Ricardo Castarlenas - Academia.edu (original) (raw)
Papers by Ricardo Castarlenas
Catalysis Letters, Apr 30, 2013
Journal of the American Chemical Society, Jul 15, 2005
Journal of the American Chemical Society, Mar 1, 2006
Treatment in acetonitrile at-30°C of the hydride-alkenylcarbyne complex [OsH(tCCHd CPh2)(CH3CN)2(... more Treatment in acetonitrile at-30°C of the hydride-alkenylcarbyne complex [OsH(tCCHd CPh2)(CH3CN)2(P i Pr3)2][BF4]2 (1) with t BuOK produces the selective deprotonation of the alkenyl substituent of the carbyne and the formation of the bis-solvento hydride-allenylidene derivative [OsH(dCdCd CPh2)(CH3CN)2(P i Pr3)2]BF4 (2), which under carbon monoxide atmosphere is converted into [Os(CHdCd CPh2)(CO)(CH3CN)2(P i Pr3)2]BF4 (3). When the treatment of 1 with t BuOK is carried out in dichloromethane at room temperature, the fluoro-alkenylcarbyne [OsHF(tCCHdCPh2)(CH3CN)(P i Pr3)2]BF4 (4) is isolated. Complex 2 reacts with terminal alkynes. The reactions with phenylacetylene and cyclohexylacetylene afford [Os{(E)-CHdCHR}(dCdCdCPh2)(CH3CN)2(P i Pr3)2]BF4 (R) Ph (5), Cy (6)), containing an alkenyl ligand beside the allenylidene, while the reaction with acetylene in dichloromethane at-20°C gives the hydrideallenylidene-π-alkyne [OsH(dCdCdCPh2)(η 2-HCtCH)(P i Pr3)2]BF4 (7), with the alkyne acting as a fourelectron donor ligand. In acetonitrile under reflux, complexes 5 and 6 are transformed into the osmacyclopentapyrrole compounds [Os{CdC(CPh2CRdCH)CMedNH}(CH3CN)2]BF4 (R) Ph (8), Cy (9)), as a result of the assembly of the allenylidene ligand, the alkenyl group, and an acetonitrile molecule. The X-ray structures of 2, 5, and 8 are also reported.
Organometallics, Jan 3, 2001
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European Journal of Inorganic Chemistry, Nov 1, 2001
The complexes [OsHCl 2 (=N=CR 2)(PiPr 3) 2 ] [CR 2 = CMe 2 (1), C a (CH 2) 4 C b H 2 (C a-C b) (3... more The complexes [OsHCl 2 (=N=CR 2)(PiPr 3) 2 ] [CR 2 = CMe 2 (1), C a (CH 2) 4 C b H 2 (C a-C b) (3)] react with Ag(CF 3 SO 3) in the presence of ligands L [H 2 O, P(OMe) 3 , CO]. The reactions in the presence of water lead to [OsHCl(=N=CR 2)(H 2 O)(P-iPr 3) 2 ][CF 3 SO 3 ] [CR 2 = CMe 2 (2), C a (CH 2) 4 C b H 2 (C a-C b) (4)], which exist as 1:1 equilibrium mixtures of the isomers 2a/4a (hydride trans to Cl) and 2c/4c (hydride trans to water) in the solid state and in solution. The structure of 2c has been determined by an X-ray diffraction study. The geometry around the metal center can be described as a distorted octahedron with trans phosphane ligands at opposite sites of an ideal coordination plane defined by the other four ligands. The reactions in the presence of P(OMe) 3 afford [OsHCl(=N= CR 2){P(OMe) 3 }(PiPr 3) 2 ][CF 3 SO 3 ] [CR 2 = CMe 2 (5a), C a (CH 2) 4 C b H 2 (C a-C b) (6a)], with the hydride and chlorine ligands trans disposed. Complexes 5a and 6a can be also ob-[a
![Research paper thumbnail of Preparation of [C,N,O]-Pincer Osmium Complexes by Alkylidene Metathesis with a Methyl Group of 2,6-Diacetylpyridine](https://attachments.academia-assets.com/111098102/thumbnails/1.jpg)
](Organometallics, May 18, 2007
All reactions were carried out with rigorous exclusion of air using Schlenk-tube techniques. Orga... more All reactions were carried out with rigorous exclusion of air using Schlenk-tube techniques. Organic solvents were dried by standard procedures and distilled under argon prior to use. The starting material [(η 6-p-cymene)OsCl(IPr)(=CHPh)]OTf (1; IPr = 1,3-Bis-(2,6-diisopropylphenyl)imidazolylidene, OTf = CF 3 SO 3) was prepared as previously described in the literature. 1 1 H, 31 P{ 1 H} and 13 C{ 1 H} NMR spectra were recorded on either a Varian Gemini 2000, a Bruker ARX 300, or a Bruker Avance 400 MHz instrument. Chemical shifts (expressed in parts per million) are referenced to residual solvent peaks (1 H, 13 C{ 1 H}) or external H 3 PO 4 (31 P{ 1 H}). Coupling constants, J, are given in hertz. Infrared spectra were run on a Perkin-Elmer 1730 spectrometer (Nujol mulls on polyethylene sheets). C, H, and N analyses were carried out in a Perkin-Elmer 2400 CHNS/O analyzer.
