Aminoborane σ Complexes: Significance of Hydride
Co-ligands in Dynamic Processes and Dehydrogenative Borylene Formation
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Abstract
Systems of the type [(<i>p</i>-cym)Ru(PR<sub>3</sub>)(H)(H<sub>2</sub>BN<sup><i>i</i></sup>Pr<sub>2</sub>)]<sup>+</sup> (R = Cy, Ph) can be synthesized
from (<i>p</i>-cym)Ru(PR<sub>3</sub>)Cl<sub>2</sub> and
H<sub>2</sub>BN<sup><i>i</i></sup>Pr<sub>2</sub>/Na[BAr<sup><i>f</i></sup><sub>4</sub>] and are best formulated as
(hydrido)ruthenium κ<sup>1</sup>-aminoborane complexes. VT-NMR
measurements have been used to probe
the σ-bond metathesis process leading to Ru–H/H–B
exchange, yielding an activation barrier of Δ<i>G</i><sup></sup><sup>⧧</sup> = 7.5 kcal mol<sup>–1</sup> at 161 K. Moreover, in contrast to the case for related non-hydride-containing
systems, reactivity toward alkenes constitutes a viable route to a
metal borylene complex via sacrificial hydrogenation
