Affiliation:
1. Molecular Inorganic Chemistry and Catalysis Inorganic and Structural Chemistry Center for Molecular Materials Faculty of Chemistry Universität Bielefeld Universitätsstrasse 25 D-33615 Bielefeld Germany
2. University of Amsterdam (UvA) Faculty of Science Van 't Hoff Institute for Molecular Sciences (HIMS) Homogeneous and Supramolecular Catalysis Group Science Park 904 1098 XH Amsterdam The Netherlands
Abstract
AbstractN‐Heterocyclic carbene (NHC) analogues of Wittig hydrocarbon, [(NHC)(Stil)(NHC)] (3a‐c) (NHC = SIPr (1a) = C[N(Dipp)CH2]2, Dipp = 2,6‐iPr2C6H3; IPr (1b) = C[N(Dipp)CH]2; Me‐IPr (1c) = C[N(Dipp)CMe]2 and Stil = C6H4CHCHC6H4) have been reported as crystalline solids. 3a‐c are prepared by two‐electron reductions of the corresponding bis‐1,3‐imidazoli(ni)um bromides [(NHC)(Stil)NHC)](Br)2 (2a‐c) with KC8 in >94 % yields. 2a‐c are accessible by the nickel catalyzed direct C−C coupling of NHCs (1a‐c) with (E)‐4,4'‐dibromostilbene. One‐electron oxidation of 3a,b yields the corresponding radical cations [(NHC)(Stil)NHC)]B(C6F5)4 4a,b. All compounds have been characterized by UV‐Vis/NMR/EPR spectroscopy as well as 2a, 3a, and 3b by single crystal X‐ray diffraction. The electronic structures of representative systems have been analyzed by quantum chemical calculations.
Funder
Deutsche Forschungsgemeinschaft