![Research paper thumbnail of Reactivity of the Imine−Vinylidene Complexes OsCl<sub>2</sub>(CCHPh)(NHCR<sub>2</sub>)(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub> [CR<sub>2</sub> = CMe<sub>2</sub>, C(CH<sub>2</sub>)<sub>4</sub>CH<sub>2</sub>]](https://attachments.academia-assets.com/111097840/thumbnails/1.jpg)
](Organometallics, Mar 9, 2001
The reactivity of the imine-vinylidene compounds OsCl 2 (dCdCHPh)(NHdCR 2)(P i Pr 3) 2 [CR 2) CMe... more The reactivity of the imine-vinylidene compounds OsCl 2 (dCdCHPh)(NHdCR 2)(P i Pr 3) 2 [CR 2) CMe 2 (1), C(CH 2) 4 CH 2 (2)] toward amines, n BuLi, and HBF 4 has been studied. Complexes 1 and 2 react with triethylamine and diallylamine to give equilibrium mixtures of the corresponding starting materials and the five-coordinate azavinylidene derivatives OsCl(dNdCR 2)(dCdCHPh)(P i Pr 3) 2 [CR 2) CMe 2 (3), C(CH 2) 4 CH 2 (4)], which are obtained as pure microcrystalline solids by reaction of 1 and 2 with n BuLi. The structure of 3 in the solid state has been determined by an X-ray diffraction study. The geometry around the metal center could be described as a distorted trigonal bipyramid with apical phophines and inequivalent angles within the Y-shaped equatorial plane. The azavinylidene group coordinates in a bent fashion with an Os-N-C angle of 157.2(6)°. Complexes 1 and 2 also react with allylamine and aniline. The reactions initially give 3 and 4. However, the amount of these compounds decreases by increasing the reaction time. This decrease is accompanied with the formation of mixed amine-phosphine compounds OsCl 2 (dCdCHPh)(NHd CR 2)(NH 2 R′)(P i Pr 3) [R′) allyl; CR 2) CMe 2 (5), C(CH 2) 4 CH 2 , (6). R′) Ph; CR 2) CMe 2 (7), C(CH 2) 4 CH 2 (8)]. The structure of 5 in the solid state has been also determined by an X-ray diffraction study. In this case, the geometry around the osmium atom can be rationalized as a distorted octahedron with the amine and phosphine ligands mutually trans disposed and the chlorine ligands mutually cis disposed. The X-ray analysis also shows that the NHhydrogen atoms of the amine and the chlorines are involved in intra-and intermolecular H‚‚‚Cl hydrogen bonding. The reactions of 1 and 2 with HBF 4 ‚OEt 2 afford the carbyne derivatives [OsCl 2 (tCCH 2 Ph)(NHdCR 2)(P i Pr 3) 2 ][BF 4 ] [CR 2) CMe 2 (9), C(CH 2) 4 CH 2 (10)]. Both 1 and 2 lose the imine ligand to give OsCl 2 (dCdCHPh)(P i Pr 3) 2 (11) in toluene under reflux. † Dedicated to Prof. Juan Bertrá n on the occasion of his 70th birthday.
