100581-50-8Relevant academic research and scientific papers
REACTION OF BIS(μ-CHALCOGENO) COMPLEXES 5-RC5H4)2M(μ-E)>2 M = Zr, Hf; R = H, t-Bu; E = S OR Se FROM METALLOCENE DICHLORIDES, AND ISOLATION OF THE MIXED μ-COMPLEXES (μ-O)(μ-E)
Tainturier, Gerard,Gautheron, Bernard,Fahim, Mohammed
, p. C4 - C6 (1985)
Metallocene dichlorides (RCp)2MCl2 (M = Zr, Hf; R = H, t-Bu) react with E/2HLiBEt3 (E = S, Se) to give the symmetrical dinuclear compounds 2.UV irradiation in toluene of 2(μ-O) in the presence of powdered sulfur or gray sel
Hindered η-cyclopentadienyl-metal rotation caused by lateral interaction of Cp-bonded substituents at chalcogen-bridged binuclear bent metallocene complexes [(RCp)2ZrX]2
Erker, Gerhard,Nolte, Rainer,Tainturier, Gérard,Rheingold, Arnold
, p. 454 - 460 (2008/10/08)
(η-Butadiene)bis(η-tert-butylcyclopentadienyl)zirconium reacts with elemental tellurium to give [(Me3CCp)2Zr(μ-Te)]2 (6). Upon controlled hydrolysis, one bridging tellurium is exchanged for oxygen to give the metallacyclic complex [(Me3CCp)2Zr]2(μ-O)(μ-Te) (7). The analogous oxygen/selenium-bridged bimetallic zirconium complex [(Me3CCp)2Zr]2(μ-O)(μ-Se) (8) is formed upon photolysis of the μ-oxo precursor (Me3CCp)2Zr(CH3)OZr(CH3)(CpCMe 3) in the presence of a suspension of elemental selenium. Complex 6 exhibits a nearly square-planar array of alternating zirconium and tellurium atoms. In contrast, the planar ZrTeZrO framework of 7 is characterized by very different bond angles at tellurium (average 72.1 (1)°) and oxygen (average 119.2 (2)°), bringing the zirconium atoms (average Zr?Zr = 3.390 (1) A?) more closely together than in 6 (Zr?Zr = 4.067 (1) A?). In the crystal each (Me3CCp)2Zr subunit is chiral, favoring a nearly C2-symmetric conformation. The bulky tert-butyl groups are oriented trans to each other in the lateral sectors of the Cp-substituted bent metallocene unit. Combination of the two chiral (Me3CCp)2Zr moieties can give rise to the formation of two diastereomeric bis(metallocene) complexes. For the bis-(tellurium)-bridged compound 6 an achiral C2h-symmetric meso form is favored, while the oxygen, tellurium-bridged analogue 7 adopts a chiral nearly C2-symmetric conformation in the solid state. Complex 7 crystallizes in the monoclinic space group Cc with cell constants a = 18.231 (5) A?, b = 18.186 (6) A?, c = 22.563 (6) A?, β = 107.57 (2)°, V = 7132 (3) A?3, Z = 8, and R(F) = 4.08%. The [(Me3CCp)2Zr](μ-X)(μ-Y) complexes feature hindered (Me3CCp)-metal rotation in solution. Activation barriers ΔG?rot ≈ 9.6 ± 0.4 kcal/mol (for 7 at 206 K) and 11.0 ± 0.4 kcal/mol (for 8 at 222 K) have been estimated by dynamic 1H NMR spectroscopy. Complexes 7 and 8 appear to be the first examples where hindered (RCp)-M rotation is induced by a lateral (RCp)?(RCp) interaction across a rigid metal complex framework.
