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1.
Eur J Ophthalmol ; 27(4): 470-475, 2017 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-27739558

RESUMO

PURPOSE: To evaluate retreatment indications/morphologic responses to ranibizumab monotherapy and combination with verteporfin photodynamic therapy (PDT). METHODS: A total of 40 patients received 3 monthly intravitreal ranibizumab 0.3 mg injections combined with either PDT or sham PDT at baseline (1:1) followed by as-needed ranibizumab based on predetermined vision/anatomical criteria. RESULTS: Retreatment criteria were visual acuity (VA) loss (59%/58%), central retinal thickness (CRT) increase (27%/26%), or both (14%/16%). One month before retreatment, intraretinal cysts (IRC) were present in 84%/74%, subretinal fluid (SRF) in 70%/63%, and at least one of them in 84%/89% of eyes. A significant decrease in mean leakage area, IRC, and SRF as well as a reduction in presence of hemorrhages and hard exudates occurred in both treatment groups at 12 months (compared to baseline). CONCLUSIONS: Retreatment indications were mostly based on VA loss, probably due to the quantitative optical coherence tomography criterion. Intraretinal cysts and SRF were earlier predictors for recurring choroidal neovascularization (CNV) activity than CRT/VA changes. Both treatment strategies were equally potent in reducing CNV activity.


Assuntos
Inibidores da Angiogênese/uso terapêutico , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/uso terapêutico , Porfirinas/uso terapêutico , Ranibizumab/uso terapêutico , Degeneração Macular Exsudativa/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais Humanizados/uso terapêutico , Neovascularização de Coroide/patologia , Feminino , Humanos , Injeções Intravítreas , Masculino , Pessoa de Meia-Idade , Retina/patologia , Retratamento , Líquido Sub-Retiniano/metabolismo , Tomografia de Coerência Óptica , Verteporfina , Acuidade Visual/fisiologia , Degeneração Macular Exsudativa/fisiopatologia
2.
Acta Crystallogr E Crystallogr Commun ; 72(Pt 4): 548-51, 2016 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-27375886

RESUMO

The title compound, [Co(C5H7O2)2(C6H12N2)] n , was obtained as a one-dimensional coordination polymer from bis-(acetyl-acetonato)di-aqua-cobalt(II), [Co(acac)2(OH2)2], and 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO), a di-amine with good bridging ability and rod-like spacer function. In the chain complex that extends along the c axis, the Co(II) atom is six-coordinated, the O-donor atoms of the chelating acac ligands occupying the equatorial positions and the bridging DABCO ligands being in trans-axial positions. In the crystal structure, the DABCO ligand is conformationally disordered in a 50:50 manner as a result of its location across a crystallographic mirror plane. The metal-metal distance is very close to that in a related compound exhibiting weak anti-ferromagnetic exchange between the Co(II) ions, and the title compound can thus be useful for obtaining more information about the contribution of different bridges to the magnetic coupling between paramagnetic ions.

3.
Dalton Trans ; 45(15): 6394-404, 2016 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-26948049

RESUMO

The platinum(ii) complex [Pt(H)2(dcpe)] (; dcpe = 1,2-bis(dicyclohexylphosphino)ethane) reacts with an excess of the dialkoxymethylsilanes (HSiMe(OR)2; R = Me, Et) to give the bis(silyl) complex [Pt(SiH2Me)2(dcpe)] () and trialkoxymethylsilanes by hydrodealkoxylation reactions. These rearrangements of the silyl ligands involve Si-O bond activations. The exchange of the alkoxy moieties against silicon-bound hydrogen atoms occurs stepwise. The intermediate complexes [Pt(H){SiMe(OEt)2}(dcpe)] (), [Pt{SiMe(OEt)2}2(dcpe)] (), [Pt{SiHMe(OEt)}2(dcpe)] () and [Pt{SiHMe(OMe)}2(dcpe)] () were detected. Treatment of the complex with an excess of dichloromethylsilane yields the bis(silyl) complex [Pt(SiMeCl2)2(dcpe)] (). The hydrido silyl complex [Pt(H)(SiMeCl2)(dcpe)] () was identified as an intermediate. The reactions of the complexes [Pt(SiH3)2(dcpe)] () and [Pt(SiH2Me)2(dcpe)] () with iodomethane lead to a transfer of the SiH3 and SiH2Me ligands. Methylsilane and dimethylsilane, respectively, as well as the platinum diiodo complex [Pt(I)2(dcpe)] () were identified as main products.

