Lanthanide oxoalkoxides

Other octanuclear lanthanide oxoalkoxides are known. They are also based on tetranuclear units arranged around square planar 0x0 ligands such as in [Erg( U4-0)(/i3-OH)i2(thd)io] (Boeyens and De Villiers, 1972 Pigure 106) and [Pr8(M4-C>)4(OC2H40Me)i6(OPMe3)2] (Hubert-Pfaizgraf et al., 1997). 

Costa E., Camus A., Marsich N.J. Copper methoxides formed by thermal decomposition of copper methyl in methanol. Inorg. Nucl. Chem. 1965 27 281 Daniele S., Hubert-Pfalzgraf L.G., Daran J.C. Building of lanthanide oxoalkoxides Synthesis and molecular structure of [Gd6(/i4-0)(/x3,77 -OR)4(R,/j -OR)6(/iv -OR)2(OR)4] (R= C2H40Me). Polyhedron 1996 15 1063... 

The first report on the coordination polymerisation of epoxide, leading to a stereoregular (isotactic) polymer, concerned the polymerisation of propylene oxide in the presence of a ferric chloride-propylene oxide catalyst the respective patent appeared in 1955 [13]. In this catalyst, which is referred to as the Pruitt Baggett adduct of the general formula Cl(C3H60)vFe(Cl)(0C3H6),CI, two substituents of the alcoholate type formed by the addition of propylene oxide to Fe Cl bonds and one chlorine atom at the iron atom are present [14]. A few years later, various types of catalyst effective for stereoselective polymerisation of propylene oxide were found and developed aluminium isopropoxide-zinc chloride [15], dialkylzinc-water [16], dialkylzinc alcohol [16], trialkylalumi-nium water [17] and trialkylaluminium-water acetylacetone [18] and trialkyla-luminium lanthanide triacetylacetonate H20 [19]. Other important catalysts for the stereoselective polymerisation of propylene oxide, such as bimetallic /1-oxoalkoxides of the [(R0)2A10]2Zn type, were obtained by condensation of zinc acetate with aluminium isopropoxide in a 1 2 molar ratio of reactants [20-22]. 

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