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- Title
Silylene‐Functionalized N‐Heterocyclic Carbene (Si−NHC).
- Authors
Rottschäfer, Dennis; Blomeyer, Sebastian; Neumann, Beate; Stammler, Hans‐Georg; Ghadwal, Rajendra S.
- Abstract
Abstract: The synthesis, structure, and reactivity of the first silylene‐functionalized N‐heterocyclic carbene (Si‐NHC), {(L1)Si}(L2), (<bold>3</bold>) (L1=PhC(N<italic>t</italic>Bu)2, L2=CCH(CNAr)2C:, Ar=2,6‐diisopropylphenyl) are reported. The ditopic carbanionic‐NHC (dc‐NHC), [Li(L2)]∞ (<bold>1</bold>) reacts with the monochlorosilylene (L1)SiCl (<bold>2</bold>) to afford <bold>3</bold>. The HOMO of <bold>3</bold> is the silylene lone‐pair orbital, whereas the HOMO−1 is located at the carbene carbon atom. Both SiII and CII functionalities of <bold>3</bold> undergo reactions with chalcogens to give heavier ketone derivatives {(L1)Si(E)}L2(E) (E=S, <bold>4</bold>; Se, <bold>5</bold>; and Te, <bold>6</bold>). Compounds <bold>4</bold>–<bold>6</bold> feature a highly polarized Siδ+−Eδ− bond with a formal charge of −0.72 (<bold>4</bold>), −0.64 (<bold>5</bold>), and −0.50 <italic>e</italic> (<bold>6</bold>) on the E atom. The Wiberg bond indices of 1.64 (<bold>4</bold>), 1.66 (<bold>5</bold>), and 1.63 (<bold>6</bold>) for the Si−E bond however indicate a moderate pπ–pπ interaction between Si and E atoms. Compound <bold>3</bold> functions as a reducing agent and induces disproportionation of Si2Cl6 to yield the silyl‐functionalized NHC, {(L1)SiCl2}(L2) (<bold>7</bold>). Treatment of <bold>3</bold> with HSiCl3 leads to the formation of the silyl‐functionalized imidazolium salt [{(L1)SiCl2}(L2H)]Cl (<bold>8</bold>). The silylene moiety of <bold>3</bold> readily forms the iridium–silylene complex [{(L2)(L1)Si}Ir(cod)Cl] (<bold>9</bold>) featuring a free NHC ligand on treatment with [Ir(cod)(μ‐Cl)]2.
- Subjects
SILYLENES; HETEROCYCLIC chemistry; CARBENE derivatives; CARBANIONS; KETONE derivatives
- Publication
Chemistry - A European Journal, 2018, Vol 24, Issue 2, p380
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201703530