title: Frustrated Lewis Pair Chemistry Derived from Bulky Allenyl and Propargyl Phosphanes.
abstract: The dimesitylpropargylphosphanes mes2 P-CH2 -C≡C-R 6 a (R=H), 6 b (R=CH3 ), 6 c (R=SiMe3 ) and the allene mes2 P-C(CH3 )=C=CH2 (8) were reacted with Piers' borane, HB(C6 F5 )2 . Compound 6 a gave mes2 PCH2 CH=CH(B(C6 F5 )2 ] (9 a). In contrast, addition of HB(C6 F5 )2 to 6 b and 6 c gave mixtures of 9 b (R=CH3 ) and 9 c (R=SiMe3 ) with the regioisomers mes2 P-CH2 -C[B(C6 F5 )2 ]=CRH 2 b (R=CH3 ) and 2 c (R=SiMe3 ), respectively. Compounds 2 b,c underwent rapid phosphane/borane (P/B) frustrated Lewis pair (FLP) reactions under mild conditions. Compound 2 c reacted with nitric oxide (NO) to give the persistent FLP NO radical 11. The systems 2 b,c cleaved dihydrogen at room temperature to give the respective phosphonium/hydridoborate products 13 b,c. Compound 13 c transferred the H(+) /H(-) pair to a small series of enamines. Compound 13 c was also a metal-free catalyst (5 mol %) for the hydrogenation of the enamines. The allene 8 reacted with B(C6 F5 )3 to give the zwitterionic phosphonium/borate 17. The -PPh2 -substituted mes2 P-propargyl system 6 d underwent a typical 1,2-P/B-addition reaction to the C≡C triple bond to form the phosphetium/borate zwitterion 20. Several products were characterized by X-ray diffraction.
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstraße 40, 48149, Münster, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Rosorius
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstraße 40, 48149, Münster, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Möricke
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstraße 40, 48149, Münster, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Wibbeling
authors.affiliation: Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington DC, 20057-1227, USA.
authors.forename: Alison C
authors.initials: AC
authors.lastname: McQuilken
authors.affiliation: Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington DC, 20057-1227, USA.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Warren
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstraße 40, 48149, Münster, Germany.
authors.forename: Constantin G
authors.initials: CG
authors.lastname: Daniliuc
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstraße 40, 48149, Münster, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Kehr
authors.affiliation: Organisch-Chemisches Institut, Universität Münster, Corrensstraße 40, 48149, Münster, Germany. erker@uni-muenster.de.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Erker
keywords: X-ray diffraction; boranes; hydroboration; hydrogen activation; phosphanes