FTIR spectra of the four isotopically substituted 1: 1 complexes of acetonitrile and boron trifluoride were recorded in Ar, N2 and Xe matrices. In Ar, previously unreported three vibrational modes of the complex were clearly observed. Several significant vibrational bands were also observed in N2 and Xe. The observed frequency shifts on complexation, Δν, were qualitatively in good agreement with the computational results, which were ...