Soluble B-N polymers: poly(alpha-olefin) analogs via metal complex-catalyzed amine borane dehydrogenation

Over the last few decades, catalytic dehydrocoupling has evolved from a mechanistically interesting chemical transformation to a practical route to inorganic polymers that have shown utility as new materials and processable ceramic precursors. In attempting to make new B-P and B-N inorganic polymers, Manners et al studied the heteronuclear dehydrocoupling of phosphine boranes and amine boranes. While the former gave high polymers such as (PhHP-BH2), evaluation of a variety of catalysts with primary and secondary amine boranes or even ammonia borane lead only to B-N cyclic oligomers. However, using an iridium phosphinito pincer complex originally employed by Goldberg and Heinekey6 for dehydrogenation of ammonia borane (AB, H3N-BH3), M3.nners now reports formation of soluble aminoborane polymers and copolymers derived from primary amine boranes (Scheme 1) With this report, an analogy is made between primary amine boranes and {alpha}-olefins. The prospects of tuning metal complex catalysts for control of B-N polymer microstructure are exciting for synthesis of new B-N materials. In addition, variation of the N substituent offers promise for processable precllISors to carbon-free B-N ceramics.