Time filter

Source Type

Fornies J.,University of Zaragoza | Fuertes S.,University of Zaragoza | Larraz C.,University of Zaragoza | Martin A.,University of Zaragoza | And 3 more authors.
Organometallics | Year: 2012

Double complex salts (DCSs) of stoichiometry [Pt(bzq)(CNR) 2][Pt(bzq)(CN) 2] (bzq = 7,8-benzoquinolinate; R = tert-butyl (1), 2,6-dimethylphenyl (2), 2-naphtyl (3)) have been prepared by a metathesis reaction between [Pt(bzq)(CNR) 2]ClO 4 and [K(H 2O)][Pt(bzq)(CN) 2] in a 1:1 molar ratio under controlled temperature conditions (range: -10 to 0 °C). Compounds 1-3 have been isolated as air-stable and strongly colored solids [purple (1), orange (2), red-purple (3)]. The X-ray structure of 2 shows that it consists of ionic pairs in which the cationic and anionic square-planar Pt(II) complexes are almost parallel to each other and are connected by Pt-Pt (3.1557(4) Å) and π⋯π (3.41-3.79 Å) interactions. Energy decomposition analysis calculations on DCSs 1-3 showed relatively strong ionic-pair interactions (estimated interaction energies of -99.1, -110.0, and -108.6 kcal/mol), which are dominated by electrostatic interactions with small contributions from dispersion (π⋯π) and covalent (Pt⋯Pt) bonding interactions involving the 5d and 6p atomic orbitals of the Pt centers. Compounds 1-3 undergo a thermal (165 °C, 24 h) irreversible ligand rearrangement process in the solid state and also in solution at temperatures above 0 °C to give the neutral complexes [Pt(bzq)(CN)(CNR)] as a mixture of two possible isomers (SP-4-2 and SP-4-3). The mechanism of this process has been thoroughly explored by combined NMR and DFT studies. DFT calculations on 1-3 show that the existing Pt⋯Pt interactions block the associative attack of the Pt(II) centers by the coordinated cyanide and/or isocyanide ligands. Moreover, they support a significant transfer of electron density from the anionic to the cationic component (0.20-0.32 |e|), which renders the isocyanide ligand dissociation more feasible than that in the "free-standing" cationic [Pt(bzq)(CNR) 2] + components as well as the dissociation of the CN - in trans position to the C bzq in the anionic [Pt(bzq)(CN) 2] - component. Therefore, the first step in the ligand rearrangement pathway is the dissociation of the isocyanide in trans position to the C bzq, yielding the [(RNC)(bzq)(μ 2- η 1,η 1-CN)Pt⋯Pt(bzq)(CN)] intermediates. The rate-limiting step corresponds to the transformation of these intermediates to the neutral [Pt(bzq)(CN)(CNR)] complexes following a synchronous mechanism involving rupture of the Pt-Pt and formation of the Pt-CN bonds through transition states formulated as [(RNC)(bzq)Pt(μ 2- η 1,η 1-CN)Pt(bzq)(CN)]. © 2012 American Chemical Society.

Arias A.,University of Zaragoza | Fornies J.,University of Zaragoza | Fortuno C.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Martin A.,University of Zaragoza
Inorganica Chimica Acta | Year: 2013

The di- and trinuclear derivatives [(RF)2Pt(μ- PPh2)2Pt(CH3CN)2], 1, [(R F)2Pt(μ-PPh2)2Pt(μ-PPh 2)2Pt(CH3CN)2], 2, (RF = C6F5) behave as synthons of di- and trinuclear fragments. Addition of azide and oxalate ions to 1 and 2, even in an excess, provides a way to isolate the tetranuclear and hexanuclear platinum complexes [NBu 4]2[{(RF)2Pt{(μ-PPh 2)2Pt}n(μ-1,1-N3)}2] (n = 1, 3; 2, 5), [NBu4]2[{(RF) 2Pt(μ-PPh2)2Pt}2(μ-C 2O4-κ2O,O′: κ 2O″,Oâ€́)}], 4, and [NBu4] 2[{(RF)2Pt(μ-PPh2) 2Pt(μ-PPh2)2Pt}2(μ-C 2O4-κ2O,O′: κ 2O″,Oâ€́)}], 6. The structures of 3-6, determined by single crystal X-ray diffraction, show a linear arrangement of the platinum centres maintained through "Pt(μ-PPh2) 2Pt" and "Pt(μ-1,1-N3)2Pt" or "Pt(μ-C2O4-κ2O,O′: κ2O″,Oâ€́)Pt" bridging fragments. Finally, addition of KCN to 2 affords the trinuclear [NBu4] 2[(RF)2Pt(μ-PPh2) 2Pt(μ-PPh2)2Pt(CN)2], 7, in which two cyanido groups are bonded to the platinum centre in a terminal way. © 2013 Elsevier B.V. All rights reserved.

