The Activation of Metal-Fluorine Bonds in Compounds of Group 4 by Aluminum Alkyls

In recent years we have developed the facile preparation of group 47#x2013;6 and main-group fluorides from the corresponding chlorides using Me₃SnF as a fluorinating reagent. Reactions of group 4 organometallic fluorides with alkyls of group 13 elements, especially those of aluminum, are of particular interest with regard to the mechanism of homogeneous catalysis for the polymerization of olefins. The formation of adducts of group 4 metallocene halides with AlMe₃ is assumed to be the first step of activation of a polymerization catalyst when AlMe₃ containing methylaluminoxane (MAO) is used. The following methylation of the metallocene centers is markedly facilitated by this electrophilic support. In order to understand the catalytic activity of those compounds, it is neccessary to examine whether a selective coordination of the fluorine atoms and an exchange for alkyl and amino groups, respectively, is possible using aluminum compounds.