New Routes to Low-Coordinate Iron Hydride Complexes: The Binuclear Oxidative Addition of H(2).

The oxidative addition and reductive elimination reactions of H(2) on unsaturated transition-metal complexes are crucial in utilizing this important molecule. Both biological and man-made iron catalysts use iron to perform H(2) transformations, and highly unsaturated iron complexes in unusual geometries (tetrahedral and trigonal planar) are anticipated to give unusual or novel reactions. In this paper, two new synthetic routes to the low-coordinate iron hydride complex L(tBu)Fe(μ-H) are reported. Et(3)SiH was used as the hydride source in one route by taking advantage of the silaphilicity of the fluoride ligand in three-coordinate L(tBu)FeF. The other synthetic method proceeded through the binuclear oxidative addition of H(2) or D(2) to a putative Fe(I) intermediate. Deuteration was verified through reduction of an alkyne and release of the deuterated alkene product. Mössbauer spectra of L(tBu)Fe(μ-H) indicate that the samples are pure, and that the iron(II) centers are high-spin.