Vibrational frequencies, force constants, coriolis constants, mean amplitudes and shrinkage effects for CH 3CC-CCX (X = H, Cl, Br an

Abstract

Normal coordinate analyses for methyldiacetylene and its 1-halo derivatives, CH 3CC-CCX (X = H, CI, Br or I), were performed on the basis of experimental vibrational frequencies not published previously. The molecules belong to a pyramidal-axial model of C 3 v symmetry. Coriolis coupling constants of the E a × E b type are given. Also the mean amplitudes of vibration, perpendicular amplitude correction coefficients and shrinkage effects were calculated. The mean amplitudes are discussed in particular, and characteristic values for certain types of interatomic distances are deduced.