title: From Dibismuthenes to Three- and Two-Coordinated Bismuthinidenes by Fine Ligand Tuning: Evidence for Aromatic BiC3N Rings through a Combined Experimental and Theoretical Study.
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 (1)H and (13)C 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.
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic).
authors.forename: Iva
authors.initials: I
authors.lastname: Vránová
authors.affiliation: Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels (Belgium). mercedes.alonso.giner@gmail.com.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Alonso
authors.affiliation: Department of Molecular Modelling, Institute of Organic Chemistry and Biochemistry ASCR, v.v.i., Flemingovo nám. 2, 166 10 Prague 6 (Czech Republic).
authors.forename: Rabindranath
authors.initials: R
authors.lastname: Lo
authors.affiliation: Department of Molecular Modelling, Institute of Organic Chemistry and Biochemistry ASCR, v.v.i., Flemingovo nám. 2, 166 10 Prague 6 (Czech Republic).
authors.forename: Robert
authors.initials: R
authors.lastname: Sedlák
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic).
authors.forename: Roman
authors.initials: R
authors.lastname: Jambor
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic).
authors.forename: Aleš
authors.initials: A
authors.lastname: Růžička
authors.affiliation: Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels (Belgium).
authors.forename: Frank
authors.initials: F
authors.lastname: De Proft
authors.affiliation: Department of Molecular Modelling, Institute of Organic Chemistry and Biochemistry ASCR, v.v.i., Flemingovo nám. 2, 166 10 Prague 6 (Czech Republic).
authors.forename: Pavel
authors.initials: P
authors.lastname: Hobza
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic). libor.dostal@upce.cz.
authors.forename: Libor
authors.initials: L
authors.lastname: Dostál
keywords: N ligands; aromaticity; bismuth; heterocycles; reduction