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1.
Org Biomol Chem ; 2020 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-32578650

RESUMO

A facile and straightforward synthesis of unsymmetrically substituted N-aryl oxalamides from 2,2'-biphenyldiamines, 2-chloroacetic acid derivatives, elemental sulfur, and water has been developed. This protocol is distinguished by efficiency in water under metal-free conditions for N-aryl oxalamides bearing a side-chain NH2-group; it can be adapted for scale-up synthesis. The scope and limitations of this transformation have been investigated.

2.
Dalton Trans ; 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32154817

RESUMO

We report the synthesis, photoluminescence and magnetic properties of two octahedral dysprosium complexes [DyR2(py)4][BPh4]·2py (1) and [DyR2(THF)4][BPh4] (2) (R = carbazolyl, py = pyridine, THF = tetrahydrofuran) exhibiting a quasi linear N-Dy-N angle in the axial direction, suitable for providing a coordination environment allowing the zero-field slow relaxation of magnetization.

3.
Org Lett ; 22(2): 604-609, 2020 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-31909627

RESUMO

Manipulating the equilibrium between a ketone and an enol by light opens up ample opportunities in material chemistry and photopharmacology. By incorporating ß-ketoester into the ethene bridge of a photoactive diarylethene, we achieved reversible light-induced tautomerization to give thermally stable enol. In a pristine state, the tautomeric equilibrium is almost completely shifted toward the ketone. Photocyclization of diarylethene results in a new equilibrium containing a significant fraction of the enol tautomer.

4.
J Org Chem ; 84(24): 15817-15826, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31729874

RESUMO

The three-component reaction of 2,2'-biphenyldiamines with 2-chloroacetic acid derivatives and elemental sulfur was developed for the practical synthesis of unknown 2-carboxamide-substituted dibenzo[d,f][1,3]diazepines. This protocol is distinguished by efficiency in water and good tolerance to functional groups and can be adapted to a large-scale synthesis. The chemoselective preparation of a variety of 2-S,N,O-substituted dibenzo[d,f][1,3]diazepines was accomplished using the developed method.

5.
Dalton Trans ; 48(32): 12018-12022, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31373595

RESUMO

We report the investigation of synthesis, structure and magnetic properties of a series of homoleptic Ln(iii) complexes coordinated by radical-anionic iminopyridine ligands of general formula [Ln(IPy)3]·solv (IPy = iminopyridine; Ln = Tb, Dy, Er, Y, Gd). The dysprosium analogue exhibits a zero-field Single-Molecule Magnet (SMM) behavior.

6.
Acta Crystallogr E Crystallogr Commun ; 75(Pt 6): 848-853, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31391980

RESUMO

The solvated centrosymmmtric title compound, [Li2(C24H34O4P)2(C10H8N2)2]·2C7H8, was formed in the reaction between {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) and 2,2'-bi-pyridine (bipy) in toluene. The structure has monoclinic (P21/n) symmetry at 120 K and the asymmetric unit consists of half a complex mol-ecule and one mol-ecule of toluene solvent. The diaryl phosphate ligand demonstrates a µ-κO:κO'-bridging coordination mode and the 2,2'-bi-pyridine ligand is chelating to the Li+ cation, generating a distorted tetra-hedral LiN2O2 coordination polyhedron. The complex exhibits a unique dimeric Li2O4P2 core. One isopropyl group is disordered over two orientations in a 0.621 (4):0.379 (4) ratio. In the crystal, weak C-H⋯O and C-H⋯π inter-actions help to consolidate the packing. Catalytic systems based on the title complex and on the closely related complex {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) display activity in the ring-opening polymerization of ∊-caprolactone and l-dilactide.

7.
Chem Asian J ; 14(17): 2979-2987, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31298502

RESUMO

New nickel-based complexes of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with BF4 - counterion or halide co-ligands were synthesized in THF and MeCN. The nickel(I) complexes were obtained by using two approaches: 1) electrochemical reduction of the corresponding nickel(II) precursors; and 2) a chemical comproportionation reaction. The structural features and redox properties of these complexes were investigated by using single-crystal X-ray diffraction (XRD), cyclic voltammetry (CV), and electron paramagnetic resonance (EPR) and UV/Vis spectroscopy. The influence of temperature and solvent on the structure of the nickel(I) complexes was studied in detail, and an uncommon reversible solvent-induced monomer/dimer transformation was observed. In the case of the fluoride complex, the unpaired electron was found to be localized on the dpp-bian ligand, whereas all of the other nickel complexes contained neutral dpp-bian moieties.

