Cluster formation of hydrogen cyanide in solid and liquid CCl4 matrices

Abstract

The cluster formation of hydrogen cyanide (HCN) in carbon tetrachloride (CCl4) matrix was studied by IR and far IR spectroscopy. This included three different phases of the matrix material: (a) The liquid (conventional solution studies), where only the formation of linear HCN dimers occurs. (b) The plastic crystalline solid (matrix isolation studies in the high temperature modification with randomly oriented rotating CCl4 molecules) where linear dimers and trimers of HCN appear to be stable. (c) The crystalline solid (matrix isolation studies in the low temperature modification with orientationally ordered CCl4 molecules) where long linear HCN chains of unspecified degree of aggregation are observed. For dilute solutions the phase transition from (a) to (b) induces a thermodynamically unstable state which relaxes towards equilibrium on a time scale of minutes depending on the temperature applied. This relaxation process is accessible to time-resolved Fourier transform IR and far IR spectroscopy.