Organometallics, Mar 13, 2007
The bis-solvato hydride-allenylidene complex [OsH(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (1) r... more The bis-solvato hydride-allenylidene complex [OsH(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (1) reacts with acetic acid to give the hydride-carbyne [OsH(κ 2-O 2 CCH 3)(tCCHdCPh 2)(P i Pr 3) 2 ]BF 4 (2), which in 1,2-dichloroethane under reflux is stable and does not evolve into its five-coordinate carbene isomer. In acetonitrile at room temperature, complex 2 is in equilibrium with [OsH{κ 1-OC(O)CH 3 }(tCCHd CPh 2)(CH 3 CN)(P i Pr 3) 2 ]BF 4 (4; ∆H°)-6.4 (0.3 kcal‚mol-1 , ∆S°)-22.9 (1.1 eu). At 353 K, complex 4 is transformed into the carbene [Os{κ 1-OC(O)CH 3 }(dCHCHdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (5; 40%), which is obtained in high yield (88%) by reaction of [Os(dCHCHdCPh 2)(CH 3 CN) 3 (P i Pr 3) 2 ]-[BF 4 ] 2 with sodium acetate in 2-propanol. The hydride-carbyne to carbene transformation is analyzed by DFT calculations.
Organometallics, Mar 15, 2007
... (1) Atwood, JD Inorganic and Organometallic Reaction Mechanism, VCH: New York, 1997; Chapter ... more ... (1) Atwood, JD Inorganic and Organometallic Reaction Mechanism, VCH: New York, 1997; Chapter 3. (2) See for example: (a) Katayama, H.; Ozawa, F. Organometallics1998, 17, 5190. (b) Schanz, H.-J.; Jafarpour, L.; Stevens, ED; Nolan, SP Organometallics1999, 18, 5187. ...
Organometallics, May 1, 2001
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Organometallics, Jun 14, 2008
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Organometallics, Nov 15, 2000
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Organometallics, Oct 23, 2008
The styryl-allenylidene complex [Os{(E)-CHdCHPh}-(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (2) r... more The styryl-allenylidene complex [Os{(E)-CHdCHPh}-(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (2) reacts with HBF 4 to giVe the styryl-alkenylcarbyne [Os{(E)-CHdCHPh}(tCCHd CPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ](BF 4) 2 (3), which in acetonitrile eVolVes into the dienylcarbene deriVatiVe [Os{dC[(E)-CHdCHPh]-CHdCPh 2 }(CH 3 CN) 3 (P i Pr 3) 2 ](BF 4) 2 (4) by means of the concerted migration of the styryl ligand from the metal center to the carbyne C R atom. A kinetic study and DFT calculations on the transformation of 3 into 4 are reported.
Organometallics, Sep 8, 2011
The first rhodium-alkylidene square-planar complex stabilized by a N-heterocyclic carbene ligand ... more The first rhodium-alkylidene square-planar complex stabilized by a N-heterocyclic carbene ligand RhCl(=CHPh)(IPr)PPh 3 (2) {IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-carbene} has been prepared by reaction of RhCl(IPr)(PPh 3) 2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of 2-olefin complexes RhCl( 2-CH 2 =CHR)(IPr)PPh 3 (3, R = H; 4 R = Ph; 5 R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate. 2 Transition-metal alkylidene species are catalytic initiators for a myriad of useful organic transformations including olefin metathesis, 1 cyclopropanation, 2 C-H insertion 3 or cycloadditions. 4 In sharp contrast with other transition metals, the number of isolated rhodium-alkylidene complexes remain scarce, apart from the seminal work developed by Werner and Milstein's groups with phosphane stabilized derivatives. 5 The commonly used method for the preparation of alkylidene complexes via diazoalkane precursors 6 failed for the direct synthesis of rhodium-carbene species bearing two electronrich phosphanes of type RhCl(=CRR')(PR 3 '') 2. This problem was elegantly circumvented by the initial treatment of less sterically demanding rhodium-stibanes with diazoalkanes and subsequent exchange reaction by phosphanes, although no benzylidene species could be obtained following this approach. 5f Latter on, Milstein and coworkers showed that rhodium-benzylidene derivatives could be attained by reaction of phenyldiazomethane with more stable square-planar pincer precursors, 5i,k and even the compound RhCl(=CHPh)(P i Pr 3) 2 was prepared by an alternative method employing a sulfur ylide as precursor for the alkylidene moiety. 5i The special stereoelectronic properties of N-heterocyclic carbenes 7 (NHCs) make them suitable ancillary ligands not only for stabilization of reactive intermediates, but also for the improvement of catalytic activity. 