93482-41-8Relevant academic research and scientific papers
Variable coordination modes and catalytic dehydrogenation of B-phenyl amine-boranes
Kumar, Amit,Priest, Isobel K.,Hooper, Thomas N.,Weller, Andrew S.
, p. 6183 - 6195 (2016)
The chemistry of N-substituted amine-boranes and their reactivity towards transition metal centres is well established but the chemistry of B-substituted amine-boranes is not. Here we present the coordination chemistry of H2PhB·NMe3 towards a range of Rh(i) fragments with different P-Rh-P ligand bite angles, {Rh(PiPr3)2}+, {Rh(PiBu3)2}+, {Rh(iPr2P(CH2)3PiPr2)}+, {Rh(Ph2P(CH2)nPPh2)}+ (n = 3, 5), as characterised by NMR spectroscopy and single-crystal X-ray diffraction. This reveals a difference in the coordination mode of the amine-borane, with large bite angle fragments favouring η2-coordination through a sigma-interaction with BH2, whereas fragments with small bite angles favour η6-coordination through the aryl group of the amine-borane. The catalytic dehydrocoupling of H2PhB·NMe2H is also explored, with the aminoborane HPhB=NMe2 found to be the sole dehydrogenation product. Stoichiometric reactivity with H2PhB·NMe2H again showed small bite angle fragments to prefer η6-aryl coordination, while the larger bite angle {Rh(PiPr3)2}+ gave rapid dehydrogenation to form a mixture of the Rh(iii) dihydride [Rh(PiPr3)2(H)2(η2-H2PhB·NMe2H)][BArF4] and the low coordinate aminoboryl complex [Rh(PiPr3)2(H)(BPhNMe2)][BArF4]. These results suggest that precatalysts which η6-bind arenes strongly should be avoided for the dehydrocoupling of amine-boranes bearing aryl substituents.
