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
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
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.