4 research outputs found
Aminoborane σ Complexes: Significance of Hydride Co-ligands in Dynamic Processes and Dehydrogenative Borylene Formation
Systems of the type [(<i>p</i>-cym)ÂRuÂ(PR<sub>3</sub>)Â(H)Â(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)ÂRuÂ(PR<sub>3</sub>)ÂCl<sub>2</sub> and
H<sub>2</sub>BN<sup><i>i</i></sup>Pr<sub>2</sub>/NaÂ[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
Aminoborane σ Complexes: Significance of Hydride Co-ligands in Dynamic Processes and Dehydrogenative Borylene Formation
Systems of the type [(<i>p</i>-cym)ÂRuÂ(PR<sub>3</sub>)Â(H)Â(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)ÂRuÂ(PR<sub>3</sub>)ÂCl<sub>2</sub> and
H<sub>2</sub>BN<sup><i>i</i></sup>Pr<sub>2</sub>/NaÂ[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
Evaluation of the Asthma Friendly Schools program
This thesis examined what makes schools want to embrace the Asthma Friendly Schools program. It also investigated the limitations and barriers of the Asthma Friendly Schools program and explored it\u27s uptake by schools and the implications of the findings for the redesign of the program
Isolation of [Ru(IPr)<sub>2</sub>(CO)H]<sup>+</sup> (IPr = 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and Reactivity toward E–H (E = H, B) Bonds
Halide abstraction
from the ruthenium N-heterocyclic carbene complex
RuÂ(IPr)<sub>2</sub>(CO)ÂHCl (IPr = 1,3-bisÂ(2,6-diisopropylphenyl)Âimidazol-2-ylidene)
with NaBAr<sub>4</sub><sup>F</sup> (BAr<sub>4</sub><sup>F</sup> =
BÂ{C<sub>6</sub>H<sub>3</sub>(3,5-CF<sub>3</sub>)<sub>2</sub>}<sub>4</sub>) gave the salt [RuÂ(IPr)<sub>2</sub>(CO)ÂH]ÂBAr<sub>4</sub><sup>F</sup> (<b>2</b>), which was shown through a combined X-ray/neutron
structure refinement and quantum theory of atoms in molecules (QTAIM)
study to contain a bifurcated Ru···η<sup>3</sup>-H<sub>2</sub>C ξ-agostic interaction involving one <sup>i</sup>Pr substituent of the IPr ligand. This system complements the previously
reported [RuÂ(IMes)<sub>2</sub>(CO)ÂH]<sup>+</sup> cation (IMes =1,3-bisÂ(2,4,6-trimethylphenyl)Âimidazol-2-ylidene),
where a non-agostic form is favored. Treatment of <b>2</b> with
CO, H<sub>2</sub>, and the amine–boranes H<sub>3</sub>B·NR<sub>2</sub>H (R = Me, H) gave [RuÂ(IPr)<sub>2</sub>(CO)<sub>3</sub>H]ÂBAr<sub>4</sub><sup>F</sup> (<b>3</b>), [RuÂ(IPr)<sub>2</sub>(CO)Â(η<sup>2</sup>-H<sub>2</sub>)ÂH]ÂBAr<sub>4</sub><sup>F</sup> (<b>4</b>), and [RuÂ(IPr)<sub>2</sub>(CO)Â(κ<sup>2</sup>-H<sub>2</sub>BH·NR<sub>2</sub>H)ÂH]ÂBAr<sub>4</sub><sup>F</sup> (R = Me, <b>5</b>; R = H, <b>6</b>), respectively. Heating <b>5</b> in the presence of Me<sub>3</sub>SiCHî—»CH<sub>2</sub> led
to alkene hydroboration and formation of the C–H activated
product [RuÂ(IPr)Â(IPr)′(CO)]ÂBAr<sub>4</sub><sup>F</sup> (<b>7</b>). X-ray characterization of <b>3</b> and <b>5</b>–<b>7</b> was complemented by DFT calculations, and
the mechanism of H<sub>2</sub>/H exchange in <b>4</b> was also
elucidated. Treatment of <b>2</b> with HBcat resulted in Ru–H
abstraction to form the boryl complex [RuÂ(IPr)<sub>2</sub>(CO)Â(Bcat)]
BAr<sub>4</sub><sup>F</sup> (<b>8</b>), which proved to be competent
in the catalytic hydroboration of 1-hexene. In <b>8</b>, a combined
X-ray/neutron structure refinement and QTAIM analysis suggested the
presence of a single Ru···η<sup>2</sup>-HC ξ-agostic
interaction