Reaction of Tp(t-Bu,me)Co(O-2) with NO yielded a mixture of Tp(t-Bu,me)Co(NO2) (2) and Tp(t-Bu),MeCo(NO3) (3) rather than the desired stable peroxynitrite complex Tp(t-Bu,Me) Co(OONO). Complexes 2 and 3 have been independently synthesized and characterized, including a crystal structure determination of 2. Reaction of Tp(t-Bu,me)Co(N-2) with NO yielded the paramagnetic cobalt nitrosyl Tp(t-Bu,me)Co(NO) (4), a {Co(NO)}(9) complex that has also been structurally characterized. Exposure of 4 to 02 in solution yielded 2 exclusively, while the major product of the same reaction carried out in the solid state was 3. A labile peroxynitrite complex is considered a likely intermediate in these reactions; indeed, in situ IR spectroscopy revealed the formation of a intermediate tentatively assigned as such in the reaction of Tp(t-Bu,Me)Co(O-2) with NO at -78 degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.
