Angewandte Chemie (International ed. in English), Oct 4, 2016
The aromatic osmacyclopropenefuran bicycles [OsTp{κ(3) -C(1) ,C(2) ,O-(C(1) H2 C(2) CHC(OEt)O)}(P... more The aromatic osmacyclopropenefuran bicycles [OsTp{κ(3) -C(1) ,C(2) ,O-(C(1) H2 C(2) CHC(OEt)O)}(P(i) Pr3 )]BF4 (Tp=hydridotris(1-pyrazolyl)borate) and [OsH{κ(3) -C(1) ,C(2) ,O-(C(1) H2 C(2) CHC(OEt)O)}(CO)(P(i) Pr3 )2 ]BF4 , with the metal fragment in a common vertex between the fused three- and five-membered rings, have been prepared via the π-allene intermediates [OsTp(η(2) -CH2 =CCHCO2 Et)(OCMe2 )(P(i) Pr3 )]BF4 and [OsH(η(2) -CH2 =CCHCO2 Et)(CO)(OH2 )(P(i) Pr3 )2 ]BF4 , and their aromaticity analyzed by DFT calculations. The bicycle containing the [OsH(CO)(P(i) Pr3 )2 ](+) metal fragment is a key intermediate in the [OsH(CO)(OH2 )2 (P(i) Pr3 )2 ]BF4 -catalyzed regioselective anti-Markovnikov hydration of ethyl buta-2,3-dienoate to ethyl 4-hydroxycrotonate.
The preparation, structure, dynamic behavior in solution, and reactivity of polyhydride complexes... more The preparation, structure, dynamic behavior in solution, and reactivity of polyhydride complexes of platinum group metals, described during the last three decades, are contextualized from both organometallic and coordination chemistry points of view. These compounds, which contain dihydrogen, elongated dihydrogen, compressed dihydride, and classical dihydride ligands promote the activation of B-H, C-H, Si-H, N-H, O-H, C-C, C-N, and C-F, among other σ-bonds. In this review, it is shown that, unlike other more mature areas, the chemistry of polyhydrides offers new exciting conceptual challenges and at the same time the possibility of interacting with other fields including the conversion and storage of regenerative energy, organic synthetic chemistry, drug design, and material science. This wide range of possible interactions foresees promising advances in the near future.
The metal fragment Os(CO)(P i Pr3)2 stabilizes boryl-dihydrideborate species, which can be viewed... more The metal fragment Os(CO)(P i Pr3)2 stabilizes boryl-dihydrideborate species, which can be viewed as snapshots of states of BH oxidative addition of a R2BH molecule and frustrated BH bond activation of a second one. Complex OsH2( 2-CH2=CHEt)(CO)(P i Pr3)2 (2) shows tendency to dissociate the olefin. The resulting dihydride OsH2(CO)(P i Pr3)2 (3) rapidly coordinates catecholborane (HBcat) and pinacolborane (HBpin) to give the corresponding -borane derivatives OsH2( 2-HBR2)(CO)(P i Pr3)2 (BR2 = Bcat (4), Bpin (5)). Complex 4 reacts with a second molecule of HBcat to release H2 and to afford the octahedral boryl-dihydrideborate derivative Os(Bcat)( 2-H2Bcat)(CO)(P i Pr3)2 (6), which undergoes a thermally activated Bcat site exchange process in solution. Borane displaces catecholborane from the dihydrideborate of 6 to generate the boryl-tetrahydrideborate Os(Bcat)( 2-H2BH2)(CO)(P i Pr3)2 (7). This compound and the Bpin counterpart Os(Bpin)( 2-H2BH2)(CO)(P i Pr3)2 (8) have been also prepared by reaction of the corresponding Os(BR2)Cl(CO)(P i Pr3)2 with Na[BH4].
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 12, 2017
Molecular phosphorescent heteroleptic bis-tridentate iridium(III) emitters have been prepared via... more Molecular phosphorescent heteroleptic bis-tridentate iridium(III) emitters have been prepared via η1-arene intermediates. In the presence of 4.0 mol of AgOTf, complex [{IrCl[κ3-N,C,N-(pyC6HMe2py)]}(μ-Cl)]2 (1; pyC6H2Me2py = 1,3-di(2-pyridyl)-4,6-dimethylbenzene) reacts with 9-(6-phenylpyridin-2-yl)-9H-carbazole (PhpyCzH) and 2-phenoxy-6-phenylpyridine (PhpyOPh) to give [Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyCzH)}]OTf (2) and [Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyOPh)}]OTf (3). The X-ray diffraction structures of 2 and 3 reveal that the carbazolyl and phenoxy substituents of the C,N,C' ligand coordinate to the metal center to form an η1-arene π-bond. Treatment of 2 and 3 with KOtBu produces the deprotonation of the coordinated carbon atom of the η1-arene group to afford the molecular phosphorescent [5t+4t']-heteroleptic iridium(III) complexes Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyCz)} (4) and Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyOC6H4)} (...