8 Specially prominent is the case of olefin metathesis, where the catalytic performances of commercially available second generation Grubb's catalyst surpass the phosphane counterparts. 9 This "NHC effect" has been also observed in osmium-alkylidene derivatives. 10 With the aim of studying the potential of NHCs ligands in rhodium-alkylidene chemistry, we have prepared a new rhodiumalkylidene complex stabilized by a NHC ligand using phenyldiazometane as alkylidene precursor and investigated its behavior towards olefins. Reaction of the bis-phosphane-NHC rhodium complex RhCl(IPr)(PPh 3) 2 11 (1) [IPr = 1,3-bis-(2,6diisopropylphenyl)imidazol-2-carbene] with a freshly prepared THF solution of phenyldiazomethane 12 at-20 ºC under argon atmosphere gave rise to a dark green solution with concomitant gas bubbling (N 2). Work up at low temperature led to the complex RhCl(=CHPh)(IPr)PPh 3 (2) as a green solid in 76 % yield (Equation 1). Related Rh-NHC-Fischer carbene complexes have been previously reported, 13 but 2
Angewandte Chemie, Apr 22, 2005
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New Journal of Chemistry, Dec 13, 2002
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The complex [Rh(μ-Cl)(IPr)(η 2-coe)] 2 {IPr = 1,3-bis(2,6diisopropylphenyl)imidazol-2-carbene, co... more The complex [Rh(μ-Cl)(IPr)(η 2-coe)] 2 {IPr = 1,3-bis(2,6diisopropylphenyl)imidazol-2-carbene, coe = cis-cyclooctene} efficiently catalyzes the coupling of alkynes and N-vinylpyrazole via C−H activation, leading to Markovnikovselective butadienylpyrazole derivatives under mild conditions. A straightforward approach to cross-conjugated acyclic trienes is also operative through a one-pot alkyne dimerizationhydrovinylation tandem reaction. The proposed mechanism involves C−H activation of vinylpyrazole directed by nitrogen coordination to the metallic center. Subsequent alkyne coordination, insertion, and reductive elimination steps lead to the coupling products. Several key intermediates participating in the catalytic cycle have been detected and characterized, including a κ-N, η 2-CC coordinated vinylpyrazole complex and a Rh IIIhydride-alkenyl species resulting from the C−H activation of the vinylpyrazole
Trabajo presentado a la 6ª Jornada de Jóvenes Investigadores en Física y Química de Aragón celebr... more Trabajo presentado a la 6ª Jornada de Jóvenes Investigadores en Física y Química de Aragón celebrada en Zaragoza el 20 de noviembre de 2014.Las estructuras de tipo pirazol han atraído un creciente interés en los últimos años debido a sus amplias aplicaciones en medicina, agricultura, ciencia de los materiales o de la química analítica. Por ello, el desarrollo de nuevas y eficientes transformaciones catalizadas por metales de transición continúa siendo un reto importante en la síntesis orgánica. En particular, las reacciones de formación de enlaces C-C que proceden a través de un mecanismo de activación C-H son de gran interés. En este contexto, los catalizadores de rodio destacan por tener una gran tolerancia y una amplia utilidad sintética. Como parte de nuestra contribución a la química de los catalizadores de rodio conteniendo carbenos N-heterocíclicos, hemos desarrollado la síntesis de nuevos derivados de butadienilpirazoles a partir de N-vinilpirazoles y diferentes alquinos terminales, internos y eninos por activación del enlace C-H y posterior acoplamiento C-C con una excelente quimio y regioselectividad y buenos rendimientos del producto aislado.Peer reviewe
European Journal of Inorganic Chemistry, Jun 1, 2007
N‐Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC‐η6‐arene ligand have ... more N‐Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC‐η6‐arene ligand have been prepared and evaluated as precursors for ring opening metathesis polymerization (ROMP). The reaction of [RuCl2(p‐cymene)]2 with electron‐rich olefins of the bis(imidazolinylidene) type containing at least one arylmethyl‐N chain (aryl: 2,4,6‐trimethylphenyl, 3,4,5‐trimethoxyphenyl) selectively leads, upon heating, to ruthenium(II) complexes 2 containing a chelating bridged carbene η6‐arene ligand. The reaction of complexes containing an additional ROCH2CH2N group with AgOTf leads to ionic complexes 5 with a tridentate trifunctional carbene/arene/ether ligand. The X‐ray structure of[RuCl2{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2{C6H2(OMe)3‐3,4,5})}] (2c) and that of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand that provides ten electrons, [RuCl{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2CH2OCH3)}][CF3SO3] (5e), have been determined. The precursors 2 in the presence of AgOTf and propargyl alcohol, in order to produce an allenylidene initiator, and complexes 5 in the presence of propargyl alcohol lead to ROMP of norbornene. It is shown that initial chloride abstraction is required and that the catalyst activity is increased by using mesityl–ruthenium precursors and coordinated branched ether complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Catalysis Letters, Apr 30, 2013
