Water/cyanobutadiyne complexes: an infrared matrix isolation and theoretical study.

The structures and energies of the 1:1 HC5N:H2O complexes in solid argon matrices have been investigated using FTIR spectroscopy and ab initio calculations, at the B3LYP/6-31G** and MP2/6-31G** levels of theory. Two types of 1:1 complexes are observed. The first one corresponds to the NH structure characterized by a hydrogen bond between H2O and the nitrogen of HC5N. The second corresponds to the OH form that involves a van der Waals interaction between the hydrogen of HC5N and the oxygen of water. HC5N can thus act either as an electrophile or as a nucleophile in complexes with water.