Gabriel García Herbosa

Universidad de Burgos | UBU · Department of Chemistry

The chemistry of the heterocyclic compounds containing one nitrogen as part of the six- membered ring, as well as two oxygen atoms (dioxazines), one oxygen and one sulfur atoms (oxathiazines), or two sulfur atoms (dithiazines) has been compiled in previous editions of Comprehensive Heterocyclic Chemistry.1, 2, 3 For the present edition, this chapte...

New cis-(1,2-azole)-aquo bis(2,2'-bipyridyl)ruthenium(II) (1,2-azole (az*H) = pzH (pyrazole), dmpzH (3,5-dimethylpyrazole), and indzH (indazole)) complexes are synthesized via chlorido abstraction from cis-[Ru(bipy)2Cl(az*H)]OTf. The latter are obtained from cis-[Ru(bipy)2Cl2] after the subsequent coordination of the 1,2-azole. All the compounds ar...

Cationic fac-[Re(CO)3(pz*H)(pypzH)]OTf (pz*H = pyrazole, pzH; 3,5-dimethylpyrazole, dmpzH; indazole, indzH; 3-(2-pyridyl)pyrazole, pypzH) were obtained from fac-[ReBr(CO)3(pypzH)] by halide abstraction with AgOTf and subsequent addition of the corresponding pyrazole. Successive deprotonation with Na2CO3 and NaOH gave neutral fac-[Re(CO)3(pz*H)(pypz...

The straightforward reaction of [Ir2(ppy)4(µ-Cl)2] with an excess of aliphatic amines yields luminescent iridium complexes of general formula [IrCl(ppy)2(amine)] [amine = n-octylamine (1), t-butylamine (2), piperidine (3)]. The higher sterical hindrance of the amine in complex 2 was the responsible of its equilibrium with the starting materials. Th...

Quantum chemical calculations can afford valuable information to understand the chemical processes and the structural features of chemical species. This tool has become very informative, and several aspects can be discussed on the thioamides under a theoretical point of view such as the effects of structure in their planarity and some cases with de...

An artificial arenite was developed from the waste of the sandstone industry. The waste sandstone was treated to obtain different grain sizes that were recombined to reproduce the natural texture. An unsaturated polyester resin was added to the mixture of grains and the cement polymerization was initiated with methyl ethyl ketone peroxide. The prod...

Considering the interest in processes related to hydrogen storage such as CO2 hydrogenation and formic acid (FA) decomposition, we have synthesized a set of Ir, Rh, or Ru complexes to be tested as versatile precatalysts in these reactions. In relation with the formation of H2 from FA, the possible applicability of these complexes in the transfer hy...

The synthesis of 3-(2pyridyl)pyrazole (pypzH) by conventional methods requires refluxing at high temperatures during more than 16 h, but this is reduced to two consecutive steps of 2 h at 100 °C, and of 10 min at 50 °C in a microwave (MW) assisted synthesis. Its coordination as chelating ligand to the “fac-ReIBr(CO)3” and “RuII(bipy)2” fragments al...

The preparation of new monodisperse polycrystalline palladium nanoparticles uniformly distributed on the surface of polymers, by simply adding a palladium(II) solution in water to the polymers, is described. The polymer...

We report the development of new fluorogenic silica nanomaterials that were able to generate fluorescence in the presence of vapours of triacetone triperoxide, TATP, an improvised explosive used in terrorist...

(1)H NMR spectroscopy at 400 MHz in toluene-d8 of evaporated mixtures of lithium ethoxide and titanium(iv) isopropoxide in ethanol, used to prepare the spinel Li4Ti5O12 by the sol-gel method, may help clarify why the atomic ratio 5Li : 5Ti and not 4Li : 5Ti is the right choice to obtain the pure phase when performing hydrolysis at room temperature....

Selected new fluorogenic probes that interact in different ways with Hg2+ and MeHg+ have been prepared and used for the chemical speciation of both cations in aqueous solution as well as in HEK293 cells. The best selective speciation of Hg2+ and MeHg+ has been achieved by in vitro approaches based on fluorogenic probes supported in cultured cells,...

The reaction of N-(2-phthalimidoethyl)-N-alkylisopropylamines and S2Cl2 gave 4-N-(2-phthalimidoethyl)-N-alkylamino-5-chloro-1,2-dithiol-3-thiones that quantitatively cycloadded to dimethyl or diethyl acetylenedicarboxylate to give stable thioacid chlorides, which in turn reacted with one equivalent of aniline or a thiole to give thioanilides or a d...

