Kinetic and thermodynamic preferences in aryl vs benzylic C-H bond activation with cationic Pt(II) complexes.
Anhydrous cationic Pt(II) complexes [(NN)Pt(CH3)(CF3CD2OD)]+ (1, NN = ArN=C(Me)-C(Me)=NAr), which are obtained by reaction of (NN)Pt(CH3)2 with B(C6F5)3 in CF3CD2OD, activate C-H bonds of benzene and methylbenzenes, with enhanced reactivity compared to the previously prepared equilibrium mixtures with the (thermodynamically favored) aquo complexes. For methylbenzenes (toluene, p-xylene, mesitylene), activation at the aromatic and benzylic positions are kinetically competitive, but the product of the latter is strongly favored thermodynamically. This unusual trend is attributed to formation of eta3-benzyl structures, which can be observed spectroscopically for 1,4-diethylbenzene activation.
Heyduk
Alan F
AF
The Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, USA.
Driver
Tom G
TG
Labinger
Jay A
JA
Bercaw
John E
JE
D001593:Benzyl Compounds / Q000737:chemistry*; D002413:Cations, Divalent; D007700:Kinetics; D009944:Organoplatinum Compounds / Q000737:chemistry*; D013816:Thermodynamics
D001593:Benzyl Compounds; D002413:Cations, Divalent; D009944:Organoplatinum Compounds