Laboratory detection of the MgNH2 radical ((X)over-tilde (2)A(1))

The MgNH2 radical has been detected in the laboratory for the first time in its (X) over tilde(2)A(1) ground state using techniques of millimeter-wave spectroscopy. This short-lived species was created using Broida oven metho ds. Multiple K-alpha asymmetry components were recorded for MgNH2 in 12 rot ational transitions in the frequency range 129-527 GHz, and spin-rotation s plittings were resolved in every component. A total of 251 separate lines w ere measured. An intensive search for a possible inversion state in MgNH2 w as also conducted but proved negative. This data set has been modeled with an S-reduced Hamiltonian and very accurate rotational, centrifugal distorti on, and spin-rotation parameters have been determined for magnesium amide. This study strongly suggests that the radical is planar with C-2 nu symmetr y, although small barriers to planarity cannot be ruled out. MgNH2 could be produced in interstellar/circumstellar gas from the association reaction o f Mg+ + NH3, as predicted by theory.