Synthesis and characterization of phenoxarsin-10-yl diorganodithiophosphinates. A folded phenoxarsine system in the first dimeric organoarsenic(III) 1,1-dithiolate associated through As ⋯ S secondary bonding

Abstract

Some phenoxarsin-10-yl diorganodithiophosphinates, O(C₆H₄)₂AsS₂PR₂(R = Me, Et or Ph), have been prepared by treating 10-chlorophenoxarsine with salts of the corresponding dithio compounds in CH₂Cl₂. The compounds were characterized by IR, mass spectrometry and ¹H, ¹³C and ³¹P NMR spectroscopy and the crystal structure of O(C₆H₄)₂AsS₂PPh₂ has been determined. The compound is monoclinic, space group P2/n, a= 8.925(6), b= 22.028(8), c= 11.341(5)Å, β= 100.70(2)° and Z= 4. It exhibits a dimeric, quasi-tricyclic structure based upon intra- and inter-molecular As ⋯ S secondary bonds (3.402 and 3.381 Å, respectively), which is unique in arsenic–sulfur chemistry. The phenoxarsine unit is non-planar with a dihedral angle of 154.4° between the planes of the two aromatic rings.