02330nas a2200277   4500008004100000022001400041245013000055210006900185260009500254300001100349490000800360520129000368653001001658653003501668653001901703653002001722653001801742653002901760653002301789653002801812100001701840700001901857700001701876700002801893856013101921       2008                        eng d  a0021-951700aEnantioselective hydrogenation of olefins by chiral iridium phosphorothioite complex covalently anchored on mesoporous silica0 aEnantioselective hydrogenation of olefins by chiral iridium phos  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcFEB  a91-1000 v2543 a<p>Chiral monodentate phosphorous-based ligands have proven effective for the enantioselective hydrogenation of olefins. Binol-derived monodentate phosphorothioite (PS) ligand was synthesized from binol and thiopropyltriethoxysilane, and its iridium complex was covalently anchored to mesoporous silica supports like SBA-15, MCM-41, and MCM-48. These catalysts were characterized by different physicochemical techniques and assessed for their catalytic performances in the heterogeneous asymmetric hydrogenation of itaconic acid and its derivatives. It was found that the catalytic activities and enantioselectivities of the heterogenized iridium complex (IrPSSBA-15) in the hydrogenation reactions were comparable to its homogeneous analogue. Binol-derived monodentate phosphorothioite ligand in heterogeneously anchored form (iridium complex) is a more effective catalyst than the reported monodentate phosphorous ligand systems in the hydrogenation reactions, possibly due to the changes in electronic properties around the iridium metal center. The effects of substrate-to-catalyst molar ratio, solvents, and temperature on substrate conversions and enantioselectivities, of the products were investigated in hydrogenation reactions. (c) 2007 Elsevier Inc. All rights reserved.</p>10abinol10aEnantioselective hydrogenation10aImmobilization10airidium complex10aitaconic acid10aMesoporous silica SBA-1510amonodentate ligand10aphosphorothioite ligand1 aSahoo, Suman1 aKumar, Pradeep1 aLefebvre, F.1 aHalligudi, Shivaraj, B.  uhttps://library.ncl.res.in/content/enantioselective-hydrogenation-olefins-chiral-iridium-phosphorothioite-complex-covalently-002512nas a2200265   4500008004100000022001400041245010800055210006900163260000800232300001100240490000800251520162600259653001801885653001401903653002001917653001801937653002301955653002601978100002302004700002102027700001702048700002602065700002502091856013002116       2022                        eng d  a0022-328X00aReactivity of four coordinate iridium complex towards hydrogen: an experimental and computational study0 aReactivity of four coordinate iridium complex towards hydrogen a  cMAY  a1223170 v9653 a<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>
10aHydrogenation10aInsertion10airidium complex10aisomerization10aOxidative addition10aReductive elimination1 aAgrawal, Nisha, K.1 aDash, Soumya, R.1 aVanka, Kumar1 aNethaji, Munirathinam1 aJagirdar, Balaji, R.  uhttps://library.ncl.res.in/content/reactivity-four-coordinate-iridium-complex-towards-hydrogen-experimental-and-computational