The gas-phase structure of azetidine: Microwave spectroscopy, and electron diffraction and normal coordinate analysis

Abstract

The geometric structure of azetidine has been determined by a combined analysis of electron diffraction and microwave data, implementing the results of a normal coordinate analysis. The following geometric parameters ( r z values) for the ring skeleton have been obtained: C N = 1.473 (3), C C = 1.563 (3)Å, CNC = 91.2 (0.4)° and puckering angle θ = 29.7 (1.4)°. The microwave spectra were analyzed for the ground state of the parent and N-deuterated species and for the υ = 1 and υ = 2 states of the puckering vibration of the parent species. Dipole moments and nitrogen quadrupole coupling constants were determined. The structural parameters are compared to previous experimental and theoretical results for azetidine and are discussed in context with the isoelectronic cyclobutane and oxetane.