4.
Dalton Trans ; 45(11): 4716-28, 2016 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-26863494

RESUMO

The dihydrido germyl complex cis,fac-[Rh(GePh3)(H)2(PEt3)3] (2) was synthesized by an oxidative addition of HGePh3 at [Rh(H)(PEt3)3] (1). Treatment of 2 with neohexene generated the rhodium(i) germyl complex [Rh(GePh3)(PEt3)3] (3). Alternatively, treatment of the methyl complex [Rh(CH3)(PEt3)3] (4) with HGePh3 furnished at room temperature also 3. Low-temperature NMR measurements revealed an initial formation of the oxidative addition product fac-[Rh(GePh3)(H)(CH3)(PEt3)3] (5), which transforms into the intermediate complex [Rh(GePh3)(H)(CH3)(PEt3)2] (6) by dissociation of a triethylphosphine ligand. The reductive elimination of methane and coordination of PEt3 afforded the germyl complex 3. Treatment of 3 with CO gave the biscarbonyl complex [Rh(GePh3)(CO)2(PEt3)2] (7). The molecular structures of the complexes 2, 3 and 7 were determined by X-ray crystallography. The germyl complex 3 reacted with 2,3,5,6-tetrafluoropyridine or pentafluorobenzene to furnish the C-H activation products [Rh(4-C5NF4)(PEt3)3] (8) and [Rh(C6F5)(PEt3)3] (9), respectively. The reaction of 3 with hexafluorobenzene or perfluorotoluene gave selectively the C-F activation products 9 and [Rh(4-C6F4CF3)(PEt3)3] (10). Treatment of 3 with pentafluoropyridine resulted in the formation of the C-F activation products 8 and [Rh(2-C5NF4)(PEt3)3] (11) in a 1 : 10 ratio. The two isomeric activation compounds [Rh{(E)-CF[double bond, length as m-dash]CF(CF3)}(PEt3)3] (12) and [Rh{(Z)-CF[double bond, length as m-dash]CF(CF3)}(PEt3)3] (13) were obtained in a 3 : 1 ratio by reaction of 3 with hexafluoropropene. On exposure to oxygen the highly air sensitive complex 12 reacts to yield the peroxido-bridged dirhodium complex [Rh{(E)-CF[double bond, length as m-dash]CF(CF3)}(µ-κ(1):η(2)-O2)(PEt3)2]2 (14). The molecular structure of 14 was determined by X-ray crystallography.

5.
Chem Commun (Camb) ; 52(20): 3931-4, 2016 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-26872070

RESUMO

Stoichiometric reactions of SF5 functionalized bromo or iodo aromatics at [Pd(PiPr3)2] (1) led to the oxidative addition products 3, 5 and 7. They were converted into their corresponding palladium fluorido complexes, which reacted readily with bis(pinacolato)diboron (B2pin2) to give the borylated SF5 aromatic compounds. Based on these studies a catalytic borylation of SF5 organyls was developed.

6.
Dalton Trans ; 45(7): 2989-96, 2016 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-26757878

RESUMO

After lithiation of PYR-H2 (PYR = [(NC(Me)C(H)C(Me)NC6H3(iPr)2)2(C5H3N)](2-)) - the precursor of an expanded ß-diketiminato ligand system with two binding pockets - with KN(TMS)2 the reaction of the resulting potassium salt with FeBr2 led to a dinuclear iron(ii) bromide complex [(PYR)Fe(µ-Br)2Fe] (1). Through treatment with KHBEt3 the bromide ligands could be replaced by hydrides to yield [PYR)Fe2(µ-H)2] (2), a distorted analogue of known ß-diketiminato iron hydride complexes, as evidenced by NMR, Mößbauer and X-ray absorption spectroscopy, as well as by its reactivity: for instance, 2 reacts with the proton source lutidinium triflate via protonation of the hydride ligands to form an iron(ii) product [(PYR)Fe2(OTf)2] (4), while CO2 inserts into the Fe-H bonds generating the formate complex [(PYR)Fe2(µ-HCOO)2] (5); in the presence of traces of water partial hydrolysis occurs so that [(PYR)Fe2(µ-OH)(µ-HCOO)] (6) is isolated. Altogether, the iron(ii) chemistry supported by the PYR(2-) ligand is distinctly different from the one of nickel(ii), where both, the arrangement of the two binding pockets and the additional pyridyl donor led to diverging features as compared with the corresponding system based on the parent ß-diketiminato ligand.


