Thioacylsulfanylarsines (RCS_2)_xAsPh_(3-x), x = 1-3: synthesis, structures, natural bond order analyses and reactions with piperidine

摘要

A series of thioacylsulfanylarsines ((RCS_2)AsPh_2, (RCS_2)_2AsPh, (RCS_2)_3As) were synthesized by treating piperidinium dithiocarboxylates with Ph_2AsCl, PhAsCl_2 or AsCl_3, respectively and characterized. Their molecular structures were determined by X-ray crystallography and compared with those of the corresponding acrylsulfanyl derivatives ((RCOS)AsPh_2, (RCOS)_2AsPh, (RCOS)_3As). They exist as monomers, and the enivronment around the arsenic atoms is distorted tetrahedral with one lone pair at the apex. The structure of the mono (dithiocarboxylate) is different from that of the corresponding thiocarboxylic acid derivative, while the bis and tris derivatives showed similar structure to the corresponding thioarboxylic acid derivatives ((RCOS)_2AsPh, (RCOS)_3As), respectively. The new compounds showed intramolecular interactions between the thiocarbonyl sulfur and the central arsenic atom. NBO (Natural Bond Orbital) analyses performed on the model compounds (CH_3CS_2)As(CH_3)_2 and (CH_3CS~1_2)-(CH_3CS~2_2)AsCH_3 at the RHF/LANL2DZ level of theoryl showed the preence of interactions between the non-bonding orbitals on the thiocarbonyl sulfur (n_s) and the #sigma#~*_(MS) orbitals together with that between the n_s and the #sigma#~*_(MC) orbitals for the former compound; for the latter the presence of both orbital interactions between n_s and #sigma#~*_(MS1) and between n_s and #sigma#~*_(MS2) are present. The reaction of the mono(dithiocarboxylate) derivative (R = 4-CH_3C_6H_4) with piperidine in ethanol gave piperidinium diphenyldithioarsinate along with the corresponding N-thioacryl-or N-acyl-piperidine. A similar reaction of the bis(dithiocarboxylate) derivative (R = 4-CH_3C_6H_4) gave the novel di(piperidinium) phenyltrithioarsonate in which two anion charges are delocalized on the AsS_3 moiety and a cyclic phenylarsine sulfide tetramer (PhAsS)_4. The diphenyldithioarsinate and phenyltreithioarsonate salts exist as a dimer and a polymer, respectively, in which 12-membered rings are formed by intermolecular N-H…S hydrogen bonds.