Infrared spectra of acetylene-water complexes: C2D2-H2O, C2D2-HDO, and C2D2-D2O

► Infrared spectra of acetylene dimers DCCD-H2O, DCCD-D2O and DCCD-HDO are studied. ► Large vibrational red shifts (−27.7 to −28.0 cm−1) are observed. ► Spectra are more easily interpretable than for the analogous HCCH-water spectra. ► Our results are generally consistent with earlier studies. ► There is a puzzling absence of transitions with Ka = 1 for C2D2-H2O and C2D2-H2O.