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1.
J Org Chem ; 84(24): 16333-16337, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31769287

RESUMO

An efficient preparative method was developed for the synthesis of previously unreported fullerenylstyrenes based on the reaction of C60 fullerene with terminal acetylenes and EtMgBr in the presence of Ti(Oi-Pr)4. The voltammetric curves of the prepared fullerenylstyrenes were studied, and good prospects for their application as acceptor materials for bulk heterojunction solar cell were demonstrated.

2.
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.

3.
Org Lett ; 21(4): 946-950, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30698444

RESUMO

The deprotonation of N-2,6-diisopropylphenyl-substituted benzoxazolium tetrafluoroborate 1 with NaH results in the formation of electron-rich diaminodioxaethylene 2. The radical cation salt 2·+·BF4- is found to be an intermediate product in the redox reaction leading from 1 to 2.

4.
Chemistry ; 25(15): 3858-3866, 2019 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-30570195

RESUMO

The electrochemical characteristics of 2-mono(2,6-diisopropylphenylimino)acenaphthene-1-one (dpp-mian) have been investigated. One-electron reduction of dpp-mian involves the iminoketone fragment, which is revealed by the EPR spectrum obtained after the electrolysis of the dpp-mian solution in tetrahydrofuran (THF). The reduction of dpp-mian with one equivalent of metallic potassium leads to a similar EPR spectrum. The sodium complex [(dpp-mian)Na(dme)]2 (1) produces an EPR signal with hyperfine coupling on the nitrogen atom of the iminoketone fragment of the dpp-mian ligand. Dpp-mian can also be reduced in a one-electron process by SnCl2 ×(dioxane). In this case, complex (dpp-mian)2 SnCl2 (2) is formed, with the tin atom displaying an oxidation state of +4. Tin(II) chloride dihydrate, SnCl2 ×2(H2 O), also reduces dpp-mian, but the two ligands bound to tin in the product form a new carbon-carbon bond between the ketone moieties of the dpp-mian monoanions to form complex (bis-dpp-mian)HSnCl3 (3). Metallic tin reduces dpp-mian to form the (bis-dpp-mian)2 Sn (4) species. Compounds 1-4 were characterized by X-ray diffraction.

5.
Dalton Trans ; 47(29): 9608-9616, 2018 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-29855006

RESUMO

The efficient catalysis of oxidative alkylation and fluoroalkylation of aromatic C-H bonds is of paramount importance in the pharmaceutical and agrochemical industries, and requires the development of convenient Ag0-based nano-architectures with high catalytic activity and recyclability. We prepared Ag-doped silica nanoparticles (Ag0/+@SiO2) with a specific nano-architecture, where ultra-small sized silver cores are immersed in silica spheres, 40 nm in size. The nano-architecture provides an efficient electrochemical oxidation of Ag+@SiO2 without any external oxidant. In turn, Ag+@SiO2 5 mol% results in 100% conversion of arenes into their alkylated and fluoroalkylated derivatives in a single step at room temperature under nanoheterogeneous electrochemical conditions. Negligible oxidative leaching of silver from Ag0/+@SiO2 is recorded during the catalytic coupling of arenes with acetic, difluoroacetic and trifluoroacetic acids, which enables the good recyclability of the catalytic function of the Ag0/+@SiO2 nanostructure. The catalyst can be easily separated from the reaction mixture and reused a minimum of five times upon electrochemical regeneration. The use of the developed Ag0@SiO2 nano-architecture as a heterogeneous catalyst facilitates aromatic C-H bond substitution by alkyl and fluoroalkyl groups, which are privileged structural motifs in pharmaceuticals and agrochemicals.

6.
Dalton Trans ; 46(1): 165-177, 2016 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-27901542

RESUMO

A series of diverse binuclear and mononuclear cyclometalated palladium(ii) complexes of different structure was investigated by electrochemical techniques combined with density functional theory (DFT) calculations. The studies including cyclic and differential pulse voltammetry, X-ray structure analysis and quantum chemical calculations revealed a regularity of the complexes oxidation potential on the metal-metal distance in the complexes: the larger Pd-Pd distance, the higher oxidation potentials. The reduction potentials feature unusually high negative values while no correlation depending on the structure could be observed. These results are in a good agreement with the electron density distribution in the complexes. Additionally, ESR data obtained for the complexes upon oxidation is reported.

