Premium
Engineering a Small HOMO–LUMO Gap and Intramolecular C−H Borylation by Diborene/Anthracene Orbital Intercalation
Author(s) -
Wang Sunewang R.,
Arrowsmith Merle,
Böhnke Julian,
Braunschweig Holger,
Dellermann Theresa,
Dewhurst Rian D.,
Kelch Hauke,
Krummenacher Ivo,
Mattock James D.,
Müssig Jonas H.,
Thiess Torsten,
Vargas Alfredo,
Zhang Jiji
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201704063
Subject(s) - homo/lumo , chemistry , intercalation (chemistry) , anthracene , crystallography , borylation , tetrahydrofuran , photochemistry , intramolecular force , diimide , moiety , stereochemistry , inorganic chemistry , aryl , organic chemistry , molecule , alkyl , solvent , perylene
Abstract The diborene 1 was synthesized by reduction of a mixture of 1,2‐di‐9‐anthryl‐1,2‐dibromodiborane(4) ( 6 ) and trimethylphosphine with potassium graphite. The X‐ray structure of 1 shows the two anthryl rings to be parallel and their π(C 14 ) systems perpendicular to the diborene π(B=B) system. This twisted conformation allows for intercalation of the relatively high‐lying π(B=B) orbital and the low‐lying π* orbital of the anthryl moiety with no significant conjugation, resulting in a small HOMO–LUMO gap (HLG) and ultimately a C−H borylation of the anthryl unit. The HLG of 1 was estimated to be 1.57 eV from the onset of the long wavelength band in its UV/Vis absorption spectrum (THF, λ onset =788 nm). The oxidation of 1 with elemental selenium afforded diboraselenirane 8 in quantitative yield. By oxidative abstraction of one phosphine ligand by another equivalent of elemental selenium, the B−B and C 1 −H bonds of 8 were cleaved to give the cyclic 1,9‐diborylanthracene 9 .