from first principles PP-I-1

PP-II-13The Role of Complex Aluminum Hydrides and Their Derivatives in theFormation and Operation of Hydrogenetion Catalysts of Group VIII MetalsSchmidt F.K., Titova Yu.Yu., Belykh L.B.Irkutsk State University, Irkutsk, Russiafkschmidt@chem.isu.ruThe study of Ziegler systems based on transition metals complexes in combination with thehydride and organic compounds of metals of I-III groups in the catalytic hydrogenation hadbeen carried out from the second half of XX century. Despite such a long period of thesesystems study and their industrial applications, in particular, in the process of hydrogenationof polymers, some aspects of the formation and the nature of the catalytically active speciesrequire further fundamental research. First of all this concerns the establishment all of thefunctions of I-III groups metal compounds in the formation and functioning of Ziegler typecatalyst. The report presents the results of studies of systems based on Ni (II), Co (II) and Pd(II) complexes, aluminum complex hydrides or their alkoxy hydride derivatives inhydrogenation catalysis. For these systems the kinetic characteristics (TOF and TON) aredetermined and the interaction of catalytic systems components is studied by spectralmethods. On the example of nickel (II), cobalt (II) and palladium (II) acetylacetonates it isrevealed that the LiAlH 4 role is not limited by reduction of the metal precursor to thenanoclusters that are 2-3 nm diameter. AlH 4 -anions adsorbed on the surface act as stabilizersof nanoparticles. In addition, the AlH 4 -anions and the products of catalytic decomposition ofLiAlH 4 and alan, formed in the redox process, block active sites, thereby reduce orcompletely suppress the catalytic activity in hydrogenation. Activity of metal clusters in thedecomposition of complex hydrides and alan can be arranged in the order: Ni >> Co> Pd.Inhibitory effect of coreagents on the catalytic activity decreases with the change of LiAlH 4by LiAlH 2 (tert-BuO) 2 and LiAlH(tert-BuO) 3 . The processes of alkoxy hydrido derivativesside-conversion in the catalytic system is revealed using spectral methods and the most likelyscheme of the disproportionation of LiAlH(tert-BuO) 3 and LiAlH 2 (tert-BuO) 2 is considered.Strategy for the synthesis of highly efficient and well-reproducible nanoscale catalysts isproposed, including the reduction of the metal precursor by LiAlH 4 (LiAlH n (OR) 3-n ) and thesubsequent activation by proton donor substance. Alcohols possess the greatest promotingeffect of the tested compounds.144