The unexpectedly aqueous stable bis-tellurium cationic complex [Co(dmgH)2{PhTe(CH2)3SO3Na}2]+(1+) (dmgH− = dimethylglyoximate) has been fully characterized in the solid state and in solution. The UV–Vis spectrum of 1+ differs from that of earlier cobaloximes, exhibiting a new low energy band centered at λmax = 425 nm (ε ∼ 26155 dm3 mol−1 cm−1) and...

Coordination of N,N‘ bidentate ligands aryl-pyridin-2-ylmethyl-amine ArNH-CH2-2-C5H4N 1 (Ar = 4-CH3-C6H4, 1a; 4-CH3O-C6H4, 1b; 2,6-(CH3)2-C6H3, 1c; 4-CF3-C6H4, 1d) to the moieties [Ru(bipy)2]2+, [Ru(η5-C5H5)L]+ (L = CH3CN, CO), or [Ru(η6-arene)Cl]2+ (arene = benzene, p-cymene) occurs under diastereoselective or diastereospecific conditions. Detaile...

Dentro del estudio de las interacciones débiles de complejos de metales de transición son reconocidas en la literatura del género dos aproximaciones: el estudio de las mismas en disolución y estado sólido. Con la Tesis Doctoral de Abigail Martínez[1] abordamos tal estudio desde los dos enfoques. En disolución, empleamos entonces la RMN de varios n...

The reactivity of complexes [PdCl2(κ2-NN′)] [NN′ = 2-C5H4N-CH=N-Ar; Ar = 2-MeC6H4, a; 4-MeC6H4, b; 2-MeOC6H4, c; 4-MeOC6H4, d; 4-CF3C6H4, e; 2,6-Me2C6H3, f; 2-iPrC6H4, g] and [Pd(κ2-acac)(κ2-NN′)][BF4] toward the nucleophilic reagent acetylacetonate (acac) has been explored. This reaction starts with nucleophilic attack on the cabonylic atom of the...

A fluorescent probe for ω-aminoacids behaves as a molecular ruler, changing the yellow fluorescent emission into blue as a function of the distance between the terminal ammonium and the carboxylate groups, permitting the quantitative detection of ω-aminoacids, their metabolites and related drugs, such as pregabalin or gabapentin, from pharmaceutica...

Square-planar complexes [PdCl{κ2-(RN = CHC6H4PPh2)R′}] (R′ = Cl; R = 4-CH3C6H4, 1a; R = 2-CH3OC6H4, 1b; R = 2-HOC6H4, 1c; R′ = CH3; R = 4-CH3C6H4, 2a; R = 2-CH3OC6H4, 2b; R = 2-HOC6H4, 2c) have been prepared and characterized. In complexes 2a–c only formation of one isomer was observed. The Pd–methyl bond arranges in a cis position to the phosphane...

An organopalladium chemical dosimeter of Hg(2+) that methylates Hg(2+), undergoing a colour change in 1 : 1 ethanol-water with submicromolar sensitivity, gives rise to an aqua-palladium complex that is methylated by MeHg(+) in the presence of a dithiol compound, undergoing another colour change, thus making the system suitable for the naked-eye det...

An organopalladium chemical dosimeter of Hg 2+ that methyl-ates Hg 2+ , undergoing a colour change in 1 : 1 ethanol–water with submicromolar sensitivity, gives rise to an aqua–palladium complex that is methylated by MeHg + in the presence of a dithiol compound, undergoing another colour change, thus mak-ing the system suitable for the naked-eye det...

The reaction of the complex [Pd(κ3-NN′O)CH3] [NN′O = 2-Py-CH=N-(o-C6H4)O–] (1a) with nitromethane affords a mixture of 2a and 2b. In this reaction methylation of the ligand takes place. These complexes display exchange equilibrium in solution. The methylation reaction is proposed to occur through nucleophilic attack of the nitronate anion on the im...

The complexes [MCl(2)(kappa2-N approximately N')] (N approximately N' = 2-C(5)H(4)N-CH2-NHAr; Ar = 4-MeC(6)H(4), a; 2,6-Me(2)C(6)H(3), b; 4-MeOC(6)H(4), c; 4-CF(3)C(6)H(4), d; M = Pd, 1a-d; Pt, 2a-d) have been prepared and fully stereochemically characterized both in the solid state and in solution. Their behavior in DMSO-d6 solution is dependent o...