Assuntos
Complexos de Coordenação/química , Complexos de Coordenação/síntese química , Compostos Ferrosos/química , Ferro/química , Cristalografia por Raios X , Ligantes , Estrutura Molecular , Espectroscopia de Mossbauer
7.
Inorg Chem ; 54(24): 11606-24, 2015 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-26624918

RESUMO

Molecular spin-crossover (SCO) compounds are attractive for information storage and photovoltaic technologies. We compared two prototypic SCO compounds with Fe(II)N6 (1, [Fe(phen)2(NCS)2], with phen = 1,10-phenanthroline) or Fe(III)S6 (2, [Fe(dedtc)3], with dedtc = N,N'-diethyldithiocarbamate) centers, which show abrupt (1) or gradual (2) thermally induced SCO, using K-edge X-ray absorption and Kß emission spectroscopy (XAS/XES) in a 8-315 K temperature range, single-crystal X-ray diffraction (XRD), and density functional theory (DFT). Core-to-valence and valence-to-core electronic transitions in the XAS/XES spectra and bond lengths change from XRD provided benchmark data, verifying the adequacy of the TPSSh/TZVP DFT approach for the description of low-spin (LS) and high-spin (HS) species. Determination of the spin densities, charge distributions, bonding descriptors, and valence-level configurations, as well as similar experimental and calculated enthalpy changes (ΔH), suggested that the varying metal-ligand bonding properties and deviating electronic structures converge to similar enthalpic contributions to the free-energy change (ΔG) and thus presumably are not decisive for the differing SCO behavior of 1 and 2. Rather, SCO seems to be governed by vibrational contributions to the entropy changes (ΔS) in both complexes. Intra- and intermolecular interactions in crystals of 1 and 2 were identified by atoms-in-molecules analysis. Thermal excitation of individual dedtc ligand vibrations accompanies the gradual SCO in 2. In contrast, extensive inter- and intramolecular phen/NCS vibrational mode coupling may be an important factor in the cooperative SCO behavior of 1.

8.
Inorg Chem ; 54(21): 10351-60, 2015 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-26478946

RESUMO

A series of heterodinuclear complexes (M-1-Re) based on a phenanthroline (phen) extended tetramesityl porphyrin ligand (H2-1) has been prepared. The phen moiety of this ligand selectively coordinates a Re(I) tricarbonyl chloride unit, whereas the metal in the porphyrin moiety has been varied: namely, Cu, Pd, Zn, Co, or Fe was used. These dinuclear complexes were fully characterized by standard analytical methods. Additionally, a crystal structure of Cu-1-Re·5.5(C7H8)·0.5(C6H6) could be obtained, and extended time-resolved emission lifetime measurements were conducted. Furthermore, their ability to catalyze the photochemical reduction of CO2 to CO was investigated. Light-driven CO2 reduction experiments were performed in dimethylformamide (DMF) using triethylamine (TEA) as the sacrificial electron donor. The TONs (turnover numbers) of CO were determined and revealed a surprising catalytic activity that is obviously independent from the redox activity of the porphyrin metal. We have recently shown that the parent M-1 compounds are active photocatalysts, but the catalytic activity was dependent on the redox activity of the porphyrin metal. In the case of the new heterodinuclear complexes M-1-Re reported in this study, the catalytic active center seems to be the Re(I) moiety and not the porphyrin. Surprisingly, Zn-1-Re proved to be the most active compound in this series showing a TONCO of 13 after 24 h of illumination using a >375 nm cutoff filter while all other compounds showed minimal activity under this condition.

