Intensities of infra-red bands - V. Bond polar properties in dimethyl acetylene

The absolute intensities of all except one of the infra-red fundamental vibration bands of dimethyl acetylene have been determined, and the results have been used to compute polar properties of the C$\chembond{1,0} $H and C$\chembond{1,0} $C bonds. It has been found that if the very probable assumption is made that the acetylenic carbon atoms carry a residual negative charge, the hydrogen atoms in the C$\chembond{1,0} $H bonds must carry a residual positive charge. The probable value of the C$\chembond{1,0} $H dipole is about 0$\cdot $4 Debye, and that of the C$\chembond{1,0} $C$\equiv $ bond about 1 Debye. Comparisons have been made with the results of similar work with related molecules.