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CO 2 and Formate Complexes of Phosphine/Borane Frustrated Lewis Pairs
Author(s) -
Peuser Ilona,
Neu Rebecca C.,
Zhao Xiaoxi,
Ulrich Matthias,
Schirmer Birgitta,
Tannert Jens A.,
Kehr Gerald,
Fröhlich Roland,
Grimme Stefan,
Erker Gerhard,
Stephan Douglas W.
Publication year - 2011
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.201100286
Subject(s) - 2 norbornyl cation , chemistry , boranes , borane , medicinal chemistry , stereochemistry , frustrated lewis pair , phosphine , lewis acids and bases , organic chemistry , catalysis , boron
The reaction of a solution of B(C 6 F 4 H) 3 and either i Pr 3 P or t Bu 3 P with CO 2 afforded the species R 3 P(CO 2 )B(C 6 F 4 H) 3 (R= i Pr ( 1 ), t Bu ( 2 )). In a similar fashion the boranes, RB(C 6 F 5 ) 2 (R=hexyl, cyclohexyl (Cy), norbornyl), ClB(C 6 F 5 ) 2 , or PhB(C 6 F 5 ) 2 were combined with t Bu 3 P and CO 2 to give the species t Bu 3 P(CO 2 )BR(C 6 F 5 ) 2 (R=hexyl ( 3 ), Cy ( 4 ), norbornyl ( 5 ), Cl ( 6 ), Ph ( 7 )). Similarly, the compounds [ t Bu 3 PH][RBH(C 6 F 5 ) 2 ] (R=hexyl ( 8 ), Cy ( 9 ), norbornyl ( 10 )) were prepared by reaction of the precursor frustrated Lewis pair (FLP) with H 2 . Subsequent reactions of 9 and 10 with CO 2 afforded the species [((C 6 F 5 ) 2 BR) 2 (μ‐HCO 2 )][ t Bu 3 PH] (R=Cy ( 11 ), norbornyl ( 12 )). In related chemistry, combinations of the boranes RB(C 6 F 5 ) 2 (R=hexyl, Cy, norbornyl) with t Bu 3 P treated with an equivalent of formic acid gave [(C 6 F 5 ) 2 BR(HCO 2 )][ t Bu 3 PH] (R=hexyl ( 13 ), Cy ( 14 ), norbornyl ( 15 )). Subsequent addition of an additional equivalent of borane provides a second synthetic route to 11 and 12 . Crystallographic studies of compounds 2 – 6 and 8 – 14 are reported and discussed. Further understanding of the FLP complexation and activation of CO 2 is provided by computational studies.