9.
Dalton Trans ; 44(45): 19553-65, 2015 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-26308149

RESUMO

The platinum(0) alkyne complexes [Pt(L)(η(2)-PhC[triple bond, length as m-dash]CPh)] 1-4 were synthesized by reactions of [Pt(cod)2] with diphenylacetylene and a phosphine ligand precursor (1: L = dcpe, 2: L = xantphos, 3: L = κ(2)-(P,N)-iPr2PC3H6NMe2, 4: L = κ(2)-(P,N)-iPr2PC2H4NMe2). Treatment of 1 or 4 with NFSI gave the complexes [Pt(F){N(SO2Ph)2}(dcpe)] (5) and [Pt(PhC[double bond, length as m-dash]CFPh){N(SO2Ph)2}{κ(2)-(P,N)-iPr2PC2H4NMe2}] (8), whereas the reactivity of 2 and 3 towards NFSI led to product mixtures. The compounds [Pt(F){N(SO2Ph)2}(xantphos)] (6a) as well as [Pt(PhC[double bond, length as m-dash]CFPh){N(SO2Ph)2}{κ(2)-(P,N)-iPr2PC2H4NMe2}] (7a) and [Pt(PhC[double bond, length as m-dash]CFPh)(F){κ(2)-(P,N)-iPr2PC2H4NMe2}] (7b) were clearly identified. Ligand exchange reactions at 8 resulted in the formation of the ß-fluorovinyl platinum(ii) complexes [Pt(PhC[double bond, length as m-dash]CFPh){OC(O)CF3}{κ(2)-(P,N)-iPr2PC2H4NMe2}] (9), [Pt(PhC[double bond, length as m-dash]CFPh)(FHF){κ(2)-(P,N)-iPr2PC2H4NMe2}] (10) and [Pt(PhC[double bond, length as m-dash]CFPh)(F){κ(2)-(P,N)-iPr2PC2H4NMe2}] (11). Treatment of 8 with dihydrogen yielded the fluorinated olefin (Z)-(1-fluoroethene-1,2-diyl)dibenzene and [Pt{N(SO2Ph)2}(H){κ(2)-(P,N)-iPr2PC2H4NMe2}] (12).

10.
Chem Commun (Camb) ; 51(78): 14613-6, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26288856

RESUMO

The activation of CO2, CS2 as well as of PhNCO at [Rh(Bpin)(PEt3)3] led to C=X bond cleavage and the formation of {RhXBpin} species (X = O, S, N). Treatment of the boryl complex [Rh(Bpin)(PEt3)3] with 0.5 equivalents of CS2 resulted in the fragmentation of CS2 and the formation of the remarkable µ-carbido complex trans-[Rh2(µ-C)(SBpin)2(PEt3)4].

11.
Angew Chem Int Ed Engl ; 54(42): 12325-8, 2015 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-26190407

RESUMO

The hitherto most realistic low-molecular-weight analogue for the 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO) is reported. The ACCOs 2-His-1-carboxylate iron(II) active site was mimicked by a TpFe moiety, to which the natural substrate ACC could be bound. The resulting complex [Tp(Me,Ph) FeACC] (1), according to X-ray diffraction analysis performed for the nickel analogue, represents an excellent structural model, featuring ACC coordinated in a bidentate fashion-as proposed for the enzymatic substrate complex-as well as a vacant coordination site that forms the basis for the first successful replication also of the ACCO function: 1 is the first known ACC complex that reacts with O2 to produce ethylene. As a FeOOH species had been suggested as intermediate in the catalytic cycle, H2 O2 was tested as the oxidant, too, and indeed evolution of ethylene proceeded even more rapidly to give 65 % yield.


Assuntos
Aminoácido Oxirredutases/química , Aminoácido Oxirredutases/metabolismo , Etilenos/biossíntese , Etilenos/química , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Modelos Moleculares , Estrutura Molecular , Oxigênio/química , Oxigênio/metabolismo , Difração de Raios X
12.
Dalton Trans ; 44(20): 9450-69, 2015 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-25915856

