: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Asymmetric hydrosilylation, transfer hydrogenation and hydrogenation of ketones catalyzed by iridium complexes

The preparation of chiral alcohols and amines by using iridium catalysis is reviewed. The methods presented include the reduction of ketones or imines by using hydrogen (hydrogenations), isopropano ...

/pdf/enantioselective-synthesis-of-alcohols-and-amines-by-iridium-55mmu5wnmj.pdf

Enantioselective synthesis of alcohols and amines by iridium-catalyzed hydrogenation, transfer hydrogenation, and related processes.

A mesoporous, silica-supported, chiral iridium catalyst with a highly ordered dimensional-hexagonal mesostructure was prepared by postgrafting the organometallic complex (1-diphenylphosphino-2-triethylsilylethane) [(R, R)-1 ,2-diphenylethyle-nediamine]iridium chloride {IrCl[PPh 2 (CH 2 ) 2 Si-(OEt) 3 ] 2 [(R,R)-DPEN] (DPEN = 1,2-diphenylethy-lenediamine)} on SBA-15 silica. During the asymmetric hydrogenation of various aromatic ketones under 40 atm of hydrogen, the mesoporous, silica-supported, chiral iridium catalyst exhibited high catalytic activity (more than 95% conversions) and excellent enantioselectivity (up to more than 99% ee). The catalyst could be recovered easily and used repetitively seven times without significantly affecting the catalytic activity and the enantioselectivity.

Enantioselective Hydrogenation of Aromatic Ketones Catalyzed by a Mesoporous Silica-Supported Iridium Catalyst

Ferrocenyl phosphine thioether ligands (PS), not containing deprotonatable functions, efficiently support the iridium catalyzed ketone hydrogenation in combination with a strong base cocatalyst. Use of an internal base ([Ir(OMe)(COD)]2 in place of [IrCl(COD)]2) is not sufficient to ensure activity and a strong base is still necessary, suggesting that the active catalyst is an anionic hydride complex. Computational investigations that include solvent effects demonstrate the thermodynamically accessible generation of the tetrahydrido complex [IrH4(PS)]− and suggest an operating cycle via a [Na+(MeOH)3···Ir–H4(PS)] contact ion pair with an energy span of 18.2 kcal/mol. The cycle involves an outer sphere stepwise H–/H+ transfer, the proton originating from H2 after coordination and heterolytic activation. The base plays the dual role of generating the anionic complex and providing the Lewis acid cocatalyst for ketone activation. The best cycle for the neutral system, on the other hand, requires an energy span...

/pdf/ketone-hydrogenation-with-iridium-complexes-with-non-n-h-373sk6x78j.pdf

Ketone Hydrogenation with Iridium Complexes with “non N–H” Ligands: The Key Role of the Strong Base

The P 2 /N 2 -coordinated cis-dihydridoiridium(III) chelate complexes (OC-6-13)-[IrH2(H2NnNH2)(PR3) 2 ]BF 4 [PR 3 = PPh 3 , H 2 N∩NH 2 = 1,2-(H 2 N) 2 C 6 H 4 (la); (1R,2R)-(H 2 N) 2 C 6 H 10 {{R,R)-dach} (1b); (R)-2,2'-diamino-1,1'-binaphthyl {(R)-dabin) (1c); PR 3 = PiPr 3 , H 2 NnNH 2 = (R,R)-dach (2a), (R)-dabin (2b); PR 3 = PCy 3 , H 2 N∩NH 2 = (R)-dabin (3)] were obtained by treating the respective diamine ligands with labile precursors such as [IrH2(OCMe2)2(PPh3)2]BF4, [{η 4 -1,5-C 8 H 12 )Ir(PPh 3 ) 2 ]BF 4 , or [IrH 5 (PR 3 ) 2 ]/HBF 4 (R = iPr, Cy). While oxidative addition of HCl to [(η 4 -1,5-C 8 H 12 )Ir(S,S)-bdpcp}]BF 4 [(S,S)-bdpcp = (1S,2S)-(Ph 2 P) 2 C 5 H 8 ] yields the usual mononuclear adduct [(η 4 -1,5-C 8 H 12 )Ir(H)(Cl){(S,S)-bdpcp}]BF 4 (4), similar treatment of [(η 4 -1,5-C 8 H 12 )Ir{(R)-binap)]BF 4 furnishes the triply chlorido-bridged diiridium complex [((R)-binap} 2 Ir 2 H 2 (μ-Cl)3]BF4 (5). Opening of the μ-Cl bridges of 5 by N,N nucleophiles was used to synthesise the three diamine/(R)-binap complexes [Ir(H)(Cl)-(H2NnNH2){(R)-binap}]BF4 [H 2 NNH 2 = (1R,2R)-H 2 NCH(Ph)CH(Ph)NH 2 {(R,R)-dpen} (6a), (R,R)-dach (6b), and H 2 NCMe 2 CMe 2 NH 2 {tmen} (6c). Whereas the dihydrides [IrH 2 ((R,R)-dach}(PR3) 2 ]BF 4 and [IrH 2 {(R)-dabin}-(PR 3 ) 2 ]BF 4 (R = iPr, Ph) are only poor (pre)catalysts for the enantioselective hydrogenation of acetophenone, complexes 6a-c catalyze the formation of 1-phenylethanol in good enantiomeric excess [ee max = 82-84 % (S)] in the presence of base. The crystal structures of la, 4, and 5 have been determined.

Synthesis and Catalytic Applications of Chiral Hydridoiridium(III) Complexes with Diamine/Bis(monophosphane) and Diamine/Diphosphane Coordination

Experimental and computational studies of two new mono-and dinuclear iridium complexes containing a Buchwald biphenyl phosphine ligand

The title solvated salt, [Ir(H)2{P(C6H11)3}2{OC(CH3)2}2]BF4·(CH3)2CO, was obtained by the protonation of [Ir(H)5{P(C6H11)3}2] with HBF4 in acetone. The cation features OC-6-13 stereochemistry, with Ir—P = 2.3159 (6) and 2.3267 (6) A, and Ir—O = 2.238 (1) and 2.276 (1) A. The BF4− anion shows threefold rotational disorder about a B—F bond, with site occupancies of 0.65, 0.25 and 0.10. While there are several intra­molecular C—H⋯O and inter­molecular C—H⋯F hydrogen-bonding inter­actions [C⋯O = 3.207 (3)–3.358 (3) A, and C⋯F = 3.434 (3) and 3.441 (3) A], the O atom of the acetone solvent mol­ecule does not act as a C—H acceptor.

(OC‐6‐13)‐Bis(acetone)dihydridobis(tricyclohexylphosphine)iridium(III) tetrafluoridoborate acetone solvate

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Synthesis and Catalytic Applications of Chiral Hydridoiridium(III) Complexes with Diamine/Bis(monophosphane) and Diamine/Diphosphane Coordination

Experimental and computational studies of two new mono-and dinuclear iridium complexes containing a Buchwald biphenyl phosphine ligand

(OC‐6‐13)‐Bis(acetone)dihydridobis(tricyclohexylphosphine)iridium(III) tetrafluoridoborate acetone solvate