Issue 12, 2013

Understanding intermolecular C–F bond activation by a transient titanium neopentylidyne: experimental and theoretical studies on the competition between 1,2-CF bond addition and [2 + 2]-cycloaddition/β-fluoride elimination

Abstract

Complex (PNP)Ti[double bond, length as m-dash]CHtBu(CH2tBu) (PNP = N[2-P(CHMe2)2-4-methylphenyl]2) eliminates H3CtBu to form transient (PNP)Ti[triple bond, length as m-dash]CtBu, which activates the C–F bond of ortho-difluoropyridine and ortho-fluoropyridine to form the alkylidene–fluoride complexes, (PNP)Ti[double bond, length as m-dash]C[tBu(NC5H3F)](F) (1) and (PNP)Ti[double bond, length as m-dash]C[tBu(NC5H4)](F) (2), respectively. When (PNP)Ti[double bond, length as m-dash]CHtBu(CH2tBu) is treated with meta-fluoropyridine, the ring-opened product (PNP)Ti(C(tBu)CC4H3-3-FNH) (3) is the only recognizable titanium metal complex formed. Theoretical studies reveal that pyridine binding disfavors 1,2-CF bond addition across the alkylidyne ligand in the case of ortho-fluoride pyridines, while sequential [2 + 2]-cycloaddition/β-fluoride elimination is a lower energy pathway. In the case of meta-fluoropyridine, [2 + 2]-cycloaddition and subsequent ring-opening metathesis is favored as opposed to C–H bond addition or sequential [2 + 2]-cycloaddition/β-hydride elimination. In all cases, C–H bond addition of ortho-fluoropyridines or meta-fluoropyridine is discouraged because such substrate must bind to titanium via its C–H bond, which is rather weak compared to the titanium–pyridine binding.

Graphical abstract: Understanding intermolecular C–F bond activation by a transient titanium neopentylidyne: experimental and theoretical studies on the competition between 1,2-CF bond addition and [2 + 2]-cycloaddition/β-fluoride elimination

Supplementary files

Article information

Article type
Paper
Submitted
26 Oct 2012
Accepted
14 Jan 2013
First published
16 Jan 2013

Dalton Trans., 2013,42, 4163-4174

Understanding intermolecular C–F bond activation by a transient titanium neopentylidyne: experimental and theoretical studies on the competition between 1,2-CF bond addition and [2 + 2]-cycloaddition/β-fluoride elimination

H. Fan, A. R. Fout, B. C. Bailey, M. Pink, M. Baik and D. J. Mindiola, Dalton Trans., 2013, 42, 4163 DOI: 10.1039/C3DT32570A

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