The millimeter spectrum was reported in
(1) A. Huckauf, A. Guarnieri, D. Lentz, and A. Fayt, 1998, J. Mol. Spectrosc. 188, 109.
The ground state fundamental rotational transition with ¹⁴N and D hyperfine splitting was published in
(2) M. Krüger, W. Stahl, and H. Dreizler, 1993, J. Mol. Spectrosc. 158, 298.
The ¹⁴N and D nuclear spin-rotation parameters were kept fixed to the value from a quantum-chemical calculation, and the nuclear spin-nuclear spin coupling parameter was kept fixed to the values calculated from the structure by
(3) H. S. P. Müller, 2020, unpublished.
The calculation may be accurate enough throughout.
¹⁴N and possibly D hyperfine splitting matter in some astronomical observations. Therefore, a separate hyperfine calculation is provided for J' ≤ 5 below 46 GHz. NOTE: The partition function does take into account the spin multiplicity of the ¹⁴N and D nuclei !
The experimental dipole moment of HCCNC was published by
(4) M. Krüger, H. Dreizler, D. Preugschat, and D. Lentz, 1991, Angew. Chem. 103, 1674.