Manganese catalysed dehydrocoupling of silanes and siloxanes with ammonia to prepare oligosilazanes and polysiloxazanes.

The halogen-free synthesis of oligosilazanes has been observed upon dehydrocoupling silanes with ammonia at 25 °C using [(BDI)Mn(μ-H)]. Extending this methodology to polymethylhydrosiloxanes afforded thermally robust polysiloxazane solids, and the dehydrocoupling of 1,3,5,7-tetramethylcyclotetrasiloxane with ammonia afforded a polysiloxazane having a weight-average molecular weight of 4300 g mol. A representative oligosilazane has been applied to a copper surface and found to afford a 20 μm thick coating that resists corrosion after 24 h under water. Addition of ammonia to [(BDI)Mn(μ-H)] allowed for characterization of the catalyst resting state, [(BDI)Mn(μ-NH)], which has been found to mediate Si-N dehydrocoupling.