Halogen abstraction by triphenylphosphine of perfluorodiazadichloroalkanes containing NCCl2N groups. X-ray structure analysis of perfluoro-2,3,5,6-tetrakis(dimethylamino)-pyrazine

The reaction of perfluoro-2,2-dichloroimidazolidine (I) with triphenylphosphine (III) yields the bicyclic olefin (IV) while (V) is obtained in the presence of H₂O. From the reaction of (CF₃)₂NCCl₂NCClN(CF₃)₂ with (III), only the cyclic dimer (VI) was isolated in a yield of 6 %, predominantly polymeric material being formed. The reaction pathways agree with a carbene as intermediate. (IV), (V) and (VI) were characterized by analyses, NMR, vibrational and mass spectra. A single crystal X-ray examination of (VI), space group P2₁/n, a 9.367(2), b 10.909(3), c 10.929(3) Å, β = 103.27(2)^o, Z = 2, R = 0.109, revealed a planar, regular pyrazine ring but nonplanar N atoms in the substituent, steric interactions being relieved by rotating the amino groups out of the pyrazine plane.