Trabajo presentado al VII International School on Organometallic Chemistry “Marcial Moreno Manas”... more Trabajo presentado al VII International School on Organometallic Chemistry “Marcial Moreno Manas” celebrado en el Campus of the Universitat Autonoma de Barcelona (UAB) del 25 al 27 de junio de 2014.
Resumen del trabajo presentado a la X International School on Organometallic Chemistry “Marcial M... more Resumen del trabajo presentado a la X International School on Organometallic Chemistry “Marcial Moreno Manas”, celebrada en Ciudad Real (Espana) del 5 al 7 de julio de 2017.
The hexahydride OsH6(PiPr3)2 competently catalyzes the hydration of aliphatic nitriles to amides.... more The hexahydride OsH6(PiPr3)2 competently catalyzes the hydration of aliphatic nitriles to amides. The main metal species under the catalytic conditions are the trihydride osmium(IV) amidate derivatives OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2, which have been isolated and fully characterized for R = iPr and tBu. The rate of hydration is proportional to the concentrations of the catalyst precursor, nitrile, and water. When these experimental findings and density functional theory calculations are combined, the mechanism of catalysis has been established. Complexes OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2 dissociate the carbonyl group of the chelate to afford κ1-N-amidate derivatives, which coordinate the nitrile. The subsequent attack of an external water molecule to both the C(sp) atom of the nitrile and the N atom of the amidate affords the amide and regenerates the κ1-N-amidate catalysts. The attack is concerted and takes place through a cyclic six-membered transition state, which involves Cnitrile···O-H···Namidate interactions. Before the attack, the free carbonyl group of the κ1-N-amidate ligand fixes the water molecule in the vicinity of the C(sp) atom of the nitrile.
The transformation of alkyl nitriles to symmetrical and asymmetrical secondary aliphatic amines p... more The transformation of alkyl nitriles to symmetrical and asymmetrical secondary aliphatic amines promoted by the hexahydride complex OsH 6 (P i Pr 3) 2 (1) is described, and the mechanisms of the reactions involved are established. Complex 1 catalyzes the aforementioned transformations of aryl-, pyridyl-, and alkoxy-functionalized alkyl nitriles with linear or branched chains. The formation of the secondary amines involves primary imines, primary amines, and secondary imines as organic intermediates. The reactions take place under mild conditions (toluene, 100°C, and 4 bar of H 2). Stoichiometric reactions of 1 with pivalonitrile and 2-methoxyacetonitrile have allowed us to isolate the trihydride azavinylidene derivatives OsH 3 {NCHR}(P i Pr 3) 2 (R = t Bu (3), CH 2 OMe (4)). Their formation involves the insertion of the N−C triple bond of the substrates into an Os−H bond of the unsaturated tetrahydride OsH 4 (P i Pr 3) 2 (A), which is generated by reductive elimination of H 2 from the hexahydride precursor. The reaction of these trihydride azavinylidene species with H 2 is the key step for the reduction of the N−C triple bond of the nitriles. In the absence of H 2 , the attack of A to the azavinylidene ligand produces the rupture of its C(sp 2)−C(sp 3) bond. As a consequence of this attack and the presence of primary imines and amines in the reaction media, the binuclear complexes (P i Pr 3) 2 H 4 Os(μ-CN)OsH 3 {κ 1-N-(NH CHCH 2 OMe)}(P i Pr 3) 2 (5) and (P i Pr 3) 2 H 4 Os(μ-CN)OsH 3 {κ 1-N-(NH 2 CH 2 CH 2 OMe)}(P i Pr 3) 2 (6) have been isolated and characterized by X-ray diffraction analysis, for 2-methoxyacetonitrile. DFT calculations reveal noticeable similarities between the hydrogenations of nitriles to primary imines and those of primary imines to primary amines.
