The Si2H radical supported by two N-heterocyclic carbenes

Marius I. Arz; Gregor Schnakenburg; Andreas Meyer; Olav Schiemann; Alexander C. Filippou

doi:10.1039/C6SC01569G

The Si₂H radical supported by two N-heterocyclic carbenes†

Marius I. Arz,^a Gregor Schnakenburg,^a Andreas Meyer,^b Olav Schiemann^b and Alexander C. Filippou*^a

* Corresponding authors

^a Institute of Inorganic Chemistry, University of Bonn, Gerhard-Domagk-Str. 1, Bonn, Germany
E-mail: filippou@uni-bonn.de

^b Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, Bonn, Germany

Abstract

Cyclic voltammetric studies of the hydridodisilicon(0,II) borate [(Idipp)(H)Si^II [double bond, length as m-dash] Si⁰(Idipp)][B(Ar^F)₄] (1H[B(Ar^F)₄], Idipp = C[N(C₆H₃-2,6-iPr₂)CH]₂, Ar^F = C₆H₃-3,5-(CF₃)₂) reveal a reversible one-electron reduction at a low redox potential (E_1/2 = −2.15 V vs. Fc⁺/Fc). Chemical reduction of 1H[B(Ar^F)₄] with KC₈ affords selectively the green, room-temperature stable mixed-valent disilicon(0,I) hydride Si₂(H)(Idipp)₂ (1H), in which the highly reactive Si₂H molecule is trapped between two N-heterocyclic carbenes (NHCs). The molecular and electronic structure of 1H was investigated by a combination of experimental and theoretical methods and reveals the presence of a π-type radical featuring a terminal bonded H atom at a flattened trigonal pyramidal coordinated Si center, that is connected via a Si–Si bond to a bent two-coordinated Si center carrying a lone pair of electrons. The unpaired electron occupies the Si [double bond, length as m-dash] Si π* orbital leading to a formal Si–Si bond order of 1.5. Extensive delocalization of the spin density occurs via conjugation with the coplanar arranged NHC rings with the higher spin density lying on the site of the two-coordinated silicon atom.

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Article information

DOI: https://doi.org/10.1039/C6SC01569G
Article type: Edge Article
Submitted: 09 Apr 2016
Accepted: 29 Apr 2016
First published: 09 May 2016
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry

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Chem. Sci., 2016,7, 4973-4979

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The Si₂H radical supported by two N-heterocyclic carbenes

M. I. Arz, G. Schnakenburg, A. Meyer, O. Schiemann and A. C. Filippou, Chem. Sci., 2016, 7, 4973 DOI: 10.1039/C6SC01569G

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