DigitalUM :: Browsing by browse.metadata.contributordepartment "Química Inorgánica"

Browsing by browse.metadata.contributordepartment "Química Inorgánica"

Now showing 1 - 20 of 137

Open Access
2-Arylacetamides as Versatile Precursors for 3-Aminoisocoumarin and Homophthalimide Derivatives: Palladium-Catalyzed Cascade Double Carbonylation Reactions
(Wiley, 2016-07-11) Frutos-Pedreño, Roberto; García-López, José-Antonio; García-López, José-Antonio; Química Inorgánica
Open Access
A new C,N-cyclometalated osmium(II) arene anticancer scaffold with a handle for functionalization and antioxidative properties
(2018-10-11) Yellol, Jyoti G ; Rothemund, Matthias; Ballester, Francisco; Rodriguez, Venancio; Yellol, Gorakh; Janiak, Christoph; Schobert, Rainer; Ruiz, Jose; Ortega Toro, Enrique; Química Inorgánica
Open Access
A New Method for High Yield Cyclopalladation of Primary and Secondary Amines. Atom-Efficient Open-to-Air Inexpensive Synthesis of Buchwald-Type Precatalysts
(ACS, 2011-07-28) Vicente, José; Saura-Llamas, Isabel; Oliva-Madrid, María-José; García-López, José-Antonio; Bautista, Delia; Vicente, José; Química Inorgánica
A new method for high yield cyclopalladation of primary and secondary amines involving the corresponding ammonium triflates, instead of the amines generally employed is reported. The method is applied for the synthesis of Buchwald-type precatalysts [Pd(C,N-C6H4CH2CH(R’)NHR- 2)X(phosphine)] that can be easily prepared by reaction of Pd(OAc)2, one equiv of the ammonium triflate [PhCH2CH(R’)NH2R]OTf and an excess of NaX, and then treating the resulting complexes [Pd2(C,N-C6H4CH2CH(R’)NHR-2)2(μ-X)2] with the appropriate phosphine. This new method has several advantages over Buchwald´s reported synthesis.
Open Access
A new way of Synthesising diarylgold(III) Complexes using organomercury compounds
(2019-11-25) Vicente, J.; Chicote Olalla, María Teresa; Arcas, A.; Artigao, M.; Jiménez, R.; Química Inorgánica
Treatment of [Me,N][AuCl, ] with di-organomercury derivatives R,Hg in which R is an orrho-nitroaryl group (R = u-OzNC,H, or 2-CH,, 6-O,NC,H,) gives anionic gold(II1) complexes of the type cis-Me,N[AuR,Cl, 1. These react with (a) KCN, to give the anionic complexes cam-Me~N[AuR~(CN)~], (b) neutral mon~entate ligands (L) to give the neutral complexes cam-[AuR~Cl(L)] (L = PPh,, PCy,, py), and (c) 1,2-bi~~phenylphosp~o)ethane (dpe) in the presence of NaClO, to give the cationic complexes cis-[AuR,(dpe)]ClO,. The complexes are thought to be the first transition metal complexes containing orfho-nitroaryl ligands.
Open Access
A photochemical dehydrogenative strategy for aniline synthesis
(Nature Research, 2020-08-06) Dighe, Shashikant; Juliá Hernández, Fabio; Luridiana, Alberto; Douglas, James J.; Leonori, Daniele; Química Inorgánica
Chemical reactions that reliably join two molecular fragments together (cross-couplings) are essential to the discovery and manufacture of pharmaceuticals and agrochemicals1,2. The introduction of amines onto functionalized aromatics at specific and pre-determined positions (ortho versus meta versus para) is currently achievable only in transition-metal-catalysed processes and requires halogen- or boron-containing substrates3,4,5,6. The introduction of these groups around the aromatic unit is dictated by the intrinsic reactivity profile of the method (electrophilic halogenation or C–H borylation) so selective targeting of all positions is often not possible. Here we report a non-canonical cross-coupling approach for the construction of anilines, exploiting saturated cyclohexanones as aryl electrophile surrogates. Condensation between amines and carbonyls, a process that frequently occurs in nature and is often used by (bio-)organic chemists7, enables a predetermined and site-selective carbon–nitrogen (C–N) bond formation, while a photoredox- and cobalt-based catalytic system progressively desaturates the cyclohexene ring en route to the aniline. Given that functionalized cyclohexanones are readily accessible with complete regiocontrol using the well established carbonyl reactivity, this approach bypasses some of the frequent selectivity issues of aromatic chemistry. We demonstrate the utility of this C–N coupling protocol by preparing commercial medicines and by the late-stage amination–aromatization of natural products, steroids and terpene feedstocks.
