Tetra-Cationic Distibane Stabilized by Bis(α-iminopyridine) and Its Reactivity
The work establishes the salt of a tetra-cationic distibane, [L<sub>2</sub>Sb<sub>2</sub>][CF<sub>3</sub>SO<sub>3</sub>]<sub>4</sub> = [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> (CF<sub>3</sub>SO<sub>3</sub> = OTf), stabilized by a bis(α-iminopyridine) ligand <b>L</b>, defying the Coulombic repulsion. The synthetic approach involved a dehydrocoupling reaction when a mixture of <b>L</b> and Sb(OTf)<sub>3</sub> in a 1:1 ratio was treated with Et<sub>3</sub>SiH/LiBEt<sub>3</sub>H as the hydride source. Compound [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> was also achieved from [LSbCl][OTf]<sub>2</sub> as a precursor and using Et<sub>3</sub>SiH. Dissolution of [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> in polar solvents unveiled the formation of the persistent <b>L</b>-stabilized dicationic Sb(II) radical monomer [<b>1</b>][OTf]<sub>2</sub>, while the addition of Me<sub>3</sub>SiOTf regenerated the dimer in the salt [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub>. The homolytic cleavage of the Sb-Sb bond in [<b>1</b>]<sub>2</sub><sup>4+</sup> has manifested in exchange reactions between [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> and Ph<sub>2</sub>Ch<sub>2</sub> (Ch = S, Se), giving [LSb(SPh)][OTf]<sub>2</sub> = [<b>2</b>][OTf]<sub>2</sub> and [LSb(SePh)][OTf]<sub>2</sub> = [<b>3</b>][OTf]<sub>2</sub>, respectively, in acetonitrile. Reaction between [<b>1</b>]<sub><b>2</b></sub>[OTf]<sub>4</sub> and <i>p</i>-benzoquinone gave [L<sub>2</sub>Sb<sub>2</sub>(C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>)][OTf]<sub>4</sub> = [<b>4</b>][OTf]<sub>4</sub>. An interesting oxygen atom insertion reaction occurred when [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> was treated with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to give [L<sub>2</sub>Sb<sub>2</sub>O][ OTf]<sub>4</sub> = [<b>5</b>][OTf]<sub>4</sub>. The oxo-bridged compound [<b>5</b>][OTf]<sub>4</sub> was also obtained from exposure of [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> in open air. The strong Mn-Mn bond in [Mn<sub>2</sub>(CO)<sub>10</sub>] could be cleaved by reacting with [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> in the presence of pyridine to form [LSbMn(CO)<sub>5</sub>][ OTf]<sub>2</sub> = [<b>6</b>][OTf]<sub>2</sub>. On the other hand, the reaction between [Co<sub>2</sub>(CO)<sub>8</sub>] and [<b>1</b>]<sub>2</sub>[OTf]<sub>4</sub> gave the oxidative addition product [L<sub>2</sub>Sb<sub>2</sub>Co(CO)<sub>3</sub>][OTf]<sub>3</sub> <b>=</b> [<b>7</b>][OTf]<sub>3</sub>. The compounds were characterized both in the solid and solution states. Computational studies gave a comprehensive understanding of the experimental findings.
Authors
- Haakon T. A. Wiedemann (ORCID: https://orcid.org/0000-0002-7130-5149)
- Katrin Beuthert (ORCID: https://orcid.org/0000-0002-8334-6212)
- Christopher W. M. Kay (ORCID: https://orcid.org/0000-0002-5200-6004)
- Moumita Majumdar (ORCID: https://orcid.org/0000-0001-5582-3475)
- Stefanie Dehnen (ORCID: https://orcid.org/0000-0002-1325-9228)
- Cem B. Yildiz (ORCID: https://orcid.org/0000-0002-0424-4673)
- Hritwik Haldar
- Satyabrata Das (ORCID: https://orcid.org/0000-0003-4929-3839)
Institutions
- Karlsruhe Institute of Technology (DE)
- Indian Institute of Science Education and Research Pune (IN)
- Bartin University (TR)
- London Centre for Nanotechnology (GB)
- University College London (GB)
- Saarland University (DE)
Publication Details
- Journal
- Journal of the American Chemical Society
- Published
- 2025-01-16
- DOI
- https://doi.org/10.1021/jacs.4c12354
- Citations
- 7
- Primary Topic
- Synthesis and characterization of novel inorganic/organometallic compounds
- Type
- article
- Field-Weighted Citation Impact
- 3.76
Funders
- Alexander von Humboldt-Stiftung
- Science and Engineering Research Board