Structural Analysis of Complexes 2, 5, 6, and 7 S3 Computational Details S4 NMR spectra of comple... more Structural Analysis of Complexes 2, 5, 6, and 7 S3 Computational Details S4 NMR spectra of complexes 2-8 S5 Energies of optimized structures S16 UV-vis spectra of complexes 2, 4, A, and B (observed and calculated) S18 Analysis of computed UV/Vis data for 2, 4, A, and B S20 Frontier molecular orbitals for complexes 2, 4, A, and B S24 Cyclic voltammograms of complexes 2, 4, A, and B S32 Normalized excitation and emission spectra for complexes 2, 4, A, and B S33 Natural transition orbital analysis for T 1 transition of complexes 2, 4, A, and B S37 References S38 S3 Experimental Section: General Information. 1 H, 31 P{ 1 H}, and 13 C{ 1 H} NMR spectra were recorded on Bruker Avance 300 or 400 MHz instrument. C, H, and N analyses were carried out in a Perkin-Elmer 2400 CHNS/O analyzer. High-resolution electrospray mass spectra were acquired using a MicroTOF-Q hybrid quadrupole time-of-flight spectrometer (Bruker Daltonics, Bremen, Germany). UV-visible spectra were registered on an Evolution 600 spectrophotomer. Steady-state photoluminescence spectra were recorded on a Jobin-Yvon Horiba Fluorolog FL-3-11 spectrofluorimeter. Lifetimes were measured using an IBH 5000F coaxial nanosecond flash lamp. Quantum yields were measured using the Hamamatsu Absolute PL Quantum Yield Measurement System C11347-11. Cyclic voltammetry measurements were performed using a Voltalab PST050 potentiostat with Pt wire as working electrode, Pt wire as counter electrode, and saturated calomel (SCE) as reference electrode. The experiments were carried out under argon in dichloromethane (10-3 M) or dichloromethane-acetonitrile (1:1) solutions (5x10-4 M), with Bu 4 NPF 6 as supporting electrolyte (0.1 M). Scan rate was 100 mV•s-1. The potentials were referenced to the ferrocene/ferrocenium (Fc/Fc +) couple. Structural Analysis of Complexes 2, 5, 6, and 7. X-ray data were collected on a Bruker Smart APEX DUO CCD diffractometer equipped with a fine focus, and 2.4 kW sealed tube source (Mo radiation, λ = 0.71073 Å). Data were collected over the complete sphere covering 0.3 o in ω. Data were corrected for absorption by using a multiscan method applied with the SADABS program. 1 The structures were solved by Patterson or direct methods and refined by full-matrix least squares on F 2 with SHELXL2016, 2 including isotropic and subsequently anisotropic displacement parameters. The hydrogen atoms were observed in the last Fourier Maps or calculated, and refined freely or using a restricted riding model. The hydride ligands were located, but in some cases they do not refine properly so distances to iridium were restricted to 1.59(1) Å.
A new class of phosphorescent tris-heteroleptic iridium(III) complexes has been discovered. The a... more A new class of phosphorescent tris-heteroleptic iridium(III) complexes has been discovered. The addition of PhMeImAgI (PhMeIm = 1-phenyl-3-methylimidazolylidene) to the dimer [Ir(μ-Cl)(COD)] (1; COD = 1,5-cyclooctadiene) affords IrCl(COD)(PhMeIm) (2), which reacts with 1-phenylisoquinoline, 2-phenylpyridine, and 2-(2,4-difluorophenyl)pyridine to give the respective dimers [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CH-isoqui)}] (3), [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CH-py)}] (4), and [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CFH-py)}] (5), as a result of the N-heterocyclic carbene (NHC)- and N-heterocycle-supported o-CH bond activation of the aryl substituents and the hydrogenation of a C-C double bond of the coordinated diene. In solution, these dimers exist as a mixture of isomers a (Im trans to N) and b (Im trans to Cl), which lie in a dynamic equilibrium. The treatment of 3-5 with Kacac (acac = acetylacetonate) yields isomers a (Im trans to N) and b (Im trans to O) of Ir{κ- C, C-(CH-I...
The formation and Atoms in Molecules (AIM) analysis of osmium(IV) and osmium(II) complexes contai... more The formation and Atoms in Molecules (AIM) analysis of osmium(IV) and osmium(II) complexes containing dihydrideborate groups and primary aminoborane ligands are reported. Complex OsH(PPr)(1) loses a hydrogen molecule and the resulting unsaturated OsH(PPr)species coordinates 9-borabicycle[3.3.1]nonane (HBbn) and pinacolborane (HBpin) to give the dihydrideborate derivatives OsH{κ- H, H-(HBR)}(PPr)(BR= Bbn (2), Bpin (3)). The bonding situation in these compounds and in the related osmium(II) derivative Os(Bcat){κ- H, H-(HBcat)}(CO)(PPr)(4) (HBcat = catecholborane) has been analyzed by the AIM method. The Laplacian distributions in the Os-H-B plane exhibit a four-membered cyclic topology possessing two Os-H and two B-H bond critical points associated with one OsHHB ring critical point, which resembles that found for BH. The tetrahydride OsH(PPr)also coordinates catecholborane, which initially affords OsH{κ- H, H-(HBcat)}(PPr)(5). In contrast to 2 and 3, complex 5 reacts with a second mo...
The preparation and photophysical properties of heteroleptic iridium(III) complexes containing a ... more The preparation and photophysical properties of heteroleptic iridium(III) complexes containing a dianionic C,C,C,C-tetradentate ligand and a cyclometalated phenylpyridine group are described. Complex [Ir(μ-OMe)(COD)](1, COD = 1,5-cyclooctadiene) reacts with 1,1-diphenyl-3,3-butylenediimidazolium iodide ([PhIm(CH)ImPh]I), in the presence NaOBu, to give [Ir(μ-I){κ- C, C, C, C-[CHIm(CH)ImCH]}](2), which leads to {[Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}](μ-OH)(μ-OMe)} (3) by treatment first with silver trifluoromethanesulfonate (AgOTf) in acetone-dichloromethane and subsequently with KOH in methanol. The reaction of 2 with AgOTf and acetonitrile affords the bis(solvento) complex [Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}(CHCN)]OTf (4). The latter promotes the pyridyl-supported heterolytic ortho-CH bond activation of the phenyl group of 2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine, 2-( p-tolyl)pyridine, and 5-methyl-2-phenylpyridine to yield Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}{κ- C, N-[Ar-py]} (Ar-py ...