Open Access
A tight binding pocket in photoluminescent N^C^N cyclometalated Pt(II), Pd(II), and Ni(II) complexes
(Royal Society of Chemistry, 2025-08-22) Niazi, Maryam; Maisuls, Iván; Strassert, Cristian A.; González Herrero, Pablo; Klein, Axel; Química Inorgánica
In the frame of our research aiming to develop e cient triplet-emitting materials, we are exploring the role of the second coordination sphere in enhancing the rigidity of structures and its controlling aspect over the extents of excited state distortions. We thus synthesised three N^C^N cyclometalated complexes [M(LBn)Cl] (M = Pt, Pd, and Ni), where the two ortho-positions of the pyridyl moieties in 1,3-di(2-pyridyl)- benzene are benzyl substituted (Bn) forming a tight binding pocket for the metal and the Cl− ancillary ligand. The molecular structures from single-crystal X-ray di raction show a markedly distorted square planar M(II) coordination with τ4 values of around 0.4. UV-vis absorption spectra show long-wavelength bands in the range 350 to 5400 nm with the energies increasing along the series Ni < Pt < Pd. The Pt(II) complex emits in solution at 298 K (λmax = 544 nm) and displays aggregated emission within poly(methyl methacrylate) (PMMA) lms at various concentrations at 298 K. The Pd(II) derivative exhibits a broad emis- sion band at 77 K in a frozen glassy 2-MeTHF matrix, peaking at 530 nm. Very di erent from the Pt(II) and Pd(II) spectra, the Ni(II) sample showed a broad emission with λmax = 699 nm at 77 K, with a quantum yield of 20% and ms lifetime. TD-DFT calculated decomposition of the assumed emissive T1 state showed similar 3MLCT character of about 30% for all three complexes, but marked di erences in LC character of about 38% for Pd and Pt and only 5% for Ni. In turn, for Ni the by far the highest MC character (42%) was calculated which strongly speaks against triplet photoluminescence from the Ni(II) complex.
Open Access
Aminoalkyl radicals as halogen-atom transfer agents for activation of alkyl and aryl halides
(American Association for the Advancement of Science, 2020-02-28) Constantin, Timothee; Zanini, Margherita; Regni, Alessio; Sheikh, Nadeem S.; Juliá Hernández, Fabio; Leonori, Daniele; Química Inorgánica
Organic halides are important building blocks in synthesis, but their use in (photo)redox chemistry is limited by their low reduction potentials. Halogen-atom transfer remains the most reliable approach to exploit these substrates in radical processes despite its requirement for hazardous reagents and initiators such as tributyltin hydride. In this study, we demonstrate that α-aminoalkyl radicals, easily accessible from simple amines, promote the homolytic activation of carbon-halogen bonds with a reactivity profile mirroring that of classical tin radicals. This strategy conveniently engages alkyl and aryl halides in a wide range of redox transformations to construct sp3-sp3, sp3-sp2, and sp2-sp2 carbon-carbon bonds under mild conditions with high chemoselectivity.
Open Access
Anticancer cyclometalated complexes of platinum group metals and gold
(2013-04-06) Cutillas, Natalia; Yellol, Gorakh-S.; de Haro, Concepción; Vicente López, Consuelo; Rodríguez, Venancio; Ruiz, José; Química Inorgánica
Open Access
Applications of halogen-atom transfer (XAT) for the generation of carbon radicals in synthetic photochemistry and photocatalysis
(American Chemical Society, 2022-01-26) Juliá Hernández, Fabio; Constantin, Timothee; Leonori, Daniele; Química Inorgánica
The halogen-atom transfer (XAT) is one of the most important and applied processes for the generation of carbon radicals in synthetic chemistry. In this review, we summarize and highlight the most important aspects associated with XAT and the impact it has had on photochemistry and photocatalysis. The organization of the material starts with the analysis of the most important mechanistic aspects and then follows a subdivision based on the nature of the reagents used in the halogen abstraction. This review aims to provide a general overview of the fundamental concepts and main agents involved in XAT processes with the objective of offering a tool to understand and facilitate the development of new synthetic radical strategies.
