The reaction of AlMe 3 with 3,5-(CF 3 ) 2 C 6 H 3 OH at room temperature renders the dinuclear [AlMe 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.

The reaction of lithiated picolines and [TiCl3(η(5)-C5Me5)] leads to several bridging or terminal imido compounds, each of which can be selectively formed by controlling the stoichiometry and temperature. Specifically, the dinuclear imido-bridged [TiCl(η(5)-C5Me5)(μ-NR)]2 (1a, NR = 2-imido-3-picoline; 1b, NR = 2-imido-5-picoline) species and the unusual Ti-Li imido-amido heterobimetallic complex [{Li(THF)}{Ti(η(5)-C5Me5)(NR)(NHR)2}] (2a, NR = 2-imido-3-picoline; 2b, NR = 2-imido-5-picoline) were isolated. Compounds 2 are in effect the first structurally characterized examples of titanium(IV) coordinated to terminal imido-pyridines. DFT-D calculations for 2a denote a multiple bond character between titanium and the imido ligand and a strong polarization of the electron density by the alkali cation in spite of the lack of intermetallic bonding.

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Aluminium attracts wide attention not only because of its rich chemistry, but also due to the important applications that exhibit in areas as diverse as organic synthesis, electronic materials, structural materials and catalysis. [1] In particular, aluminoxanes play a key role as co-catalysts in the Ziegler-Natta polymerization processes. [2] As well, aluminium alkoxide derivatives have proven to be very efficient catalysts in many polymerization reactions, such as ring opening polymerization. [3] As a continuation of our work on functionalized aryloxide aluminium derivatives [4] we have extended our studies to silanols. The generation of molecular aluminosiloxanes compounds has an additional interest since this kind of species have shown to be useful both as model compounds for open-framework silicates and as precursors for the preparation of mixed metal oxide materials under mild conditions. [5] We are particularly interested in achieving a good control of the structures obtained by controlling the reactions conditions. In this communication we present our latest results and our studies in relation to the different outcome depending on the aluminum precursor. Thus when AlMe 3 is used the expected dimer [AlMe 2 (OR)] 2 is formed, however if AlClMe 2 is the precursor, unexpected results are attained such as the mixed alkoxide/syloxide derivative [AlCl(OR) OSi(OR) 3 ] 2 shown in figure 1. Figure1.The new derivatives prepared were determined by X-ray diffraction methods, elemental analysis and NMR.[1] A. J. Downs, ed., Chemistry of Aluminium, Gallium, Indium and Thallium, Blackie Academic, Glasgow, 1993; P.P. Power, Chem. Rev., 1999, 99, 3463; . Os-Cl bond lengths in the complex anion lay between 2,328-2,356 Å, Ru-N average bond length in complex cation is 2,111 Å, Ru-Cl is 2,334 Å. Distances between metals are typical for this kind of compounds. The smallest Ru…Os distance is 5,773 Å. Thermal stability of the complexes in different atmospheres was also investigated. It was found that the decomposition of I or II in hydrogen or helium atmosphere at 650° C gives a single-phase metal product with the hcp lattice. Cell parameters of obtained phases are close to cell parameters of original Ru-Os alloys obtained at 2000° C [6, 7].)