Rotational Constants. Bond Distances and Angles

The rotational and centrifugal distortion constants A, B, C, Dk, Djk, Dj, Di, and D2 of the ground and the vibrational states V4=1, Vg = 1, and Ve = 1 were obtained by analyzing the corresponding vibration-rotation bands. The constants (in cm ) of the ground state are listed in the following table  

Earlier values of rotational constants were based on low-resolution spectra and on the assumption that trans- 2 2 and C/S-N2H2 are both present [3, 4]. Constants for the V4=1, Vg = 1, Ve = 1 states are given in [1] and for the Vg = 1 state (also for trans-N2D2) in [2]. Calculated centrifugal distortion constants are reported in [5]. 

Bond distances and angles for planar frans-N2H2 were determined from the rotational constants of trans-N2 2 and trans-N202 quoted above [2]  

Earlier experimental data are either incomplete [3] or incorrect [4]. The following table compares equilibrium-structural data determined for trans-H2H2 and C/S-N2H2 by the most recent quantum-chemical calculations at a high level of theory. 

Results of comparable studies are given in [9 to 12]. Theoretical studies on the structure of diazene done before experimental data were available are described in [13 to 17]. 

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