title: Arylimido-Bridged Dinuclear Ti(μ-NAr)2Ti Scaffold for Alkyne Insertion into the ortho-C-H Bond of Arylimido Ligands.
abstract: Dinuclear titanium dialkyl complexes bridged by two μ-arylimido ligands, [CpTi(CH2SiMe3)(μ-NAr)]2(Cp=cyclopentadienyl) activated an ortho-aryl C-H bond of an μ-arylimido ligand to form a four-membered titanacycle. The subsequent insertion reaction of 1-(trimethylsilyl)propyne into a metal-carbon bond of the four-membered titanacycle yielded the corresponding six-membered titanacycle. Further ortho-C-H bond activation of the other μ-arylimido ligand and an insertion reaction proceeded to give dinuclear titanium complexes with two six-membered titanacycles. An Eyring plot in the temperature range 130-150 °C revealed activation parameters for the alkenylation reaction, and deuterium-labeling experiments showed that the C-H bond activation step is the rate determining step. Relative Gibbs free energies of the starting complexes, reaction intermediates, and transition states were calculated by using DFT calculations.
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Nagae
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Hato
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Kawakita
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Tsurugi
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Mashima
keywords: C−H activation; N ligands; alkynes; reaction mechanisms; titanium