Journal of the American Chemical Society, Jul 15, 2005
Journal of the American Chemical Society, Mar 1, 2006
Treatment in acetonitrile at-30°C of the hydride-alkenylcarbyne complex [OsH(tCCHd CPh2)(CH3CN)2(... more Treatment in acetonitrile at-30°C of the hydride-alkenylcarbyne complex [OsH(tCCHd CPh2)(CH3CN)2(P i Pr3)2][BF4]2 (1) with t BuOK produces the selective deprotonation of the alkenyl substituent of the carbyne and the formation of the bis-solvento hydride-allenylidene derivative [OsH(dCdCd CPh2)(CH3CN)2(P i Pr3)2]BF4 (2), which under carbon monoxide atmosphere is converted into [Os(CHdCd CPh2)(CO)(CH3CN)2(P i Pr3)2]BF4 (3). When the treatment of 1 with t BuOK is carried out in dichloromethane at room temperature, the fluoro-alkenylcarbyne [OsHF(tCCHdCPh2)(CH3CN)(P i Pr3)2]BF4 (4) is isolated. Complex 2 reacts with terminal alkynes. The reactions with phenylacetylene and cyclohexylacetylene afford [Os{(E)-CHdCHR}(dCdCdCPh2)(CH3CN)2(P i Pr3)2]BF4 (R) Ph (5), Cy (6)), containing an alkenyl ligand beside the allenylidene, while the reaction with acetylene in dichloromethane at-20°C gives the hydrideallenylidene-π-alkyne [OsH(dCdCdCPh2)(η 2-HCtCH)(P i Pr3)2]BF4 (7), with the alkyne acting as a fourelectron donor ligand. In acetonitrile under reflux, complexes 5 and 6 are transformed into the osmacyclopentapyrrole compounds [Os{CdC(CPh2CRdCH)CMedNH}(CH3CN)2]BF4 (R) Ph (8), Cy (9)), as a result of the assembly of the allenylidene ligand, the alkenyl group, and an acetonitrile molecule. The X-ray structures of 2, 5, and 8 are also reported.
Organometallics, Jan 3, 2001
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European Journal of Inorganic Chemistry, Nov 1, 2001
The complexes [OsHCl 2 (=N=CR 2)(PiPr 3) 2 ] [CR 2 = CMe 2 (1), C a (CH 2) 4 C b H 2 (C a-C b) (3... more The complexes [OsHCl 2 (=N=CR 2)(PiPr 3) 2 ] [CR 2 = CMe 2 (1), C a (CH 2) 4 C b H 2 (C a-C b) (3)] react with Ag(CF 3 SO 3) in the presence of ligands L [H 2 O, P(OMe) 3 , CO]. The reactions in the presence of water lead to [OsHCl(=N=CR 2)(H 2 O)(P-iPr 3) 2 ][CF 3 SO 3 ] [CR 2 = CMe 2 (2), C a (CH 2) 4 C b H 2 (C a-C b) (4)], which exist as 1:1 equilibrium mixtures of the isomers 2a/4a (hydride trans to Cl) and 2c/4c (hydride trans to water) in the solid state and in solution. The structure of 2c has been determined by an X-ray diffraction study. The geometry around the metal center can be described as a distorted octahedron with trans phosphane ligands at opposite sites of an ideal coordination plane defined by the other four ligands. The reactions in the presence of P(OMe) 3 afford [OsHCl(=N= CR 2){P(OMe) 3 }(PiPr 3) 2 ][CF 3 SO 3 ] [CR 2 = CMe 2 (5a), C a (CH 2) 4 C b H 2 (C a-C b) (6a)], with the hydride and chlorine ligands trans disposed. Complexes 5a and 6a can be also ob-[a
Organometallics, May 18, 2007
All reactions were carried out with rigorous exclusion of air using Schlenk-tube techniques. Orga... more All reactions were carried out with rigorous exclusion of air using Schlenk-tube techniques. Organic solvents were dried by standard procedures and distilled under argon prior to use. The starting material [(η 6-p-cymene)OsCl(IPr)(=CHPh)]OTf (1; IPr = 1,3-Bis-(2,6-diisopropylphenyl)imidazolylidene, OTf = CF 3 SO 3) was prepared as previously described in the literature. 1 1 H, 31 P{ 1 H} and 13 C{ 1 H} NMR spectra were recorded on either a Varian Gemini 2000, a Bruker ARX 300, or a Bruker Avance 400 MHz instrument. Chemical shifts (expressed in parts per million) are referenced to residual solvent peaks (1 H, 13 C{ 1 H}) or external H 3 PO 4 (31 P{ 1 H}). Coupling constants, J, are given in hertz. Infrared spectra were run on a Perkin-Elmer 1730 spectrometer (Nujol mulls on polyethylene sheets). C, H, and N analyses were carried out in a Perkin-Elmer 2400 CHNS/O analyzer.
