Monomer, dimers and trimers of cyanogen N-oxide, N=C-C=N -> O. An X-ray, FVT-MS/IR and theoretical investigation

The structures of the trimers 4 and 5 of cyanogen N-oxide, NC-CNO 2 are est ablished by X-ray crystallography and C-13 NMR spectroscopy. Triethyl phosp hite reduction of 4 and 5 affords the 1,2,4-oxadiazolyl-1,2,5-oxadiazole 6. Deoxygenation of the N-oxide moieties in furoxans 1, 4, and 5 also takes p lace easily on the walls of the mass spectrometer. FVT-MS and FVT-IR invest igations of furoxans 1, 4, and 5 reveal that small amounts of cyano isocyan ate, NC-NCO 3 accompany the formation of the main thermolysis product, NC-C NO 2. The isomerisation of 2 to 3 has a high calculated activation barrier but is catalysed efficiently by Ag2S. The IR and mass spectra of 3 are anal ysed.