Synthesis of Aminosilane Chemical Vapor Deposition Precursors and Polycarbosilazanes through Manganese-Catalyzed Si-N Dehydrocoupling

Compounds that feature Si-N bonds are of widespread importance to the electronics and coating industries. Aminosilanes and polysilazanes are currently prepared by adding amines to halosilanes, an inefficient methodology that generates stoichiometric quantities of ammonium salt waste. Herein, we describe the syntheses of aminosilane chemical vapor deposition precursors, polycarbosilazanes, and perhydropolysilazane through the ambient-temperature dehydrocoupling of amines to silane (SiH₄). Specifically, the β-diketiminate manganese hydride dimer [(^2,6-iPr2PhBDI)Mn(μ-H)]₂has been used to catalyze the formation of commercial aminosilane monomers from secondary and primary amines, highly cross-linked polycarbosilazane powders from diamines and triamines, and perhydropolysilazane from ammonia. The mechanism of dehydrocoupling was explored, and the addition of isopropylamine to [(^2,6-iPr2PhBDI)Mn(μ-H)]₂resulted in σ-bond metathesis to eliminate H₂and generate [(^2,6-iPr2PhBDI)Mn(μ-NHiPr)]₂. In the presence of SiH₄, H-Si addition across newly formed Mn-N bonds regenerates the precatalyst, offering a straightforward catalytic cycle for halogen-free Si-N bond formation.