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Synthesis and Structure of an o ‐Carboranyl‐Substituted Three‐Coordinate Borane Radical Anion
Author(s) -
Krebs Johannes,
Haehnel Martin,
Krummenacher Ivo,
Friedrich Alexandra,
Braunschweig Holger,
Finze Maik,
Ji Lei,
Marder Todd B.
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202100938
Subject(s) - borane , chemistry , cyclic voltammetry , excited state , crystallography , ion , photochemistry , carborane , medicinal chemistry , organic chemistry , electrochemistry , catalysis , atomic physics , physics , electrode
Bis(1‐(4‐tolyl)‐carboran‐2‐yl)‐(4‐tolyl)‐borane [(1‐(4‐MeC 6 H 4 )‐ closo ‐1,2‐C 2 B 10 H 10 ‐2‐) 2 (4‐MeC 6 H 4 )B] ( 1 ), a new bis( o ‐carboranyl)‐(R)‐borane was synthesised by lithiation of the o ‐carboranyl precursor and subsequent salt metathesis reaction with (4‐tolyl)BBr 2 . Cyclic voltammetry experiments on 1 show multiple distinct reduction events with a one‐electron first reduction. In a selective reduction experiment the corresponding paramagnetic radical anion 1 .− was isolated and characterized. Single‐crystal structure analyses allow an in‐depth comparison of 1 , 1 .− , their calculated geometries, and the S 1 excited state of 1 . Photophysical studies of 1 show a charge transfer (CT) emission with low quantum yield in solution but a strong increase in the solid state. TD‐DFT calculations were used to identify transition‐relevant orbitals.