26412-87-3 NSC75831 Pyridine SO3 (1:1) complex Pyridine compound with sulfur trioxide (1:1) Pyridine sulfotrioxide Pyridine, compd. with sulfur trioxide (1:1) Pyridine-sulfur trioxide complex Pyridine-sulfur trioxide complex (1:1) Sulfur trioxide pyridine complex