RESUMO

The rhodium(i) silyl carbonyl complexes [Rh{Si(OEt)3}(CO)(dippp)] () and [Rh{Si(OEt)3}(CO)(dippe)] () (dippp = 1,3-bis(diisopropylphosphino)propane, dippe = 1,2-bis-(diisopropylphosphino)ethane) were synthesized on treatment of the methyl compounds [Rh(CH3)(CO)(dippp)] () or [Rh(CH3)(CO)(dippe)] () with HSi(OEt)3 at low temperature. The methyl complexes and were prepared starting from the binuclear complexes [{Rh(µ-Cl)(dippp)}2] () and [{Rh(µ-Cl)(dippe)}2] (), respectively. The silyl complexes and as well as the precursors [{Rh(µ-I)(dippp)}2] (), [Rh(X)(CO)(dippp)] (: X = CH3, : X = I) and [Rh(X)(CO)(dippe)] (: X = CH3, : X = Cl) were characterized by NMR and IR spectroscopy and the structures in the solid state were determined by X-ray crystallography. The silyl complex converts into the carbonyl-bridged complex [{Rh(µ-CO)(dippp)}2] () above temperatures of -30 °C by loss of the silyl ligand, whereas is more thermally stable and a reaction to the binuclear complex [{Rh(µ-CO)(dippe)}2] () was observed at 50 °C. The silyl complex reacted under irradiation with hexafluorobenzene and pentafluoropyridine to give the C-F activation products [Rh(C6F5)(CO)(dippe)] () and [Rh(2-C5F4N)(CO)(dippe)] (), respectively. As additional products the silyl dicarbonyl complex [Rh{Si(OEt)3}(CO)2(dippe)] () and the cationic complex [Rh2(µ-H)(µ-CO)2(dippe)2](+)[SiF5](-) () were identified. Compound was synthesized independently by treatment of with gaseous CO. In a similar manner, the dippp analogue [Rh{Si(OEt)3}(CO)2(dippp)] () was also prepared starting from . Photochemical reaction of with pentafluorobenzene and 2,3,5,6-tetrafluoropyridine resulted selectively in C-H bond activation to afford and [Rh(4-C5F4N)(CO)(dippe)] (), respectively.

13.
Chemistry ; 21(6): 2594-602, 2015 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-25522205

RESUMO

The cationic zinc triple-decker complex [Zn2 Cp*3 ](+) [BAr(F) 4 ](-) (BAr(F) 4 =B(3,5-(CF3 )2 C6 H3 )4 ) exhibits catalytic activity in intra- and intermolecular hydroamination reactions in the absence of a cocatalyst. These hydroaminations presumably proceed through the activation of the C-C multiple bond of the alkene or alkyne by a highly electrophilic zinc species, which is formed upon elimination of the Cp* ligands. The reaction of [Zn2 Cp*3 ](+) [BAr(F) 4 ](-) with henylacetylene gives the hydrocarbonation product (Cp*)(Ph)CCH2 , which might be formed via a similar reaction pathway. Additionally, several other structurally well-defined cationic zinc organyls have been examined as precatalysts for intermolecular hydroamination reactions without the addition of a cocatalyst. These studies reveal that the highest activity is achieved in the absence of any donor ligands. The neutral complex [ZnCp(2S) 2 ] (Cp(2S) =C5 Me4 (CH2 )2 SMe) shows a remarkably high catalytic activity in the presence of a Brønsted acid.

14.
Angew Chem Int Ed Engl ; 54(4): 1352-6, 2015 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-25477030

RESUMO

The reaction of 1,1,3,3-tetraphenyl-1,3-disiloxandiol (LH2) with n-butyllithium and CrCl2 results in a mononuclear chromium(II) complex (1) that further reacts with O2 at low temperatures to yield a mononuclear chromium(III) superoxide complex [L2CrO2(THF)][Li2(THF)3] (2). The crystal structure revealed that the chromium superoxido entity is stabilized by the coordination to an adjacent lithium cation. Complex 2 thus contains an unprecedented heterobimetallic [Cr(III)(µ-O2)Li(+)] core; beyond this it is the first chromium superoxide for which a temperature-dependent magnetic characterization could be achieved, and the first structurally characterized representative with chromium in an exclusive O-donor environment.

15.
Ophthalmologica ; 233(2): 66-73, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25471330

RESUMO

PURPOSE: To investigate the injection frequency and visual acuity (VA) outcomes with combination therapy (ranibizumab plus verteporfin photodynamic therapy, PDT) versus monotherapy (ranibizumab). METHODS: A total of 40 patients with exudative age-related macular degeneration were randomized 1:1 to ranibizumab 0.3 mg plus single standard verteporfin PDT or ranibizumab 0.3 mg plus sham PDT. Ranibizumab was administered 3 times monthly followed by 'as needed' to month 12 based on predetermined vision/anatomical criteria. Retreatment rates, VA outcomes and safety were assessed. RESULTS: During months 3-12, combination therapy patients required fewer ranibizumab injections (mean 1.3) compared with monotherapy patients (2.8). Mean VA improved by 9.0 letters with combination therapy versus 7.5 letters in the monotherapy group at month 12. Both treatment regimens were well tolerated. CONCLUSION: The need for ranibizumab retreatment might be reduced by administering a single verteporfin PDT on the same day as the first ranibizumab injection, without compromising VA outcomes or safety.