7.
Dalton Trans ; 45(30): 11976-82, 2016 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-27385649

RESUMO

We have developed Ni(III)-doped silica nanoparticles ([(bpy)xNi(III)]@SiO2) as a recyclable, low-leaching, and efficient oxidative functionalization nanocatalyst for aromatic C-H bonds. The catalyst is obtained by doping the complex [(bpy)3Ni(II)] on silica nanoparticles along with its subsequent electrooxidation to [(bpy)xNi(III)] without an additional oxidant. The coupling reaction of arenes with perfluoroheptanoic acid occurs with 100% conversion of reactants in a single step at room temperature under nanoheterogeneous conditions. The catalyst content is only 1% with respect to the substrates under electrochemical regeneration conditions. The catalyst can be easily separated from the reaction mixture and reused a minimum of five times. The results emphasize immobilization on the silica support and the electrochemical regeneration of Ni(III) complexes as a facile route for developing an efficient nanocatalyst for oxidative functionalization.

8.
Dalton Trans ; 44(19): 8833-8, 2015 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-25864923

RESUMO

Ni-catalyzed electroreductive olefin perfluoroalkylation affords both monomeric and dimeric products depending on the reaction media. Recycling of the catalyst can be achieved by immobilization of a (bpy)NiBr2 complex on silica nanoparticles decorated with anchoring amino-groups. Switching the homogeneous and heterogeneous catalysts is found to be one more factor to control the product ratio. This catalytic technique is both green and atom economical and combines the advantages of nanoheterogeneous catalysis and electrocatalysis.

9.
Molecules ; 19(9): 13603-13, 2014 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-25185067

RESUMO

New well-defined, paramagnetic nickel complexes have been prepared and characterized by X-ray crystallography. The complexes were found to be active for the cross-coupling of alkyl electrophiles (especially ethyl 2-bromobutyrate) with alkyl Grignard reagents. The ligand architecture in these new complexes could potentially be rendered chiral, opening up future possibilities for performing asymmetric cross-coupling reactions.


Assuntos
Aminofenóis/síntese química , Complexos de Coordenação/síntese química , Níquel/química , Cristalografia por Raios X , Modelos Moleculares , Conformação Molecular
10.
Chemistry ; 20(11): 3169-82, 2014 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-24523072

RESUMO

Eight-membered cyclic functional bisphosphines, namely 1,5-di-aryl-3,7-di(2-pyridyl)-1,5-diaza-3,7-diphosphacyclooctanes (aryl=2-pyridyl, m-tolyl, p-tolyl, diphenylmethyl, benzyl, (R)-(+)-(α-methyl)benzyl), with 2-pyridyl substituents on the phosphorus atoms have been synthesized by condensation of 2-pyridylphosphine, formaldehyde, and the corresponding primary amine. The structures of some of these bisphosphines have been investigated by X-ray crystallography. The bisphosphines readily form neutral P,P-chelate complexes [(κ(2)-P,P-L)MCl2], cationic bis-P,P-chelate complexes [(κ(2)-P,P-L)2 M](2+), or a five-coordinate complex [(κ(2)-P,P-L)2 NiBr]Br. The electrochemical behavior of two of the nickel complexes, and their catalytic activities in electrochemical hydrogen evolution and hydrogen oxidation, including the fuel-cell test, have been studied.

11.
Inorg Chem ; 50(17): 8630-5, 2011 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-21797263

RESUMO

A synthesis has been developed that allows the isolation of four-coordinate [(tpy)Ni-Br] (1, tpy = terpyridine) in high yield. Complex 1 has been structurally characterized, and the X-ray data reveal a square-planar geometry, unlike the known [(tpy')Ni-I] (tpy' = 4,4',4''-tri-tert-butyl-terpyridine) but similar to [(tpy)Ni-CH(3)]. In the solid-state, EPR spectroscopy indicates, however, that unlike [(tpy)Ni-CH(3)], the electronic structure of 1 is a metal-centered, not a ligand-centered radical. Density functional theory (DFT) analyses support this assignment. The preparation of 1 also facilitated the analysis of the redox potentials of a series of terpyridine nickel derivatives. It was found that the overall ligand sphere (one vs two coordinated terpyridine ligands) plays more of a role in determining the redox potentials of these derivatives than do the formal oxidation states of the nickel ions in the solution phase.


Assuntos
Níquel/química , Compostos Organometálicos/química , Piridinas/química , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Oxirredução , Estereoisomerismo
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