Nomenclature of Inorganic Chemistry. Second Edition

Abstract

Abstract

Polynuclear Magnesium and Magnesium−Titanium Species. Syntheses and Crystal Structures of [Mg4(μ3,η2-ddbfo)2(μ,η2-ddbfo)2(μ,η1-ddbfo)2(η1-ddbfo)2], [Mg4(μ3-OMe)2(μ,η2-ddbfo)2(μ,η1-ddbfo)2(η1-ddbfo)2(CH3OH)5], and [Mg4(μ3,η2-thffo)2(μ,η<

“…In our model compounds 4a , b , the titanium atom is bridge-bonded to the two magnesium atoms through two pairs of X (X = Cl, OR). Due to the presence of these bidentate chelating agents and terminal two X ligands in the cis position, the geometry of coordination at the Ti atoms, in 4a , is chiral, and can be denoted as Δ or Λ according to IUPAC rules for chiral octahedral compounds . As is apparent from Scheme , aggregate 4a is very similar to Ti 2 Cl 6 reliefs proposed earlier by Corradini, as precursors of stereospecific active centers experimentally observed for the two TiCl 3 /AlR 3 and TiCl 4 /MgCl 2 /AlR 3 classes of catalysts. , The 4b species has a symmetry center, because the two terminal X atoms are in the trans position and the titanium atom could be regarded as a nonstereospecific center.…”

Mechanisms of Propagation and Termination Reactions in Classical Heterogeneous Ziegler−Natta Catalytic Systems: A Nonlocal Density Functional Study

“…In our model, the Ti atom is bridge-bonded to the two Mg atoms through two pairs of Cl atoms. Due to the presence of these bidentate chelating agents, the geometry of coordination at the Ti atom is chiral, and can be denoted as Δ or Λ according to IUPAC rules for chiral octahedral compounds. , As remarked by molecular mechanics studies,13b the chirality of this simplified model site is not sufficient to ensure stereospecificity during polymerization. However, all the models we have considered are of Δ chirality.…”