Knowledge Bank

Two stereoisomers of sevoflurane dimer have been detected using chirped pulse FTMW spectroscopy from 2-8 GHz. The identified complexes are distinguished by their differing helicities, and together both isomers form a diastereomeric pair, one being homochiral (RR/SS) and the other heterochiral (RS/SR). For both isomers, all 8 $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}$C isotopologues have been assigned, and two $\mathrm{<mrow\; data-mjx-texclass="ORD">18</mrow>}$O isotopologues have also been detected for the homochiral isomer, for a total of 18 isotopologues. MP2/6-311++g(d,p) calculations predict the heterochiral isomer as 1.2 kJ mol$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ above the homochiral species, which is consistent with the observed relative intensities between the two species. A summary of these microwave results, including a comparison between the Kraitchman and ab initio structures, will be presented.