GAS-PHASE REACTION OF COPPER ATOMS WITH TETRAMETHYLETHYLENE - SEQUENTIAL LIGAND ADDITION VIA NON-STEADY-STATE KINETICS

The reaction kinetics of copper atoms with tetramethylethylene (TME) h ave been studied, using Ar buffer gas near room temperature. Reaction proceeds by sequential addition of two TME ligands, with the second li gand addition reaction in competition with thermal dissociation of the 1:1 complex At 316 K, thermal dissociation of the 1:2 complex also oc curs. Relative reaction rates are such that the removal kinetics of Cu show biexponential and, at 316 K, triexponential decay behavior. A de tailed analysis of Cu removal kinetics has been undertaken, using a gl obal analysis technique that allows details of the reaction mechanism to be investigated. Kinetic and thermochemical parameters are derived from the data and are shown to be mutually consistent, using RRKM unim olecular reaction theory calculations. Binding energies are reported f or CuTME and Cu(TME)2 complexes: DELTAE0-degrees[Cu - TME] = 42 +/- 6 kJ mol-1; DELTAE0-degrees[TMECu - TME] = 75 +/- 10 kJ mol-1. A ''chemi cal activation'' reaction channel is explicitly included in the analys is. This reaction occurs by successive collision of two ligand molecul es with Cu, without intervening third-body stabilization of the 1:1 co llision complex by inert buffer gas.