Sadaba D.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Delso I.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Delso I.,University of Zaragoza | Tejero T.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Merino P.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH
Tetrahedron Letters | Year: 2011

Optically active five-membered cyclic nitrones are readily obtained in a one-pot procedure via the organocatalytic Michael addition of aldehydes to nitroolefins and in situ reductive cyclization. Application of the methodology to the synthesis of tricyclic compounds through intramolecular 1,3-dipolar cycloaddition reactions (DFT calculations have also been performed) is also demonstrated. All the reactions were carried out in water as a solvent and excellent ee values (ee >99%) were obtained. © 2011 Elsevier Ltd. All rights reserved.

PubMed | University of Zaragoza
Type: | Journal: Chemistry (Weinheim an der Bergstrasse, Germany) | Year: 2016

The anionic trifluoromethylgold(I) derivatives [CF

Montagner D.,University of Padua | Sanz Miguel P.J.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH
Dalton Transactions | Year: 2011

The neutral complex [PtCl(PyDT)]5 (PyDT = (CH2) 4NCS2 -) represents the first example of a Pt5 metallacycle. This unique architecture based on chiral S-bridged PtII monomers was prepared by thermal degradation of the reaction product of PtCl2 and a pyrrolidinedithioester. © 2011 The Royal Society of Chemistry.

Delso I.,Servicio de Resonancia Magnetica Nuclear | Delso I.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Tejero T.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Goti A.,CNR Institute of Chemistry of organometallic Compounds | Merino P.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH
Journal of Organic Chemistry | Year: 2011

Two new polyhydroxylated nortropane analogues closely related with Calystegines have been prepared in excellent chemical yields and complete selectivity. A synthetic strategy based on consecutive nucleophilic allylation, oxidation, and intramolecular dipolar cycloaddition was developed. The formation of key intermediate cycloadducts were observed to take place through the recently confirmed thermally induceded 2-aza-Cope rearrangement of nitrones. © 2011 American Chemical Society.

Esteruelas M.A.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Lopez A.M.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Mora M.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Onate E.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH
ACS Catalysis | Year: 2015

Complex OsH2(CO)(PiPr3)2, generated from OsH2(CO)(η2-CH2=CHEt)(PiPr3)2 by dissociation of the olefin, promotes the release of 1 equiv of H2 from ammonia-borane and the formation of polyaminoborane. The dehydrogenation rate law is of the form d[H2]/dt = k[Os] with activation parameters of ΔH‡ = 19.6 ± 2.5 kcal·mol-1 and ΔS‡ = 6 ± 9 cal·mol-1·K-1. On the basis of kinetic results, spectroscopic NMR observations, and DFT calculations, the dihydride-dihydrogen derivative OsH2(η2-H2)(CO)(PiPr3)2 is proposed as a key intermediate for the dehydrogenation. Its formation involves the concerted BH- and NH-hydrogen transfers from the amine-borane to the metal center and to a hydride ligand, respectively. © 2014 American Chemical Society.

Palacios L.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Di Giuseppe A.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Opalinska A.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Castarlenas R.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | And 3 more authors.
Organometallics | Year: 2013

The neutral square-planar complexes Rh(acac)(IPr)(η2-olefin) have been prepared from [Rh(μ-Cl)(IPr)(η2-olefin)] 2 (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-carbene; olefin = cyclooctene, ethylene) and sodium acetylacetonate (acac). Protonation of the acetylacetonato complexes with triflic acid opens the way to the formation of the putative bare [Rh-IPr]+ fragment that has been stabilized at low temperature by labile ligands such as triflate, cyclooctene, and acetonitrile to generate Rh(OTf)(IPr)(η2-coe), [Rh(IPr)(η2-coe) (NCCH3)2]OTf, and [Rh(IPr)(NCCH3) 3]OTf complexes. The derivative [Rh(IPr)(η2-coe) (NCCH3)2]OTf was further characterized by an X-ray diffraction analysis. © 2013 American Chemical Society.