Organometallics, Mar 9, 2001
The reactivity of the imine-vinylidene compounds OsCl 2 (dCdCHPh)(NHdCR 2)(P i Pr 3) 2 [CR 2) CMe... more The reactivity of the imine-vinylidene compounds OsCl 2 (dCdCHPh)(NHdCR 2)(P i Pr 3) 2 [CR 2) CMe 2 (1), C(CH 2) 4 CH 2 (2)] toward amines, n BuLi, and HBF 4 has been studied. Complexes 1 and 2 react with triethylamine and diallylamine to give equilibrium mixtures of the corresponding starting materials and the five-coordinate azavinylidene derivatives OsCl(dNdCR 2)(dCdCHPh)(P i Pr 3) 2 [CR 2) CMe 2 (3), C(CH 2) 4 CH 2 (4)], which are obtained as pure microcrystalline solids by reaction of 1 and 2 with n BuLi. The structure of 3 in the solid state has been determined by an X-ray diffraction study. The geometry around the metal center could be described as a distorted trigonal bipyramid with apical phophines and inequivalent angles within the Y-shaped equatorial plane. The azavinylidene group coordinates in a bent fashion with an Os-N-C angle of 157.2(6)°. Complexes 1 and 2 also react with allylamine and aniline. The reactions initially give 3 and 4. However, the amount of these compounds decreases by increasing the reaction time. This decrease is accompanied with the formation of mixed amine-phosphine compounds OsCl 2 (dCdCHPh)(NHd CR 2)(NH 2 R′)(P i Pr 3) [R′) allyl; CR 2) CMe 2 (5), C(CH 2) 4 CH 2 , (6). R′) Ph; CR 2) CMe 2 (7), C(CH 2) 4 CH 2 (8)]. The structure of 5 in the solid state has been also determined by an X-ray diffraction study. In this case, the geometry around the osmium atom can be rationalized as a distorted octahedron with the amine and phosphine ligands mutually trans disposed and the chlorine ligands mutually cis disposed. The X-ray analysis also shows that the NHhydrogen atoms of the amine and the chlorines are involved in intra-and intermolecular H‚‚‚Cl hydrogen bonding. The reactions of 1 and 2 with HBF 4 ‚OEt 2 afford the carbyne derivatives [OsCl 2 (tCCH 2 Ph)(NHdCR 2)(P i Pr 3) 2 ][BF 4 ] [CR 2) CMe 2 (9), C(CH 2) 4 CH 2 (10)]. Both 1 and 2 lose the imine ligand to give OsCl 2 (dCdCHPh)(P i Pr 3) 2 (11) in toluene under reflux. † Dedicated to Prof. Juan Bertrá n on the occasion of his 70th birthday.
Organometallics, Mar 13, 2007
The bis-solvato hydride-allenylidene complex [OsH(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (1) r... more The bis-solvato hydride-allenylidene complex [OsH(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (1) reacts with acetic acid to give the hydride-carbyne [OsH(κ 2-O 2 CCH 3)(tCCHdCPh 2)(P i Pr 3) 2 ]BF 4 (2), which in 1,2-dichloroethane under reflux is stable and does not evolve into its five-coordinate carbene isomer. In acetonitrile at room temperature, complex 2 is in equilibrium with [OsH{κ 1-OC(O)CH 3 }(tCCHd CPh 2)(CH 3 CN)(P i Pr 3) 2 ]BF 4 (4; ∆H°)-6.4 (0.3 kcal‚mol-1 , ∆S°)-22.9 (1.1 eu). At 353 K, complex 4 is transformed into the carbene [Os{κ 1-OC(O)CH 3 }(dCHCHdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (5; 40%), which is obtained in high yield (88%) by reaction of [Os(dCHCHdCPh 2)(CH 3 CN) 3 (P i Pr 3) 2 ]-[BF 4 ] 2 with sodium acetate in 2-propanol. The hydride-carbyne to carbene transformation is analyzed by DFT calculations.
