Thiodipropionate ZnII Complexes: Synthesis, DFT Studies, and X-ray Structure of [{Zn(phen)(H2O)}2(μ-tdp)2]·3H2O

4 páginas, 4 figuras, 2 tablas, 1 esquema.The zinc thiodipropionate complex [Zn(tdp)] (1) [tdp = S(CH2CH2COO)22–] was obtained by reaction of aqueous zinc dichloride with a 1:1 mixture of Na2CO3 and thiodipropionic acid. The bonding preferences of the tdp anion were studied by DFT methods. The reaction of 1 with o-phenanthroline (phen) gave the dinuclear compound [{Zn(phen)(H2O)}2(μ-tdp)2]·3H2O (2), which was characterized by X-ray analysis.This work was supported by Spanish Ministerio de Ciencia e Innovación and Junta de Andalucía.Peer reviewe

Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts

[EN] Tremorine and precursors of gemini surfactants were synthesised in a one-pot, three-step, double-catalytic A3 coupling reaction and characterised by structural and spectroscopic methods. The cationic [Au-I(L1)]SbF6 complex is a more active catalyst compared to neutral L2- and L3-Au-I bis(trifluoromethanesulfonyl) imidate complexes (L1, L2= Buchwald-type biaryl phosphane; L3= triphenylphosphine) in promoting the double A(3) coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide-bridged cationic di-gold(I) L1 and L2 complexes were isolated and characterised by means of single-crystal X-ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the AuI catalyst by formation of the less active iodido-bridged cationic digold(I) L1 complex, which was fully characterised by single-crystal X-ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl-bridged Au-2(I)-L intermediates, isolation of which lends support to the proposed double A(3) coupling mechanism.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-R1) and Generalidad Valenciana (Prometeo 2013-014) is gratefully acknowledged.Grirrane, A.; Alvarez-González, E.; García Gómez, H.; Corma Canós, A. (2017). Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts. Chemistry - A European Journal. 23(12):2792-2801. https://doi.org/10.1002/chem.201605269S27922801231

Supported palladium nanoparticles as heterogeneous ligand-free catalysts for the Hiyama C C coupling of vinylsilanes and halobenzenes leading to styrenes

[EN] Palladium nanoparticles supported on magnesia is a highly efficient solid, reusable catalyst to promote in the absence of phosphine ligands the coupling of vinylsilanes with iodo- and bromobenzenes to form styrenes.Financial support by Spanish Ministry of Science and Innovation (Consolider MULTICAT and CTQ 2012-32316) is gratefully acknowledged. The Generalidad Valenciana is also thanked for partial financial support (Prometeo Grant).Grirrane, A.; García Gómez, H.; Corma Canós, A. (2013). Supported palladium nanoparticles as heterogeneous ligand-free catalysts for the Hiyama C C coupling of vinylsilanes and halobenzenes leading to styrenes. Journal of Catalysis. 302:49-57. doi:10.1016/j.jcat.2013.02.019S495730

Multinuclear silver(I) XPhos complexes with cyclooctatetraene: photochemical C-C bond cleavage of acetonitrile and cyanide bridged Ag cluster formation

[EN] Cationic mono-, di-, tri-and tetra-nuclear silver complexes with Buchwald-type phosphane (XPhos) and cyclooctatetraene (COT) have been synthesized and characterized. Formation of [(XPhos-Ag) n(COT)][SbF6](n) (n = 1 and 2) complexes was confirmed by single-crystal X-ray crystallography and multinuclear NMR spectroscopy. Variable-temperature NMR spectroscopy in CD2Cl2 solution shows the fluxionality of the COT ring in the mono-Ag(I) XPhos complex. Fluxionality of COT was also confirmed in the case of the di-Ag(I) XPhos complex by solid-state and solution P-31 NMR spectroscopy. The C-C bond cleavage of coordinated acetonitrile [XPhos-Ag(I)-NCCH3] resulting in cyanide bridged Ag cluster formation [(XPhos-Ag)(2)(mu-CN)(n)(mu-Ag)(n-1)] (n = 1, 2, 3 and 4) upon light excitation of [(XPhos-Ag)(n)(COT)] was confirmed by HRESI-MS, UV-Absorption and HR-TEM.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-C2-1-R) and Generalidad Valenciana (Prometeo 2013-014) is gratefully acknowledged. We also thank Dr Vidal-Moya J. A. (ITQ) for assistance and discussions on NMR analysis.Grirrane ., A.; Alvarez-González, E.; Albero-Sancho, J.; García Gómez, H.; Corma Canós, A. (2016). Multinuclear silver(I) XPhos complexes with cyclooctatetraene: photochemical C-C bond cleavage of acetonitrile and cyanide bridged Ag cluster formation. Dalton Transactions. 45(13):5444-5450. https://doi.org/10.1039/c6dt00370bS54445450451