Coordination of N,N' bidentate ligands aryl-pyridin-2-ylmethyl-amine ArNH-CH2-2-C5H4N 1 (Ar = 4-CH3-C6H4, 1a; 4-CH3O-C6H4, 1b; 2,6-(CH3)2-C6H3, 1c; 4-CF3-C6H4, 1d) to the moieties [Ru(bipy)2]2+, [Ru(eta5-C5H5)L]+ (L = CH3CN, CO), or [Ru(eta6-arene)Cl]2+ (arene = benzene, p-cymene) occurs under diastereoselective or diastereospecific conditions. Det...

http://hdl.handle.net/10259/58 ********************************** In the present work it is studied the synthesis, structural characterization and reactivity of mono- bi- and tetranuclear complexes of Palladium (II) and Platinum (II). We present the mononuclear complexes with the ortomethalated hydrazone, formulated: [Pd{C6H4-N(R)-N=C(CH3)-C5H4N}(κ...

The synthesis of N-[4-(2-hydroxyethyl)-1,2,4-oxathiazinan-3-ylidene]-benzamide (2a) and N-[4-(2-hydroxyethyl)-1,2,4-oxathiazinan-3-ylidene]-2-fluorobenzamide (2b) by oxidation of the corre-sponding 1,1-bis(2-hydroxyethyl)-3-aroylthioureas with potassium iodate in aqueous solution is re-ported. Variable temperature 1 H NMR spectra of 2a prove that t...

A phosphorous functionalized isoindole derivative has beenformed in the cyclization reaction of 3-chloro-p-tolylmethylene-1,1-diethylthiourea with lithium diphenylphosphide. The reaction involves thiourea desulfuration and C-S to P-S sulfur transfer.

A singular hydrazonato complex of palladium has induced the unexpected orthometallation of acetophenonephenylhydrazone on the phenyl group. This is the first X-ray characterized example of an orthopalladated E-arylhydrazone of general formula ArC(R″)NNHAr′ where the metallated aryl is Ar′ although palladation on Ar is not hindered. Structural evi...

Carbonylation in dichloromethane at room temperature of the dimeric ortho-palladated complex [Pd{C6H4C(CH3)NNHC6H5}(μ-Cl)]2 yields in a first step the monocarbonyl [Pd{C6H4C(CH3)NNHC6H5}Cl(CO)] which very slowly (days) undergoes in solution reductive elimination of palladium to give high yield of the isoindolinone derivative, 2-anilino-3-methyl...

The syntheses and structures of neutral complexes [PdCl(Py-2-CH=NAr)(Me)] (Ar = 4-MeC₆H₄, 4-MeOC₆H₄, 4-CF₃C₆H₄) and cationic complexes [Pd(Py-2-CH=NAr)(Me)(MeCN)]SbF₆ (Ar = 4-MeC₆H₄, 4-MeOC₆H₄, 4-CF₃C<sub>6<...

Palladium complexes of formula [PdLCl]X (X = Cl 1, BF42) containing the pincer terdentate ligands L [L = 2,6-(ArNHCH2)2C5H3N (Ar = 4-MeC6H41a and 2a, 4-MeOC6H41b and 2b); L = 2,6-(4-MeC6H4NMeCH2)2C5H3N 1c and 2c] have been synthesised as cis–trans diastereomeric mixtures. The chiral nature of both amine arms of the pincer ligands accounts for the m...

The synthesis and structure of a unique asymmetric folded binuclear anionic complex of palladium containing two different hydrazonato ligands and showing a Pd-N(amido) bond cis to a Pd-C(aryl) bond is described.

The synthesis, electrochemistry, and structural characterization of the mononuclear complex [Pd{C6H4N(H)NC(CH3)C5H4N}(p-tolN−NNp-tol)] (1) containing the monodentate 1,3-di-p-tolyltriazenido ligand is described. Compound 1 is an example of a stable species containing a Pd−N amido bond cis to a Pd−C aryl bond. Kinetic parameters for the dynamic intr...

Palladium(II) amino complexes of formula [PdX2(NC5H4CH2NHAr)] (X = Cl, Ar = 2,6 dimethylphenyl; X = C6F5, Ar = 4-methylphenyl) undergo dehydrogenation reactions with NaOMe under stoichiometric or catalytic conditions to give imino complexes [PdX2(NC5H4CH NAr)] ; the catalytic pathway supports the accepted β-hydrido elimination mechanism in N-...

The acid dissociation constants of some orthopalladated complexes have been determined in 10% v/v DMSO/water mixed solvent. The positive charge is located on the Pd(II) atom; in basic medium the H atom on the ligand is partially released, which convert these complexes into zwitterions. The ionization constants of the two overlapping equilibria of t...

