Roberto Sánchez-Delgado

City University of New York - Brooklyn College | CUNY · Department of Chemistry

A new hybrid compound 5 containing a ruthenocene, a 4-aminoquinoline, and a 1,2,4-trioxane within a single molecular structure has been synthesized and evaluated for antimalarial potential. In order to ascertain the role of each component of hybrid 5, its antimalarial activity has been measured against chloroquine-resistant and chloroquine-sensitiv...

In previous studies we reported a novel series of organometallic compounds, RuII complexed with clotrimazole, displaying potent trypanosomatid activity with unnoticeable toxicity toward normal mammalian cells. In view of the promising activity of Ru-clotrimazole complexes against Leishmania major (L. major), the present work sought to investigate t...

The efficacy of chloroquine, once the drug of choice in the fight against Plasmodium falciparum, is now severely limited due to widespread resistance. Amodiaquine is one of the most potent antimalarial 4-aminoquinolines known and remains effective against chloroquine-resistant parasites, but toxicity issues linked to a quinone-imine metabolite limi...

Abstract Image A series of organometallic ruthenium(II) complexes containing iminophosphorane ligands have been synthesized and characterized. Cationic compounds with chloride as counterion are soluble in water (70–100 mg/mL). Most compounds (especially highly water-soluble 2) are more cytotoxic to a number of human cancer cell lines than cisplatin...

A new catalyst composed of Rh nanoparticles supported on magnesium oxide was prepared by mild hydrogenation of a pre-adsorbed organometallic precursor, and characterized by TEM, XRD, XPS, and hydrogen chemisorption measurements. The catalyst contains 5 wt% Rh as similar to 50 nm metallic nanoparticles uniformly distributed on the surface of MgO, in...

The development of catalysts capable of promoting hydrogenation of aromatics while being resistant to poisoning by nitrogen- and sulfur-containing species is of much interest in connection with hydrotreating of fossil fuels. We report a catalyst composed of ruthenium nanoparticles supported on magnesia, designed to promote heterolytic hydrogen spli...

Ruthenium-based compounds have intriguing anti-cancer properties, and some of these novel compounds are currently in clinical trials. To continue the development of new metal-based drug combinations, we coupled ruthenium (Ru) with the azole compounds ketoconazole (KTZ) and clotrimazole (CTZ), which are well-known antifungal agents that also display...

In our ongoing search for new metal-based chemotherapeutic agents against leishmaniasis and Chagas disease, six new ruthenium-ketoconazole (KTZ) complexes have been synthesized and characterized, including two octahedral coordination complexes-cis,fac-[Ru(II)Cl2(DMSO)3(KTZ)] (1) and cis-[Ru(II)Cl2(bipy)(DMSO)(KTZ)] (2) (where DMSO is dimethyl sulfo...

The pharmacological properties of any drug are related to their ability to interact with macromolecular blood components. The interaction of human serum albumin (HSA) and apotransferrin (ATf) with six Ru(II) complexes containing ketoconazole (KTZ), which we have previously reported to be active against Leishmania major and Trypanosoma cruzi, has be...

A new catalyst composed of Pd nanoparticles supported on MgO has been prepared by the room temperature NaBH(4) reduction of Na(2)PdCl(4) in methanol in the presence of the support. TEM measurements reveal well-dispersed Pd particles of mean diameter 1.7 nm attached to the MgO surface. Further characterization was achieved by ICP-AES, XPS, XRD, H(2)...

Eight new ruthenium complexes of clotrimazole (CTZ) with high antiparasitic activity have been synthesized, cis,fac-[Ru(II)Cl(2)(DMSO)(3)(CTZ)] (1), cis,cis,trans-[Ru(II)Cl(2)(DMSO)(2)(CTZ)(2)] (2), Na[Ru(III)Cl(4)(DMSO)(CTZ)] (3), Na[trans-Ru(III)Cl(4)(CTZ)(2)] (4), [Ru(II)(η(6)-p-cymene)Cl(2)(CTZ)] (5), [Ru(II)(η(6)-p-cymene)(bipy)(CTZ)][BF(4)](2...

Three new ruthenium complexes with bidentate chloroquine analogue ligands, [Ru(η(6)-cym)(L(1))Cl]Cl (1, cym = p-cymene, L(1) = N-(2-((pyridin-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine), [Ru(η(6)-cym)(L(2))Cl]Cl (2, L(2) = N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) and [Ru(η(6)-cym)(L(3))Cl] (3, L(3) = N-(2-...

