Regresar

Molecular heterobimetallic aluminoxanes and aluminoxane sulfides containing group 4 metals

Abstract:

Reactivity studies of aluminoxane hydroxide and hydrogensulfide [{ MeLAl(EH)}2(μ-O)] {MeL = CH[CMe(NAr)] 2- (Ar = 2,4,6-Me3C6H2); E = O (1), S (2)} with Group 4 amides led to the molecular heterobimetallic aluminoxanes [(MeLAlO)2(μ-O){M(NR2) 2}] [M = Ti, R = Me (3); M = Zr, R = Me (4), Et (5); M = Hf, R = Me (6), Et (7)] and aluminoxane sulfides [(MeLAlS)2(μ-O) {M(NR2)2}] [M = Ti, R = Me (8), Et (9); M = Zr, R = Me (10), Et (11); M = Hf, R = Me (12), Et (13)], respectively. The structural analyses of these compounds reveal six-membered inorganic cores that exhibit Al-E-M (E = O, S; M = Ti, Zr, Hf) moieties. Compounds 10-13 exhibit strong O···M (M = Zr, Hf) transannular bonding, whereas 8 and 9 exhibit relatively short Ti-S bond lengths. DFT calculations performed on 8-13 at the B3LYP/LANL2DZ level of theory indicate that the titanium atoms in 8 and 9, despite having the lowest transannular bond index, have the highest total Wiberg bond indexes. This can be rationalized in terms of the high Ti-S bond indexes, which indicate an important degree of electron density delocalized from the sulfur atoms to the titanium atom. A series of Group 4 heterobimetallic aluminoxanes and aluminoxane sulfides have been prepared. The aluminoxane sulfides exhibit unprecedented Al-S-M (M = Zr, Hf) moieties. The structural and electronic features of these compounds were investigated by DFT calculations. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.