Chirality is conserved in the deprotonation of the complex PdCl2(La) (La = 2-[(N-p-tolylamino)methyl]pyridine; 1a) leading to the folded diastereomer of [PdCl(μ-La-H)]2 (2a), where the p-tolyl groups are syn exo and the same enantiomer of 1a shapes both halves of the amido-bridged dimer. The dimerization of different enantiomers of 1a (R with S), w...

The reversible metallation-demetallation reaction of dinuclear rhodium(II) complexes of type [Rh2(μ-O2CR)3(O2CR) 0/1{P(o-ClC6H3/4)(C6H 4/5)Ph}] (R = CH3, CF3) has been studied in the presence of HO2CR in chloroform and toluene solutions. In all cases the substitution of the bridging acetato (or trifluoroacetato) groups is much faster than the corre...

The tetranuclear complexes [{Pd2(µ-RNNNR)2}2(µ-X)4](R = C6H4Me-p, X = Cl or I), in which two triazenido-bridged dipalladium units are linked by halide bridges to give an S4N4-like Pd4Cl4 core, are novel precursors to redox-active triazenido-bridged derivatives.

The absorption spectra, emission spectra, emission lifetimes and photochemical and electrochemical behaviour of six monomeric cyclometallated complexes [Pd(CNN)X]0,+ (where CNN is the C-deprotonated form of 2-acetylpyridine-phenylhydrazone and X is I−, Cl−, 4-Mepy, PPh3, P(OPh)3, P(OMe)3) and two dimeric cyclometallated complexes [(CNN)Pd(XX)Pd(NNC...

The iodide-abstraction reaction of [{Rh2(µ-I)(CO)(bipy)(µ-RNNNR)2}2][PF6]21(bipy = 2,2′-bipyridyl, R =p-tolyl) with AgPF6 in MeCN gave [Rh2(CO)(NCMe)2(bipy)(µ-RNNNR)2][PF6]22 which slowly decarbonylated at room temperature to [Rh2(NCMe)3(bipy)(µ-RNNNR)2][PF6]23. The crystal structure of 3 shows a Rh–Rh single bond [2.534(2)Å] and one of the three t...

Cyclopalladated complexes of 2-acetylpyridine phenylhydrazone [Pd(C6H4N(H)N=C(CH3)-C5H4N)Cl] (2) and [Pd(C6H4N(H)N=C(CH3)C5H4N)L]BF4 (L = PPh3 (3a), P(OMe)3 (3b), P(OPh)3 (3c), CH3C5H4N (3d), C4H8S (3e)) containing readily deprotonable N-H bonds have been prepared. Blue zwitterionic species, obtained after deprotonation of the cationic complexes, a...

The X-my crystal structure analyses of the three redoX pairs [Rh2(CO)2LL'{mu-PhNC(Me)NPh}2]z [z = 0, 1; L = L' = PPh3 (1, 1+); L - L' = P(OPh)3 (2, 2+); L = PPh3, L' - P(OPh)3 (3, 3+)] are reported and the molecular structures compared with those Of [Rh2(CO)2(PPh3)2(mu-RNNNR)2]z [z - 0, 1; R = p-tolyl (4,4+)]. These have locally planar rhodium coor...

Chemical or electrochemical oxidation of the orthometallated amido dimeric complex [Pd-o-C6H4-C(Me)=N-NPh)L]2 (L= P(OMe)3,1) leads to double carbon-carbon coupling on the para carbons of the phenyl groups giving tetrapalladia units [Pd4]n+ (n = 0,1,2,3,4) related by fully reversible monoelectronic electron transfers. The species [Pd4]4+ undergoes s...

Chemical or electrochemical oxidation of the chiral orthometalated amido dimeric complex [Pd-o-C6H4-C(Me)=N-NPh)L]2 (L = P(OMe)3) leads to double carbon-carbon coupling on the para carbons of the phenyl groups, giving pure diastereomeric tetrapalladia units [Pd4]n+ (n = 0-4) related by fully reversible monoelectronic electron transfers. The species...

Treatment of [{Rh2l(CO)(bipy)(µ-RNNNR)2}2][PF6]22 with AgPF6 and dppm gives [Rh2(µ-CO)(bipy)(L–L)(µ-RNNNR)2]2+(5; L–L = dppm), X-ray and MO studies on which show that it may be viewed as an open-book [Rh2]6+ core bridged by a ‘ketonic’ CO2– ligand; this isomer is in equilibrium in solution with a face-to-face isomer in which the carbonyl ligand is...

A study of the products of oxidative dimerization of complexes such as (I) using cyclic voltammetry and rotating-electrode techniques demonstrates that the first compound isolated is (II) rather than a product with an additional unlocalized hydrogen atom.

