Isolation of [Ru(IPr)2(CO)H]+ (IPr = 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and Reactivity toward E–H (E = H, B) Bonds
Abstract
Halide abstraction from the ruthenium N-heterocyclic carbene complex Ru(IPr)2(CO)HCl (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with NaBAr4F (BAr4F = B{C6H3(3,5-CF3)2}4) gave the salt [Ru(IPr)2(CO)H]BAr4F ( 2 ), 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···η3-H2C ξ-agostic interaction involving one iPr substituent of the IPr ligand. This system complements the previously reported [Ru(IMes)2(CO)H]+ cation (IMes =1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene), where a non-agostic form is favored. Treatment of 2 with CO, H2, and the amine–boranes H3B·NR2H (R = Me, H) gave [Ru(IPr)2(CO)3H]BAr4F ( 3 ), [Ru(IPr)2(CO)(η2-H2)H]BAr4F ( 4 ), and [Ru(IPr)2(CO)(κ2-H2BH·NR2H)H]BAr4F (R = Me, 5 ; R = H, 6 ), respectively. Heating 5 in the presence of Me3SiCH═CH2 led to alkene hydroboration and formation of the C–H activated product [Ru(IPr)(IPr)′(CO)]BAr4F ( 7 ). X-ray characterization of 3 and 5 – 7 was complemented by DFT calculations, and the mechanism of H2/H exchange in 4 was also elucidated. Treatment of 2 with HBcat resulted in Ru–H abstraction to form the boryl complex [Ru(IPr)2(CO)(Bcat)] BAr4F ( 8 ), which proved to be competent in the catalytic hydroboration of 1-hexene. In 8 , a combined X-ray/neutron structure refinement and QTAIM analysis suggested the presence of a single Ru···η2-HC ξ-agostic interaction.
Citation
Riddlestone , I M , McKay , D , Gutmann , M J , Macgregor , S A , Mahon , M F , Sparkes , H A & Whittlesey , M K 2016 , ' Isolation of [Ru(IPr) 2 (CO)H] + (IPr = 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and Reactivity toward E–H (E = H, B) Bonds ' , Organometallics , vol. 35 , no. 9 , pp. 1301-1312 . https://doi.org/10.1021/acs.organomet.6b00173
Publication
Organometallics
Status
Peer reviewed
ISSN
0276-7333Type
Journal article
Rights
Copyright © 2016 American Chemical Society. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://dx.doi.org/10.1021/acs.organomet.6b00173
Description
Experiments at the ISIS Pulsed Neutron and Muon Source were supported by a beamtime allocation (Experiment 1510181) from the Science and Technology Facilities Council (STFC). The EPSRC (grants EP/J009962/1 and EP/J010677/1) is thanked for financial support.Collections
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