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The polarized low-temperature crystal absorption spectra of tetramethyl-1,3-cyclobutanedithione–$h12$ and $-d12$ (II) have been measured in the visible region, and $n\pi \ast$ excited states identified as follows :$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}Au$ with origin $(h12/d12)$ at 16829/16836 $cm-1; 1Au$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}B1g$ with nearly degenerate origins near $18000cm-1$ and probably $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}Au$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}B1g$ near $19500cm-1$. The singlet excited states lie close together and perturb each other strongly. Isotope shifts, and anologies to the spectrum of the dione (I)$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$, played an important part in the analysis. As in the dione (I), CH/CD stretching vibrations in the peripheral methyl are groups are active in intensity borrowing, and the effects of excitation are delocalized over the entire molecule. Preliminary results for the $C2v$ molecule (III) will also be presented. [Figure]