Knowledge Bank

The ground vibrational state of arsabenzene $(C5H5As)$ was studied. Rotational constants are $A=4871.03+0.18$ MHz, $B=2295.87\pm 0.01$ MHz, and $C=1560.10\pm 0.01$ MHz. The small inertial defect (0.08 amu-{\AA}$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$) is consistent with a planar structure. Arsenic quadrupole coupling constants were determined as $Xaa=-186.4\pm 0.1$ MHz, $Xbb=43.5\pm 0.2$ MHz, and $Xcc=142.9\pm 0.2$ MHz. The molecular dipole moment was measured as 1.09 $\pm$ 0.02 D. The quadrupole data was analyzed in terms of a simple $\sigma$ $\Pi$ model with $\sigma$ and $\Pi$ bonds to arsenic.