The incorporation of bipy into the redox active unit (I) has given (III), the precursor to a wide range of isolable, asym.

A study of the products of oxidative dimerization of arylamido complexes of platinum using cyclic voltammetry and rotating-electrode techniques has demonstrated that the first compound isolated from the oxidation of trans-[Pt(NHPh)Cl(PEt3)2] is [{PtCl(PEt3)2}2(µ-N2C12H10)][PF6]2, rather than [{PtCl(PEt3)2}2(µ-N2C12H11)][PF6]2. Consequently, its tra...

The lone pair on the amine nitrogen of the complexes [PdCl(o-C6H4-C(R)=N-NHPh)L] shows little tendency to coordinate, and removal of Cl- with T1[ClO4] does not afford dimers but monomers with coordinated FBF3- or OClO3- in place of Cl-. Removal of HCl with NaOMe renders the deprotonated nitrogen very coordinating, and deeply colored C,N-chelate, N,...

The reaction of [{Rh(CO)2(µ-RNNNR)}2](1; R =p-tolyl) with 2,2′-bipyridyl (bipy) in boiling n-heptane gives [Rh2(CO)2(bipy)(µ-RNNNR)2](2) which undergoes two one-electron oxidations at a platinum-bead electrode in CH2Cl2. Chemical oxidation of (2) with [Fe(η-C5H5)2]+ gives [Rh2(CO)2(bipy)(µ-RNNNR)2]+(2+) the X-ray structure of which, as a dichlorome...

The complexes MoX2(CO)3(bipy) (X=Cl, Br, I) undergo substitution of a single CO ligand by Ph2PCH2PPh2 (dppm) and Ph2PCH2CH2PPh2 (dppe) to give seven-coordinate complexes MoX2(CO)2(bipy)(LL) (X=Cl, Br, I; LL=dppm, dppe). Spontaneous isomerization to [MoX(CO)2(bipy)(dppm)]X was observed for X=I in dichloromethane at room temperature. However MoCl2(...

The complex [{Ir(µ-Cl)(η4-cod)}2](cod = cyclo-octa-1,5-diene) reacts with the triazene RNNNHR (R =p-tolyl) to give [IrCl(RNNNHR)(η4-cod)](1) which yields [IrCl(CO)2(RNNNHR)](2) on treatment with CO gas. Deprotonation of (2) with NEt3 in CH2Cl2 at –10 °C gives the dimer [{Ir(CO)2(µ-RNNNR)}2](3), which undergoes thermal substitution with PPh3 to yiel...

Cyclic voltammetry shows that [Rh2(CO)4(µ-L′)2][1, L′= RNNNR, R =p-tolyl; 2, L′= R′NC(Me)NR′, R′= Ph], [Rh2(CO)2L2(µ-RNNNR)2](3, L = PPh3 or CNBut), [Rh2(CO)2(PPh3)L{µ-R′NC(Me)NR′}2](4,L = CO), [Rh2(η4-diene)2(µ-RNNNR)2][5, diene = nbd (norborna-2,5-diene) or cod (cyclo-octa-1,5-diene)], and [Rh2(CO)3(CNBut)(µ-RNNNR)2](6) undergo at least two diffu...

The diphosphine Ph2PCH2PPh2(dppm) reacts with [MoBr2(CO)3(bipy)](bipy = 2,2′-bipyridine) or [MoBr2(CO)3(phen)](phen = 1,10-phenanthroline) to give the seven-co-ordinate complexes [MoBr2(CO)2(bipy)(dppm)](1a) and [MoBr2(CO)2(phen)(dppm)](1b) respectively. Sunlight irradiation of (1a) in dichloromethane solution leads to the mixed bidentate monocarbo...

The [Rh2]2+ complex [Rh2(CO)2(bipy)(µ-RNNNR)2](2, bipy = 2,2′-bipyridyl, R =p-tolyl) is the precursor to asymmetric, redox-active [Rh2]3+ and [Rh2]4+ derivatives such as [Rh2(CO)L(bipy)(µ-RNNNR)2]z(3+, L = PPh3, z= 1; 4, L = I, z= 0) and [Rh2(CO)(S2CNMe2)(piby)(µ-RNNNR)2][PF6](5) respectively.

A series of seven-coordinate molybdenum(II) complexes containing carbonyl, triphenylphosphine, bromide and/or O-donor and S-donor anionic bidentate ligands have been prepared in high yield. The synthesis involves the reaction of the six-coordinate complex Mo(CO)2(PPh3)2Br2 with the sodium salt of the appropriate ligand, in dichloromethane/methanol...