title: Structure of the decamethyl titanocene cation, a metallocene with two agostic C-h bonds, and its interaction with fluorocarbons.
abstract: The tetraphenylborate salt of the decamethyl titanocene cation, [Cp*2Ti][BPh4] (1, Cp* = C5Me5), was prepared by reaction of Cp*2TiH with [Cp2Fe][BPh4] and by reaction of Cp*2TiMe with [PhNMe2H][BPh4]. The crystal structure of 1 shows that the Cp*2Ti cation has a bent metallocene structure with agostic interactions with the metal center of two adjacent methyl groups on one of the Cp* ligands. Compound 1 reacts readily with THF to give the adduct [Cp*2Ti(THF)][BPh4] (2). In fluorobenzene, 1 forms the eta1-fluorobenzene adduct [Cp*2Ti(eta1-FC6H5)][BPh4] (3), which was structurally characterized. In contrast to the thermal stability of 3, addition of alpha,alpha,alpha-trifluorotoluene to either 1 or 2 results in C-F activation to give Cp*2TiF2 and PhCF2CF2Ph as the main products. This reactivity toward benzylic C-F bonds is also reflected in the reactivity toward the fluorinated borate anions [B(C6F5)4]- and {B(3,5-(CF3)2C6H3]4}-: reaction of Cp*2TiMe with their [PhNMe2H]+ salts results in a stable complex for the former anion, whereas rapid C-F activation is observed for the latter.
authors.affiliation: Center for Catalytic Olefin Polymerization, Stratingh Institute for Chemistry and Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Marco W
authors.initials: MW
authors.lastname: Bouwkamp
authors.forename: Jeanette
authors.initials: J
authors.lastname: de Wolf
authors.forename: Isabel
authors.initials: I
authors.lastname: del Hierro Morales
authors.forename: Jeroen
authors.initials: J
authors.lastname: Gercama
authors.forename: Auke
authors.initials: A
authors.lastname: Meetsma
authors.forename: Sergei I
authors.initials: SI
authors.lastname: Troyanov
authors.forename: Bart
authors.initials: B
authors.lastname: Hessen
authors.forename: Jan H
authors.initials: JH
authors.lastname: Teuben