Title : A well-defined Fe catalyst system bearing a tetradentate pnnp ligand: Selective synthesis of hydrosiloxanes via dehydronegative coupling of silanols with hydrosilanes
Abstract:
Iron complexes with low toxicity and high terrestrial abundance have recently drawn increasing attention as a new class of catalyst precursors in an attempt to develop environmentally benign and sustainable methods for organic synthesis. Intensive studies on Fe complexes have been conducted to date; however, examples of well-defined reactions remain scarce compared with those of 4d or 5d metal complexes. In this study, a well-defined iron complex system was established using PNNP-R (R = Ph and Cy) as a strong σ-donating ligand with a rigid meridional tetradentate structure. Reactive Fe(0) complexes [{Fe(PNNP-R)}2(μ-N2 )] were synthesized by the reaction of the corresponding iron diharide with NaBEt3 H and structurally fully characterized. The reaction proceeded via the iron dihydride intermediate [Fe(H)2 (PNNP-R)], which underwent H2 reductive elimination, supporting the hemilabile behavior of PNNP-R. [{Fe(PNNP-R)}2 (μ-N2 )] catalyzed dehydrogenative coupling of silanols with silanes to selectively form various hydrosiloxanes, which are important building blocks for the synthesis of a range of siloxane compounds. The system exhibited the highest catalytic efficiency among the previously reported transition-metal-catalyzed systems.
Audience Take Away:
- One method to precisely design of Fe complexes using a strong ?-donating ligand.
- Synthetic procedures of reactive Fe(0) complexes bearing labile N2 or silane ligands.
- Importance of hydosiloxanes as a raw materials for the silicone production.
