Aromatic Imines in the Titanocene Coordination Sphere—Titanaaziridine vs 1-Aza-2-titanacyclopent-4-ene Structures
摘要:
Two independent synthetic routes to eta(2)-imine titanocene complexes were developed. On one hand side, ligand exchange reactions of bis(trimethylsilyl)acetylene by (p-Tolyl)HC-NPh (3) employing the Rosenthal reagent Cp2Ti{eta(2)-C-2(SiMe3)(2)} (1) lead to Cp2Ti{eta(2)-(p-Tolyl)CH-NPh} (5), exhibiting a titanaaziridine structure. On the other hand, the direct reductive complexation of 3 by using Cp2TiCl2 (2) and Mg as reducing agent leads also to 5, one of the rare known titanoceneaziridines without additional ligands. By using the ketimine (p-Tolyl)(2)C-NPh (4) instead of the aldimine 3, an unexpected coordination mode was found by X-ray diffraction, exhibiting an azatitanacyclopent-4-ene structure involving one tolyl fragment. In such a way, via the reductive complexation of 4, employing 2 or Cp*TiCl3 (12), the 1-aza-2-titanacyclopent-4-ene complexes 6 and 13 are formed. Density functional calculations at the M06-2X level identify these new complexes 6 and 13 as 1-aza-2-titanacyclopent-4-enes, in agreement with an analysis based on the experimental structural parameters. A theoretical study of the bonding between the titanocene fragment and the imine ligand reveals that steric factors are more pronounced for titanaaziridines and disfavor their formation compared to azatitanacyclopentenes. This provides a rationalization for the preferred formation of titanoceneaziridines in the case of aldimine ligands and azatitanacyclopentenes when ketimines are applied. Whereas titanoceneaziridine 5 undergoes insertion reactions into the TiC carbon s-bond with aldehydes, ketones, or carbodiimides to the five-membered titanacycles 20 and 21, complex 6 appears to be inert in comparable reactions
amidines. Ynamides reacted with benzophenoneimines in the presence of triflic imide as a catalyst. Ynamides bearing a sulfonamide moiety gave the corresponding 2-amino-3,4-dihydroquinolines selectively in good to high yields. In contrast, yne-carbamates gave the corresponding α,β-unsaturated amidines exclusively. These methods permit simple preparation of stericallycrowded polysubstituted quinolines and
observed. By insertion of the isocyanate CyNCO the formation of a Ti–N bond in 6a is preferred in comparison to the insertion of the isothiocyanate PhNCS, where a Ti–S bond is formed (7a). By reacting 2a with aldimine PhN═C(H)(p-tolyl) the nonsymmetric titanaimidazolidine derivative 8a is formed by subsequent ketimine–aldimine coupling. By derivatization of 2a with LiN(Me)Cy the formation of a the titanadihydropyrrole
Imines in the Titanium Coordination Sphere: η
<sup>1</sup>
‐Imine Complexes as Sources of Azavinylidenes and Four‐Membered Imine–Amido‐
<i>N</i>
,
<i>N′</i>
Chelates
In titanium imine complexes the ligand can exhibit several bonding modes. While η2-imine complexes are intermediates in several catalytic transformations and well investigated, the potential of imines to coordinate through the lone pair of electrons of the nitrogen atom by a dative bond to the titanium center is studied herein. The formation of several bis-η1 complexes by the reaction of Schiff bases
New materials for electroluminescence and the utilization thereof
申请人:Heun Susanne
公开号:US20070080343A1
公开(公告)日:2007-04-12
The present invention relates to organic semiconductors which contain structural units L=X and in addition structural units which emit light from the triplet state. The materials according to the invention are more soluble and easier to synthesise and are therefore more suitable for use in organic light-emitting diodes than comparative materials in accordance with the prior art.
MATERIALS FOR ELECTROLUMINESCENCE AND THE UTILIZATION THEREOF
申请人:Heun Susanne
公开号:US20100102305A1
公开(公告)日:2010-04-29
The present invention relates to organic semiconductors which contain structural units L=X and in addition structural units which emit light from the triplet state. The materials according to the invention are more soluble and easier to synthesise and are therefore more suitable for use in organic light-emitting diodes than comparative materials in accordance with the prior art.