In the search for new therapeutic tools against neglected diseases produced by trypanosomatid parasites, and particularly against African Trypanosomiasis, whose etiological agent is Trypanosoma brucei, organoruthenium compounds with bioactive nitrofuran containing thiosemicarbazones (L) as co-ligands were obtained. Four ruthenium(II) complexes with...

Three platinum-chloroquine complexes, trans-Pt(CQDP)(2)(I)(2) [1], trans-Pt(CQDP)(2)(Cl)(2) [2] and trans-Pt(CQ)(2)(Cl)(2) [3], were prepared and their most probable structure was established through a combination of spectroscopic analysis and density functional theory (DFT) calculations. Their interaction with DNA was studied and their activity ag...

A nanostructured catalyst composed of Ru nanoparticles immobilized on poly(4-vinylpyridine) (PVPy) has been synthesized by NaBH(4) reduction of RuCl(3)·3H(2)O in the presence of the polymer in methanol at room temperature. TEM measurements show well-dispersed Ru nanoparticles with an average diameter of 3.1 nm. Both powder XRD patterns and XPS data...

The mechanism of antimalarial action of [Au(CQ)(PPh(3))]PF(6) (1), which is active in vitro against CQ-resistant P. falciparum and in vivo against P. berghei, has been investigated in relation to hemozoin formation and DNA as possible important targets. Complex 1 interacts with heme and inhibits β-hematin formation both in aqueous medium and near w...

The interactions of π-arene-Ru(II)-chloroquine complexes with human serum albumin (HSA), apotransferrin and holotransferrin have been studied by circular dichroism (CD) and UV-Visible spectroscopies, together with isothermal titration calorimetry (ITC). The data for [Ru(η(6)-p-cymene)(CQ)(H(2)O)Cl]PF(6) (1), [Ru(η(6)-benzene)(CQ)(H(2)O)Cl]PF(6) (2)...

The complexes [Ru(eta(6)-p-cymene)(CQ)Cl(2)] (1), [Ru(eta(6)-benzene)(CQ)Cl(2)] (2), [Ru(eta(6)-p-cymene)(CQ)(H(2)O)(2)][BF(4)](2) (3), [Ru(eta(6)-p-cymene)(en)(CQ)][PF(6)](2) (4), [Ru(eta(6)-p-cymene)(eta(6)-CQDP)][BF(4)](2) (5) (CQ = chloroquine base; CQDP = chloroquine diphosphate; en = ethylenediamine) interact with DNA to a comparable extent t...

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The complexes [Rh(PhBP3)(cod)] (1) and [{Ru(PhBP3)(μ-Cl)}2] (8), containing the tripodal phosphanoborate ligand [PhB(CH2PPh2)3]−, are efficient catalysts for the selective hydrogenation of cinnamaldehyde to the corresponding allyl alcohol. Complex 8 is one of the most efficient catalysts reported to date for this reaction, in terms of activity (TOF...

We have measured water/n-octanol partition coefficients, pK a values, heme binding constants, and heme aggregation inhibition activity of a series of ruthenium–π-arene–chloroquine (CQ) complexes recently reported to be active against CQ-resistant strains of Plasmodium falciparum. Measurements of heme aggregation inhibition activity of the metal com...

A new family of rhodium and iridium compounds with the bulky tris(ortho-methoxyphenyl) phosphine (PAn3) was synthesized and characterized by NMR methods. The X-ray crystal structures of RhCl(PAn3)(COD) (1) and Ir[(PBz3)(PAn3)(COD)]PF6 (4) have been determined. A stabilizing agostic interaction has been crystallographically observed in both compound...

The new Ru(II) chloroquine complexes [Ru(eta(6)-arene)(CQ)Cl2] (CQ = chloroquine; arene = p-cymene 1, benzene 2), [Ru(eta(6)-p-cymene)(CQ)(H2O)2][BF4]2 (3), [Ru(eta(6)-p-cymene)(CQ)(en)][PF6]2 (en = ethylenediamine) (4), and [Ru(eta(6)-p-cymene)(eta(6)-CQDP)][BF4]2 (5, CQDP = chloroquine diphosphate) have been synthesized and characterized by use o...

The mechanism of antimalarial action of the ruthenium-chloroquine complex [RuCl(2)(CQ)](2) (1), previously shown by us to be active in vitro against CQ-resistant strains of Plasmodium falciparum and in vivo against P. berghei, has been investigated. The complex is rapidly hydrolyzed in aqueous solution to [RuCl(OH(2))(3)(CQ)](2)[Cl](2), which is pr...