8.
Acta Crystallogr E Crystallogr Commun ; 75(Pt 4): 456-459, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31161056

RESUMO

Single crystals of the title compound, [Al(iBu)2(O2CCPh3)]2 or [Al2(C4H9)4(C20H15O2)2], have been formed in the reaction between tris-(tetra-hydro-furan)-tris-(tri-phenyl-acetato)-neodymium, [Nd(Ph3CCOO)3(THF)3], and triiso-butyl-aluminium, Al(iBu)3, in hexane followed by low-temperature crystallization (243 K) from the reaction mixture. The structure has triclinic (P ) symmetry at 120 K. The dimeric complex [Al(iBu)2(O2CCPh3-µ-κO:κO')]2 is located about an inversion centre. The tri-phenyl-acetate ligand displays a µ-κO:κO'-bridging coordination mode, leading to the formation of an octa-gonal Al2O4C2 core. The complex displays HPh⋯CPh inter-molecular inter-actions.

9.
Org Biomol Chem ; 17(20): 4990-5000, 2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-30964495

RESUMO

A general strategy for the preparative benzannulation of aromatic heterocycles via photocyclization of 1,2-dihetarylethenes was proposed for the first time. The strategy includes two steps, namely, modular assembly of dihetarylethenes from widely available 3-hetarylacetic acids and 2-bromo-1-hetarylethanones, and subsequent preparative photorearrangement (using a UV lamp at 365 nm as the light source). This approach is efficient for the annulation of a wide range of heterocycles and provides C-, N-, O- or S-substituents in the benzoheterocycles obtained. The photochemical step is a metal-, acid-, and oxidant-free reaction, which requires non-inert conditions, and can be easily monitored by NMR spectroscopy. Applicability of the proposed strategy was tested in the synthesis of a wide range of substituted carbazoles and benzo[b]thiophenes as well as on a gram-scale benzannulation of 3-indoleacetic acid. Our study disclosed how to overcome two notable obstacles to the successful photorearrangement of dihetarylethenes: undesired reactions associated with photogenerated singlet oxygen, and the instability of desired products. The first problem was successfully solved by the addition of DABCO, while development of an in situ alkylation protocol to trap unstable photoproducts allowed us to overcome the second issue.

10.
Dalton Trans ; 48(5): 1732-1746, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30637425

RESUMO

A series of iminophosphinite POCN pincer Ni(ii) complexes, (POCN)NiMe and (POCN)NiLn(BX4) (L = CH3CN, n = 0, 1; X = F, Ph, C6F5), have been developed and subjected to catalytic hydrosilylation of alkenes, aldehydes and ketones and hydroboration of carbonyl compounds. The stoichiometric reactivity of (POCN)NiMe and (POCN)Ni(BF4) with PhSiH3 and HBPin suggests that catalytic reactions proceed via the hydride intermediate (POCN)NiH. With regard to reactions with HBPin, efficient and mild hydroboration of a variety of carbonyl compounds, including highly chemoselective hydroboration of benzaldehyde in the presence of other common potent reductive functional groups, such as alkenes, alkynes, esters, amides, nitriles, nitro compounds and even ketones, and the first example of base metal catalyzed hydroboration of amides, including mild direct hydroborative reduction of primary and secondary amides to borylated amines were demonstrated for (POCN)NiMe.

11.
Chemistry ; 25(2): 459-463, 2019 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-30411413

RESUMO

The first example of intermolecular hydrophosphination of styrene, 2-vinylpyridine and phenylacetylene with PH3 catalyzed by bis-(amido) complexes [(Me3 Si)2 N]2 M(NHC)2 (M=Ca, Yb, Sm) coordinated by NHC ligands is described. The reactions of styrene with PH3 proceed under mild conditions in quantitative yields to afford only anti-Markovnikov product and allow for the chemoselective synthesis of primary, secondary and tertiary phosphines. Addition of phenylacetylene to PH3 regardless the initial molar substrates ratio results in the exclusive formation of a tertiary tris-(Z-styryl)-phosphine. Crucial effect of the Lewis base coordinated to the metal ion in precatalyst on catalytic activity in styrene hydrophosphination with PH3 was demonstrated. Free NHCs were also found to be able to promote addition of PH3 to styrene, however they provide much lower reaction rates compared to the metal complexes.

