KINETICS OF THE THERMAL-DECOMPOSITION OF FERROCENYL AZIDE - CHARACTEROF FERROCENYL NITRENE

The Arrhenius parameters for the thermal decomposition of ferrocenyl a zide in isooctane are A = (5.1 +/- 1.4) X 10(12) s-1 and E(act) = 113. 1 +/- 0.9 (kJ mol-1) and the rate is relatively insensitive to solvent (isooctane, benzene, acetoritrile: 1:1.7:2.4). The results indicate a relatively nonpolar transition state which is considerably ''tighter' ' than for a normal bond fission reaction. The Arrhenius parameters ar e comparable to those for aromatic azides and do not offer any support for anchimeric assistance by the iron atom. A kinetic scheme is prese nted which accounts for the observed products: Nitrogen, ferrocene, am inoferrocene, azoferrocene, and insoluble material. Rates of hydrogen abstraction by the intermediate ferrocenyl nitrene from cyclohexane, b enzene, and acetonitrile are used to show that the nitrene is nucleoph ilic. (C) 1994 John Wiley & Sons, Inc.