Molecular complexes between carbon suboxide and acetylene derivatives: a cryogenic matrix and theoretical study Original Research Article

The structure and energy of the 1:1 acetylene/C3O2 and cyanoacetylene/C3O2 complexes in solid argon matrices have been investigated using FTIR spectroscopy and ab initio calculations, at the MP2/DZV and MP2/6-31G(d, p) levels. These complexes are characterized by a large shift of the νCCO, νCH and δCCH modes to lower frequencies. Predicted frequency shifts for the Tel shaped structures were found to be in good agreement with the observed complex vibrational frequency shifts. These complexes are indicative of an electrophilic attack on the Cβ atom of the C3O2 moiety. Examination of the structures shows a strong hydrogen bond between the Cβ carbon of the C3O2 moiety and the acid acetylenic hydrogen and a pinching of the CCC valence bond angles (13°) for the C3O2 subunit.