Organometallics, Mar 15, 2007
... (1) Atwood, JD Inorganic and Organometallic Reaction Mechanism, VCH: New York, 1997; Chapter ... more ... (1) Atwood, JD Inorganic and Organometallic Reaction Mechanism, VCH: New York, 1997; Chapter 3. (2) See for example: (a) Katayama, H.; Ozawa, F. Organometallics1998, 17, 5190. (b) Schanz, H.-J.; Jafarpour, L.; Stevens, ED; Nolan, SP Organometallics1999, 18, 5187. ...
Organometallics, May 1, 2001
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Organometallics, Jun 14, 2008
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Organometallics, Nov 15, 2000
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Organometallics, Oct 23, 2008
The styryl-allenylidene complex [Os{(E)-CHdCHPh}-(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (2) r... more The styryl-allenylidene complex [Os{(E)-CHdCHPh}-(dCdCdCPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ]BF 4 (2) reacts with HBF 4 to giVe the styryl-alkenylcarbyne [Os{(E)-CHdCHPh}(tCCHd CPh 2)(CH 3 CN) 2 (P i Pr 3) 2 ](BF 4) 2 (3), which in acetonitrile eVolVes into the dienylcarbene deriVatiVe [Os{dC[(E)-CHdCHPh]-CHdCPh 2 }(CH 3 CN) 3 (P i Pr 3) 2 ](BF 4) 2 (4) by means of the concerted migration of the styryl ligand from the metal center to the carbyne C R atom. A kinetic study and DFT calculations on the transformation of 3 into 4 are reported.
Organometallics, Sep 8, 2011
The first rhodium-alkylidene square-planar complex stabilized by a N-heterocyclic carbene ligand ... more The first rhodium-alkylidene square-planar complex stabilized by a N-heterocyclic carbene ligand RhCl(=CHPh)(IPr)PPh 3 (2) {IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-carbene} has been prepared by reaction of RhCl(IPr)(PPh 3) 2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of 2-olefin complexes RhCl( 2-CH 2 =CHR)(IPr)PPh 3 (3, R = H; 4 R = Ph; 5 R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate. 2 Transition-metal alkylidene species are catalytic initiators for a myriad of useful organic transformations including olefin metathesis, 1 cyclopropanation, 2 C-H insertion 3 or cycloadditions. 4 In sharp contrast with other transition metals, the number of isolated rhodium-alkylidene complexes remain scarce, apart from the seminal work developed by Werner and Milstein's groups with phosphane stabilized derivatives. 5 The commonly used method for the preparation of alkylidene complexes via diazoalkane precursors 6 failed for the direct synthesis of rhodium-carbene species bearing two electronrich phosphanes of type RhCl(=CRR')(PR 3 '') 2. This problem was elegantly circumvented by the initial treatment of less sterically demanding rhodium-stibanes with diazoalkanes and subsequent exchange reaction by phosphanes, although no benzylidene species could be obtained following this approach. 5f Latter on, Milstein and coworkers showed that rhodium-benzylidene derivatives could be attained by reaction of phenyldiazomethane with more stable square-planar pincer precursors, 5i,k and even the compound RhCl(=CHPh)(P i Pr 3) 2 was prepared by an alternative method employing a sulfur ylide as precursor for the alkylidene moiety. 5i The special stereoelectronic properties of N-heterocyclic carbenes 7 (NHCs) make them suitable ancillary ligands not only for stabilization of reactive intermediates, but also for the improvement of catalytic activity. 8 Specially prominent is the case of olefin metathesis, where the catalytic performances of commercially available second generation Grubb's catalyst surpass the phosphane counterparts. 9 This "NHC effect" has been also observed in osmium-alkylidene derivatives. 10 With the aim of studying the potential of NHCs ligands in rhodium-alkylidene chemistry, we have prepared a new rhodiumalkylidene complex stabilized by a NHC ligand using phenyldiazometane as alkylidene precursor and investigated its behavior towards olefins. Reaction of the bis-phosphane-NHC rhodium complex RhCl(IPr)(PPh 3) 2 11 (1) [IPr = 1,3-bis-(2,6diisopropylphenyl)imidazol-2-carbene] with a freshly prepared THF solution of phenyldiazomethane 12 at-20 ºC under argon atmosphere gave rise to a dark green solution with concomitant gas bubbling (N 2). Work up at low temperature led to the complex RhCl(=CHPh)(IPr)PPh 3 (2) as a green solid in 76 % yield (Equation 1). Related Rh-NHC-Fischer carbene complexes have been previously reported, 13 but 2
