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.