Cyanoacetylene, HC3N (H–C≡C–C≡N), is an organic molecule that is the simplest cyanopolyyne (H(–C≡C–)n–C≡N). It was one of the first molecules detected in space using radioastronomical techniques (Turner 1971). It is also an important component of Titan’s atmosphere (Kunde et al. 1981), where it is found in the gas phase in the upper atmosphere and in ice form in the lower stratosphere (see, e.g., Anderson et al. 2010). It is a trace constituent in cometary atmospheres (comae). Cyanoacetylene has been proposed as a prebiotic reagent for the formation of pyrimidine bases, nucleosides, and nucleotides (Sanchez and Orgel 1970; Powner et al. 2009).