Chalcogen chemistry. Part VIII. Complexes of arylselenium and aryltellurium trichlorides with pyridine, 4-picoline, and 4-picoline N-oxide

Abstract

Arylselenium and aryltellurium trichlorides form crystalline 1 : 1 adducts with pyridine (py), 4-picoline (pic), and picoline N-oxide (pico). The selenium complexes are pale yellow and moderately sensitive to atmospheric moisture while the tellurium analogues are colourless and fairly stable to moist air. In contrast to p-MeOC₆H₄TeCl₃-(tmtu)(tmtu = tetramethylthiourea) which is molecular in solution land a weak electrolyte, ArTeCl₃(py) and ArTeCl₃(pic) behave as 1 : 1 electrolytes in solution. The behaviour of ArSeCl₃(py), ArSeCl₃(pic), and ArTeCl₃-(pico) in solution is intermediate to the above. It is likely that square pyramidal ArMCl₃(:B) molecules exist in the solid state, but available i.r. data do not allow an unambiguous conclusion in this regard.