12.
Chemistry ; 25(2): 474-478, 2019 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-30376601

RESUMO

The synthesis, and magnetic and photoluminescence investigations of two bifunctional dysprosium complexes based on tridentate Schiff base ligands is reported. Magnetic investigations reveal a genuine single-molecule magnet (SMM) behavior, with out-of-phase signals up to 60 K, and tunable emission arising from the Schiff base ligands.

13.
Acta Crystallogr E Crystallogr Commun ; 74(Pt 12): 1790-1794, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30574375

RESUMO

The title compound, [Al2La2(C20H15O2)4(CH3)6(CH3O)2]·4CH3C6H5 or [{La(Ph3CCOO)2(Me3AlOMe)}2]·4CH3C6H5, was formed in a reaction between lanthanum tris-(tetra-methyl-aluminate) and tri-phenyl-acetic acid (1:1) with unintended partial oxidation. The tri-phenyl-acetate ligand exhibits µ2-κ1 O:κ1 O' bridging and µ2-κ2 O,O':κ1 O semi-bridging coordination modes, forming a dimeric La2(µ-OCO)4 core. The semi-bridging tri-phenyl-acetate group provides additional bonding with an La3+ cation via the π-system of one of its phenyl rings. The tri-methyl-meth-oxy-aluminate anion, which is coordinated to the La3+ cation by its O atom, displays a rather long La-CMe bond. Two toluene mol-ecules are each disordered over two orientations about centres of symmetry with site occupancy factors of 0.5. The title compound represents the first example of an LnIII complex containing both alkyl alkoxide aluminate and π-bounded arene fragments.

14.
Dalton Trans ; 48(1): 35-39, 2018 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-30444521

RESUMO

We report the synthesis and magnetic investigation of a dysprosium pentagonal bipyramidal complex [Dy(THF)5Cl2][BPh4] (1) exhibiting a linear Cl-Dy-Cl sequence suitable for providing a coordination environment allowing a zero-field slow relaxation of the magnetization. Besides, the complex also shows dual luminescence originating from [BPh4]- and Dy3+.

15.
Acta Crystallogr E Crystallogr Commun ; 74(Pt 10): 1433-1438, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30319795

RESUMO

The title compound, [Mn(C24H34O4P)(CH3OH)5](C24H34O4P)·3CH3OH, was formed in the reaction between a hydrate of a manganese(II) salt [either Mn(NO3)2(H2O)6 or MnCl2(H2O)4] with a methanol solvate of lithium bis-(2,6-diiso-propyl-phen-yl) phosphate, {Li[OOP(O-2,6- i Pr2C6H3)2]·(CH4O)3}·CH4O, in methanol. The structure has monoclinic (Cc) symmetry at 150 K. The complex consists of an [Mn{OOP(O-2,6- i Pr2C6H3)2}(CH3OH)5]+ cation, an [OOP(O-2,6- i Pr2C6H3)2]- anion and three non-coordinating methanol mol-ecules. The anion demonstrates disorder of an isopropyl group [occupancy ratio is 0.57 (4):0.43 (4)]. The di-aryl-phosphate ligand in the cation exhibits a κ1 O terminal coordination mode. The Mn atom is in a nearly unperturbed octa-hedral environment. The [Mn{OOP(O-2,6- i Pr2C6H3)2}(CH3OH)5]+ cation exhibits one intra-molecular O-H⋯O bond, and is coordinated via two inter-molecular O-H⋯O hydrogen bonds to the [OOP(O-2,6- i Pr2C6H3)2]- anion. The cations, anions and non-coordinating methanol mol-ecules are linked into infinite chains along the c-axis direction via 0-H⋯O hydrogen bonding. The complex is of inter-est as a possible inhibitor for the thermal decomposition of polydi-methyl-siloxane. The crystal studied was refined as an inversion twin with a domain ratio of 0.47 (3):0.53 (3).

