Mechanistic insights into iron catalyzed dehydrogenation of formic acid: β-hydride elimination vs. direct hydride transfer

Density functional theory calculations reveal a complete reaction mechanism with detailed energy profiles and transition state structures for the dehydrogenation of formic acid catalyzed by an iron complex, [P(CH2CH2PPh2)(3)FeH](+). In the cationic reaction pathway, a beta-hydride elimination process is confirmed to be the rate-determining step in this catalytic reaction. A potential reaction pathway starting with a direct hydride transfer from HCOO- to Fe is found to be possible, but slightly less favorable than the catalytic cycle with a beta-hydride elimination step.