Tris(2-sulfidopyridine N-oxide-κ 2 O,S)arsenic(III): An arsenic(III) complex having three 5-membered rings

The reaction of arsenic(III) oxide and 2-mercaptopyridine N-oxide in methanol at 25°C led to a yellowish powder containing microcrystals of tris(2-sulfidopyridine N-oxide-κ²O,S)arsenic(III) suitable for X-ray analysis(triclinic, P$\overline 1 $, a = 9.6961(5) Å, b = 10.3412(6) Å, c = 10.4879(6) Å, α = 70.684(5)°, β = 75.249(4)°, γ = 62.061(4)°, Z = 2). Each of the three 2-mercaptopyridine N-oxide ligand chelates to the arsenic atom through the S and the loosely-coordinating O atom, thus forming a pseudo-chelate 5-membered ring that is not usual in the arsenic structural chemistry.