Reactions of R<sub>3</sub>PNNPR<sub>3</sub> Species with Boranes: Classical Adducts, FLPs, and Radical Cations
Although the nature of bis-phosphazine species is of much interest, there are few reports of their reactivity. Herein, we show that the bis-phosphazine species Ph<sub>3</sub>PNNPPh<sub>3</sub> 1 react with Lewis acids to give the Lewis acid adducts Ph<sub>3</sub>PNN(B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>)PPh<sub>3</sub> 3 and Ph<sub>3</sub>PN(BF<sub>3</sub>)N(BF<sub>3</sub>)PPh<sub>3</sub> 4. Compound 1 also generates a frustrated Lewis pair (FLP) in the presence of BPh<sub>3</sub> and thermolysis of 1/BPh<sub>3</sub>, or 3 at 80 °C released N<sub>2</sub> while 4 was stable at 80 °C. In contrast, the species Cy<sub>3</sub>PNNPCy<sub>3</sub> 2 reacted with B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> to effect single electron transfer affording a frustrated radical pair (FRP). Independent reactions of 1 and 2 with [Cp<sub>2</sub>Fe][BF<sub>4</sub>] gave the corresponding radical salts [R<sub>3</sub>PNNPR<sub>3</sub>]<sup>•+</sup>[BF<sub>4</sub>] (R = Cy 5b Ph 6). Structural and computational data show the N─N bond is strengthened in the bis-phosphazine radical cation.
Authors
- Vaibhav Bedi (ORCID: https://orcid.org/0000-0001-7538-2478)
- Zheng‐Wang Qu (ORCID: https://orcid.org/0000-0001-6631-3681)
- Douglas W. Stephan (ORCID: https://orcid.org/0000-0001-8140-8355)
- Stefan Grimme (ORCID: https://orcid.org/0000-0002-5844-4371)
- Andrew Niles L. Ocampochua
Institutions
- University of Bonn (DE)
- University of Toronto (CA)
Publication Details
- Journal
- Angewandte Chemie International Edition
- Published
- 2025-03-11
- DOI
- https://doi.org/10.1002/anie.202503331
- Citations
- 3
- Primary Topic
- Organoboron and organosilicon chemistry
- Type
- article
- Field-Weighted Citation Impact
- 2.81