C8DT02654H.pdf (1.3 MB)
Bis(pentalene)dititanium chemistry: C–H, C–X and H–H bond activation
journal contribution
posted on 2023-06-09, 15:37 authored by Nikolaos Tsoureas, Jennifer C Green, Geoff ClokeThe reaction of the bis(pentalene)dititanium complex Ti2(µ:?5,?5-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 acti- vation 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-imid- azole, 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 s-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 s-bond metathesis. Finally, treatment of (3) with HCl affords the chloro-derivative (9) [(NHC)Ti(µ-H)Ti{(µ,?5:?5)Pn†}2Cl], whereas pro- tonation with [NEt3H]BPh4 yielded a cationic hydride (10) featuring an agostic interaction between a Ti centre and an iPr Me group.
Funding
Activation and Functionalisation of Carbon Dioxide by Low Valent Uranium Complexes; G1619; EPSRC-ENGINEERING & PHYSICAL SCIENCES RESEARCH COUNCIL; EP/M023885/1
History
Publication status
- Published
File Version
- Accepted version
Journal
Dalton TransactionsISSN
1477-9226Publisher
Royal Society of ChemistryExternal DOI
Issue
41Volume
47Page range
14531-14539Department affiliated with
- Chemistry Publications
Research groups affiliated with
- Energy and Materials Chemistry Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2018-10-25First Open Access (FOA) Date
2019-09-17First Compliant Deposit (FCD) Date
2018-10-24Usage metrics
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