The vibrational spectra, molecular structure and conformation of organic azides: Part II. 2-Azido-1,3-butadiene

Abstract

A sample of 2-azido-1,3-butadiene was synthesized from 4-bromo-1,2-butadiene and tetramethylguanidinium azide. Although the sample is highly explosive, we succeeded in making a structure determination by gaseous electron diffraction. IR spectra of the vapour, of the matrix isolated species in argon at 15 K, and of an amorphous and crystalline solid at 90 K were recorded. A Raman spectrum of the liquid, including semiquantitative polarization data, was obtained at 240 K. The title compound was found to be planar with the CNN angle 117° oriented syn to the adjacent CC double bond, the NNN angle was ca. 177° oriented anti to the CN bond. The following bond distances ( r a) were obtained: NN(N), 114.3; NN(C), 125.3; CN, 143.4; CC, 135.0; and CC, 146.7 pm. No additional conformers were observed in the vapour, liquid, amorphous or crystalline states.