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 [( 2,6-iPr 2 Ph BDI)Mn(μ-H)] 2 . 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 -1 . 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 [( 2,6-iPr 2 Ph BDI)Mn(μ-H)] 2 allowed for characterization of the catalyst resting state, [( 2,6-iPr 2 Ph BDI)Mn(μ-NH 2 )] 2 , which has been found to mediate Si-N dehydrocoupling.