Open Access
Aromatic C−H Activation in the Triplet Excited State of Cyclometalated Platinum(II) Complexes Using Visible Light
(2016-04-08) Juliá Hernández, Fabio; González Herrero, Pablo; Química Inorgánica
The visible-light driven cyclometalation of arene substrates containing an N-donor heteroaromatic moiety as directing group by monocy-clometalated Pt(II) complexes is reported. Precursors of the type [PtMe(C^N)(N^CH)], where N^CH is 2-phenylpyridine (ppyH) or related compunds with diverse electronic properties and C^N is the corresponding cyclometalated ligand, afford homoleptic cis-[Pt(C^N)2] complexes upon irradiation with blue LEDs at room temperature with evolution of methane. Heteroleptic derivatives cis-[Pt(ppy)(C'^N')] are obtained analogously from [PtMe(ppy)(N'^C'H)], where N'^C'H represents an extended set of heteroaromatic compounds. Experimental and computational studies demonstrate an unprecedented C–H oxidative addition, which is initiated by a triplet excited state of metal-to-ligand charge-transfer (MLCT) character and leads to a detectable Pt(IV) methyl hydride intermediate.
Open Access
Assembly of Heterometallic Rigid-Rod Complexes and Coordination Oligomers from Gold(I) Metalloligands
(American Chemical Society, 2015-06-18) Cámara, Verónica; Barquero, Natalia; Bautista, Delia; Gil-Rubio, Juan; Vicente, José; Química Inorgánica
The reactions of TpylC6H4C≡CAuL (Tpyl = 2,2':6',2''-terpyridin-4'-yl; L = PPh3, CNXy; Xy = 2,6-dimethylphenyl) with MX2·nH2O (M = Fe, X = ClO4; M = Co, X = BF4; M = Zn, X = TfO, ClO4) in a 2:1 molar ratio give complexes [M(TpylC6H4C≡CAuL)2]X2. Similarly, the reactions of PPN[(TpylC6H4C≡C)2Au] (PPN = (Ph3P)2N) with an equimolar amount of MX2·nH2O give coordination oligomers [M{(TpylC6H4C≡C)2Au}]nXn (M = Fe, Zn, X = ClO4; M = Co, X = BF4). The complexes and oligomers have been isolated and characterized. The crystal structures of [Fe(TpylC6H4C≡CAuCNXy)2](ClO4)2 and [Co(TpylC6H4C≡CAuPPh3)2](BF4)2 have been determined by X-ray diffraction. The hydrodynamic sizes of complexes [M(TpylC6H4C≡CAuPPh3)2]X2 and coordination oligomers [M{(TpylC6H4C≡C)2 Au}]nXn have been studied by NMR diffusion spectroscopy and Dynamic Light Scattering (DLS) measurements.
Open Access
Attaching CF3 groups to organic molecules using trifluoroacetates via ion-shielding photoelectrocatalysis
(Springer / Science China Press, 2024-08-30) Visiedo Jiménez, Paula; Juliá Hernández, Francisco; Química Inorgánica
Open Access
Bimetallic platinum(II) complexes with bridging di-NHC and N^C^C ligands: synthesis and photophysical properties
(Royal Society of Chemistry, 2025-10-02) Mariano Paredes; Vivancos Ureña, Ángela; Poveda Otazo, Dionisio; González Herrero, Pablo; Química Inorgánica; Facultades de la UMU::Facultad de Química
Three new bimetallic Pt(II) compounds of the type [{Pt(dmtppy)}2{μ-(ImMe)2(CH2)n}] [n = 1 (1), 3 (2), 6 (3)], where dmtppy is the dimetalated tridentate N^C^C ligand 2-(4,4’’-dimethyl-[1,1’:3’,1’’-terphenyl]-5’-yl) pyridine and ImMe is N-methylimidazol-N-yl-2-ylidene, have been synthesized in order to explore their ability to form molecular assemblies that affect their luminescence. Restricted rotation around the Pt–carbene bond leads to mixtures of atropisomers, which hinder the growth of single crystals. The com- plexes show efficient emissions with high phosphorescence quantum yields in 2 wt% doped PMMA films at 298 K (PLQY: 73–77%). Significant modifications of their photophysical properties in fluid solution are observed upon variation of the solvent, with the highest efficiencies found in 2-methyltetrahydrofurane (up to 63% quantum yield for complex 3). In the case of complex 1, which contains the shortest linkage, the formation of excimers in MeCN and MeOH causes a significant quenching of the emission, with a substantial decrease in the quantum yield.
