43047-37-6Relevant articles and documents
A mechanistic investigation of carbon-hydrogen bond stannylation: Synthesis and characterization of nickel catalysts
Johnson, Samuel A.,Doster, Meghan E.,Matthews, Jacob,Shoshani, Manar,Thibodeau, Michelle,Labadie, Amanda,Hatnean, Jillian A.
, p. 8135 - 8143 (2012/08/08)
The complex (iPr3P)Ni(η2-Bu 3SnCHCH2)2 (1a) was characterized by NMR spectroscopy and was identified as the active species for catalytic C-H bond stannylation of partially fluorinated aromatics, for example in the reaction between pentafluorobenzene and Bu3SnCHCH2, which generates C6F5SnBu3 and ethylene. The crystalline complex (iPr3P)Ni(η2-Ph 3SnCHCH2)2 (1b) provides a more easily handled analogue, and is also capable of catalytic stannylation with added Ph 3SnCHCH2 and C6F5H. Mechanistic studies on 1b show that the catalytically active species remains mononuclear. The rate of catalytic stannylation is proportional to [C6F 5H] and inversely proportional to [Ph3SnCHCH2]. This is consistent with a mechanism where reversible Ph3SnCHCH 2 dissociation provides (iPr3P) Ni(η2-Ph3SnCHCH2), followed by a rate-determining reaction with C6F5H to generate the stannylation products. Kinetic competition reactions between the fluorinated aromatics pentafluorobenzene, 1,2,4,5-tetrafluorobenzene, 1,2,3,5- tetrafluorobenzene, 1,2,4-trifluorobenzene, 1,3,5-trifluorobenzene and 1,3-difluorobenzene all suggest significant Ni-aryl bond formation in the rate-determining step under catalytic conditions. Labelling studies are consistent with an insertion of the hydrogen of the arene into the vinyl group, followed by β-elimination or β-abstraction of the SnPh3 moiety.
