@article {48133,
	title = {Reactivity of four coordinate iridium complex towards hydrogen: an experimental and computational study},
	journal = {Journal of Organometallic Chemistry},
	volume = {965},
	year = {2022},
	month = {MAY},
	pages = {122317},
	type = {Article},
	abstract = {<p>
	Reaction of a four coordinate, 16-electron Ir complex, [Ir-(iPr)4(POCOP)(PPh3)] (4 ) (((iPr)4)(POCOP= 2,6-bis(di-isopropyl phosphinito)benzene, kappa(3)-C6H3-1,3-[OP((iPr))(2)](2)), with H-2 resulted in an oxidative addition product, cis-dihydride complex, cis-[Ir(H)(2) ((iPr)4)(POCOP)(PPh3)] ( cis-5 ) presumably via the intermediacy of a sigma complex, [Ir(eta(2)-H-2)((iPr)4)(POCOP)(PPh3)]. The cis-dihydride complex completely isomerizes to the trans-dihydride complex trans-[Ir(H)(2) ((iPr)4)(POCOP)(PPh3)] ( trans-5 ) under ambient conditions in about 3 h. It was found that the steric and electronic features on the iridium center have significant influence on the approach of H-2 onto the metal center followed by oxidative addition and isomerization. The isomerization process was studied in detail and all the mechanistic aspects have been elucidated using a combination of both experimental work and computation. The cis-dihydride complex isomerizes to the trans-dihydride by compensating the trans influence of the strongly trans-directing hydride ligand. A mechanism involving the exchange of the position of PPh3 with a hydride ligand cis to itself via PPh3 dissociation and re-coordination thereby resulting in the formation of the trans-dihydride complex, has been proposed for the isomerization. The cis-dihydride was found to be a highly active catalyst for hydrogenation of ethy-lene. A competing reactivity study of cis-dihydride between isomerization versus insertion of C2H4 into the Ir-H bond, was studied experimentally and computationally. (c) 2022 Elsevier B.V. All rights reserved.</p>
},
	keywords = {Hydrogenation, Insertion, iridium complex, isomerization, Oxidative addition, Reductive elimination},
	issn = {0022-328X},
	doi = {10.1016/j.jorganchem.2022.122317},
	author = {Agrawal, Nisha K. and Dash, Soumya R. and Vanka, Kumar and Nethaji, Munirathinam and Jagirdar, Balaji R.}
}
@article {49960,
	title = {(NHC-olefin)-nickel(0) nanoparticles: an efficient and selective catalyst for hydrogenation reactions at low temperature and pressure},
	journal = {Journal of Catalysis},
	volume = {453},
	year = {2026},
	month = {JAN},
	pages = {116487},
	type = {Article},
	abstract = {<p>
	The reduction of a NHC-cinnamyl nickel(II) organometallic complex through the use of different MeMgBr or MeMgCl reagents led to two types of NHC-olefin-coordinated nickel nanoparticles. Both of these unsupported nickel-NHC based nanomaterials behaved under hydrogen pressure as effective and selective catalysts operating at low temperature (\&lt;= 80 degrees C), pressure (\&lt;= 20 bar) and loading (\&lt;= 6 mol\%) for the reductions of broad scopes of alkenes, alkynes, imines and heterocycles, including a challenging tetra-substituted alkene. Among these two nickel-NHC nanocatalysts, the one generated with MeMgCl showed a significant high catalytic activity with high yields and could stand the comparison with Raney nickel and state-of-the-art nickel nanocatalysts. For example, by studying the hydrogenation of 1-phenylcyclohexene in ethanol at 60 degrees C under 10 bar of H2, 3 mol\% of this catalyst achieved the reaction within a single hour on a 5 mmol/0.8 g substrate scale with a yield of 96 \%, a turnover number (TON) of 32 and a turnover frequency (TOF) of 32. Characterizations confirmed the coordination of the NHC-olefin ligands to the nickel nanoparticles, the reduced state of the nickel and the (poly-) crystallinity of the nanoparticles.</p>
},
	keywords = {alkenes, Alkynes, heterocycles, Hydrogenation, imines, N -heterocyclic carbene ligand, nanocatalysis, Nickel},
	issn = {0021-9517},
	doi = {10.1016/j.jcat.2025.116487},
	author = {Avello, Marta G. and Singh, Geetika and Truong-Phuoc, Lai and Vidal, Loic and Papaefthimiou, Vasiliki and Chesse, Matthieu and Gruber, Nathalie and Chetcuti, Michael J. and Vanka, Kumar and Ritleng, Vincent and Pham-Huu, Cuong and Michon, Christophe}
}
