Fig. 2: Reaction design and mechanism analysis.
From: Photocatalytic phosphine-mediated water activation for radical hydrogenation
a, Hydrogen evolution through photocatalytic triphenylphosphine-mediated water activation. b, General mechanism for HAT of PR3–OH intermediates to closed-shell unactivated alkenes. c, Reaction optimization for transfer hydrogenation of 1a and BDE of the O–H bond in various PR3–OH intermediates, obtained by density functional theory (DFT) calculations. Yields were determined by gas chromatography–mass spectrometry (GC–MS) with tetradecane as the internal standard. Calculated activation energy for the intermolecular HAT from the P3–OH intermediate to styrene and propene as model reaction. The structure displays the spin density distribution of the Ph3P–OH radical indicating delocalization of the radical spin from the phosphorus atom into the adjacent phenyl ring. P6, bis(4-methoxyphenyl)(methyl)phosphine. ΔG, reaction free energy (298K); ΔG≠, free energy barrier (298K); ΔH298(vac), enthalpy of bond dissociation.
