Knowledge Bank

Radiofrequency and microwave spectra of $NH3-CO$ and $NH3-N2O$ have been measured using the molecular beam electric resonance technique. For $NH3-N2O$ an asymmetrical top spectrum is observed and is complicated by internal rotation of the $NH3$ subunit. The rotational constants for the ground internal rotor state are: A=12722.6(8) MHz, B=4083.4(3) MHz, and C=3070.0(3) MHz. $NH3-N2O$ is a T-shoped complex with a N--N weak bond length of 3.2{\AA}. The electric dipole moment component along the a inertial axis is 1.514(9) D. Attempts are presently underway to determine the height of the threefold barrier to internal rotation. It should be noted that the structurally similar complex, $NH3-CO2$, has no threefold barrier. The $K=013J=0.11-2$ transitions have been observed for $NH3-CO,NH2D-CO,NHD2-CO,ND3-CO,NH3-13CO$. The spectroscopic constants are: [FIGURE] The observed isotopic dependence of the rotational constants is consistent with a structure which has the nitrogen directed toward the carbon. The spectrum is complicated by non-rigidity and is not completely understood. The structure determined from the K=0 transitions is consistent with the orientation of amine-carbonyl groups observed in organic crystals.""