Characterization of a byproduct in the alkylation of DMIT: Alkylation on the least nucleophilic sulfur atom

Abstract

It is generally accepted that the alkylation of (Et4N) 2-[Zn(DMIT)2] (1) is a very clean reaction that produces 4,5-bis(alkylthio)-1,3-dithiole-2-thiones 4 in very high yields. Although this procedure has been widely used, we have found that, in addition to the 4,5-bis(alkylthio)-1,3-dithiole-2-thione products 4, highly unexpected byproducts are formed during the alkylation reaction in which the thione functionalities of DMIT in (Et4N)2[Zn(DMIT)2] (1) are alkylated instead of the more reactive thiolate groups. These byproducts were identified as a novel type of compounds, namely bis(2-alkylthio-1,3- dithiol-1-ium-4,5-dithiolato)zinc compounds 3, being composed of two identical 2-alkylthio-1,3-dithiol-1-ium-4,5-dithiolate moieties coordinated to a single zinc(II) atom and were characterized by elemental analyses and different spectroscopic techniques as well as single-crystal X-ray structure analyses. A comparison of the physical properties of compounds 3 and (Et4N) 2[Zn(DMIT)2] (1) has been carried out. The outcome of these investigations revealed significant differences in the physical properties of these two systems. © Wiley-VCH Verlag GmbH & Co. KGaA, 2006.