Publisher Summary This chapter focuses on new models for homogeneous systems effective in the syn... more Publisher Summary This chapter focuses on new models for homogeneous systems effective in the synthesis of functionalized organic molecules from basic hydrocarbon units. It also explains that hydrides are the best anchorages to nail unsaturated organic molecules in transition-metal compounds. Furthermore, the addition of X–H bonds to olefins and alkynes are well known processes in organic chemistry. In addition, the reaction of chloro-transition-metal complexes with main-group organometallic complexes is an early-developed method to prepare tansition-metal organometallic compounds containing η1-carbon ligands. The design of new catalysts and new processes requires a basic knowledge of the leading factors of the catalytic cycles, that is, the stoichiometric steps of the catalysis. The chapter also reviews the reactivity of transition-metal hydride compounds toward unsaturated organic molecules, mainly olefins and alkynes that are traditionally centered in monohydrides. In general, the reactions lead to the insertion products, alkyl or alkenyl, which have a limited chemistry.
Complex Cp N TiCl 3 (1) (Cp N) C 5 H 4 CH 2 CH 2 NMe 2) reacts with 1.0, 2.0, and 3.0 equiv of Me... more Complex Cp N TiCl 3 (1) (Cp N) C 5 H 4 CH 2 CH 2 NMe 2) reacts with 1.0, 2.0, and 3.0 equiv of MeMgCl to give Cp N TiMeCl 2 (2), Cp N TiMe 2 Cl (3), and Cp N TiMe 3 (4), respectively. In the solid state, the amino group of the pendant substituent of the cyclopentadienyl ligand is weakly coordinated to the metal center (d(Ti-N)) 2.445(2) Å in 2 and 2.433(4) Å in 3), transoid disposed to a methyl ligand. In solution, the N-donor substituent is involved in a coordination-dissociation equilibrium (∆H°) 2.4 (0.3 kcal‚mol-1 and ∆S°) 6.5 (0.9 cal‚mol-1 ‚K-1 for 2, ∆H°) 3.8 (0.4 kcal‚mol-1 and ∆S°) 12.3 (1.0 cal‚mol-1 ‚K-1 for 3, and ∆H°) 4.4 (0.1 kcal‚mol-1 and ∆S°) 17.9 (0.4 cal‚mol-1 ‚K-1 for 4). In moist benzene, complex 3 affords the dinuclear species Cp N TiCl(µ-O) 2 ClTiCp N (5), containing a planar Ti 2-(µ-O) 2 core. In the solid state, the pendant amino groups of 5 are also coordinated to the metal centers (d(Ti-N)) 2.421(2) Å). Like in 2, 3, and 4, the amino groups of 5 are involved in a coordination-dissociation equilibrium (∆H°) 4.9 (0.2 kcal‚(mol of Ti)-1 and ∆S°) 20.7 (0.6 cal‚K-1 ‚(mol of Ti)-1). Complex 1 also reacts with LiNH(2,6-i Pr 2 C 6 H 3). The reaction leads to the six-coordinate amido-imido derivative {(2,6i Pr 2 C 6 H 3)NH}Cp N Ti{N(2,6-i Pr 2 C 6 H 3)} (6), which shows a strong coordination of the pendant amino group to the titanium atom (d(Ti-N amino)) 2.227(2) Å). In solution the amino group remains coordinated. Complex 4 has been found to be an efficient catalyst precursor for the intermolecular regioselective anti-Markovnikov hydroamination of asymmetric alkynes. The reactions give enamineimine mixtures, which are transformed into the corresponding secondary amines.
As a part of our work on the chemistry of the i Pr 3 P−Os−P i Pr 3 skeleton, we have recently stu... more As a part of our work on the chemistry of the i Pr 3 P−Os−P i Pr 3 skeleton, we have recently studied the reactions of the complex OsH 2 Cl 2 (P i Pr 3 ) 2 with 1-methyl-1-(trimethylsilyl)allene and 1,1-dimethylallene and proved that disubstituted allene substrates coordinated to the ...
... Miguel A. Esteruelas,* Ana M. López, Enrique Oñate, and Eva Royo. ... (b) Calhorda, MJ; Romão... more ... Miguel A. Esteruelas,* Ana M. López, Enrique Oñate, and Eva Royo. ... (b) Calhorda, MJ; Romão, CC; Veiros, LF Chem. Eur. J. 2002, 8, 868, and references therein. (5) (a) Gamasa, MP; Gimeno, J.; Gonzalez-Cueva, M.; Lastra, E. J. Chem. Soc., Dalton Trans. 1996, 2547. ...
