P-Functionalized tetrathiafulvalenes from 1,3-dithiole-2-thiones?

Abstract

A protocol for the synthesis of mono- and bis-phosphanylated 1,3-dithiole-2-thiones 2 and 3 is presented. The reaction of 2 or 3 with hydrogen peroxide–urea or elemental sulfur led to the corresponding P(V) chalcogenide 1,3-dithiole-2-thiones 4–7. All compounds were characterized by ³¹P, ¹H and ¹³C NMR and IR spectroscopy and elemental analyses. Additionally, compounds 3 and 4 were analysed by single-crystal X-ray diffraction analysis. The reaction of 3 with P(OEt)₃ led selectively to the tetrakis-phosphanylated tetrathiafulvalene derivative IIvia a reductive C²,C² coupling reaction. A thorough computational analysis for the mechanism of phosphite-mediated reductive dimerization of 1,3-dithiole-2-thiones was performed.