IntroductionHydrogenation of C=C BondsHydrogenation of CC BondsHydrogenation of Other SubstratesConcluding Remarks

A series of catalysts composed of ruthenium nanoparticles immobilized on poly(4-vinylpyridine) was prepared by NaBH(4) reduction of RuCl(3).3H(2)O in methanol in the presence of the polymer; TEM measurements of a 10 wt % Ru/P4VPy material indicate that ruthenium particles of 1-2 nm predominate. This catalyst is efficient for the selective hydrogena...

A kinetic study of the homogeneous hydroformylation of 1-hexene to the corresponding aldehydes (heptanal and 2-methyl-hexanal) was carried out using a rhodium catalyst formed by addition of 1 equiv. of 1,2-bis(diphenylphosphino)ethane (dppe) to Rh(acac)(CO)2 under mild reaction conditions (80 °C, 1–7 atm H2 and 1–7 atm CO) in toluene; in all cases...

Cationic rhodium and iridium complexes of the type [M(COD)(PPh3)2]PF6 (M = Rh, 1a; Ir, 1b) are efficient precatalysts for the hydroformylation of 1-hexene to its corresponding aldehydes (heptanal and 2-methylhexanal), under mild pressures (2–5 bar) and temperatures (60 °C for Rh and 100 °C for Ir) in toluene solution; the linear to branched ratio (...

The new water soluble complex [HRu(CO)(CH 3 CN)(TPPTS) 3 ]BF 4 (TPPTS = tris[(m-sulfonated)phenyl]phosphine P(m-C 6 H 4 SO 3 Na) 3) has been synthesized by ligand exchange techniques from the corresponding PPh 3 derivative in a methoxyethanol–water mixture. The new complex was char-acterized by FTIR, UV–vis, and 1 H NMR and 31 P { 1 H} NMR spectros...

New rhodium and iridium complexes, with the formula [MCl(PBz3)(cod)] [M=Rh (1), Ir (2)] and [M(PBz3)2(cod)]PF6 [M=Rh (3), Ir (4)] (cod=1,5-cyclooctadiene), stabilized by the tribenzylphosphine ligand (PBz3) were synthesized and characterized by elemental analysis and spectroscopic methods. The molecular structures of 1 and 2 were determined by sing...

The iridium complexes [Ir(PBz3)2(COD)]PF6 and [Ir(py)(PBz3)(COD)]PF6 are effective catalyst precursors for the homogeneous hydrogenation of N-(β-naphthylmethylene)aniline (NβNA) to naphthalene-2-ylmethylphenylamine (PBz3 = tribenzylphosphine; COD = 1,5-cyclooctadiene; py = pyridine). For comparative purposes, other iridium and rhodium catalysts mod...

In the present work, are shown the operational conditions necessary for get an increase in the normal/iso ratio for aldehiydes which are the products for the hydroformylation reactions of 1 – hexene using RhH(CO)(TPPTS)3 complex.

The new water-soluble rhodium complex [Rh(μ-Pz)(CO)(TPPTS)]2 (I) with TPPTS tris-meta-sulfonatophenylphosphine and Pz=pyrazolate ligand, has been synthesized by the reaction of the rhodium precursor [Rh(acac)(CO)2] with TPPTS and pyrazol in aqueous solution under inert atmosphere and characterized by FT-IR, UV–vis, 1H NMR, 31P{1H} NMR. This complex...

ortho-Hydroxybenzaldehyde semicarbazone (salicylaldehyde semicarbazone) undergoes chemo-selective hydrolysis of the iminic carbon nitrogen double bond through its reaction with [RuCl2(dmso)4] in ethanol in the presence of water, yielding free salicylaldehyde and semicarbazide that remains coordinated to the ruthenium ion as a bidentate N,O-donor to...

The hydroformylation of medium-chain C6 olefins and of allyl alcohol was achieved with paraformaldehyde in dioxane solution using rhodium catalysts with mono-, bi-, and tri-dentate phosphine ligands. The highest activities with n/i ratios around 2, were obtained for a system derived from [Rh(dppe)2]+, prepared in situ by reaction of Rh(acac)(CO)2 w...

