Issue 41, 2018

Bis(pentalene)dititanium chemistry: C–H, C–X and H–H bond activation

Abstract

The reaction of the bis(pentalene)dititanium complex Ti2(μ:η55-Pn)2 (Pn = C8H4(1,4-SiiPr3)2) (1) with the N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene results in intramolecular C–H activation of an isopropyl substituent to form a tucked-in hydride (3). Whilst pyridine will also effect this cyclometallation reaction to form (5), the pyridine analogue of (3), the bases 1,2,4,5-tetramethyl-imidazole, 2,6-lutidine, DABCO or trimethylphosphine are ineffective. The reaction of (1) with 2,6-dichloro-pyridine affords crystallographically characterised (6) which is the product of oxidative addition of one of the C–Cl bonds in 2,6-dichloro-pyridine across the Ti–Ti double bond in (1). The tucked-in hydride (3) reacts with hydrogen to afford a dihydride complex (4) in which the tuck-in process has been reversed; detailed experimental and computational studies on this reaction using D2, HD or H2/D2 support a mechanism for the formation of (4) which does not involve σ-bond metathesis of H2 with the tucked-in C–H bond in (3). The reaction of (3) with tBuCCH yields the corresponding acetylide hydrido complex (7), where deuteration studies show that again the reaction does not proceed via σ-bond metathesis. Finally, treatment of (3) with HCl affords the chloro-derivative (9) [(NHC)Ti(μ-H)Ti{(μ,η55)Pn}2Cl], whereas protonation with [NEt3H]BPh4 yielded a cationic hydride (10) featuring an agostic interaction between a Ti centre and an iPr Me group.

Graphical abstract: Bis(pentalene)dititanium chemistry: C–H, C–X and H–H bond activation

Supplementary files

Article information

Article type
Paper
Submitted
29 ⵢⵓⵏ 2018
Accepted
17 ⵛⵓⵜ 2018
First published
17 ⵛⵓⵜ 2018

Dalton Trans., 2018,47, 14531-14539

Bis(pentalene)dititanium chemistry: C–H, C–X and H–H bond activation

N. Tsoureas, J. C. Green and F. G. N. Cloke, Dalton Trans., 2018, 47, 14531 DOI: 10.1039/C8DT02654H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements