Cyanoacetylenic complexes as pre-reactional species leading to the HC7N synthesis. Part II: Experimental and theoretical identifications of the HC5N:C2H2 complex

The structure and energy of the 1:1 HC5N-C2H2 complexes in solid argon matrices have been investigated using FTIR spectroscopy and DFT calculations, at the B3LYP/6-31G** level of theory. Two 1:1 complexes have been observed. The first one corresponds to a Linear structure characterized by a hydrogen bond between C2H2 and the HC5N nitrogen atom. The second one, a T1-shaped structure, shows an interaction between the HC5N hydrogen atom and the C2H2 π system. This shows that HC5N acts either as an electrophile or as a nucleophile with acetylene.