From Dibismuthenes to Three‐ and Two‐Coordinated Bismuthinidenes by Fine Ligand Tuning: Evidence for Aromatic BiC3N Rings through a Combined Experimental and Theoretical Study |
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Authors: | Iva Vránová Dr Mercedes Alonso Dr Rabindranath Lo Dr Robert Sedlák Dr Roman Jambor Prof Ale? R??i?ka Prof Frank De Proft Prof Pavel Hobza Dr Libor Dostál |
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Institution: | 1. Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic);2. Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels (Belgium);3. Department of Molecular Modelling, Institute of Organic Chemistry and Biochemistry ASCR, v.v.i., Flemingovo nám. 2, 166 10 Prague 6 (Czech Republic) |
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Abstract: | The reduction of N,C,N‐chelated bismuth chlorides C6H3‐2,6‐(CH?NR)2]BiCl2 where R=tBu ( 1 ), 2′,6′‐Me2C6H3 ( 2 ), or 4′‐Me2NC6H4 ( 3 )] or N,C‐chelated analogues C6H2‐2‐(CH?N‐2′,6′‐iPr2C6H3)‐4,6‐(tBu)2]BiCl2 ( 4 ) and C6H2‐2‐(CH2NEt2)‐4,6‐(tBu)2]BiCl2 ( 5 ) is reported. Reduction of compounds 1 – 3 gave monomeric N,C,N‐chelated bismuthinidenes C6H3‐2,6‐(CH?NR)2]Bi where R=tBu ( 6 ), 2′,6′‐Me2C6H3 ( 7 ) or 4′‐Me2NC6H4 ( 8 )]. Similarly, the reduction of 4 led to the isolation of the compound C6H2‐2‐(CH?N‐2′,6′‐iPr2C6H3)‐4,6‐(tBu)2]Bi ( 9 ) as an unprecedented two‐coordinated bismuthinidene that has been structurally characterized. In contrast, the dibismuthene {C6H2‐2‐(CH2NEt2)‐4,6‐(tBu)2]Bi}2 ( 10 ) was obtained by the reduction of 5 . Compounds 6 – 10 were characterized by using 1H and 13C NMR spectroscopy and their structures, except for 7 , were determined with the help of single‐crystal X‐ray diffraction analysis. It is clear that the structure of the reduced products (bismuthinidene versus dibismuthene) is ligand‐dependent and particularly influenced by the strength of the N→Bi intramolecular interaction(s). Therefore, a theoretical survey describing the bonding situation in the studied compounds and related bismuth(I) systems is included. Importantly, we found that the C3NBi chelating ring in the two‐coordinated bismuthinidene 9 exhibits significant aromatic character by delocalization of the bismuth lone pair. |
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Keywords: | aromaticity bismuth heterocycles N ligands reduction |
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