16.
J Org Chem ; 83(21): 13427-13445, 2018 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-30351948

RESUMO

We have discovered synthetic access to ß-hydroperoxy-ß-peroxylactones via BF3-catalyzed cyclizations of a variety of acyclic precursors, ß-ketoesters and their silyl enol ethers, alkyl enol ethers, enol acetates, and cyclic acetals, with H2O2. Strikingly, independent of the choice of starting material, these reactions converge at the same ß-hydroperoxy-ß-peroxylactone products, i.e., the peroxy analogues of the previously elusive cyclic Criegee intermediate of the Baeyer-Villiger reaction. Computed thermodynamic parameters for the formation of the ß-hydroperoxy-ß-peroxylactones from silyl enol ethers, enol acetates, and cyclic acetals confirm that the ß-peroxylactones indeed correspond to a deep energy minimum that connects a variety of the interconverting oxygen-rich species at this combined potential energy surface. The target ß-hydroperoxy-ß-peroxylactones were synthesized from ß-ketoesters, and their silyl enol ethers, alkyl enol ethers, enol acetates, and cyclic acetals were obtained in 30-96% yields. These reactions proceed under mild conditions and open synthetic access to a broad selection of ß-hydroperoxy-ß-peroxylactones that are formed selectively even in those cases when alternative oxidation pathways can be expected. These ß-peroxylactones are stable and can be useful for further synthetic transformations.

17.
Molecules ; 23(10)2018 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-30304797

RESUMO

A safe and efficient synthesis of 4,7-dibromo[1,2,5]thiadiazolo[3,4-d]pyridazine from the commercial diaminomaleonitrile is reported. Conditions for selective aromatic nucleophilic substitution of one or two bromine atoms by oxygen and nitrogen nucleophiles are found, whereas thiols formed the bis-derivatives only. Buchwald-Hartwig or Ullmann techniques are successful for incorporation of a weak nitrogen base, such as carbazole, into the [1,2,5]thiadiazolo[3,4-d]pyridazine core. The formation of rather stable S…η²-(N=N) bound chains in 4,7-bis(alkylthio)-[1,2,5]thiadiazolo[3,4-d]pyridines makes these compounds promising for the design of liquid crystals.


Assuntos
Piridazinas/química , Tiadiazóis/química , Modelos Moleculares , Nitrogênio/química , Piridazinas/síntese química , Compostos de Sulfidrila/química
18.
Acta Crystallogr C Struct Chem ; 74(Pt 10): 1105-1115, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30284975

RESUMO

A simple and effective synthetic route to homo- and heteroleptic rare-earth (Ln = Y, La and Nd) complexes with a tridentate Schiff base anion has been demonstrated using exchange reactions of rare-earth chlorides with in-situ-generated sodium (E)-2-{[(2-methoxyphenyl)imino]methyl}phenoxide in different molar ratios in absolute methanol. Five crystal structures have been determined and studied, namely tris(2-{[(2-methoxyphenyl)imino]methyl}phenolato-κ3O1,N,O2)lanthanum, [La(C14H12NO2)3], (1), tris(2-{[(2-methoxyphenyl)imino]methyl}phenolato-κ3O1,N,O2)neodymium tetrahydrofuran disolvate, [La(C14H12NO2)3]·2C4H8O, (2)·2THF, tris(2-{[(2-methoxyphenyl)imino]methyl}phenolato)-κ3O1,N,O2;κ3O1,N,O2;κ2N,O1-yttrium, [Y(C14H12NO2)3], (3), dichlorido-1κCl,2κCl-µ-methanolato-1:2κ2O:O-methanol-2κO-(µ-2-{[(2-methoxyphenyl)imino]methyl}phenolato-1κ3O1,N,O2:2κO1)bis(2-{[(2-methoxyphenyl)imino]methyl}phenolato)-1κ3O1,N,O2;2κ3O1,N,O2-diyttrium-tetrahydrofuran-methanol (1/1/1), [Y2(C14H12NO2)3(CH3O)Cl2(CH4O)]·CH4O·C4H8O, (4)·MeOH·THF, and bis(µ-2-{[(2-methoxyphenyl)imino]methyl}phenolato-1κ3O1,N,O2:2κO1)bis(2-{[(2-methoxyphenyl)imino]methyl}phenolato-2κ3O1,N,O2)sodiumyttrium chloroform disolvate, [NaY(C14H12NO2)4]·2CHCl3, (5)·2CHCl3. Structural peculiarities of homoleptic tris(iminophenoxide)s (1)-(3), binuclear tris(iminophenoxide) (4) and homoleptic ate tetrakis(iminophenoxide) (5) are discussed. The nonflat Schiff base ligand displays µ2-κ3O1,N,O2:κO1 bridging, and κ3O1,N,O2 and κ2N,O1 terminal coordination modes, depending on steric congestion, which in turn depends on the ionic radii of the rare-earth metals and the number of coordinated ligands. It has been demonstrated that interligand dihedral angles of the phenoxide ligand are convenient for comparing steric hindrance in complexes. (4)·MeOH has a flat Y2O2 rhomboid core and exhibits both inter- and intramolecular MeO-H...Cl hydrogen bonding. Catalytic systems based on complexes (1)-(3) and (5) have demonstrated medium catalytic performance in acrylonitrile polymerization, providing polyacrylonitrile samples with narrow polydispersity.