Angewandte Chemie (International ed. in English), Oct 4, 2016
The aromatic osmacyclopropenefuran bicycles [OsTp{κ(3) -C(1) ,C(2) ,O-(C(1) H2 C(2) CHC(OEt)O)}(P... more The aromatic osmacyclopropenefuran bicycles [OsTp{κ(3) -C(1) ,C(2) ,O-(C(1) H2 C(2) CHC(OEt)O)}(P(i) Pr3 )]BF4 (Tp=hydridotris(1-pyrazolyl)borate) and [OsH{κ(3) -C(1) ,C(2) ,O-(C(1) H2 C(2) CHC(OEt)O)}(CO)(P(i) Pr3 )2 ]BF4 , with the metal fragment in a common vertex between the fused three- and five-membered rings, have been prepared via the π-allene intermediates [OsTp(η(2) -CH2 =CCHCO2 Et)(OCMe2 )(P(i) Pr3 )]BF4 and [OsH(η(2) -CH2 =CCHCO2 Et)(CO)(OH2 )(P(i) Pr3 )2 ]BF4 , and their aromaticity analyzed by DFT calculations. The bicycle containing the [OsH(CO)(P(i) Pr3 )2 ](+) metal fragment is a key intermediate in the [OsH(CO)(OH2 )2 (P(i) Pr3 )2 ]BF4 -catalyzed regioselective anti-Markovnikov hydration of ethyl buta-2,3-dienoate to ethyl 4-hydroxycrotonate.
The preparation, structure, dynamic behavior in solution, and reactivity of polyhydride complexes... more The preparation, structure, dynamic behavior in solution, and reactivity of polyhydride complexes of platinum group metals, described during the last three decades, are contextualized from both organometallic and coordination chemistry points of view. These compounds, which contain dihydrogen, elongated dihydrogen, compressed dihydride, and classical dihydride ligands promote the activation of B-H, C-H, Si-H, N-H, O-H, C-C, C-N, and C-F, among other σ-bonds. In this review, it is shown that, unlike other more mature areas, the chemistry of polyhydrides offers new exciting conceptual challenges and at the same time the possibility of interacting with other fields including the conversion and storage of regenerative energy, organic synthetic chemistry, drug design, and material science. This wide range of possible interactions foresees promising advances in the near future.
The metal fragment Os(CO)(P i Pr3)2 stabilizes boryl-dihydrideborate species, which can be viewed... more The metal fragment Os(CO)(P i Pr3)2 stabilizes boryl-dihydrideborate species, which can be viewed as snapshots of states of BH oxidative addition of a R2BH molecule and frustrated BH bond activation of a second one. Complex OsH2( 2-CH2=CHEt)(CO)(P i Pr3)2 (2) shows tendency to dissociate the olefin. The resulting dihydride OsH2(CO)(P i Pr3)2 (3) rapidly coordinates catecholborane (HBcat) and pinacolborane (HBpin) to give the corresponding -borane derivatives OsH2( 2-HBR2)(CO)(P i Pr3)2 (BR2 = Bcat (4), Bpin (5)). Complex 4 reacts with a second molecule of HBcat to release H2 and to afford the octahedral boryl-dihydrideborate derivative Os(Bcat)( 2-H2Bcat)(CO)(P i Pr3)2 (6), which undergoes a thermally activated Bcat site exchange process in solution. Borane displaces catecholborane from the dihydrideborate of 6 to generate the boryl-tetrahydrideborate Os(Bcat)( 2-H2BH2)(CO)(P i Pr3)2 (7). This compound and the Bpin counterpart Os(Bpin)( 2-H2BH2)(CO)(P i Pr3)2 (8) have been also prepared by reaction of the corresponding Os(BR2)Cl(CO)(P i Pr3)2 with Na[BH4].
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 12, 2017
Molecular phosphorescent heteroleptic bis-tridentate iridium(III) emitters have been prepared via... more Molecular phosphorescent heteroleptic bis-tridentate iridium(III) emitters have been prepared via η1-arene intermediates. In the presence of 4.0 mol of AgOTf, complex [{IrCl[κ3-N,C,N-(pyC6HMe2py)]}(μ-Cl)]2 (1; pyC6H2Me2py = 1,3-di(2-pyridyl)-4,6-dimethylbenzene) reacts with 9-(6-phenylpyridin-2-yl)-9H-carbazole (PhpyCzH) and 2-phenoxy-6-phenylpyridine (PhpyOPh) to give [Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyCzH)}]OTf (2) and [Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyOPh)}]OTf (3). The X-ray diffraction structures of 2 and 3 reveal that the carbazolyl and phenoxy substituents of the C,N,C' ligand coordinate to the metal center to form an η1-arene π-bond. Treatment of 2 and 3 with KOtBu produces the deprotonation of the coordinated carbon atom of the η1-arene group to afford the molecular phosphorescent [5t+4t']-heteroleptic iridium(III) complexes Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyCz)} (4) and Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C'-(C6H4pyOC6H4)} (...
