SYNTHESIS, STRUCTURE, AND CONFORMATIONAL DYNAMICS OF BRIDGEHEAD-SUBSTITUTED NITROSAMINES - DI-1-ADAMANTYLNITROSAMINE AND DI-1-NORBORNYLNITROSAMINE

The synthesis of two bridgehead-substituted nitrosamines, di-1-adamant ylnitrosamine (1) and di-1-norbornylnitrosamine (2), is described, and their solid state crystal structures are reported. Large bridgehead s ubstituents increase the NNO angle of the nitrosamine (compared to tha t found for dimethylnitrosamine) without deconjugating the NNO pi syst em significantly. This structural change correlates with a red-shifted optical absorption, a diminished N,N rotational barrier, and a greate r ease of oxidation of these hindered nitrosamines than is observed fo r dimethylnitrosamine. The electronic basis of these structure/functio n correlations is examined. It is concluded that 1 is more strained th an N-nitroso-2,2,6,6-tetramethylpiperidine (3) which is more strained than 2 and that a raised (in energy) NO n orbital is primarily respon sible for the extreme properties of the former.