Advantages of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes as Metallocene Sources Towards Other Synthetically used Systems. Issue 8 (23rd July 2019)

• Record Type: Journal Article
• Authors: Rosenthal, Uwe
• Is Part Of: ChemistryOpen. Volume 8:Issue 8(2019)
• Page Start: 1036
• Page End: 1047
• Publication Date: 2019-07-23
• Subjects: organometallic synthesis -- group 4 transition metals -- metallocenes -- reactivity -- selectivity; Chemistry -- Periodicals; 540; 540.5
• DOI: 10.1002/open.201900196
• Languages: English
• ISSNs: 2191-1363

Abstract

Abstract: Active species for synthetic and catalytic applications are formed from well defined complexes or mixtures of compounds. For group 4 metallocenes, three pathways for the formation of the reactive complex fragment [Cp′2 M] are known: (i) reductive mixtures and well defined complexes which are able to form the metallocene fragments either by (ii) addition or (iii) substitution reactions. In this account for each of theses systems (i)–(iii) a prominent example will be discussed in detail, (i) the Negishi reagent Cp2 ZrCl2 /n‐BuLi, (ii) bis(η 5 : η 1 ‐pentafulvene) complexes and (iii) metallocene bis(trimethylsilyl)acetylene complexes, to show the advantages and the disadvantages for each of these methods for synthetic applications. This account summarizes some main advantages of group 4 metallocene bis(trimethylsilyl)acetylene complexes as metallocene generating agents over other synthetically used systems. For each of the special purposes, all described systems have advantages as well as disadvantages. The aim of this overview is to help synthetic chemists in selecting the most effective system on the basis of [Cp′2 M] (M=Ti, Zr) for synthetic or catalytic puposes. Abstract : Good – Better – Best ? Reactive fragments [Cp′2 M] of group 4 metallocenes are formed from reductive mixtures or well defined complexes by addition or substitution reactions. A comparison of the use of the (i) Negishi reagent Cp2 ZrCl2 /2 n ‐BuLi, (ii) the Beckhaus' bis(η 5 : η 1 ‐pentafulvene) complexes, and (iii) complexes Cp′2 M(L)(η 2 ‐Me3 SiC2 SiMe3 ) reveals advantages and disadvantages for these systems (M=Ti, Zr).