Theoretical study of the reaction of Cl+ with C3H2

A theoretical study of the (ClC3H2)(+) species has been carried out. Two di fferent models, the complete MP4 at MP2 geometries and the QCISD(T) at B3LY P geometries, have been employed. Our calculations predict that the global minimum is a cyclic isomer with a three-membered carbon ring, ClC3H2+((1)A( 1)), whereas two different open-chain structures, ClCCCH2+((1)A(1)) and ClH CCCH+((1)A'), lie similar to 19 and 15 kcal/mol, respectively, higher in en ergy. The lowest-lying triplet state is an open-chain structure, ClCCCH2+(( 3)A "), which lies >57 kcal/mol above the global minimum. These theoretical results allow the development of thermodynamic arguments about the reactio n pathways of the process Cl+ +- C3H2 For the reaction of Cl+ with vinylide necarbene (1-C3H2), the production of ClCCCH+ is both thermodynamically and kinetically favored, and even the formation of ClC3H+ is also more exother mic than the charge transfer. In the reaction of Cl+ with cyclopropenyliden e (c-C3H2), the production of both cyclic and open-chain chlorine-carbon co mpounds seems to be severely hindered; hence, charge transfer should be the dominant process. Consequently, only the reaction of Cl+ with 1-C3H2 seems to be a possible source of chlorine-carbon compounds in space, and the pre ferred product should be linear ClCCCH+, which could be a precursor to ClCC C.