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Syntheses and Reductions of C-Dimesitylboryl-1,2-dicarba-closo-dodecaboranes

Kahlert, J.; Böhling, L.; Brockhinke, A.; Stammler, H.-G.; Newmann, B.; Rendina, L.M.; Low, P.J.; Weber, L.; Fox, M.A.

Syntheses and Reductions of C-Dimesitylboryl-1,2-dicarba-closo-dodecaboranes Thumbnail


Authors

J. Kahlert

L. Böhling

A. Brockhinke

H.-G. Stammler

B. Newmann

L.M. Rendina

P.J. Low

L. Weber



Abstract

Two C-dimesitylboryl-1,2-dicarba-closo-dodecaboranes, 1-(BMes2)-2-R-1,2-C2B10H10 (1, R = H, 2, R = Ph), were synthesised by lithiation of 1,2-dicarba-closo-dodecaborane and 1-phenyl-1,2-dicarba-closo-dodecaborane, respectively, with n-butyllithium and subsequent reaction with fluorodimesitylborane. These novel compounds were structurally characterised by X-ray crystallography. Compounds 1 and 2 are hydrolysed on prolonged exposure to air to give mesitylene and boronic acids 1-(B(OH)2)-2-R-1,2-C2B10H10 (3, R = H, 4, R = Ph respectively). Addition of fluoride anions to 1 and 2 resulted in boryl-carborane bond cleavage to give dimesitylborinic acid HOBMes2. UV absorption bands at 318–333 nm were observed for 1 and 2 corresponding to local π–π*-transitions within the dimesitylboryl groups while visible emissions at 541–664 nm with Stokes shifts of 11920–16170 cm−1 were attributed to intramolecular charge transfer transitions between the mesityl and cluster groups. Compound 2 was shown by cyclic voltammetry to form a stable dianion on reduction. NMR spectra for the dianion [2]2− were recorded from solutions generated by reductions of 2 with alkali metals and compared with NMR spectra from reductions of 1,2-diphenyl-ortho-carborane 5. On the basis of observed and computed 11B NMR shifts, these nido-dianions contain bowl-shaped cluster geometries. The carborane is viewed as the electron-acceptor and the mesityl group is the electron-donor in C-dimesitylboryl-1,2-dicarba-closo-dodecaboranes.

Citation

Kahlert, J., Böhling, L., Brockhinke, A., Stammler, H., Newmann, B., Rendina, L., …Fox, M. (2015). Syntheses and Reductions of C-Dimesitylboryl-1,2-dicarba-closo-dodecaboranes. Dalton Transactions, 44(21), 9766-9781. https://doi.org/10.1039/c5dt00758e

Journal Article Type Article
Acceptance Date Apr 24, 2015
Publication Date Jun 7, 2015
Deposit Date Apr 30, 2015
Publicly Available Date Mar 29, 2024
Journal Dalton Transactions
Print ISSN 1477-9226
Electronic ISSN 1477-9234
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 44
Issue 21
Pages 9766-9781
DOI https://doi.org/10.1039/c5dt00758e

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Copyright Statement
This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.





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