Iron Complex-Catalyzed Ammonia–Borane Dehydrogenation. A Potential Route toward B–N-Containing Polymer Motifs Using Earth-Abundant Metal Catalysts

• DOI: 10.1021/ja210542r
• Publication Date: 2012-03-19T13:59:55Z
• Authors: R. Tom Baker; John C. Gordon; Charles W. Hamilton; Neil J. Henson; Po-Heng Lin; Steven Maguire; Muralee Murugesu; Brian L. Scott; Nathan C. Smythe
• Keywords: Ammonia Borane; Boranes

Ammonia-borane (NH(3)BH(3), AB) has garnered interest as a hydrogen storage material due to its high weight percent content and ease of H(2) release relative metal hydrides. As consequence dehydrogenation, B-N-containing oligomeric/polymeric materials are formed. The ability control this process dictate the identity generated polymer opens up possibility targeted synthesis new materials. While precious metals have been used in regard, construct such using earth-abundant Fe presents more economical approach. Four complexes containing amido phosphine supporting ligands were synthesized, their reactivity with AB was examined. Three-coordinate Fe(PCy(3))[N(SiMe(3))(2)](2) (1) four-coordinate Fe(DEPE)[N(SiMe(3))(2)](2) (2) yield mixture (NH(2)BH(2))(n) (NHBH)(n) products 1.7 equiv released per but cannot be recycled (DEPE = 1,2-bis(diethylphosphino)ethane). In contrast, supported by bidentate P-N ligand (4) can second cycle afford similar product mixture. Intriguingly, symmetric analogue 4 (Fe(N-N)(P-P), 3), only generates does so minutes at room temperature. This marked difference may result chemistry Fe(II) vs Fe(0).