Gold Nanoparticles Supported on Ceria Nanoparticles Modulate Leukocyte–Endothelium Cell Interactions and Inflammation in Type 2 Diabetes

Diabetes; Gold-ceria nanoparticle; InflammationDiabetes; Nanopartícula de oro-ceria; InflamaciónDiabetis; Nanopartícula d'or-cèria; InflamacióGold-ceria nanoparticles (Au/CeO2) are known to have antioxidant properties. However, whether these nanoparticles can provide benefits in type 2 diabetes mellitus (T2D) remains unknown. This work aimed to study the effects of Au/CeO2 nanoparticles at different rates of gold purity (10, 4.4, 1.79 and 0.82) on leukocyte–endothelium interactions and inflammation in T2D patients. Anthropometric and metabolic parameters, leukocyte–endothelium interactions, ROS production and NF-κB expression were assessed in 57 T2D patients and 51 healthy subjects. T2D patients displayed higher Body Mass Index (BMI) and characteristic alterations in carbohydrate and lipid metabolism. ROS production was increased in leukocytes of T2D patients and decreased by Au/CeO2 at 0.82% gold. Interestingly, Au/CeO2 0.82% modulated leukocyte–endothelium interactions (the first step in the atherosclerotic process) by increasing leukocyte rolling velocity and decreasing rolling flux and adhesion in T2D. A static adhesion assay also revealed diminished leukocyte–endothelium interactions by Au/CeO2 0.82% treatment. NF-κB (p65) levels increased in T2D patients and were reduced by Au/CeO2 treatment. Cell proliferation, viability, and apoptosis assays demonstrated no toxicity produced by Au/CeO2 nanoparticles. These results demonstrate that Au/CeO2 nanoparticles at 0.82% exert antioxidant and anti-inflammatory actions in the leukocyte–endothelium interaction of T2D patients, suggesting a protective role against the appearance of atherosclerosis and cardiovascular diseases when this condition exists.This study was financed by grants PI22/00424, PI19/00838, PI19/0437 and CIBERehd CB06/04/0071 by Carlos III Health Institute and by the European Regional Development Fund (ERDF “A way to build Europe”); ACIF/2020/370 (P.D.-P.), GRISOLIAP/2019/091 (F.C.) and APOSTD/2020/145 (S.L.-D); S.R.-L is recipient of a Maria Zambrano fellowship ZA21-049, from the requalification of the Spanish university system from the Ministry of Universities of the Government of Spain, financed by the European Union, Next Generation EU, PROMETEO/2019/027 by the Ministry of Health of the Valencian Regional Government. C.L.-M. was supported by Erasmus+ internship grant through Uppsala University, Sweden

Isolation and X-ray characterization of palladium N complexes in the guanylation ofaromatic amines. Mechanistic implications

