Unexpected New Chemistry of the Bis(thioimidazolyl)methanes

[reaction: see text] The synthesis of the linkage isomers of the bis(thioimidazolyl)methane family of compounds, namely CH(2)(N-tim)(2) (1) and CH(2)(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 ClCH(2)(S-tim) (3) was isolated and characterized. The chloromethyl derivative 3 readily decomposes on warming to give the ionic compound [CH(2)(mu-C(4)H(5)N(2)S)(2)CH(2)](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 CH(2)(S-tim)(2) (2) could be converted at temperatures greater than 120 degrees C to CH(2)(N-tim)(2) (1) by a thermal isomerization that proceeds via the remaining possible linkage isomer CH(2)(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.