Azidoacetylene – interpretation of gas phase infrared spectra based on high-level vibrational configuration interaction calculations

Abstract

Azidoacetylene is a highly explosive substance, which has been synthesized and characterized for the first time quite recently [Banert et al., Angew. Chem., Int. Ed., 2012, 51, 7515]. As outlined in this work, the vibrational spectrum of azidoacetylene is dominated by strong couplings. For that reason, we have studied the vibrational spectrum of the title compound by gas phase measurements and high-level vibrational structure calculations beyond the harmonic approximation. Based on the interplay of theory and experiment, we were able to identify all fundamentals, strong Fermi resonances and intense overtones, which contribute to the spectrum.

Synthesis, Characterization and Reactions of (Azidoethynyl)trimethylsilane

“…The IR data of 6 are similar to the corresponding frequencies which were observed for 3 after measurement in chloroform at −20 °C [13]. In the latter case, however, the intensity pattern was quite different owing to strong vibrational coupling by Fermi resonances [15].…”

“…In solution at low temperature, the unique azide 3 was characterized by NMR and IR spectroscopy. The latter method was also utilized to analyze unstable 3 in the gas phase or in argon matrix, and to monitor the thermal or photochemical decay to generate cyanocarbene 4 [15,16]. In the case of the parent compound 3, previous ab initio studies predicted the highest barrier for the loss of dinitrogen, whereas ethynyl azides with a substituent at C-2 should more easily undergo the cleavage reaction [17].…”

Breakthrough Potential in Near-Infrared Spectroscopy: Spectra Simulation. A Review of Recent Developments

“…Other anharmonic methods may also be mentioned, e.g., vibrational configuration interaction (VCI) (Whitehead and Handy, 1975) and vibrational coupled-cluster (VCC) (Christiansen, 2004) methods. These computationally highly expensive approaches are rarely found in the literature being used for the simulation of MIR spectra of simple molecules, particularly in cases where certain vibrational intricacies cannot be omitted (Oschetzki et al, 2013). Ongoing development in high-power computing may result in an increased application of these methods in the future.…”

Vibrational Spectrum and Gas‐Phase Structure of Disulfur Dinitride (S2N2)

“…14 The many‐mode expansion of the potential energy surface used in these calculations was truncated after the three‐mode coupling terms, and is thus considered to be more accurate than the quartic force field used in the VPT2 calculations. However, the three‐mode coupling terms were determined in combination with basis sets of double‐ζ quality, which usually is an excellent approximation once explicitly correlated coupled‐cluster theory is used 43. Vibrational angular momentum terms were included within the Watson Hamiltonian for non‐rotating molecules ( J =0) 44.…”