The millimeter/submillimeter spectrum of LiSH (X̃1A′): further investigations of the metal–sulfur bond

The pure rotational spectrum of LiSH and its 6Li and deuterium isotopomers has been recorded in the region 73–521 GHz using millimeter/sub-millimeter direct absorption techniques. These species were created by the reaction of H2S or D2S and lithium vapor in a dc discharge. Extensive Ka ladder structure was observed for all three isotopomers, indicating that LiSH is a near-prolate asymmetric top with a X̃1A′ electronic state. Rotational parameters have been determined for the three species, enabling the calculation of a rm(1) structure. The Li–S–H bond angle was found to be 93°, indicating a high degree of covalent bonding in this molecule.