@article {50004, title = {Heterolytic cleavage of the B{\textendash}H bond in H3B{\textperiodcentered}L (L = THF, NMe2H) by an electrophilic Ir(iii) pincer complex [Ir(H)(PMe3)(tBu4POCOP)][BAr F4]}, volume = {55}, year = {2025}, month = {NOV}, pages = {476-491}, type = {Article}, abstract = {
Six- and five-coordinate iridium complexes, [Ir(H)Cl(PMe3)(tBu4POCOP)] (2) (tBu4POCOP = κ3-C6H3-2,6-(OPtBu2)2) and [Ir(H)(PMe3)(tBu4POCOP)][BArF4] (3), respectively, have been synthesized and characterized. The reactivity of the electrophilic 16-electron iridium(III) complex\ 3\ with H2, H3B{\textperiodcentered}THF, H3B{\textperiodcentered}NMe2H, and H3B{\textperiodcentered}NMe3\ was investigated. The reaction of complex\ 3\ with H2\ resulted in the formation of\ trans-[Ir(H)(η2-H2)(PMe3)(tBu4POCOP)][BArF4] complex\ 5. Complex\ 3\ was found to activate the B{\textendash}H bonds in H3B{\textperiodcentered}THF and H3B{\textperiodcentered}NMe2H (DMAB) in a heterolytic fashion. The reaction of complex\ 3\ with H3B{\textperiodcentered}THF at 298 K afforded\ trans-[Ir(H)2PMe3(tBu4POCOP)] complex\ 6\ and a boronium compound, [H2B(THF)2][BArF4]. Monitoring the reaction from 179 to 298 K by NMR spectroscopy revealed the formation of a σ-borane intermediate,\ trans-[Ir(H)(η1-HBH2{\textperiodcentered}THF)PMe3(tBu4POCOP)][BArF4] (3a-Int),\ en route\ to the final products observed at 298 K. The formation of this intermediate species was also investigated by density functional theory (DFT) calculations. The reaction of complex\ 3\ with H3B{\textperiodcentered}NMe2H at 298 K yielded a mixture of complexes\ 3\ and\ 5\ and a cyclic diborazane [H2BNMe2]2. The reaction was found to proceed\ via\ intermediates, a σ-borane complex,\ trans-[Ir(H)(η1-HBH2{\textperiodcentered}NMe2H)PMe3(tBu4POCOP)][BArF4] (3b), complex\ 6, [(NHMe2)2BH2][BArF4], and H2B[double bond, length as m-dash]NMe2. Complex\ 3\ exhibited no reactivity with H3B{\textperiodcentered}NMe3.

}, doi = {DOI https://doi.org/10.1039/D5DT01780G}, author = {Pradhan, Mitarani and Surati, Zeel Y. and Pal, Apurba Kumar and Vanka, Kumar and Jagirdar, Balaji R.} }