Trabajo presentado al VII International School on Organometallic Chemistry “Marcial Moreno Manas”... more Trabajo presentado al VII International School on Organometallic Chemistry “Marcial Moreno Manas” celebrado en el Campus of the Universitat Autonoma de Barcelona (UAB) del 25 al 27 de junio de 2014.
Resumen del trabajo presentado a la X International School on Organometallic Chemistry “Marcial M... more Resumen del trabajo presentado a la X International School on Organometallic Chemistry “Marcial Moreno Manas”, celebrada en Ciudad Real (Espana) del 5 al 7 de julio de 2017.
The hexahydride OsH6(PiPr3)2 competently catalyzes the hydration of aliphatic nitriles to amides.... more The hexahydride OsH6(PiPr3)2 competently catalyzes the hydration of aliphatic nitriles to amides. The main metal species under the catalytic conditions are the trihydride osmium(IV) amidate derivatives OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2, which have been isolated and fully characterized for R = iPr and tBu. The rate of hydration is proportional to the concentrations of the catalyst precursor, nitrile, and water. When these experimental findings and density functional theory calculations are combined, the mechanism of catalysis has been established. Complexes OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2 dissociate the carbonyl group of the chelate to afford κ1-N-amidate derivatives, which coordinate the nitrile. The subsequent attack of an external water molecule to both the C(sp) atom of the nitrile and the N atom of the amidate affords the amide and regenerates the κ1-N-amidate catalysts. The attack is concerted and takes place through a cyclic six-membered transition state, which involves Cnitrile···O-H···Namidate interactions. Before the attack, the free carbonyl group of the κ1-N-amidate ligand fixes the water molecule in the vicinity of the C(sp) atom of the nitrile.
The transformation of alkyl nitriles to symmetrical and asymmetrical secondary aliphatic amines p... more The transformation of alkyl nitriles to symmetrical and asymmetrical secondary aliphatic amines promoted by the hexahydride complex OsH 6 (P i Pr 3) 2 (1) is described, and the mechanisms of the reactions involved are established. Complex 1 catalyzes the aforementioned transformations of aryl-, pyridyl-, and alkoxy-functionalized alkyl nitriles with linear or branched chains. The formation of the secondary amines involves primary imines, primary amines, and secondary imines as organic intermediates. The reactions take place under mild conditions (toluene, 100°C, and 4 bar of H 2). Stoichiometric reactions of 1 with pivalonitrile and 2-methoxyacetonitrile have allowed us to isolate the trihydride azavinylidene derivatives OsH 3 {NCHR}(P i Pr 3) 2 (R = t Bu (3), CH 2 OMe (4)). Their formation involves the insertion of the N−C triple bond of the substrates into an Os−H bond of the unsaturated tetrahydride OsH 4 (P i Pr 3) 2 (A), which is generated by reductive elimination of H 2 from the hexahydride precursor. The reaction of these trihydride azavinylidene species with H 2 is the key step for the reduction of the N−C triple bond of the nitriles. In the absence of H 2 , the attack of A to the azavinylidene ligand produces the rupture of its C(sp 2)−C(sp 3) bond. As a consequence of this attack and the presence of primary imines and amines in the reaction media, the binuclear complexes (P i Pr 3) 2 H 4 Os(μ-CN)OsH 3 {κ 1-N-(NH CHCH 2 OMe)}(P i Pr 3) 2 (5) and (P i Pr 3) 2 H 4 Os(μ-CN)OsH 3 {κ 1-N-(NH 2 CH 2 CH 2 OMe)}(P i Pr 3) 2 (6) have been isolated and characterized by X-ray diffraction analysis, for 2-methoxyacetonitrile. DFT calculations reveal noticeable similarities between the hydrogenations of nitriles to primary imines and those of primary imines to primary amines.
