A theoretical study on the reaction of C₃H⁺ with H₂O

The mechanism for the ion-molecule reaction of the carbene cation C₃H⁺ with H₂O in gas phase is investigated at the QCISD(T)/6-311 + G(2df,p)//B3LYP/6-31G(d,p) level. It is shown that three low-lying dissociation products may be produced exothermically via complex reaction channels. Our calculated mechanism for the formation of the three products can reasonably explain the product distribution measured by Raksit and Bohme. The possible formation of the elusive interstellar propynal, propadienone and cyclopropenone via the ion-molecule reaction between C₃H⁺ and H₂O is also discussed. The results presented in this article may be useful for understanding the chemical behavior of the carbene cation C₃H⁺ and also other carbene cations either in burning or interstellar processes.