19.
Inorg Chem ; 57(16): 10199-10213, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30051707

RESUMO

A new approach to design "antenna-ligands" to enhance the photoluminescence of lanthanide coordination compounds has been developed based on a π-type ligand-the polyphenyl-substituted cyclopentadienyl. The complexes of di-, tri-, and tetraphenyl cyclopentadienyl ligands with Tb and Gd have been synthesized and all the possible structural types from mononuclear to di- and tetranuclear complexes, as well as a coordination polymer were obtained. All types of the complexes have been studied by single-crystal X-ray diffraction and optical spectroscopy. All terbium complexes are luminescent at ambient temperature and two of them have relatively high quantum yields (50 and 60%). Analysis of energy transfer process has been performed and supported by quantum chemical calculations. The role of a low-lying intraligand charge transfer state formed by extra coordination with K+ in the Tb3+ ion luminescence sensitization is discussed. New aspects for design of lanthanide complexes containing π-type ligands with desired luminescence properties have been proposed.

20.
Acta Crystallogr C Struct Chem ; 74(Pt 5): 548-557, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29726463

RESUMO

A new packing polymorph of bis(2,6-di-tert-butyl-4-methylphenolato-κO)bis(tetrahydrofuran-κO)magnesium, [Mg(C15H23O)2(C4H8O)2] or Mg(BHT)2(THF)2, (BHT is the 2,6-di-tert-butyl-4-methylphenoxide anion and THF is tetrahydrofuran), (1), has the same space group (P21) as the previously reported modification [Nifant'ev et al. (2017d). Dalton Trans. 46, 12132-12146], but contains three crystallographically independent molecules instead of one. The structure of (1) exhibits rotational disorder of the tert-butyl groups and positional disorder of a THF ligand. The complex of bis(2,6-di-tert-butyl-4-methylphenolato-κO)bis(µ2-ethyl glycolato-κ2O,O':κO)dimethyldialuminium, [Al2(CH3)2(C4H7O3)2(C15H23O)2] or [(BHT)AlMe(OCH2COOEt)]2, (2), is a dimer located on an inversion centre and has an Al2O2 rhomboid core. The 2-ethoxy-2-oxoethanolate ligand (OCH2COOEt) displays a µ2-κ2O,O':κO semi-bridging coordination mode, forming a five-membered heteronuclear Al-O-C-C-O ring. The same ligand exhibits positional disorder of the terminal methyl group. The redetermined structure of the heptanuclear complex octakis(µ3-benzyloxo-κO:κO:κO)hexaethylheptazinc, [Zn7(C2H5)6(C7H7O)8] or [Zn7(OCH2Ph)8Et6], (3), possesses a bicubic Zn7O8 core located at an inversion centre and demonstrates positional disorder of one crystallographically independent phenyl group. Cambridge Structural Database surveys are given for complexes structurally analogous to (2) and (3). Complexes (2) and (3), as well as derivatives of (1), are of interest as catalysts for the ring-opening polymerization of ℇ-caprolactone, and polymerization results are reported.

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