Structural Analysis of Complexes 2, 5, 6, and 7 S3 Computational Details S4 NMR spectra of comple... more Structural Analysis of Complexes 2, 5, 6, and 7 S3 Computational Details S4 NMR spectra of complexes 2-8 S5 Energies of optimized structures S16 UV-vis spectra of complexes 2, 4, A, and B (observed and calculated) S18 Analysis of computed UV/Vis data for 2, 4, A, and B S20 Frontier molecular orbitals for complexes 2, 4, A, and B S24 Cyclic voltammograms of complexes 2, 4, A, and B S32 Normalized excitation and emission spectra for complexes 2, 4, A, and B S33 Natural transition orbital analysis for T 1 transition of complexes 2, 4, A, and B S37 References S38 S3 Experimental Section: General Information. 1 H, 31 P{ 1 H}, and 13 C{ 1 H} NMR spectra were recorded on Bruker Avance 300 or 400 MHz instrument. C, H, and N analyses were carried out in a Perkin-Elmer 2400 CHNS/O analyzer. High-resolution electrospray mass spectra were acquired using a MicroTOF-Q hybrid quadrupole time-of-flight spectrometer (Bruker Daltonics, Bremen, Germany). UV-visible spectra were registered on an Evolution 600 spectrophotomer. Steady-state photoluminescence spectra were recorded on a Jobin-Yvon Horiba Fluorolog FL-3-11 spectrofluorimeter. Lifetimes were measured using an IBH 5000F coaxial nanosecond flash lamp. Quantum yields were measured using the Hamamatsu Absolute PL Quantum Yield Measurement System C11347-11. Cyclic voltammetry measurements were performed using a Voltalab PST050 potentiostat with Pt wire as working electrode, Pt wire as counter electrode, and saturated calomel (SCE) as reference electrode. The experiments were carried out under argon in dichloromethane (10-3 M) or dichloromethane-acetonitrile (1:1) solutions (5x10-4 M), with Bu 4 NPF 6 as supporting electrolyte (0.1 M). Scan rate was 100 mV•s-1. The potentials were referenced to the ferrocene/ferrocenium (Fc/Fc +) couple. Structural Analysis of Complexes 2, 5, 6, and 7. X-ray data were collected on a Bruker Smart APEX DUO CCD diffractometer equipped with a fine focus, and 2.4 kW sealed tube source (Mo radiation, λ = 0.71073 Å). Data were collected over the complete sphere covering 0.3 o in ω. Data were corrected for absorption by using a multiscan method applied with the SADABS program. 1 The structures were solved by Patterson or direct methods and refined by full-matrix least squares on F 2 with SHELXL2016, 2 including isotropic and subsequently anisotropic displacement parameters. The hydrogen atoms were observed in the last Fourier Maps or calculated, and refined freely or using a restricted riding model. The hydride ligands were located, but in some cases they do not refine properly so distances to iridium were restricted to 1.59(1) Å.
A new class of phosphorescent tris-heteroleptic iridium(III) complexes has been discovered. The a... more A new class of phosphorescent tris-heteroleptic iridium(III) complexes has been discovered. The addition of PhMeImAgI (PhMeIm = 1-phenyl-3-methylimidazolylidene) to the dimer [Ir(μ-Cl)(COD)] (1; COD = 1,5-cyclooctadiene) affords IrCl(COD)(PhMeIm) (2), which reacts with 1-phenylisoquinoline, 2-phenylpyridine, and 2-(2,4-difluorophenyl)pyridine to give the respective dimers [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CH-isoqui)}] (3), [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CH-py)}] (4), and [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CFH-py)}] (5), as a result of the N-heterocyclic carbene (NHC)- and N-heterocycle-supported o-CH bond activation of the aryl substituents and the hydrogenation of a C-C double bond of the coordinated diene. In solution, these dimers exist as a mixture of isomers a (Im trans to N) and b (Im trans to Cl), which lie in a dynamic equilibrium. The treatment of 3-5 with Kacac (acac = acetylacetonate) yields isomers a (Im trans to N) and b (Im trans to O) of Ir{κ- C, C-(CH-I...
The formation and Atoms in Molecules (AIM) analysis of osmium(IV) and osmium(II) complexes contai... more The formation and Atoms in Molecules (AIM) analysis of osmium(IV) and osmium(II) complexes containing dihydrideborate groups and primary aminoborane ligands are reported. Complex OsH(PPr)(1) loses a hydrogen molecule and the resulting unsaturated OsH(PPr)species coordinates 9-borabicycle[3.3.1]nonane (HBbn) and pinacolborane (HBpin) to give the dihydrideborate derivatives OsH{κ- H, H-(HBR)}(PPr)(BR= Bbn (2), Bpin (3)). The bonding situation in these compounds and in the related osmium(II) derivative Os(Bcat){κ- H, H-(HBcat)}(CO)(PPr)(4) (HBcat = catecholborane) has been analyzed by the AIM method. The Laplacian distributions in the Os-H-B plane exhibit a four-membered cyclic topology possessing two Os-H and two B-H bond critical points associated with one OsHHB ring critical point, which resembles that found for BH. The tetrahydride OsH(PPr)also coordinates catecholborane, which initially affords OsH{κ- H, H-(HBcat)}(PPr)(5). In contrast to 2 and 3, complex 5 reacts with a second mo...
The preparation and photophysical properties of heteroleptic iridium(III) complexes containing a ... more The preparation and photophysical properties of heteroleptic iridium(III) complexes containing a dianionic C,C,C,C-tetradentate ligand and a cyclometalated phenylpyridine group are described. Complex [Ir(μ-OMe)(COD)](1, COD = 1,5-cyclooctadiene) reacts with 1,1-diphenyl-3,3-butylenediimidazolium iodide ([PhIm(CH)ImPh]I), in the presence NaOBu, to give [Ir(μ-I){κ- C, C, C, C-[CHIm(CH)ImCH]}](2), which leads to {[Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}](μ-OH)(μ-OMe)} (3) by treatment first with silver trifluoromethanesulfonate (AgOTf) in acetone-dichloromethane and subsequently with KOH in methanol. The reaction of 2 with AgOTf and acetonitrile affords the bis(solvento) complex [Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}(CHCN)]OTf (4). The latter promotes the pyridyl-supported heterolytic ortho-CH bond activation of the phenyl group of 2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine, 2-( p-tolyl)pyridine, and 5-methyl-2-phenylpyridine to yield Ir{κ- C, C, C, C-[CHIm(CH)ImCH]}{κ- C, N-[Ar-py]} (Ar-py ...
