Heteroatom‐Substituted Group 4 Bis(indenyl)metallocenes

Abstract

The synthesis, characterization and applications of heteroatom‐substituted group 4 bis(indenyl)metallocene complexes is reviewed. In recent years, an increasing number of group 4 metallocenes with electronically modified cyclopentadienyl ligands have been reported with, in some cases, considerably altered catalytic properties. This microreview focuses on bis(indenyl) complexes of titanium, zirconium and hafnium that contain nitrogen, oxygen and sulfur atoms directly bonded to the five‐ or six‐membered rings of the indenyl ligand framework. The catalytic performance is briefly reviewed, with emphasis on catalytic olefin polymerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The first synthesised examples of di-siloxy-substituted cyclopentadienyl zirconocenes, their synthesis, structure and activity in ethylene polymerisation

“…Table 3 shows polymerisation data for the 5a-c complexes under co-polymerisation conditions using ethylene and 1-hexene, with MAO as co-activator. It shows that all three complexes 5a-c have a low polymerisation activity compared with previously published structures [14,18]. Molecular weights of the hexene-ethylene copolymers are markedly high in the case of 5a with M w = 919,000 and much lower with 5c, M w = 65,500.…”

“…There are 7 XRD structures of previously published siloxy-substituted-bis-zirconocenes that can be found in the CCDC database [14]. They are all indenyl or tetra-hydroindenyl type zirconocenes with one siloxy substituent in the 5-ring and having an ethylene bridged structure.…”

“…An important group of zirconocenes in this respect is the siloxy substituted bis-indenyl metallocenes which have been investigated by Leino, Luttikhedde and Kallio et al who have shown them to be highly active in olefin polymerisation and well behaving in the polymerisation process [14]. The more unusual behaviour of this complex family has been investigated by Kallio et al, [15,16] who reported hexaisobutylalumoxane (HIBAO) as a well functioning co-catalyst in combination with siloxy substituted zirconocenes.…”

Molybdenum complexes containing substituted cyclopenta[l]phenanthrenyl ligand

“…Synthesis of amino-functionalized cyclopentadienes [23,24] and indenes [23][24][25][26] through reaction of the cyclopentenone (indanone) with secondary amines and their use for synthesis of the transition metal complexes [22][23][24][25][26] was the subject of several studies. However this is the first example of applying this method to the synthesis of the cyclopentadienyl-based framework containing both tertiary amino and carboxylic ester groups.…”

Synthesis of Fused‐Ring Indenes by Ruthenium‐Catalyzed Ring‐Closing Metathesis

“…[8][9][10][11] Recently, e.g., Halterman, [12,13] Takahashi et al, [14] and Takai and co-workers [15] have reported efficient metal-mediated or metal-catalyzed methods for preparation of new indenyl frameworks.…”