Chlorination of (AsPh2)2O: Supramolecular structure of dihydroxodiphenylarsonium hydrogensulfate [AsPh2(OH)2] [HOSO3]

Chlorination of (AsPh 2 ) 2 O with either elemental chlorine or sulfuryl chloride leads to cleavage of the oxobridge. With an excess of chlorine, the oxidation products are diphenylarsenic(V) trichloride and dihydroxodiphenylarsonium chloride. Oxidation of (AsPh 2 ) 2 O with SO 2 Cl 2 in a 1:1 molar ratio on the other hand gives diphenylarsenic(III) chloride and dihydroxodiphenylarsonium chloride. With an excess of SO 2 Cl 2 , diphenylarsenic(V) chloride, AsPh 2 Cl 3 , and dihydroxodiphenylarsonium hydrogensulfate [AsPh 2 (OH) 2 ] [HOSO 3 ] are the products. X-ray crystallography shows the latter has a supramolecular structure based on centrosymmetric dimeric ([HOSO 3 ][AsPh 2 (OH) 2 ]} 2 units formed by hydrogen bonding between pairs of tetrahedral cationic [AsPh 2 (OH) 2 ] + and anionic [HOSO 3 ] - units, which are then cross linked by further hydrogen bonds.