Micro wave Spectra of Furazan I. The Doubly Determined Substitution Structure

Abstract

Double Resonance Modulation (DRM) microwave spectroscopy has been used to determine the rotational constants of isotopic forms of normal (C2H2N2O2) and perdeuterated furazan (C2D2N2O). From these data the complete substitution structures have been derived by Kraitchman methods and by the computer program GEOM. The latter procedure fails to give correct results due to the decrease of the moment of inertia about the C2v -axis and the simultaneous interchange of inertial axes in the 18O-3,4-d2-form. The following bondlengths (in Å) and angles (in degrees) are best compatible with the total body of isotopic information: 0 - N = 1.3729 [6] ∢ NON = 111.15 [8] N -C = 1.3032 [13] ∢ ONC = 105.53 [5] C -C =1.4211 [9] ∢ NCC = 108.89 [3] C -H = 1.0763 [5] ∢ CCH = 130.16 [3] Here, the uncertainties cover small differences between normal and d2-furazan as well as discrepancies resulting from different schemes of structure calculation.