Photolysis of 2, 4, 6-trimethyl-3, 5-bis (trifluoromethyl) pyridine (I) afforded 2, 4, 6-trimethyl-3, 5-bis (trifluoromethyl)-1-azabicyclo [2. 2. 0] hexa-2, 5-diene (II), a stable derivative of 1, 4-bonded Dewar pyridine. Protons of 2- and 6-methyl groups in II were exchanged with deuterium atoms in the presence of a base, while those of 4-methyl group were not. II was converted to I on thermolysis or catalysis by the action of some metal ions. Stable complexes, Pd (II)2Cl2 (VI) and Pt (II)2Cl2 (VI'), were isolated. VI was thermally converted to Pd (I) (II) Cl2 (VII), which was in turn converted to Pd (I)2Cl2 (VIII). The structure of VII was established as square and coplanartrans-(N-)σ-structure by X-ray analysis.
