1358755-07-3Relevant academic research and scientific papers
Development of a generic mechanism for the dehydrocoupling of amine-boranes: A stoichiometric, catalytic, and kinetic study of H 3B?NMe2H using the [Rh(PCy3) 2]+ fragment
Sewell, Laura J.,Lloyd-Jones, Guy C.,Weller, Andrew S.
, p. 3598 - 3610 (2012)
The multistage Rh-catalyzed dehydrocoupling of the secondary amine-borane H3B?NMe2H, to give the cyclic amino-borane [H 2BNMe2]2, has been explored using catalysts based upon cationic [Rh(PCy3)2]+ (Cy = cyclo-C6H11). These were systematically investigated (NMR/MS), under both stoichiometric and catalytic regimes, with the resulting mechanistic proposals for parallel catalysis and autocatalysis evaluated by kinetic simulation. These studies demonstrate a rich and complex mechanistic landscape that involves dehydrogenation of H3B?NMe2H to give the amino-borane H2B=NMe2, dimerization of this to give the final product, formation of the linear diborazane H 3B?NMe2BH2?NMe2H as an intermediate, and its consumption by both B-N bond cleavage and dehydrocyclization. Subtleties of the system include the following: the product [H2BNMe2]2 is a modifier in catalysis and acts in an autocatalytic role; there is a parallel, neutral catalyst present in low but constant concentration, suggested to be Rh(PCy3) 2H2Cl; the dimerization of H2B=NMe2 can be accelerated by MeCN; and complementary nonclassical BH??? HN interactions are likely to play a role in lowering barriers to many of the processes occurring at the metal center. These observations lead to a generic mechanistic scheme that can be readily tailored for application to many of the transition-metal and main-group systems that catalyze the dehydrocoupling of H3B?NMe2H.
