REACTIONS OF ARSINIC AND ARSONIC ACIDS WITH H₂S AND H₂Se: CRYSTAL STRUCTURE OF 1,4-DIPHENYL-1,4-DIARSA-2,3,5-TRISELENACYCLOPENTANE

Abstract

The reactions of a series of arsinic and arsonic acids with hydrogen sulfide and hydrogen selenide have been investigated. The various arsinic acids were found to produce a variety of products, but the reaction was characterized by the reduction of arsenic(V) to arsenic(III), loss of hydroxyl groups bonded to arsenic and, to a lesser degree, the rupture of arsenic-carbon bond(s). Phenylcarboxymethylarsinic acid yielded, on reaction with H₂S or H₂Se, 1,4-diphenyl-1,4-diarsa-2,3,5-trichalocogenapentanes, where the chalcogen atom is S or Se. Arsonic acids yielded as final products compounds having a range of stoichiometries ranging from RAsS to R-7As₂S₃. 1,4-Diphenyl-1,4-diarsa-2,3,5-triselenacyclopentane consists of a non-planar, five-membered ring in which the As–C bond distances are 1.962 Å, the As—Se bond distances are 2.388 Å and the Se—Se bond distance is 2.334 Å. The bond distances are very close to those which are expected for single, covalent bonds.

Key Words:

• Arsinic acids
• Arsonic acids
• Hydrogen sulfide
• Hydrogen selenide
• Arsenic heterocyclics
• Selenium heterocyclics