Open Access
Bis[2-( phenylazo)phenyl-C1N']gold(III) Complexes. Crystal and Molecular Structure of Bis[2-( pheny1azo)phenyl-C1 N']gold(III) Tetrach loroau rate
(2019-10-30) Vicente, J.; Chicote Olalla, María Teresa; Bermudez, M. D.; Solans, X.; Font-Altaba, M.; Química Inorgánica
Open Access
Blue Copper Proteins: A rigid machine for efficient electron transfer, a flexible device for metal uptake
(2015-08-31) Pérez-Henarejos, Sergio Alejo; Alcaraz, Luis Antonio; Donaire González, Antonio; Química Inorgánica
Blue copper proteins (BCPs) are small and generally soluble copper-containing proteins which participate in monoelectron transfer processes in biological systems. An overview of their electronic and tertiary structure is detailed here. The well-established entatic/rack-induced mechanism is explained by comparing thermodynamic parameters between the folded (tense) and the unfolded (relaxed) forms of the BCP rusticyanin. Recently, NMR solution data have shown that the active sites of BCPs in absence of the metal ion, i.e. in the apoforms, are flexible in the micro-to-second timescale. The rigidity proposed by the entatic/rack-induced mechanism is an imperative for the holoprotein to perform electron transfer; while the flexibility of the apocupredoxin is necessary to uptake the metal ion from the metallochaperones. These apparently contradictory requirements are discussed in the present work. Finally, the role of azurin and some peptides derived from it in anticancer therapy are also described.
Open Access
C-H Activation in Primary 3-Phenylpropylamines: Synthesis of Seven-Membered Palladacycles through Orthometalation. Stoichiometric Preparation of Benzazepinones and Catalytic Synthesis of Ureas
(ACS, 2016-06-06) Frutos-Pedreño, Roberto; García Sánchez, Eva; Oliva-Madrid, María José; Bautista, Delia; Martínez-Viviente, Eloísa; Saura-Llamas, Isabel; Vicente, José; Química Inorgánica
The dimeric cyclometalated complexes [Pd2{C,N-C6H4CH2CH2C(R)(Me)NH2-2}2(µ-Cl)2] (R = Me (1a), H (1b)) are prepared by reacting 1,1-dimethyl-3-phenylpropylammonium or 1-methyl-3-phenylpropylammonium triflate with Pd(OAc)2 in a 1:1 molar ratio, and subsequent treatment with excess NaCl. The mononuclear derivatives [Pd{C,N-C6H4CH2CH2C(R)(Me)NH2-2}Cl(L)] (L = PPh3, R = Me (3a), H (3b); L = 4-picoline (4-pic), R = Me (4a), H (4b)) were prepared from 1a,b, by splitting the chloro-bridges with the neutral ligands L. A conformational analysis of the mononuclear palladacycles in solution has been carried out. Insertion of CO takes place into the Pd–C bond of complexes 1a,b affording Pd(0) and the tetrahydro-benzazepinone 5a or 5b, which possesses potential pharmacological interest. Additionally, the triflate salt A or B undergoes catalytic carbonylation with CO to afford the corresponding N,N’-dialkylurea, using Pd(OAc)2/Cu(OAc)2, in boiling acetonitrile. The crystal structures of 3a·1/2H2O, 3b, 4b·CHCl3, and 5a were determined by X-ray diffraction studies.
