Unexpected New Chemistry of the Bis(thioimidazolyl)methanes

The synthesis of the linkage isomers of the bis(thioimidazolyl)methane family of compounds, namely
CH2(N-tim)2 (1) and CH2(S-tim)2 (2) (where tim = thio(methyl)imidazolyl) has been reinvestigated
in order to optimize the yields, to complete the characterization of these known compounds, and
also to ascertain the effect of varying heteroatom binding on their electrochemistry. During the
course of these studies, the reactive intermediate ClCH2(S-tim) (3) was isolated and characterized.
The chloromethyl derivative 3 readily decomposes on warming to give the ionic compound [CH2(μ-C4H5N2S)2CH2](Cl)2 (4), which was converted to the hexafluorophosphate salt (5) and then was
characterized by single-crystal X-ray diffraction. It was also shown that CH2(S-tim)2 (2) could be
converted at temperatures greater than 120 °C to CH2(N-tim)2 (1) by a thermal isomerization that
proceeds via the remaining possible linkage isomer CH2(S-tim)(N-tim). Electrochemical studies on
1−3 in acetonitrile reveals that each undergoes irreversible (one electron per ring) oxidations above
0.7 V versus Ag/AgCl, while the ionic compound 5 shows an irreversible reduction wave centered
at −1.09 V.