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Diiminomethan is the higher energy isomer of
cyanamine, H2NCN. Relative intensity
measurements suggest the difference to be about
15 KJ/mol or 1700 K. These measurements
as well as a substantional number transitions
were reported in
(1) M. Birk, M. Winnewisser, and E. A. Cohen,
1989, J. Mol. Spectrosc. 136, 402.
Further transition frequencies near 1.1 THz
come from
(2) W. Jabs, M. Winnewisser, S. P. Belov, T. Klaus,
and G. Winnewisser,
1997, Chem. Phys. 225, 77.
Further lines were published in
(3) V. Wagener, M. Winnewisser, and M. Bellini,
1995, J. Mol. Spectrosc. 170, 323.
However, transitions near 2.5 THz reported in (1) and (3)
deviate systematically by slightly more than 1 MHz;
the latter is the combined uncertainty for each line.
Therefore, data from (3) were not used in the fit.
As a consequence, predictions above
Ka" = 1 should be viewed
with some caution. Because of the fairly large body of
transitions measured by FT-FIR, the predictions should
not deviate by much more than 5 MHz.
Apparently the tunneling of the HNCNH molecule should
be described by four states. The measured data, however,
can only provide information on two states – even
theoretically. Therefore, the final fits have been
carried out by employing two tunneling states only.
A 5 : 7 spin-statistical weight ratio was
considered in the predictions.
The dipole moment was reported in (1).
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