In the context of palladium-catalyzed guanylation of anilines herein, we have been able to characterize and isolate bis(anilino) and bis(guanidino)Pd(II) complexes using reaction conditions under which stoichiometric amounts of palladium salts are used. Characterization of these palladium complexes strongly supports a mechanistic proposal for the catalytic guanylation of anilines using PdCl2(NCCH3)2 as catalyst that involves the intermediacy of these Pd(II) complexes.Financial support by the Spanish Ministry of Economy and competitiveness (Severo Ochoa and CTQ2012-36351) and Generalidad Valenciana (Prometeo 2012-014) is gratefully acknowledged.Grirrane, A.; García Gómez, H.; Álvarez, E. (2013). Isolation and X-ray characterization of palladium N complexes in the guanylation ofaromatic amines. Mechanistic implications. Beilstein Journal of Organic Chemistry. 9:1455-1462. https://doi.org/10.3762/bjoc.9.165S145514629Membrino, A., Paramasivam, M., Cogoi, S., Alzeer, J., Luedtke, N. W., & Xodo, L. E. (2010). Cellular uptake and binding of guanidine-modified phthalocyanines to KRAS/HRASG-quadruplexes. Chem. Commun., 46(4), 625-627. doi:10.1039/b918964eBlondeau, P., Segura, M., Pérez-Fernández, R., & de Mendoza, J. (2007). Molecular recognition of oxoanions based on guanidinium receptors. Chem. Soc. Rev., 36(2), 198-210. doi:10.1039/b603089kThevissen, K., Pellens, K., De Brucker, K., François, I. E. J. A., Chow, K. K., Meert, E. M. K., … Cammue, B. P. A. (2011). Novel fungicidal benzylsulfanyl-phenylguanidines. Bioorganic & Medicinal Chemistry Letters, 21(12), 3686-3692. doi:10.1016/j.bmcl.2011.04.075Berlinck, R. G. S., Burtoloso, A. C. B., & Kossuga, M. H. (2008). The chemistry and biology of organic guanidine derivatives. Natural Product Reports, 25(5), 919. doi:10.1039/b507874cBerlinck, R. G. S., & Kossuga, M. H. (2005). Natural guanidine derivatives. Natural Product Reports, 22(4), 516. doi:10.1039/b209227cBae, I., Han, H., & Chang, S. (2005). Highly Efficient One-Pot Synthesis ofN-Sulfonylamidines by Cu-Catalyzed Three-Component Coupling of Sulfonyl Azide, Alkyne, and Amine. Journal of the American Chemical Society, 127(7), 2038-2039. doi:10.1021/ja0432968Omae, I. (2003). General Aspects of Tin-Free Antifouling Paints. Chemical Reviews, 103(9), 3431-3448. doi:10.1021/cr030669zLiu, C., Zhou, S., Wang, S., Zhang, L., & Yang, G. (2010). Rare earth metal bis(trimethylsilyl)amido complexes bearing pyrrolyl-methylamide ligand. Synthesis, structure, and catalytic activity towards guanylation of amines. Dalton Transactions, 39(38), 8994. doi:10.1039/c0dt00246aOng, T.-G., Yap, G. P. A., & Richeson, D. S. (2003). Catalytic Construction and Reconstruction of Guanidines:  Ti-Mediated Guanylation of Amines and Transamination of Guanidines. Journal of the American Chemical Society, 125(27), 8100-8101. doi:10.1021/ja035716jMontilla, F., Pastor, A., & Galindo, A. (2004). Guanylation of aromatic amines catalyzed by vanadium imido complexes. Journal of Organometallic Chemistry, 689(6), 993-996. doi:10.1016/j.jorganchem.2004.01.005Zhang, W.-X., Li, D., Wang, Z., & Xi, Z. (2009). Alkyl Aluminum-Catalyzed Addition of Amines to Carbodiimides: A Highly Efficient Route to Substituted Guanidines. Organometallics, 28(3), 882-887. doi:10.1021/om801035tRowley, C. N., Ong, T.-G., Priem, J., Richeson, D. S., & Woo, T. K. (2008). Analysis of the Critical Step in Catalytic Carbodiimide Transformation: Proton Transfer from Amines, Phosphines, and Alkynes to Guanidinates, Phosphaguanidinates, and Propiolamidinates with Li and Al Catalysts. Inorganic Chemistry, 47(24), 12024-12031. doi:10.1021/ic801739aOng, T.-G., O’Brien, J. S., Korobkov, I., & Richeson, D. S. (2006). Facile and Atom-Efficient Amidolithium-Catalyzed C−C and C−N Formation for the Construction of Substituted Guanidines and Propiolamidines. Organometallics, 25(20), 4728-4730. doi:10.1021/om060539rZHU, X., XU, F., & SHEN, Q. (2009). An Efficient Guanylation of Aromatic Amines Catalyzed by Samarium Diiodide. Chinese Journal of Chemistry, 27(1), 19-22. doi:10.1002/cjoc.200990017Wu, Y., Wang, S., Zhang, L., Yang, G., Zhu, X., Liu, C., … Rong, J. (2009). Efficient guanylation of aromatic and heterocyclic amines catalyzed by cyclopentadienyl-free rare earth metal amides. Inorganica Chimica Acta, 362(8), 2814-2819. doi:10.1016/j.ica.2008.12.030Li, D., Guang, J., Zhang, W.-X., Wang, Y., & Xi, Z. (2010). Zn(OTf)2-catalyzed addition of amines to carbodiimides: efficient synthesis of guanidines and unpredicted formation of Zn–N amido species. Organic & Biomolecular Chemistry, 8(8), 1816. doi:10.1039/b923249bGrirrane, A., Garcia, H., Corma, A., & Álvarez, E. (2012). Orthogonal CN Plus CC Tandem Reaction of Iodoanilines Leading to Styrylguanidines Catalyzed by Supported Palladium Nanoparticles. Chemistry - A European Journal, 18(47), 14934-14938. doi:10.1002/chem.201202823Bon, V., Orysyk, S., & Pekhnyo, V. (2009). trans-Dichloridobis(4-methoxyaniline-κN)palladium(II). Acta Crystallographica Section E Structure Reports Online, 65(6), m673-m673. doi:10.1107/s1600536809018509Anderson, R. A., & Einstein, F. W. B. (1978). Dichlorobis(di-tert-butylcarbodiimide)palladium(II). Acta Crystallographica Section B, 34(1), 271-272. doi:10.1107/s0567740878002770Bodanszky, M. (1993). Peptide Chemistry. doi:10.1007/978-3-642-78206-

