Reactions of a Four-Membered Borete with Carbon,Silicon, and Gallium Donor Ligands: Fused and Spiro-Type Boracycles |
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| Authors: | Zeynep Güven Lars Denker Hadi Dolati Daniela Wullschläger Dr Bartosz Trzaskowski Dr René Frank |
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| Institution: | 1. Department of Inorganic and Analytical Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany;2. Centre of New Technologies, University of Warsaw, Banacha 2?C, 02-097 Warszawa, Poland |
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| Abstract: | Donor-acceptor cyclopropanes or cyclobutanes are dipolar reagents, which are widely used in the synthesis of complex organic (hetero)cycles in ring expansion reactions. Applying this concept to boron containing heterocycles, the four-membered borete cyclo-iPr2N-BC10H6 reacted with the carbon donor ligands 2,6-xylylisonitrile and the carbene IMes :C(NMesCH)2 with ring expansion and ring fusion, respectively. In particular, the tetracyclic structure formed with IMes displays zwitterionic character and absorption in the visible region. In contrast to the carbene IMes, the heavier carbenoids :Si(NDippCH)2 and :Ga(AmIm) with a two-coordinate donor atom afford spiro-type bicyclic compounds, which display four-coordinate geometry at silicon or gallium. (TD-)DFT calculations provide deeper insight into the mechanism of formation and the absorption properties of these new compounds. |
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| Keywords: | donor-acceptor cyclobutanes inorganic polycycles inorganic spirocycles gallium carbenoids N-heterocyclic carbenes ring expansion reactions silicon carbenoids |
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