Controlled Synthesis of Novel Aryloxide Polynuclear Aluminum Species. Study of Their Catalytic Properties in Polymerization Processes † Gema Martínez, Sergio Pedrosa, Vanessa Tabernero, Marta E. G. Mosquera,* and Tomás Cuenca* Departamento de Química Inorgánica. Facultad de Farmacia, UniVersidad de Alcalá. 28871 Alcalá de Henares, Madrid, Spain ReceiVed January 31, 2008 The reaction of AlMe 3 with 3,5-(CF 3 ) 2 C 6 H 3 OH at room temperature renders the dinuclear [AlMe 2 (OR)] 2 (1) (OR ) 3,5-(CF 3 ) 2 C 6 H 3 O), trinuclear {[AlMe 2 (OR)] 2 [AlMe(OR) 2 ]} (2), or tetranuclear {[AlMe 2 (OR)] 2 - [AlMe(OR) 2 ] 2 }(3) derivative depending on the reaction conditions (solvent and stoichiometry of the reagents). All compounds have been characterized by elemental analysis and NMR spectroscopy, and their crystal structures determined by X-ray diffraction methods. Catalytic studies reveal that these compounds show high activity in ring-opening polymerization of cyclohexene oxide (CHO). The activity in the catalytic process varies significantly with solvent and temperature conditions. Introduction Aluminum organometallic and coordination compounds gen- erate great interest due to their key role in many catalytic reactions. 1–5 Since the discovery of MAO, 6,7 different alkyla- luminoxanes have held a vital role as cocatalysts in Ziegler– Natta polymerization processes. 8–14 In addition, aluminum alkoxide derivatives have proven to be very efficient catalysts in many polymerization reactions, such as ring-opening polymerization. 15–20 The appeal of aluminum is complemented by a rich structural chemistry; thus aluminum derivatives of a vast nuclearity range have been described. 21–28 In this note we report the synthesis and structural character- ization of new aluminum aryloxide complexes. A large number of aluminum aryloxide compounds have been described, 29 containing in most cases nonfunctionalized aryl groups. Our work is focused on the study of new aryloxide derivatives with functionalized aryl moieties since we are interested in analyzing the influence of functionality on the compounds’ properties. In this context, we have studied the reaction between the fluorinated phenol 3,5-(CF 3 ) 2 C 6 H 3 OH and AlMe 3 . The outcome of the reaction depends strongly on the reaction conditions; varying the solvent, reaction time, and Al:phenol ratio allows the synthesis of di-, tri-, and tetrametallic derivatives. The behavior of these aluminum species in polymerization processes is also described. Results and Discussion Reactions of AlMe 3 with 3,5-(CF 3 ) 2 C 6 H 3 OH. Trimethyl aluminum reacts with 3,5-(CF 3 ) 2 C 6 H 3 OH at room temperature, † In memory of Juan Antonio Delgado, deceased on July 14, 2007. * Corresponding authors. Tel: 34918854779. Fax: 34 918854683. E-mail: tomas.cuenca@uah.es; martaeg.mosquera@uah.es. (1) Pindur, U.; Lutz, G.; Otto, C. Chem. ReV. 1993, 93, 741–761. 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