Assuntos
Inibidores da Angiogênese/uso terapêutico , Anticorpos Monoclonais Humanizados/uso terapêutico , Fotoquimioterapia , Fármacos Fotossensibilizantes/uso terapêutico , Acuidade Visual/fisiologia , Degeneração Macular Exsudativa/tratamento farmacológico , Idoso , Terapia Combinada , Método Duplo-Cego , Feminino , Humanos , Injeções Intravítreas , Masculino , Porfirinas/uso terapêutico , Ranibizumab , Retratamento , Resultado do Tratamento , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidores , Verteporfina , Degeneração Macular Exsudativa/diagnóstico , Degeneração Macular Exsudativa/fisiopatologia
16.
Inorg Chem ; 53(14): 7294-308, 2014 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-24981960

RESUMO

The potential of iron molybdates as catalysts in the Formox process stimulates research on aggregated but molecular iron-molybdenum oxo compounds. In this context, [(Me3TACN)Fe](OTf)2 was reacted with (nBu4N)2[MoO4], which led to an oxo cluster, [[(Me3TACN)Fe][µ-(MoO4-κ(3)O,O',O″)]]4 (1, Fe4Mo4) with a distorted cubic structure, where the corners are occupied by (Me3TACN)Fe(2+) and [Mo═O](4+) units in an alternating fashion, being bridged by oxido ligands. The cyclic voltammogram revealed four reversible oxidation waves that are assigned to four consecutive Fe(II) → Fe(III) transfers and motivated attempts to isolate compounds containing the respective cations. Indeed, a salt with a Fe(II)2Fe(III)2Mo(VI)4 constellation, [Fe4Mo4](TCNQ)2 (2), could be isolated after treatment with TCNQ. The Fe(II)Fe(III)3Mo(VI)4 stage could be reached via oxidation with DDQ or 3 equiv of thianthrenium hexafluorophosphate (ThPF6), giving [Fe4Mo4](DDQ)3 (4) or [Fe4Mo4](PF6)3 (5), respectively. The fully oxidized Fe(III)4Mo(VI)4 state was generated through oxidation with 4 equiv of ThPF6, leading to [Fe4Mo4](PF6)4, which showed a unique behavior: upon storage, one of the [Mo═O](4+) corners inverts, so that the terminal oxido ligand is located in the interior of the cage, leading to the formation of [[(Me3TACN)Fe]4[µ-([MoO4]3[MoO4(MeCN-κN)])-κ(3)O,O',O″)](PF6)4 (7). In this form, the compound could no longer be employed to enter the cyclic voltammogram recorded for 1, 3, and 5 from the oxidized side; no discrete redox events were observed. Compounds 1-3 and 7 were characterized structurally and 1, 3, and 7 additionally by SQUID measurements and Mössbauer spectroscopy. The data reveal a high degree of charge delocalization. (16)O/(18)O exchange experiments with labeled water performed with 1 revealed an interesting parallel with the Formox catalyst: water-(18)O exchanges its label with all of the oxido ligands (bridging and terminal). This property relates to the ion mobility being held responsible for the activity of iron molybdate catalysts compared to neat MoO3 or Fe2O3.

17.
Inorg Chem ; 53(13): 6867-74, 2014 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-24914615

RESUMO

Mononuclear nickel(II) thiolate complexes [L(tBu)Ni(SEt)] (1) and [L(tBu)Ni(aet)] (2, aet = (-)S(CH2)2NH2) (L(tBu) = [HC(C((t)Bu)NC6H3((i)Pr)2)2](-)), supported by a bulky nacnac ligand, were synthesized by treatment of the nickel(II) bromide precursor [L(tBu)Ni(Br)] (I) with the potassium salts of ethanethiol and cysteamine, respectively. The nickel atom in 1 features a planar T-shaped environment, while the Ni ion within 2 shows a distorted square planar coordination geometry, as the aminoethanethiolate (aet) is coordinated as a chelating ligand. In 2 the ß-diketiminate ligand binds in a rarely observed κ(2)C,N coordination mode. Reduction of complex 1 or its benzenethiolate analogue [L(tBu)Ni(SPh)] (II) by KC8 resulted in the formation of dinuclear Ni(I) thiolates (K·OEt2)(K)[L(tBu)Ni(SEt)]2 (3) and (K·OEt2)2[L(tBu)Ni(SPh)]2 (4), respectively. In these compounds [L(tBu)Ni(SR)](-) units are held together by potassium cations produced in the reduction process. All compounds mentioned were structurally characterized by single-crystal X-ray crystallography.


