Premium
9‐Borabarbaralanes
Author(s) -
Herberich Gerhard E.,
Marx HanW.,
Moss Stefan,
Schleyer Paul Von Ragué,
Wagner Trixie
Publication year - 1996
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.19960020416
Subject(s) - chemistry , van der waals force , degenerate energy levels , quantum chemical , bicyclic molecule , derivative (finance) , crystal structure , density functional theory , acceptor , crystal (programming language) , stereochemistry , crystallography , medicinal chemistry , computational chemistry , molecule , physics , organic chemistry , quantum mechanics , computer science , financial economics , programming language , economics
The reaction of MgCOT(thf) x with t BuBF 2 or PhBCl 2 affords the first 9‐borabarbaralanes 2 (C 8 H 8 BR, a : R = t Bu; b : RPh). With the aminoboron dihalides BCl 2 N i Pr 2 and BCl 2 N(SiMe 3 ) t Bu 9‐borabicyclo[4.2.1]‐nona‐2,4,7‐trienes 3 ( a : RN i Pr 2 , b : RN(SiMe 3 ) t Bu) and the trans ‐9‐borabicyclo[4.3.0]nona‐2,4,7‐triene 4 are obtained. The bicyclic compounds 3a and 3 b are converted into 9‐borabarbaralanes 2c and 2 d , respectively, by irradiation in solution as well as by heating. All 9‐borabarbaralanes 2 are fluxional in solution. In the crystalline state, the B ‐phenyl derivative 2b displays a well‐ordered van der Waals crystal structure. The theoretical prediction that the degenerate Cope rearrangement in barbaralanes will be retarded by π‐acceptor groups in the 9 position has been verified. Quantum chemical calculations employing density functional theory support and help interpret the experimental findings. The isoelectronic 9‐barbaralyl cations, in contrast, have such high Cope barriers that other rearrangement pathways are followed instead.