The crystal structure of 4-oxo-3H-2[N-(p-methoxyphenyl)- iminium]6-methyl-8-(p-methoxyphenyl)-imidazo[l,2-a]l,3,5-triazine tri-fluoroacetate [C2oh20n5O3]+[CF3COO]_was determined by single-crystal X-ray diffraction. The compound is monoclinic, space group P21/c. The unit cell parameters are a = 10.404(3),b = 12.997(3), c = 16.511(3)A, β = 92.45(3)°,V = 2230.6Å3,Z = 4,Dx= 1.463 and D m= 1.44(2)g. cm' ‘3. The structure was solved by direct methods, and the full-matrix least-squares refinement gave the R value of 0.060 for 2387 observed reflections. The nitrogen atom of the methoxyphenylimine group is protonated to give the univalent cation. The methyl imidazotriazinone ring system and the methoxy-phenyl and the methoxyphenyliminium groups are all planar but are twisted with respect to each other. Strong hydrogen bonding is observed between the carboxylate oxygen atoms of the CF3COO-ion and the two NH groups of the cation, one of the bonds being extremely short (O… N 2.666 A). © by Akademische Verlagsgesellschaft 1982