Ketoconazole (KTZ) has been used as a second-line agent in hormone-refractory cancer therapy. Since transition metal complexes including those of Ru(III), show important anticancer activity with limited toxicity, we investigated the potential antitumor efficacy of Ru(II) complexed to KTZ or clotrimazole (CTZ) compared to Ru(II) alone or uncomplexed...

The complexes RhH(CO)L3, where L=PPh3, P(m-C6H4SO3Na)3 (TPPTS), and (C6H5)2P(m-C6H4SO3Na) (TPPMS) were used as catalyst precursors for a comparative study of the catalytic hydroformylation of several C6 alkenes and alkene mixtures under moderate reaction conditions in homogeneous (PPh3) and aqueous-biphasic (TPPTS, TPPMS) media. The biphasic system...

A number of new Au(I) and Au(III) complexes of chloroquine (CQ) have been prepared, characterized, and evaluated in vitro against several strains of Plasmodium falciparum. [(CQ)Au(PPh(3))][NO(3)] (2) was synthesized by reaction of AuCl(PPh(3)) with AgNO(3) followed by treatment with CQ. Similar reactions of AuCl(PR(3)) (R = Me, Et) with KPF(6) and...

The complexes [Ir(H)2(eta1-N-L)2(PPh3)2]PF6, L = py (1), iQ (2) and pip (3) (py = pyridine, iQ = isoquinoline, pip = piperidine) have been synthesized in high yields by hydrogenation of [Ir(cod)(PPh3)2]PF6 in the presence of the appropriate nitrogen compound. When hydrogen is bubbled through 1,2-dichloroethane solutions of 1 or 2, two new species w...

The water-soluble complex Ru(H)2(CO)(TPPMS)3 where TPPMS: (C6H5)2P(m-C6H4SO3Na) was obtained by phosphine ligand exchange from the corresponding PPh3 derivative in a water–toluene mixture and characterized by FTIR, UV-Vis, and 1H NMR and 31P{1H} spectroscopy. The complex was used as a catalyst precursor for the aqueous-biphasic catalytic hydroformy...

Complexes of the type [Ru(II)Cl(2)(DMSO)(2)L], where L are 5-nitrofurylsemicarbazone derivatives, were prepared in an effort to combine the potential anti-tumor activity of the metal and the free ligands. The new complexes are excellent DNA binding agents for calf thymus DNA. So, their in vitro anti-tumor activity was tested in cellular models and...

Parasitic diseases represent a major world health problem with very limited therapeutic options, most of the available treatments being decades old and suffering from limited efficacy and/or undesirable collateral effects. The use of metal complexes as chemotherapeutic agents against these ailments appears as a very attractive alternative. Although...

Parasitic diseases represent a major world health problem with very limited therapeutic options, most of the available treatments being decades old and suffering from limited efficacy and/or undesirable collateral effects. The use of metal complexes as chemotherapeutic agents against these ailments appears as a very attractive alternative. Although...

The synthesis and characterization of the first two Re complexes with semicarbazone ligands is presented. Selected ligands are 5-Nitro-2-furaldehyde sernicarbazone (Nitrofurazone) (L1) and its derivative 3-(5-Nitrofuryl)acroleine semicarbazone (L2). Complexes of general formula [(ReOCl2)-O-V(PPh3)L], where L = L1 and L2, were prepared in good yield...

Nucleophilic attack of the beta-carbon of an Ir(III)-alkenyl functionality onto the alpha-carbon of a coordinated nitrile- or aldehyde occurs intramoleculary to yield initially iridacyclic structures. Nitriles give rise to isolable complexes that contain delocalized five-membered rings (iridapyrroles, e.g. 3'-8') in a reaction catalyzed by H2O (for...

N,N, N',N'-Tetraethylethylenediamine undergoes simple or double intramolecular dealkylation reactions in the presence of the complexes [RuCl2(diene)]n (diene = cod, nbd) or trans-[RuCl2(diene)(morfoline)2 at 80 degrees C to afford chelating amine ligands which contains one or two N-H functionalities.

In spite of the large-scale industrial applications of the hydrodesulfurization (HDS) process, and of the large number of studies of this reaction on heterogeneous catalysts, some aspects of the mechanisms involved are not yet fully understood. This article summarizes the most striking aspects of coordination and organometallic chemistry that are p...

