Nitro and Nitroso Metathesis Reactions with Monomeric Zirconium Imido Complexes.
The bis(cyclopentadienyl)(tert-butylimido)zir-conium complex 1 undergoes ambient-temperature metathesis reactions with nitro- and nitrosoarenes, providing a rare nonphotochemical synthesis of cis-azoxy and cis-azo compounds, respectively. 2-Nitro-2-methylpropane also undergoes metathesis to give trans-(tert-butylazoxy)-2-methylpropane. This reaction was studied kinetically, and the rate was found to be first order in both 1 and substrate and inversely proportional to the concentration of tetrahydrofuran, with activation parameters DeltaH(double dagger) = 15 +/- 2 kcal mol(-1) and DeltaS(double dagger) = -26 +/- 3 cal mol(-1) K(-1).
Blum
Suzanne A
SA
Center for New Directions in Organic Synthesis, Department of Chemistry, University of California, Berkeley, California 94720.
Bergman
Robert G
RG