Selective B-H versus N-H Bond Activation in Ammonia Borane by [Ir(dPPM)2]OTf

Ammonia borane (AB, NH3 center dot BH3) was activated selectively on the boron hydrogen atoms by [Ir(dppm)(2)]OTf, as shown by variable-temperature (31)p, B-11 and H-1 NMR studies, to yield cis- and trans- [Ir(H)(2)(dppm)(2)]OTf dihydrides. X-ray crystal structures of these complexes were obtained. DFT calculations suggest the key reaction intermediate to be a Lewis base (L) stabilised adduct, cis-[Ir(H)(BH2 center dot L)(dPPM)(2)](+) ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)