The molecular structure, conformation and vibrational amplitudes of 1,6-dibromo-1,5-hexadiyne (1,6-dibromopropargyl) in the vapour phase

Abstract

The molecular structure and conformation of 1,6-dibromo-1,5-hexadiyne have been studied by gas electron diffraction. The molecules were found to exist in an anti/gauche conformational mixture, with about equal amounts of the two conformers. The main structural parameters ( r a and angle α) are: C 3C 4 1.563(7) Å; C 2C 3 1.468(3) Å; CC 1.220(2) Å; CBr 1.794(1) Å; CH 1.087(8) Å; ∠ C 2C 3C 4 111.5(4)°. No significant deviation from linearity could be detected in the BrCCC fragments. A normal coordinate analysis for both conformers of 1,6-dibromo-1,5-hexadiyne has also been carried out, and mean amplitudes of vibration and perpendicular amplitude correction coefficients have been calculated at 0 K and 298 K.