Experimental and computational studies of the molybdenum-flanking arene interaction in quadruply bonded dimolybdenum complexes with terphenyl ligands

To clarify the nature of the MoCarene interaction in terphenyl complexes with quadruple MoMo bonds, ether adducts of composition [Mo2(Ar′)(I)(O2CR)2(OEt2)] have been prepared and characterized (Ar′=ArXyl2, R=Me; Ar′=ArMes2, R=Me; Ar′=ArXyl2, R=CF3) (Mes=mesityl; Xyl=2,6‐Me2C6H3, from now on xylyl) and their reactivity toward different neutral Lewis bases investigated. PMe3, P(OMe)3 and PiPr3 were chosen as P‐donors and the reactivity studies complemented with the use of the C‐donors CNXyl and CN2C2Me4 (1,3,4,5‐tetramethylimidazol‐2‐ylidene). New compounds of general formula [Mo2(Ar′)(I)(O2CR)2(L)] were obtained, except for the imidazol‐2‐ylidene ligand that yielded a salt‐like compound of composition [Mo2(ArXyl2)(O2CMe)2(CN2C2Me4)2]I. The MoCarene interaction in these complexes has been analyzed with the aid of X‐ray data and computational studies. This interaction compensates the coordinative and electronic unsaturation of one of the Mo atoms in the above complexes, but it seems to be weak in terms of sharing of electron density between the Mo and Carene atoms and appears to have no appreciable effect in the length of the MoMo, MoX, and MoL bonds present in these molecules

Gold catalysts for the synthesis of aromatic azocompounds from nitroaromatics in one step

