Chemistry of polyfunctional molecules. Part 86. Organoarsenic compounds derived from 1,3-bis(di-iodoarsino)propane with monocyclic, tricyclic, and straight-chain structures; X-ray crystal structure of 2,8,13,14-tetraoxa-1,3,7,9-tetra-arsatricyclo[7.3.1.1]tetradecane

Abstract

Treatment of (C₆H₅)₃As(CH₂)₃As(C₆H₅)₂(1) with HI gives under elimination of benzene I₂As(CH₂)_3^- AsI₂(2). The reduction of (2) with sodium in tetrahydrofuran leads to the heterocyclic compound I[graphic omitted]sI (3). Hydrolysis of (2) yields the new tricyclic compound (CH₂)₃As₄O₄(CH₂)₃(4). The oxidative solvolysis of (2) with H₂O₂ results in the formation of (HO)₂OAs(CH₂)₃AsO(OH)₂(5). All the compounds have been characterized by elemental analysis, i.r., Raman, ¹H n.m.r., and mass spectra and by conductivity measurements. The crystal structure of compound (4) has been solved by X-ray diffraction. Crystals are monoclinic, space group P2₁/c, with a= 6.886(2), b= 14.745(5), c= 11.577(4)Å, β= 94.15(3)°, and Z= 4. Data collection yielded 4 183 reflections, of which 2 026 with I 3σ(I) gave R= 0.038. The molecule consists of a tricyclic ring system. The main skeleton is an eight-membered As₄O₄ ring comparable to the endo–endo structure of N₄S₄. The As atoms are linked together by two (CH₂)₃ chains forming an open-envelope conformation. The solid state and a solution of (4) in CS₂ show appreciable evidence for the existence of intramolecular C–H ⋯ O–As bonding.