The complexes [Cu(CTZ)(4)]Cl(2).2H(2)O (1), [Cu(CTZ)Cl(2)](2) (2), [Cu(KTZ)(3)Cl(2)] (3), and [Cu(KTZ)Cl(2)](2).2H(2)O (4) were prepared by reaction of CuCl(2) with CTZ and KTZ (where CTZ = 1-[[(2-chlorophenyl)diphenyl]methyl]-1H-imidazole and KTZ = cis-1-acetyl-4-[4-[[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phen...

The complexes RuCl3(CTZ)3·2CH3OH (1) and RuCl3(KTZ)2(H2O)·2H2O (2) were prepared by reaction of RuCl3·3H2O with CTZ and KTZ, respectively, while RuCl2(KTZ)2 (4) was prepared by reaction of RuCl2(CH3CN)4 with KTZ (CTZ=1-[(2-chlorophenyl)diphenylmethyl-1H-imidazole, and KTZ=cis-1-acetyl-4-[4-[[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dio...

The complexes RuCl3(CTZ)3·2CH3OH (1) and RuCl3(KTZ)2(H2O)·2H2O (2) were prepared by reaction of RuCl3·3H2O with CTZ and KTZ, respectively, while RuCl2(KTZ)2 (4) was prepared by reaction of RuCl2(CH3CN)4 with KTZ (CTZ=1-[(2-chlorophenyl)diphenylmethyl-1H-imidazole, and KTZ=cis-1-acetyl-4-[4-[[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dio...

The role of transition metal complexes as catalysts for homogeneous hydrogenation reactions has been extensively investigated during the last few decades. This paper reviews recently disclosed work by a number of research laboratories including ours, which shows that the study of the kinetics of such processes is a particularly important tool which...

A catalyst system for selective hydrogenation of sulfur-containing and nitrogen-containing compounds of a heteroaromatic organic phase includes a mixture of a noble metal selected from Group VIII of the Periodic Table of Elements and a water-soluble ligand. A process for preparing the catalyst system and hydrogenation process using the catalyst sys...

A catalyst system for selective hydrogenation of sulfur-containing and nitrogen-containing compounds of a heteroaromatic organic phase includes a mixture of a noble metal selected from Group VIII of the Periodic Table of Elements and a water-soluble ligand. A process for preparing the catalyst system and hydrogenation process using the catalyst sys...

The ruthenium(II) tris-acetonitrile complex [(triphos)Ru(MeCN)3]BPh4 (1) is an extremely efficient catalyst precursor for the regioselective hydrogenation of benzo[b]thiophene (BT) to 2,3-dihydrobenzo[b]thiophene (DHBT) in homogeneous phase under mild reaction conditions (THF, 40−100 °C, 1−30 bar H2) [triphos = MeC(CH2PPh2)3]. At 30 bar of H2 and 1...

A catalyst system for selective hydrogenation of sulfur-containing and nitrogen-containing compounds of a heteroaromatic organic phase includes a mixture of a noble metal selected from Group VIII of the Periodic Table of Elements and a water-soluble ligand. A process for preparing the catalyst system and hydrogenation process using the catalyst sys...

The syntheses and characterization of metal imidazole complexes showing activity against Trypanosoma cruzi, the causative agent of Chagas disease, are presented, RuCl2(CTZ)2 (2) and RuCl2(BTZ)2 (4) were prepared by reaction of RuCl2(NCCH3)4 (1) with the appropriate ligand (CTZ, clotrimazole = 1-[(2-chlorophenyl)diphenylmethyl]-1H-imidazole; BTZ = 1...

Two-phase hydrogenation of heteroaromatic compounds such as quinoline (Q) and benzothiophene (BT) were performed using as catalytic precursor a mixture of ruthenium trichloride and an excess of the water-soluble ligand m-sulfonatophenildiphenylphosphine, in its sodium salt form (TPPMS). The products obtained from the hydrogenation were 1,2,3,4-tetr...

In the presence of strong bases, the CS insertion complexes (triphos)Rh[η3-S(C6H4)CHCH2] and (triphos)Rh(η3-SCHCHCHCH2) as well as the π-alkyne complex [(triphos)Rh(η2-MeO2CCCCO2Me)]PF6 are catalyst precursors for the hydrogenation of thiophene (T), benzo[b]thiophene (BT) and dibenzo[b,d]thiophene (DBT) in tetrahydrofuran solution [triphos = M...

Reaction of AuPPh3Cl with chloroquine (CQ) and KPF6 leads to the new complex [Au(PPh3)(CQ)]PF6 (1) which was found to be considerably more active than CQ diphosphate and other previously reported metal-CQ complexes against two chloroquine-resistant strains of Plasmodium falciparum in vitro and also active against Plasmodium berghei in vitro and in...