Publisher Summary This chapter focuses on new models for homogeneous systems effective in the syn... more Publisher Summary This chapter focuses on new models for homogeneous systems effective in the synthesis of functionalized organic molecules from basic hydrocarbon units. It also explains that hydrides are the best anchorages to nail unsaturated organic molecules in transition-metal compounds. Furthermore, the addition of X–H bonds to olefins and alkynes are well known processes in organic chemistry. In addition, the reaction of chloro-transition-metal complexes with main-group organometallic complexes is an early-developed method to prepare tansition-metal organometallic compounds containing η1-carbon ligands. The design of new catalysts and new processes requires a basic knowledge of the leading factors of the catalytic cycles, that is, the stoichiometric steps of the catalysis. The chapter also reviews the reactivity of transition-metal hydride compounds toward unsaturated organic molecules, mainly olefins and alkynes that are traditionally centered in monohydrides. In general, the reactions lead to the insertion products, alkyl or alkenyl, which have a limited chemistry.
Complex Cp N TiCl 3 (1) (Cp N) C 5 H 4 CH 2 CH 2 NMe 2) reacts with 1.0, 2.0, and 3.0 equiv of Me... more Complex Cp N TiCl 3 (1) (Cp N) C 5 H 4 CH 2 CH 2 NMe 2) reacts with 1.0, 2.0, and 3.0 equiv of MeMgCl to give Cp N TiMeCl 2 (2), Cp N TiMe 2 Cl (3), and Cp N TiMe 3 (4), respectively. In the solid state, the amino group of the pendant substituent of the cyclopentadienyl ligand is weakly coordinated to the metal center (d(Ti-N)) 2.445(2) Å in 2 and 2.433(4) Å in 3), transoid disposed to a methyl ligand. In solution, the N-donor substituent is involved in a coordination-dissociation equilibrium (∆H°) 2.4 (0.3 kcal‚mol-1 and ∆S°) 6.5 (0.9 cal‚mol-1 ‚K-1 for 2, ∆H°) 3.8 (0.4 kcal‚mol-1 and ∆S°) 12.3 (1.0 cal‚mol-1 ‚K-1 for 3, and ∆H°) 4.4 (0.1 kcal‚mol-1 and ∆S°) 17.9 (0.4 cal‚mol-1 ‚K-1 for 4). In moist benzene, complex 3 affords the dinuclear species Cp N TiCl(µ-O) 2 ClTiCp N (5), containing a planar Ti 2-(µ-O) 2 core. In the solid state, the pendant amino groups of 5 are also coordinated to the metal centers (d(Ti-N)) 2.421(2) Å). Like in 2, 3, and 4, the amino groups of 5 are involved in a coordination-dissociation equilibrium (∆H°) 4.9 (0.2 kcal‚(mol of Ti)-1 and ∆S°) 20.7 (0.6 cal‚K-1 ‚(mol of Ti)-1). Complex 1 also reacts with LiNH(2,6-i Pr 2 C 6 H 3). The reaction leads to the six-coordinate amido-imido derivative {(2,6i Pr 2 C 6 H 3)NH}Cp N Ti{N(2,6-i Pr 2 C 6 H 3)} (6), which shows a strong coordination of the pendant amino group to the titanium atom (d(Ti-N amino)) 2.227(2) Å). In solution the amino group remains coordinated. Complex 4 has been found to be an efficient catalyst precursor for the intermolecular regioselective anti-Markovnikov hydroamination of asymmetric alkynes. The reactions give enamineimine mixtures, which are transformed into the corresponding secondary amines.
As a part of our work on the chemistry of the i Pr 3 P−Os−P i Pr 3 skeleton, we have recently stu... more As a part of our work on the chemistry of the i Pr 3 P−Os−P i Pr 3 skeleton, we have recently studied the reactions of the complex OsH 2 Cl 2 (P i Pr 3 ) 2 with 1-methyl-1-(trimethylsilyl)allene and 1,1-dimethylallene and proved that disubstituted allene substrates coordinated to the ...
... Miguel A. Esteruelas,* Ana M. López, Enrique Oñate, and Eva Royo. ... (b) Calhorda, MJ; Romão... more ... Miguel A. Esteruelas,* Ana M. López, Enrique Oñate, and Eva Royo. ... (b) Calhorda, MJ; Romão, CC; Veiros, LF Chem. Eur. J. 2002, 8, 868, and references therein. (5) (a) Gamasa, MP; Gimeno, J.; Gonzalez-Cueva, M.; Lastra, E. J. Chem. Soc., Dalton Trans. 1996, 2547. ...
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