The gas phase vibrational spectroscopy of cryogenically cooled C2n + 1N− anions with n = 1 − 5 is investigated in the spectral range of the C≡C and C≡N stretching modes (1850–2400 cm–1) by way of infrared photodissociation (IRPD) spectroscopy of messenger-tagged C2n+1N–· mD2 complexes. The IRPD spectra are assigned based on a comparison to previously reported anharmonic and harmonic CCSD(T) vibrational frequencies and intensities. Experimentally determined and predicted anharmonic vibrational transition energies lie within ± 21 cm–1. For the harmonic CCSD(T)/vqz+ vibrational frequencies a scaling factor of 0.9808 is determined, resulting in comparable absolute deviations. The influence of the D2-messenger molecules on the structure and the IRPD spectrum is found to be small. Compared to the results of previous IR matrix isolation studies additional, in particular weaker, IR-active transitions are identified.