Passarelli V.,Centro Universitario Of La Defensa | Perez-Torrente J.J.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Oro L.A.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH
Inorganic Chemistry | Year: 2014

The iridium(I) complexes of formula Ir(cod)(SiNP)+ (1 +) and IrCl(cod)(SiNP) (2) are easily obtained from the reaction of SiMe2{N(4-C6H4CH3)PPh 2}2 (SiNP) with [Ir(cod)(CH3CN) 2]+ or [IrCl(cod)]2, respectively. The carbonylation of [1][PF6] affords the cationic pentacoordinated complex [Ir(CO)(cod)(SiNP)]+ (3+), while the treatment 2 with CO gives the cation 3+ as an intermediate, finally affording an equilibrium mixture of IrCl(CO)(SiNP) (4) and the hydride derivative of formula IrHCl(CO)(SiNP-H) (5) resulting from the intramolecular oxidative addition of the C-H bond of the SiCH3 moiety to the iridium(I) center. Furthermore, the prolonged exposure of [3]Cl or 2 to CO resulted in the formation of the iridium(I) pentacoordinated complex Ir(SiNP-H)(CO)2 (6). The unprecedented κ3C,P,P′ coordination mode of the [SiNP-H] ligand observed in 5 and 6 has been fully characterized in solution by NMR spectroscopy. In addition, the single-crystal X-ray structure of 6 is reported. © 2014 American Chemical Society.

Martin A.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Belio U.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Fuertes S.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH | Sicilia V.,Institute Sintesis Quimica y Catalisis Homogenea ISQCH
European Journal of Inorganic Chemistry | Year: 2013

Complexes of the type [Pt(C6F5)(bzq)L] {bzq = 7,8-benzoquinolinate; L = PPh3 (2), 2,6-diphenylpyridine (pyPh 2, 3), tetrahydrothiophene (tht, 4), MeCN (5)} were prepared by replacing the acetone ligand in [Pt(C6F5)(bzq)(Me 2CO)] (1) with the corresponding L ligand. The structures of complexes 2-4 were established by X-ray diffraction. Despite their neutral nature, complexes 1-5 react with AgClO4 in a 2:1 molar ratio to give the corresponding trinuclear complexes [{Pt(C6F5)(bzq)L} 2Ag]ClO4 {L = Me2CO (6), PPh3 (7), pyPh2 (8), tht (9), MeCN (10)}, which contain Pt → Ag dative bonds. The structures of complexes 7, 9, and 10 were established by X-ray diffraction, which confirmed the existence of Pt-Ag bonds (ca. 2.8 Å) and short η1 bonding Ag-C interactions with the Cipso atom of bzq (ca. 2.4 Å). Moreover, complexes 3, 4, 7, 9, and 10 show intermolecular π⋯π interactions between the aromatic rings of the bzq ligands (separations of ca. 3.5 Å). The reactions of 1-5 with [Ag(PPh3)(OClO3)] in a 1:1 molar ratio proceed with interchange of the ligands between the metals and the formation of [{Pt(bzq)(C6F5)(PPh3)}2Ag]ClO 4 (7) and [AgL2]ClO4 (X-ray). Only in the case of L = pyPh2 (3) was the dinuclear complex [(C6F 5)(bzq)(PPh3)PtAg(pyPh2)]ClO4 (11) identified, and its structure was determined by X-ray diffraction. Complex 11 contains a Pt → Ag [2.8147(1) Å] bond and a η1-Ag- Cipso(bzq) interaction [2.293(1) Å]. The electronic absorption and luminescence behaviors of 1-11 were investigated. The lower-lying absorption bands of the mononuclear complexes are ascribed to ligand-centered [ 1IL, π-π* (bzq)] character mixed with some metal-to-ligand charge transfer [1MLCT 5d(Pt) → π*(bzq)]. For the trinuclear complexes, these bands are assigned to 1ILCT/1MM′LCT [π-π*(bzq)]/{d/s(Pt,Ag)} → π*(bzq)] transitions and to mixed 1MLCT/ 1L′LCT [MLCT 5d(Pt) → π*(bzq)]/[L′LCT, Arf → bzq] for dinuclear complex 11 on the basis of time-dependent TD (DFT) calculations carried out on 2, 4, 5, 9, 10, and 11Me in CH2Cl2. Only 2 and the heteronuclear compounds are emissive in the solid state at room temperature; however, all of the complexes are emissive at 77 K (solids and glasses). In each case, the main phosphorescent emission seems to be due to a transition similar in character to the lowest-energy electronic absorption. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Loading Institute Sintesis Quimica y Catalisis Homogenea ISQCH collaborators
Loading Institute Sintesis Quimica y Catalisis Homogenea ISQCH collaborators