Infrared combination band intensities of CH out-of-plane vibrations for pyridine and its deuterium derivatives in CS2 solution

Abstract Absolute band intensities of the CH(D) out-of-plane binary combinations were measured for pyridine and its 2- d -, 3- d -, and 4- d -derivatives in CS 2 solution. The band assignments and the force field used here were those given in one of our previous papers. The band intensities were calculated by introducing the following two parameters: the CH(D) bond moment μ(CH) and the second derivative with respect to its out-of-plane deformation, ∂ 2 μ( CH ) ∂θ 2 . For both the frequencies and the band intensities, the observed values were in very good agreement with the calculated values, by taking μ(CH) = 0.7 D and ∂ 2 μ( CH ) ∂θ 2 = −1.38 D/rad 2 at the equilibrium position. These two parameters were remarkably close to those of benzene and thiophene.