Formation and Structures of [1,2–Bis(N-tert-butylcarbamoyl)cyclopentadienyl]zirconium Complexes – Coordination Chemistry of a “Fulvenologous” Malonic Amide Anion Ligand System
✍ Scribed by Katrin Klaß; Lothar Duda; Nina Kleigrewe; Gerhard Erker; Roland Fröhlich; Elina Wegelius
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 256 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Functionalized Cp ligand / κ 2 O,OЈ-Chelate / Carboxamido-substituted cyclopentadienides / Zirconium complexes Treatment of sodium cyclopentadienide with two molar membered metallacyclic structural type is found in the reaction products of 6 with ZrCl 4 (THF) 2 in 1:1 and 2:1 molar equivalents of tert-butyl isocyanate yields sodium 1,2-bis(Ntert-butylcarbamoyl)cyclopentadienide (6). The [C 5 H 3 (1,2-ratios. The former yields the distorted octahedral complex ZrCl 3 C 5 H 3 (CONHCMe 3 ) 2 ( ), the latter gives the CONHCMe 3 ) 2 ]Na reagent 6 adds to Cp 2 Zr(CH 3 )Cl ( ) to yield Cp 2 Zr(CH 3 )[C 5 H 3 (CONHCMe 3 ) 2 ] (9). In 9 the chiral octahedral system ZrCl 2 [C 5 H 3 (CONHCMe 3 ) 2 ] 2 (13). In solution, complex 13 undergoes a thermally induced C 5 H 3 (CONHCMe 3 ) 2 ligand is bonded to zirconium through one of its carboxamido-oxygen atoms (κO-coordination).
enantiomerization process (Λ v ∆ interconversion), for which a Gibbs activation energy of ∆G ‡ enant = 14.0 ± 0.3 kcal mol -1 Treatment of 6 with CpZrCl 3 (THF) 2 yields CpZrCl 2 C 5 H 3 -(CONHCMe 3 ) 2 11. In 11 the 1,2-bis(N-tert-butyl-was determined by dynamic 1 H-NMR spectroscopy. The κ 2 O,OЈ-coordination of the [C 5 H 3 (1,2-CONHCMe 3 ] -ligand carbamoyl)cyclopentadienide moiety serves as a C ssymmetric chelate ligand, binding to zirconium through both in the complexes 11, 12, and 13 was secured by X-ray crystal structure analyses. carbamoyl oxygens (κ 2 O,OЈ-coordination). The same seven-We had previously shown that the cyclopentadienyl anion [a] Organisch-Chemisches Institut der Universität Münster, pentadienide electron density, a situation might arise where Corrensstr. 40, D-48149 Münster, Germany the remaining Cp-nucleophilicity is not sufficient to warrant