MAGNETIC-RESONANCE STUDIES OF THE STRUCTURE AND THE RED PHOTOLYSIS REACTIONS OF 2-CHLORO-2-NITROSONORBORNANE

Detailed NMR studies have shown that at 298 K optically-inactive satur ated blue solutions of 2-chloro-2-nitrosonorbornane in CDCl3 contain a mixture of the monomeric and dimeric forms of the compound in a ratio of dimer. monomer = 1:40 (+/-2):this ratio changes with a change in t emperature. The analysis assigns the configuration at the drop C(2)(NO )(Cl) centre and shows that the monomeric form has the structure (4), in which the NO group is on the same side of the molecule as the bridg ing drop C(7)H-2 group. White, solid 2-chloro-2-nitrosonorbornane is a 1 : 1 : 1 : 1 mixture of four diastereoisomeric forms of trans-diazod ioxide (5). The white solid readily sublimes at ambient temperature an d monomeric vapour forms a blue-green cast on its surface. Red-irradia tion of the compound, in vacuo, produces white crystals and a viscous brown oil. The white crystals contain norbornan-2-one (6), the syn- an d anti-forms of the norbornan-2-one oximes, (7) and (8), and a lactam, (9). These compounds are present in the viscous brown oil which also contains three other compounds to which the structures (10), (11) and (12) are assigned. The reaction mixture is EPR silent. The spectroscop ic evidence enables some of the steps in the red photolysis reactions of (4) to be unravelled.