Angewandte Chemie, Apr 22, 2005
ABSTRACT
New Journal of Chemistry, Dec 13, 2002
ABSTRACT
The complex [Rh(μ-Cl)(IPr)(η 2-coe)] 2 {IPr = 1,3-bis(2,6diisopropylphenyl)imidazol-2-carbene, co... more The complex [Rh(μ-Cl)(IPr)(η 2-coe)] 2 {IPr = 1,3-bis(2,6diisopropylphenyl)imidazol-2-carbene, coe = cis-cyclooctene} efficiently catalyzes the coupling of alkynes and N-vinylpyrazole via C−H activation, leading to Markovnikovselective butadienylpyrazole derivatives under mild conditions. A straightforward approach to cross-conjugated acyclic trienes is also operative through a one-pot alkyne dimerizationhydrovinylation tandem reaction. The proposed mechanism involves C−H activation of vinylpyrazole directed by nitrogen coordination to the metallic center. Subsequent alkyne coordination, insertion, and reductive elimination steps lead to the coupling products. Several key intermediates participating in the catalytic cycle have been detected and characterized, including a κ-N, η 2-CC coordinated vinylpyrazole complex and a Rh IIIhydride-alkenyl species resulting from the C−H activation of the vinylpyrazole
Trabajo presentado a la 6ª Jornada de Jóvenes Investigadores en Física y Química de Aragón celebr... more Trabajo presentado a la 6ª Jornada de Jóvenes Investigadores en Física y Química de Aragón celebrada en Zaragoza el 20 de noviembre de 2014.Las estructuras de tipo pirazol han atraído un creciente interés en los últimos años debido a sus amplias aplicaciones en medicina, agricultura, ciencia de los materiales o de la química analítica. Por ello, el desarrollo de nuevas y eficientes transformaciones catalizadas por metales de transición continúa siendo un reto importante en la síntesis orgánica. En particular, las reacciones de formación de enlaces C-C que proceden a través de un mecanismo de activación C-H son de gran interés. En este contexto, los catalizadores de rodio destacan por tener una gran tolerancia y una amplia utilidad sintética. Como parte de nuestra contribución a la química de los catalizadores de rodio conteniendo carbenos N-heterocíclicos, hemos desarrollado la síntesis de nuevos derivados de butadienilpirazoles a partir de N-vinilpirazoles y diferentes alquinos terminales, internos y eninos por activación del enlace C-H y posterior acoplamiento C-C con una excelente quimio y regioselectividad y buenos rendimientos del producto aislado.Peer reviewe
European Journal of Inorganic Chemistry, Jun 1, 2007
N‐Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC‐η6‐arene ligand have ... more N‐Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC‐η6‐arene ligand have been prepared and evaluated as precursors for ring opening metathesis polymerization (ROMP). The reaction of [RuCl2(p‐cymene)]2 with electron‐rich olefins of the bis(imidazolinylidene) type containing at least one arylmethyl‐N chain (aryl: 2,4,6‐trimethylphenyl, 3,4,5‐trimethoxyphenyl) selectively leads, upon heating, to ruthenium(II) complexes 2 containing a chelating bridged carbene η6‐arene ligand. The reaction of complexes containing an additional ROCH2CH2N group with AgOTf leads to ionic complexes 5 with a tridentate trifunctional carbene/arene/ether ligand. The X‐ray structure of[RuCl2{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2{C6H2(OMe)3‐3,4,5})}] (2c) and that of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand that provides ten electrons, [RuCl{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2CH2OCH3)}][CF3SO3] (5e), have been determined. The precursors 2 in the presence of AgOTf and propargyl alcohol, in order to produce an allenylidene initiator, and complexes 5 in the presence of propargyl alcohol lead to ROMP of norbornene. It is shown that initial chloride abstraction is required and that the catalyst activity is increased by using mesityl–ruthenium precursors and coordinated branched ether complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)