Assuntos
Complexos de Coordenação/química , Iminas/química , Níquel/química , Compostos de Sulfidrila/química , Monóxido de Carbono/química , Ligantes , Modelos Moleculares , Oxigênio/química
18.
Dalton Trans ; 43(18): 6786-801, 2014 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-24647920

RESUMO

The rhodium(I) boryl complex [Rh(Bpin)(PEt3)3] (1) reacts with the ketones α,α,α-trifluoroacetophenone and 9-fluorenone by insertion of the C=O bond to give [Rh{η(3)-C(CF3)(OBpin)C6H5}(PEt3)2] (4) and [Rh{η(5)-C13H8(OBpin)}(PEt3)2] (6), whereas the reaction with acetophenone leads to the formation of [Rh(H)(PEt3)3] (2), [Rh(OBpin)(PEt3)3] (3) and (E)-(Ph)CH=CHBpin. Treatment 1 of with ketimines generates [Rh{η(3)-C6H5=C(Ph)N(Ph)(Bpin)}(PEt3)2] (7), [Rh{(η(3)-C12H8)N(Ph)(Bpin)}(PEt3)2] (8) or [Rh{CPh2N(H)(Bpin)}(PEt3)2] (9). The insertion of aldimines into the Rh-B bond gives access to [Rh[η(3)-CH{N(C6H13)Bpin}C6H5](PEt3)2] (11) or [Rh[η(3)-CH{N(Ph)Bpin}C6H5](PEt3)2] (12). The latter is converted into the C-H activation product [Rh{(C6H4)-o-N(Bpin)(CH2Ph)}(PEt3)3] (13). Complex 13 reacts with B2pin2 to yield the boryl complex 1 and the amine PhCH2N(Bpin)(C6H4-o-Bpin).

19.
Angew Chem Int Ed Engl ; 53(10): 2745-9, 2014 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-24453166

RESUMO

The degradation of SF6 and SF5 organyls by S-F and S-C bond-activation reactions at [{Rh(µ-H)(dippp)}2] under mild conditions is reported. Fluorido and thiolato species were identified as products or intermediates, and were characterized by X-ray diffraction analysis and multinuclear NMR spectroscopy. An unprecedented cyclic process for the conversion of the potent greenhouse gas SF6 into H2S was developed.

20.
Dalton Trans ; 43(2): 806-16, 2014 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-24154868

RESUMO

The reaction between [(TPA)Fe(MeCN)2](OTf)2 and [nBu4N](Cp*MoO3) yields the novel tetranuclear complex [(TPA)Fe(µ-Cp*MoO3)]2(OTf)2, 1, with a rectangular [Mo-O-Fe-O-]2 core containing high-spin iron(ii) centres. 1 proved to be an efficient initiator/(pre)catalyst for the autoxidation of cis-cyclooctene with O2 to give cyclooctene epoxide. To test, which features of 1 are essential in this regard, analogues with zinc(ii) and cobalt(ii) central atoms, namely [(TPA)Zn(Cp*MoO3)](OTf), 3, and [(TPA)Co(Cp*MoO3)](OTf), 4, were prepared, which proved to be inactive. The precursor compounds of 1, [(TPA)Fe(MeCN)2](OTf)2 and [nBu4N](Cp*MoO3) as well as Cp2*Mo2O5, were found to be inactive, too. Reactivity studies in the absence of cyclooctene revealed that 1 reacts both with O2 and PhIO via loss of the Cp* ligands to give the triflate salt 2 of the known cation [((TPA)Fe)2(µ-O)(µ-MoO4)](2+). The cobalt analogue 4 reacts with O2 in a different way yielding [((TPA)Co)2(µ-Mo2O8)](OTf)2, 5, featuring a Mo2O8(4-) structural unit which is novel in coordination chemistry. The compound [(TPA)Fe(µ-MoO4)]2, 6, being related to 1, but lacking Cp* ligands failed to trigger autoxidation of cyclooctene. However, initiation of autoxidation by Cp* radicals was excluded via experiments including thermal dissociation of Cp2*.

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