The complexes [M(COD)(PPh3)2]PF6 (M = Rh, 1a; Ir, 1b) are highly efficient precatalysts for the homogeneous hydrogenation of benzo[b]thiophene (BT) to 2,3-dihydrobenzo[b]thiophene (DHBT). Both complexes react rapidly with BT and H2 to produce the corresponding [M(H)2(η1(S)-BT)2(PPh3)2]PF6 (M = Rh, 2a; Ir, 2b), which enter the catalytic cycle. In th...

NMR data for two Ru-TPPMS complexes previously described as unsaturated monomeric species have led to their reformulation as the chloro-bridged dimers [RuCl(TPPMS)2(μ-Cl)]2(1) and [RuH(TPPMS)2(μ-Cl)]2(2); three new water-soluble complexes OsH4(TPPMS)3(3), OsHCl(CO)(TPPMS)2(4), and [OsCl(TPPMS)2(μ-Cl)]2(5) have been synthesized and characterized. Co...

The carbonylation and cyclization of N-alkylallylamines to γ-butyrolactams is efficiently achieved by use of or RhCl(CO)(PPh3)2 as catalyst precursors under mild conditions (70°C, 10 bar) when (4:1) mixtures are used instead of pure CO. Mechanistic studies on the Rh and the analogous Ir system allowed the deduction of a major catalytic cycle in whi...

Chloroquine free base (CQ) reacts with [Rh(COD)Cl]2 (COD = 1,5-cyclooctadiene) and RuCl3.-3H2O/Zn to yield Rh(COD)(CQ)Cl (1) and [RuCl2(CQ)]2 (2), respectively. The two novel metal- CQ complexes, which were characterized mainly by 1D and 2D NMR spectroscopy, were tested against Plasmodium berghei. The in vitro activity of 1 was comparable to that o...

The complexes Ru(PPh3)2Cl2(L)2 (L = 4-But-py, 4-vinyl-py, 4-CN-py, 4-Me-py, 3-Me-py, L2 = 4,4′-bipy) have been prepared by reaction of RuCl2(PPh3)3 with the appropriate ligand under mild conditions and characterized by elemental analysis, IR, NMR (1H and 31P) and UV-vis spectra; the RuII derivatives display a RuP2Cl2N2 core with a trans, cis, cis a...

The reactivity of the Ir(III) complex (triphos)IrH(eta(2)(C,S)-DBT) (1), obtained by insertion of the [(triphos)IrH] fragment into a C-S bond of DBT, has been studied in THF [triphos = MeC(CH(2)PPh(2))(3); DBT = dibenzo[b,d]thiophene]. Compound 1 reacts with CO (5 atm, greater than or equal to 50 degrees C) to give the 2-phenylthiophenolate complex...

The thermally generated 16-electron fragments [(triphos)MH] (M = Rh, Ir) react with benzo[b]thiophene by C-S bond scission to yield the 2-vinylthiophenolate derivatives (triphos)M[eta(3)-S(C6H4)CH=CH2] (M = Rh, 1; Ir, 2) which display a rich redox-induced reactivity [triphos = MeC(CH(2)PPh(2))(3)]. Removal of one electron from 1 or 2 leads to the c...

The thermally generated 16-electron fragment [(triphos)RhH] reacts with benzo[b]thiophene (BT) by C-S bond scission to ultimately yield the 2-vinylthiophenolate complex (triphos)Rh[eta(3)-S(C6H4)CH=CH2] (1), which is an efficient catalyst precursor for the hydrogenation of BT into 2-ethylthiophenol (ETSH) and, to a lesser extent, into 2,3-dihydrobe...

A kinetic study of the regioselective homogeneous hydrogenation of quinoline (Q) to 1,2,3,4-tetrahydroquinoline (THQ) was carried out using the cationic complex [RuH(CO)(NCMe)2(PPh3)2]BF4 (1) as the precatalyst. The experimentally determined rate law wasr = {k2K1/(1+K1[H2])}[Ru0][H2]2, which becomesr = {k2K1[Ru0]-[H2]2 at low hydrogen concentration...

The kinetic selectivity for C-H vs C-S activation of dibenzothiophene (DBT) by the [(triphos)IrH] fragment has been observed upon either thermolysis of(triphos)Ir(H)(2)(C2H5) in THF in the temperature range from 70 to 160 degrees C or dehydrohalogenation of (triphos)Ir(H)(2)Cl with t-BuLi at room temperature [triphos = MeC(CH(2)PPh(2))(3)]. C-H bon...

