New carbon sulfides based on 4,5-dimercapto-1,2-dithiole-3-thione (.beta.-C3S52-): [C3S5]n, C6S8, and C5S7

Abstract

This investigation centers on the preparation of new binary carbon sulfides based on the 1,2-dithiole-3-thione subunit as found in the precursor dithiolate C[sub 3]S[sub 5][sup 2[minus]]. Tricyclic S[sub 6]S[sub 8], 1, was obtained in high yield by thermal elimination of H[sub 2]S from the dimercaptan [beta]-C[sub 3]S[sub 5]H[sub 2]. A crystallographic study confirmed a tricyclic structure of idealized D[sub 2h] symmetry containing an unusual planar 1,4-dithiin unit. The crystals of 1 are monoclinic, space group P2[sub 1]/c. The final R and R[sub w] values were 0.036 and 0.042, respectively. The bicyclic carbon sulfide C[sub 5]S[sub 7], 3, was prepared from reduction of C[sub 4]S[sub 6], 2, with LiBEt[sub 3]H, followed by addition of thiophosgene. Oxidation of Cp[sub 2] Ti([beta]-C[sub 3]S[sub 5]) or Zn([beta]-C[sub 3]S[sub 5])[sub 2][sup 2[minus]] with SO[sub 2]Cl[sub 2] afforded [[beta]-C[sub 3]S[sub 5]][sub n], 4, an orange insoluble solid. Degradation of [[beta]-C[sub 3]S[sub 5]][sub n] with dimethyl acetylenedicarboxylate (DMAD) afforded C[sub 3]S[sub 5][center dot]2DMAD, 5, together with small amounts of C[sub 3]S[sub 5][center dot]3DMAD, 6. The single-crystal X-ray structure of C[sub 3]S[sub 5][center dot]-2DMAD revealed a folded 1,4-dithiin linked to a planar 1,3-dithiole. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at R =more » 0.036 and R[sub w] = 0.047. The DMAD treatment proceeds in a similar manner with [M([beta]-C[sub 3]S[sub 5])[sub 2]][sup 2[minus]] (M = Zn, Ni) to yield [M(C[sub 3]S[sub 5][center dot]DMAD)[sub 2]][sup 2[minus]]. The C[sub 3]S[sub 5][center dot]DMAD ligand can subsequently be removed from the zinc complex by reaction with thiophosgene giving bicyclic C[sub 4]S[sub 6][center dot]DMAD, which can also be obtained via Cp[sub 2]Ti(C[sub 3]S[sub 5][center dot]DMAD).« less