Open Access
Carbon-Hydrogen Activation of Ketones by 2-Phenylazophenylgold(III) Complexes to give Ketonylgold(III) Complexes
(2019-11-25) Vicente, J.; Bermúdez, Maria Dolores; Carrillo, María Pilar; G. Jones, Peter; Química Inorgánica
Complexes [AuR(acac-C)CI] {R = pap (C,H,N=NPh-2) la or mpap [C,H,(N=NC,H4Me-4)-2-Me-5] 1 b; Hacac = acetylacetone} or 'AuR(CI)(OCIO,)' (R = pap 2a or mpap 2b) react with various ketones MeC(0)R' to give [AuR{CH,C(O)R'}CI] [R = pap, R' = Et 3, Pr" 4, Pr' 5, Bui 6 or C,H,(OMe),-3,4,5 7; R = mpap, R' = Me 81. Whereas la does not react with MeC(O)CH,CI, 2a gives a mixture of the expected [Au(pap){CH,C(O)CH,CI}CI] and [Au(pap)Cl,J. However, other ketones [R'C(O)R''] (R' = Me; R" = Ph, CH,=CH, trans-PhCH=CH or MeCO; R' = R" = CH,CI or Et) or 2-methylcyclohexanone do not react at room temperature with 2a. The reactions of 2a with other species containing activated methyl groups [MeCO,Et, MeC(O)NH, or MeCN] either do not occur or give products in which there is no carbonhydrogen activation. Thus, 2a reacts with dimethyl sulfoxide (dmso) to give the first organogold(iii) complex with this ligand, [Au(pap)(dmso),J [CIO,], 9. It reacts with Nal to give [Au(pap)CI(I)] 10. Complex 8 reacts with NaCI0,-H,O and pyridine (py) or 2,2'-bipyridine (bipy) to give [Au(mpap)(CH,C(O)Me>L]ClO, (L = py 11 or bipy 12). The following reactions were also studied: [Au(pap)Cl(acac-C)] + PPh, or AgCIO, to give [Au(pap)Cl(acac-C)(PPh,)] 13 or [Au(pap)(acac- 0,O')l Cli3,14, respectively. Complexes 13 and 14 do not give an acetonyl complex with acetone; 14 is the first cationic acetylacetonatogold( lit) complex. A plausible reaction pathway is proposed for ketone carbon-hydrogen activation starting from complexes 2. Low-temperature crystal structures were determined for [Au(mpap)CI,] [space group PT, a = 7.902(2), b = 9.527(2), c = 10.378(3) A, x = 86.77(2), p = 77.32(2), y = 67.42(2)", R = 0.0241 and 11 [space group P2,/n, a = 8.693(5), b = 15.800(8), c = 16.489(8) A, j3 = 94.51 (4)", R = 0.0271. The latter is the first crystal structure of an acetonylgold(iii) complex, and it could be shown conclusively that the CH,C(O)Me group is bonded through the carbon atom. Both structures show the expected square-planar co-ordination around the gold atom, with some distortion from the narrow chelate rings. In the first complex the higher trans influence of the aryl group leads to a lengthening of the trans Au-CI bond (2.347 A) with respect to the cis bond (2.274 A).
Open Access
Catalysis in the excited state: bringing innate transition metal photochemistry into play
(American Chemical Society, 2025-03-05) Juliá Hernández, Fabio; Química Inorgánica; Facultad de Química
Transition metal catalysis is an indispensable tool for organic synthesis that has been harnessed, modulated and perfected for many decades by careful selection of metal centers and ligands, giving rise to synthetic methods with unparalleled efficiency and chemoselectivity. Recent developments have demonstrated how light irradiation can also be recruited as a powerful tool to dramatically alter the outcome of catalytic reactions, providing access to innovative pathways with remarkable synthetic potential. In this context, the adoption of photochemical conditions as a mainstream strategy to drive organic reactions has unveiled exciting opportunities to exploit the rich excited-state framework of transition metals for catalytic applications. This Perspective examines the advances on the application of transition metal complexes as standalone photocatalysts, exploiting the innate reactivity of their excited states beyond the common use as photoredox catalysts. An account of relevant examples is dissected to provide a discussion on the electronic reorganization, the orbitals involved and the associated reactivity of different types of excited states. This analysis aims to provide practitioners with fundamental principles and guiding strategies to understand, design and apply light-activation strategies to homogeneous transition metal catalysis for organic synthesis.
Open Access
Copper-catalysed amination of alkyl iodides enabled by halogen-atom transfer
(Nature Research, 2021-07-12) Gorski, Bartosz; Barthelemy, Anne-Laure; Douglas, James J.; Juliá Hernández, Fabio; Leonori, Daniele; Química Inorgánica
Despite the fact that nucleophilic displacement (SN2) of alkyl halides with nitrogen nucleophiles is one of the first reactions introduced in organic chemistry teaching, its practical utilization is largely limited to unhindered (primary) or activated (α-carbonyl, benzylic) substrates. Here, we demonstrate an alternative amination strategy where alkyl iodides are used as radical precursors instead of electrophiles. Use of α-aminoalkyl radicals enables the efficient conversion of the iodides into the corresponding alkyl radical by halogen-atom transfer, while copper catalysis assembles the sp3 C–N bonds at room temperature. The process provides SN2-like programmability, and application in late-stage functionalization of several densely functionalized pharmaceuticals demonstrates its utility in the preparation of valuable N-alkylated drug analogues.
Open Access
Cyclometalated iridium(III) luminescent complexes in therapy and phototherapy
(2018) Zamora, Ana; Vigueras Bautista, Gloria; Rodríguez, Venancio; Santana Lario, María Dolores; Ruiz, José; Química Inorgánica