The fragment [(triphos)Rh], generated by thermolysis of (triphos)RhH3 (1) in refluxing THF, reacts with thiophene (T) or benzo[b]thiophene (BT) to yield (triphos)Rh(eta(3)-SCH=CH-CH=CH2) (2) and (triphos)Rh{eta(3)-S(C6H4)CH=CH2} (3), respectively [triphos = MeC(CH(2)PPh(2))(3)]. Compound 2 is selectively protonated at the terminal metal-bonded carb...

Homogeneous catalysis by osmium complexes is more promising than hitherto realized. Most of the reactions studied have concentrated on simple model substrates, and therefore a demonstration of the utility of these catalysts for reactions of more sophisticated organic molecules is needed; highly selective reduction of terminal and internal carbon-ca...

Density functional calculations have been carried out to study the pyramidal coordination of the sulfur in the thiophene complex [Cp(CO)(2)Fe(eta(1)-T)](+) (Cp = cyclopentadienyl; T = thiophene). Total energy calculations showed the optimal value of the angle between the Fe-S bond and the thiophene plane to be 120 degrees. An analysis of the change...

In spite of the large scale industrial applications of the hydrodesulfurization (HDS) process, and of the considerable number of studies of this reaction on heterogeneous catalysts, the mechanisms involved are not yet clearly understood. In this article we first summarize the main mechanistic pathways that have been proposed to occur on surfaces fo...

The eta 4-benzene complexes [(triphos)Ir(C6H6)]Y (Y = BPh(4), 1a; PF6, 1b) react with benzo[b]thiophene (BT) at room temperature to give the unprecedented [(triphos)Ir(eta(3)-C,C,S-C8H6S)]Y (Y = BPh(4), 2a; PF6, 2b) in which intact BT is coordinated to the metal center through the S atom and the C-2=C-3 bond. 2a and 2b are transformed upon mild the...

The mechanism of the regioselective hydrogenation of benzo[b]thiophene (BT) to 2,3-dihydrobenzo[b]thiophene (DHBT) in 2-methoxyethanol solution at 125-degrees-C and ambient or subambient pressure of H-2, using [Rh(COD) (PPh3)2] PF6 (1) (COD = 1,3-cyclooctadiene) as the catalyst procursor has been investigated by a combination of kinetic, chemical,...

Thermolysis of the bis(thiophene) (T) dihydride L(PPh3)2Ir(H)2(eta1-SC4H4)2]PF6 (1) in 1,2-dichloroethane at 80-degrees-C gives the thioallyl complex [(PPh3)2IrH(eta4-SC4H5)]PF6 (2) by a stereospecific endo migration of one of the coordinated hydrides. Reaction of the thioallyl complex with H-2 under mild conditions yields the bis(tetrahydrothiophe...

The kinetics and mechanism of the regiospecific homogeneous hydrogenation of quinoline (Q) to 1,2,3,4-tetrahydroquinoline (THQ) using [Rh(COD)(PPh3)2]PF6 (1) as the catalyst precursor in toluene solution under mild reaction conditions have been studied. The experimentally determined rate law is r(i) = k(cat)[Rh][H-2]2, where k(cat) = 50 +/- 6 M-2 s...

The complexes [IrH2(eta1S-Th)2(PPh3)2]PF6 (Th = thiophene (2), benzo[b]thiophene (3), dibenzothiophene (4) and tetrahydrothiophene (5)) have been synthesized in high yields by hydrogenation of [Ir(COD)(PPh3)2]PF6 (COD = 1,5-cyclooctadiene) in the presence of the appropriate thiophene. The structures of 2 and 5 have been determined by X-ray diffract...

The eta4-benzene complex [(triphos)Ir(C6H6)]BPh4 reacts with thiophene to give the iridathiabenzene complex [(triphos)Ir(eta2-C,S-C4H4S)]BPh4 (1) [triphos = MeC(CH2PPh2)3]. Compound 1 is selectively converted to the butadienethiolate complex [(triphos)Ir(eta3-SCH=CHCH=CH2)](2) by reaction with LiHBEt3 via the (thiapentadienyl)-hydride kinetic inter...

