Knowledge Bank

The rotational spectrum of the $C3v$-symmetric trimethyl-tin-chloride $(CH3)3SnCl$, a molecule with three methyl tops connected to a tin atom, has been studied using a pulsed supersonic jet COBRA Fourier-transform microwave spectrometer. The spectrum exhibits rather dense line patterns, which arise from the internal rotation of the three methyl tops, the quadrupole coupling interaction of the chlorine atom, and the large number of isotopic combinations of tin and chlorine. To support a spectroscopic analysis we are exploring the high barrier group-theoretical tunneling-rotational formalism appropriate for the PI group $G162$. We will discuss different tunneling pathways and compare the resulting splitting patterns for rotational levels with the FT-MW results. Stark-effect measurements can be used to between levels of the six different species of $G162$, since the $I1,I2,I3$ and $E2$ levels will exhibit first-order Stark-splittings, while the $A1$ and $I4$ levels will have only a second-order Stark-effect. We suspect that levels of $A1$ and $A2$ species in $G162$ can be fitted to a rigid rotor Hamiltonian. At the time of writing the abstract, a theoretical proof that a rigid rotor fit is indeed possible for these --$\mathrm{<mrow\; data-mjx-texclass="ORD">162</mrow>}$ species is in progress. We have also recorded the spectrum of $(CH3)2SiH-Sn(CH3)3$, a molecule with a Si-Sn atom backbone and three inequivalent $G162$ results will be extended to the $G486$ group appropriate for this molecule.