FTIR‐spectroscopy of molecular clusters in liquid solutions and cryogenic solids

Small hydrogen bonded molecular clusters of HCN have been investigated in CCl 4 solutions and in solid Ar, N 2 , and CCl 4 matrices by means of FTIR spectroscopy in the spectral range 4000 ‐ 10 cm −1 . In Ar and N 2 matrices aggregated species up to tetramers can readily be identified. HCN dimers have been formed selectively in these matrices by photofragmentation of s‐tetrazine. Both the intra‐ and intermolecular modes observed are consistent with a linear dimer structure. Photolysis of s‐triazine generated selectively HCN trimers, obviously with a cyclic structure stabilized by the matrix cage. On the other hand, linear trimers and tetramers were detected in Ar and N 2 matrices after time and temperature controlled diffusion of isolated monomers and dimers, respectively. Linear configurations are also typical for the HCN aggregation in CCI 4 . In liquid solutions no HCN clusters larger than dimers were observed. In the plastic crystalline phase of CCl 4 , on the other hand, dimers and trimers are present. Only in the crystalline CCl 4 phase larger HCN chains of unspecified length may be formed.