Kinetic and mechanistic studies of the homogeneous hydrogenation of benzaldehyde were carried out using the cationic complex [RuH(CO)(NCMe)2(PPh3)2]BF4 (1) as the catalyst precursor, which was very efficient under mild reaction conditions in 2-methoxyethanol as the solvent. The experimental rate law was found to be r=(K1k2/1 + K1[PhCHO])[Ru][PhCHO]...

The complexes MHCl(CO)(AsPh3)3 (1: M=Ru and2: M=Os) readily react with Ph2PCH2CH2AsPh2 (Arphos) to yield MHCl(CO) (AsPh3) (Arphos) (3: M=Ru and4: M=Os) and with acetic acid to produce MCl(CO) (OCOMe) (AsPh3)2 (5: M=Ru and6: M=Os); the new compounds were characterized by elemental analysis, i.r. and1H n.m.r. spectroscopy. Complexes (1–6) are efficie...

The interaction of RuHCl(CO)(PPh3)3 (1) with CD3CN leads to the formation of a mixture containing two isomeric forms of the complex RuHCl(CO)(NCCD3)(PPh3)2(2' + 4') plus the cationic species [RuH(CO)(NCCD3)2(PPh3)2]+ (3'), as shown by in situ H-1 and P-31 NMR experiments and other reactivity studies. If 1 is reacted with CH3CN int he presence of Na...

The reactivities of the title complexes (I) toward hydrogen, alkynes and oxygen are studied.

The homogeneous selective hydrogenation of benzothiophene to 1,2-dihydrobenzothiophene and of quinoline to 1,2,3,4-tetrahydroquinoline is efficiently achieved by the use of RuCl2(PPh3)3, [RuHCl(CO)(PPh3)3], [OsHCl(CO)(PPh3)3], RhCl(PPh3)3, [Rh(cod)(PPh3)2]PF6, and [Ir(cod)(PPh3)2]PF6 (cod = cyclooctadiene) at 170°C and 115 bar and 150°C and 30 bar...

The reactivities of the hydrido carbonyl complexes OsHCl(CO)(PR3)2 (PR3 = PMe-t-Bu2 (1), P-i-Pr3 (2)) toward hydrogen, alkynes, and oxygen have been studied. The solutions of 1 and 2 are rapidly decolorized upon contact with H2 under ambient conditions; the decolorized solution of 2 shows in benzene-d6 a 1H NMR spectrum that is consistent with the...

Molecular orbital (CNDO) calculations on the interaction of Mo(CO)n (n = 3, 5) fragments with thiophene suggest that formation of the hitherto unknown complexes Mo(η1S-thiophene)(CO)5 and Mo(η5-thiophene)(CO)3 is possible. The nature of the thiophene-metal bond is mainly sp-sp with some d-d and sp-d contributions. Thiophene is more strongly bound i...

The reactivities of the hydrido carbonyl complexes OsHCl(CO)(PRâ)â (PRâ = PMe-t-Buâ (1), P-i-Prâ (2)) toward hydrogen, alkynes, and oxygen have been studied. The solutions of 1 and 2 are rapidly decolorized upon contact with Hâ under ambient conditions; the decolorized solution of 2 shows in benzene-dâ a ¹H NMR spectrum that is consistent with the...

A mixture of norbornene (I) and styrene (II) is treated with the diazoester (III) in the presence of diruthenium tetraacetate to yield the usual cyclopropanation products (IV) and (V), together with the cis-divinylcyclopentanes (VI) and (VII).

The adsorption of the cluster Rh6(CO)16 on the surface of partially hydroxylated magnesia leads mainly to the dianionic cluster [Mg]2+ [Rh6(CO)15]2−, which has been characterized by in situ infrared spectroscopy, extraction by surface anion exchange, and analysis of gases evolved. It is suggested that Rh6(CO)16 undergoes on the surface a nucleophil...

The silica-supported, oxide-bound cluster (I) is an efficient catalyst for the hydrogenation of ethylene under mild reaction conditions.

The interaction of (I) with (N(PPh3)2)NO2 results in a novel oxygen transfer from the nitrite ion and a conversion of a coordinate MeCN ligand into an amido group on the cluster surface.

The silica-supported cluster Os3(CO)10(μ-H)(μ-OSi←) (1) efficiently catalyzes the hydrogenation of ethylene under mild reaction conditions; the reaction is zero order in ethylene and first order in hydrogen. The reaction kinetics as well as volumetric and IR studies of the interaction of 1 with C2H4, H2, and CO indicate a mechanism involving the in...