Selective hydrosiloxane synthesis via dehydrogenative coupling of silanols with hydrosilanes catalysed by Fe complexes bearing a tetradentate PNNP ligand.

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)}(μ-N)] were synthesized by a reaction of the corresponding iron dihalide with NaBEtH and structurally characterized. The reaction proceeded via the iron dihydride intermediate [Fe(H)(PNNP-R)], which underwent H reductive elimination, supporting the hemilabile behavior of PNNP-R. [{Fe(PNNP-R)}(μ-N)] catalyzed the 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. This system exhibited higher catalytic efficiency than the previously reported precious-metal-catalyzed systems.