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

Abstract

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—H and C—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—H bonds must carry a residual positive charge. The probable value of the C—H dipole is about 0-4 Debye, and that of the C—C≡ bond about 1 Debye. Comparisons have been made with the results of similar work with related molecules.