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A Highly Reactive Geminal P/B Frustrated Lewis Pair: Expanding the Scope to C−X (X=Cl, Br) Bond Activation
Author(s) -
Samigullin Kamil,
Georg Isabelle,
Bolte Michael,
Lerner HansWolfram,
Wagner Matthias
Publication year - 2016
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.201504791
Subject(s) - frustrated lewis pair , chemistry , geminal , adduct , borane , intramolecular force , heterolysis , lewis acids and bases , stereochemistry , nuclear magnetic resonance spectroscopy , hydrogen bond , triethylborane , crystallography , medicinal chemistry , molecule , catalysis , organic chemistry
The geminal frustrated Lewis pair t Bu 2 PCH 2 B(Fxyl) 2 ( 1 ; Fxyl=3,5‐(CF 3 ) 2 C 6 H 3 ) is accessible in 65 % yield from t Bu 2 PCH 2 Li and (Fxyl) 2 BF. According to NMR spectroscopy and X‐ray crystallography, 1 is monomeric both in solution and in the solid state. The intramolecular P ⋅⋅⋅ B distance of 2.900(5) Å and the full planarity of the borane site exclude any significant P/B interaction. Compound 1 readily activates a broad variety of substrates including H 2 , EtMe 2 SiH, CO 2 /CS 2 , Ph 2 CO, and H 3 CCN. Terminal alkynes react with heterolysis of the C−H bond. Haloboranes give cyclic adducts with strong P−BX 3 and weak R 3 B−X bonds. Unprecedented transformations leading to zwitterionic XP/BCX 3 adducts occur on treatment of 1 with CCl 4 or CBr 4 in Et 2 O. In less polar solvents (C 6 H 6 , n ‐pentane), XP/BCX 3 adduct formation is accompanied by the generation of significant amounts of XP/BX adducts. FLP 1 catalyzes the hydrogenation of PhCH=N t Bu and the hydrosilylation of Ph 2 CO with EtMe 2 SiH.