[EN] One-step selective hydrogenation of nitroaromatics to obtain symmetric azocompounds with high yields has been performed with a gold supported on cerium oxide catalysts. Au/TiO2 and Au/CeO2 catalysts direct the reaction by two different pathways and with different selectivities. In situ FTIR studies reveal that the surface concentration of the intermediate nitrosobenzene is decisive in directing the reaction trough the different reaction pathways. In this way, while on Au/TiO2 a fast hydrogenation of the nitrosobenzene intermediate leads to a low surface concentration of the nitrosocompound, on Au/CeO2 nitrosobenzene is more stabilized on the catalyst surface leading to a lower hydrogenation and a higher coupling rate, resulting in high selectivities to azobenzene. On Au/CeO2, the relative weak adsorption of the azo with respect to the azoxycompound on the catalyst surface avoids the consecutive hydrogenation of azocompounds to the corresponding anilines until all the azoxy has been consumed. Asymmetric azobenzenes have also been obtained with very high yields on TiO2, through the Mills reaction.The authors wish to acknowledge the financial support from the Spanish Ministries of Education and Science and Economy and Competitiveness under the project Consolider-Ingenio 2010 (CSD2009-00050 "Development of more efficient catalysts for the design of sustainable chemical processes and clean energy production") and the Severo Ochoa program (SEV-2012-0267), respectively. D.C. thanks the Spanish MEC for postgraduate scholarship, project MAT2006-14274-C02-01.Cómbita Merchán, DF.; Concepción Heydorn, P.; Corma Canós, A. (2014). Gold catalysts for the synthesis of aromatic azocompounds from nitroaromatics in one step. Journal of Catalysis. 311:339-349. https://doi.org/10.1016/j.jcat.2013.12.014S33934931

Identifying the Azobenzene/Aniline reaction intermediate on TiO2-(110) : a DFT Study

Density functional theory (DFT) calculations, both with and without dispersion corrections, have been performed to investigate the nature of the common surface reaction intermediate that has been shown to exist on TiO2(110) as a result of exposure to either azobenzene (C6H5N═NC6H5) or aniline (C6H5NH2). Our results confirm the results of a previous DFT study that dissociation of azobenzene into two adsorbed phenyl imide (C6H5N) fragments, as was originally proposed, is not energetically favorable. We also find that deprotonation of aniline to produce this surface species is even more strongly energetically disfavored. A range of alternative surface species has been considered, and while dissociation of azobenzene to form surface C6H4NH species is energetically favored, the same surface species cannot form from adsorbed aniline. On the contrary, adsorbed aniline is much the most stable surface species. Comparisons with experimental determinations of the local adsorption site, the Ti–N bond length, the molecular orientation, and the associated C 1s and N 1s photoelectron core level shifts are all consistent with the DFT results for adsorbed aniline and are inconsistent with other adsorbed species considered. Possible mechanisms for the hydrogenation of azobenzene required to produce this surface species are discussed

Activity of ceria and ceria-supported gold nanoparticles for the carbamoylation of aliphatic amines by dimethyl carbonate

Aliphatic amines react sluggishly with dimethyl carbonate (DMC) to give a mixture of N-methylation and carbamoylation. Nanoparticulated ceria as catalyst increases, in general, conversion and selectivity toward carbamoylation. This increase in catalytic activity and selectivity toward carbamoylation is even increased by deposition of Au nanoparticles on ceria. However, in contrast to aromatic amines for which a complete selectivity toward carbamoylation using ceria-supported Au nanoparticles can be achieved, the catalytic carbamoylation of aliphatic amines by ceria-supported Au nanoparticles occurs only with moderate selectivity.Financial support by the Spanish Ministry of Science and Innovation (Consolider 2010-CSD2009-0050 and CTQ2009-11586) is gratefully acknowledged. R.J. thanks the Spanish Ministry of Education for a postgraduate scholarship.Juárez Marín, R.; Corma Canós, A.; García Gómez, H. (2011). Activity of ceria and ceria-supported gold nanoparticles for the carbamoylation of aliphatic amines by dimethyl carbonate. Pure and Applied Chemistry. 84(3):685-694. https://doi.org/10.1351/PAC-CON-11-06-06S685694843Galzerano, P., Agostino, D., Bencivenni, G., Sambri, L., Bartoli, G., & Melchiorre, P. (2010). Controlling Stereoselectivity in the Aminocatalytic Enantioselective Mannich Reaction of Aldehydes with In Situ Generated N-Carbamoyl Imines. Chemistry - A European Journal, 16(20), 6069-6076. doi:10.1002/chem.20090321