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A titanium redox-switch enables reversible C-C bond forming and splitting reactions

G. Jafari, Mehrafshan ; Fehn, Dominik ; Sandoval-Pauker, Christian ; Gau, Michael R. ; Meyer, Karsten ; Pinter, Balazs ; Mindiola, Daniel J. and Reinholdt, Anders LU (2025) In Chemical Science 16(38). p.17714-17724
Abstract

Using an Earth-abundant transition metal to mediate formation and splitting of C-C σ-bonds, in response to electrical stimuli, constitutes a promising strategy to construct complex organic skeletons. Here, we showcase how [nBu4N][N3] reacts with an isocyanide adduct of a tetrahedral and high-spin TiII complex, [(TptBu,Me)TiCl] (1), to enact N-atom transfer, C-N bond formation, and C-C coupling, to form a dinuclear complex, [(TptBu,Me)Ti{AdN(N)C-C(N)NAd}Ti(TptBu,Me)] (3), with two TiIII ions bridged by a disubstituted oxalimidamide ligand (nBu = n-butyl, TptBu,Me = hydrotris(3-tert-butyl-5-methylpyrazol-1-yl)borate, Ad =... (More)

Using an Earth-abundant transition metal to mediate formation and splitting of C-C σ-bonds, in response to electrical stimuli, constitutes a promising strategy to construct complex organic skeletons. Here, we showcase how [nBu4N][N3] reacts with an isocyanide adduct of a tetrahedral and high-spin TiII complex, [(TptBu,Me)TiCl] (1), to enact N-atom transfer, C-N bond formation, and C-C coupling, to form a dinuclear complex, [(TptBu,Me)Ti{AdN(N)C-C(N)NAd}Ti(TptBu,Me)] (3), with two TiIII ions bridged by a disubstituted oxalimidamide ligand (nBu = n-butyl, TptBu,Me = hydrotris(3-tert-butyl-5-methylpyrazol-1-yl)borate, Ad = 1-adamantyl). Magnetic and computational studies reveal two magnetically isolated d1 TiIII ions, and electrochemical studies unravel a reversible two-electron oxidation at −0.87 V vs. [FeCp2]0/+. Despite these observations, chemical oxidation of 3, ultimately, leads to rupture of the oxalimidamide moiety with C-C bond splitting to form [(TptBu,Me)Ti{1,3-μ2-AdNCN}2Ti(TptBu,Me)][B(C6F5)4]2 (4), which displays an antiferromagnetically coupled Ti2III,III configuration, mediated by superexchange through its bridging carbodiimide ligands. A comparative reactivity study of isocyanide toward a transient vanadium nitride [(TptBu,Me)V 00000000000000000 00000000000000000 00000000000000000 01111111111111110 00000000000000000 01111111111111110 00000000000000000 01111111111111110 00000000000000000 00000000000000000 00000000000000000 N(THF)] (5) gives further insight into the structure of putative intermediates involved in the coupling sequence.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Chemical Science
volume
16
issue
38
pages
11 pages
publisher
Royal Society of Chemistry
external identifiers
  • pmid:40910133
  • scopus:105017590134
ISSN
2041-6520
DOI
10.1039/d5sc04824a
language
English
LU publication?
yes
id
c66757e9-3911-46cd-a48a-86a026b2f425
date added to LUP
2025-11-25 15:40:03
date last changed
2025-11-26 03:00:04
@article{c66757e9-3911-46cd-a48a-86a026b2f425,
  abstract     = {{<p>Using an Earth-abundant transition metal to mediate formation and splitting of C-C σ-bonds, in response to electrical stimuli, constitutes a promising strategy to construct complex organic skeletons. Here, we showcase how [<sup>n</sup>Bu<sub>4</sub>N][N<sub>3</sub>] reacts with an isocyanide adduct of a tetrahedral and high-spin Ti<sup>II</sup> complex, [(Tp<sup>tBu,Me</sup>)TiCl] (1), to enact N-atom transfer, C-N bond formation, and C-C coupling, to form a dinuclear complex, [(Tp<sup>tBu,Me</sup>)Ti{AdN(N)C-C(N)NAd}Ti(Tp<sup>tBu,Me</sup>)] (3), with two Ti<sup>III</sup> ions bridged by a disubstituted oxalimidamide ligand (<sup>n</sup>Bu = n-butyl, Tp<sup>tBu,Me</sup> = hydrotris(3-tert-butyl-5-methylpyrazol-1-yl)borate, Ad = 1-adamantyl). Magnetic and computational studies reveal two magnetically isolated d<sup>1</sup> Ti<sup>III</sup> ions, and electrochemical studies unravel a reversible two-electron oxidation at −0.87 V vs. [FeCp<sub>2</sub>]<sup>0/+</sup>. Despite these observations, chemical oxidation of 3, ultimately, leads to rupture of the oxalimidamide moiety with C-C bond splitting to form [(Tp<sup>tBu,Me</sup>)Ti{1,3-μ<sub>2</sub>-AdNCN}<sub>2</sub>Ti(Tp<sup>tBu,Me</sup>)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub> (4), which displays an antiferromagnetically coupled Ti<sub>2</sub><sup>III,III</sup> configuration, mediated by superexchange through its bridging carbodiimide ligands. A comparative reactivity study of isocyanide toward a transient vanadium nitride [(Tp<sup>tBu,Me</sup>)V 00000000000000000 00000000000000000 00000000000000000 01111111111111110 00000000000000000 01111111111111110 00000000000000000 01111111111111110 00000000000000000 00000000000000000 00000000000000000 N(THF)] (5) gives further insight into the structure of putative intermediates involved in the coupling sequence.</p>}},
  author       = {{G. Jafari, Mehrafshan and Fehn, Dominik and Sandoval-Pauker, Christian and Gau, Michael R. and Meyer, Karsten and Pinter, Balazs and Mindiola, Daniel J. and Reinholdt, Anders}},
  issn         = {{2041-6520}},
  language     = {{eng}},
  number       = {{38}},
  pages        = {{17714--17724}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Chemical Science}},
  title        = {{A titanium redox-switch enables reversible C-C bond forming and splitting reactions}},
  url          = {{http://dx.doi.org/10.1039/d5sc04824a}},
  doi          = {{10.1039/d5sc04824a}},
  volume       = {{16}},
  year         = {{2025}},
}