In a glovebox, an oven dried screw-capped 2 mL vial was charged with [ Me IPr tBu -Ni(η 6 -C6H6)] 9 (25 μmol), degassed (free pump thaw) toluene-d8 (0.25 mL) was then added. Another oven dried screw-capped 2 mL vial was charged with ketone 1i (25 μmol), degassed (free pump thaw) toluene-d8 (0.25 mL) was then added. Both vials were pre-cooled to -78 o C. Then mix both solution and added in to J-Young NMR tube. The tube was immediately taken out of glovebox and insert into dry ice acetone bath. The tube was shaken and quickly placed into the probe of the NMR spectrometer pre-cooled to -80 °C. The probe temperature was increased gradually and tested by 1 H NMR every 20 o C gradient (the temperature was stable for 10 min before starting scanning). Figure . Observation of hydride signal on 1 H NMR.