C3H radical molecule has been reported just recently (5). Toward mc-l the column density of C-C3H is comparable to that of linear C3H, I-C3H, and is about one order of magnitude lower than that of C-C3H2 (5). 

Many new interstellar molecules have been detected recently, chiefly at the IRAM and Nobeyama facilities, and new gas phase syntheses have bran proposed to explain their abundances. The syntheses of the newly observed radicals C5H and CgH have already been discussed. Below we consider syntheses for the cyclic molecules C3H and C3H2, the organo-sulfur species CCS and CCCS, and PN. 

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