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A series of zinc complexes of the general formula {[ZnCl(ArN=C(An)-C(An)=NAr)](+)}(2)[Zn(2)Cl(6)](2-) (where Ar = 2-(1-benzyl-1H-1,2,3-triazol-4-yl)phenyl 2a, 2-(1-(1-phenylethyl)-1H-1,2,3-triazol-4-yl)phenyl 2b, 2-(1-phenyl-1H-1,2,3-triazol-4-yl)phenyl 2c; An = acenaphthene backbone) were prepared by the condensation of acenaphthenequinone with th...
Citations
... Their key feature is the ability to reversibly accept up to four electrons and reversibly exchange them with coordinating metal, which may facilitate the course of multi-electron chemical processes. Thus, the complexes with iminoacenaphthenes are often applied in olefin polymerization reactions [12][13][14][15][16][17][18] and also exhibit a high catalytic activity in many organic reactions [19][20][21][22][23][24][25][26]. ...
The organometallic complex [Pd(dpp-bian)(C4(COOMe)4)]·(C2H5)2O (1·(C2H5)2O) is obtained by the interaction of [Pd2(dba)3] (dba = dibenzylideneacetone) with dimethyl ether of acetylenedicarboxylic acid and 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in the 1:4:2 molar ratio. During the oxidative addition reaction the 1,2,3,4-tetrakis(methoxycarbonyl)buta-1,3-dienyl dianion is formed from two molecules of dimethyl ether of acetylenedicarboxylic acid. This dianion is coordinated to palladium(II) via 1 and 4 carbon atoms with the formation of the palladacyclopentadienyl moiety. The crystal structure is determined by the single crystal X-ray diffraction analysis. The 1·(C2H5)2O compound crystallizes in the orthorhombic crystal system (Pbca) with unit cell parameters a = 16.9069(3) Å, b = 23.5618(6) Å, c = 23.8902(7) Å, V = 9516.83(40) ų. Each palladium atom has an almost square planar environment composed of two dpp-bian nitrogen atoms and two carbon atoms of the (C4(COOMe)4)2– anion. The cyclic voltammogram of 1 in acetonitrile reveals irreversible oxidation at Ea = 1.43 V, reversible reduction at E1/2 = 0.62 V, and irreversible reduction at Eb = 1.52 V. The electronic structure of complex 1 is studied within the density functional theory. [Figure not available: see fulltext.]
... Acenaphthene-1,2-diimine (R-bian) ligands (Scheme 1) are of particular note, as they are capable of accepting up to four electrons due to the reduction of both diimine and naphthalene components. Metal complexes with R-bian ligands are being actively studied in connection with the search for new effective catalysts for organic synthesis, as well as for materials with unusual redox and magnetic properties [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. ...
A new monoiminoacenaphthenone 3,5-(CF3)2C6H3-mian (complex 2) was synthesized and further exploited, along with the already known monoiminoacenaphthenone dpp-mian, to obtain oxidovanadium(IV) complexes [VOCl2(dpp-mian)(CH3CN)] (3) and [VOCl(3,5-(CF3)2C6H3-bian)(H2O)][VOCl3(3,5-(CF3)2C6H3-bian)]·2.85DME (4) from [VOCl2(CH3CN)2(H2O)] (1) or [VCl3(THF)3]. The structure of all compounds was determined using X-ray structural analysis. The vanadium atom in these structures has an octahedral coordination environment. Complex 4 has an unexpected structure. Firstly, it contains 3,5-(CF3)2C6H3-bian instead of 3,5-(CF3)2C6H3-mian. Secondly, it has a binuclear structure, in contrast to 3, in which two oxovanadium parts are linked to each other through V=O···V interaction. This interaction is non-covalent in origin, according to DFT calculations. In structures 2 and 3, non-covalent π-π staking interactions between acenaphthene moieties of the neighboring molecules (distances are 3.36–3.40 Å) with an estimated energy of 3 kcal/mol were also found. The redox properties of the obtained compounds were studied using cyclic voltammetry in solution. In all cases, the reduction processes initiated by the redox-active nature of the mian or bian ligand were identified. The paramagnetic nature of complexes 3 and 4 has been proven by EPR spectroscopy. Complexes 3 and 4 exhibited high catalytic activity in the oxidation of alkanes and alcohols with peroxides. The yields of products of cyclohexane oxidation were 43% (complex 3) and 27% (complex 4). Based on the data regarding the study of regio- and bond-selectivity, it was concluded that hydroxyl radicals play the most crucial role in the reaction. The initial products in the reactions with alkanes are alkyl hydroperoxides, which are easily reduced to their corresponding alcohols by the action of triphenylphosphine (PPh3). According to the DFT calculations, the difference in the catalytic activity of 3 and 4 is most likely associated with a different mechanism for the generation of ·OH radicals. For complex 4 with electron-withdrawing CF3 substituents at the diimine ligand, an alternative mechanism, different from Fenton’s and involving a redox-active ligand, is assumed.
... In recent years, zinc complexes containing chelating N,O-, N,N-chromophores have become the focus of intense research [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. These complexes contain chromophores that emit visible light at wavelengths depending on the composition and structure of the material, thereby the colour of emission. ...
A series of pyrene-based salicylaldimine-type ligands containing n-octyl or cyclohexyl or phenyl groups at imine nitrogen group, 1-hydroxy-2-[(N-substituted-imino)methyl]-pyrenes (octyl 1, cyclohexyl 1b and phenyl 1c), were synthesized and characterized. The ligands reacting with zinc acetate in the presence of sodium acetate gave the bis(salicylaldiminato)-type Zn(II) complexes, [bis[2-[(N-substituted-imino)methyl]-1-pyrenolato-N,O] zinc(II)] (octyl 1(Zn), cyclohexyl 1b(Zn), phenyl 1c(Zn)). The new ligands and complexes were characterized by 1H NMR, IR spectroscopy, mass spectroscopy, elemental analysis, UV-vis spectroscopy, fluorescence spectroscopy, and X-ray diffraction. The influence of the π-extended conjugation of the pyrene-based salicylaldiminato-type ligands coordinated to Zn2+ greatly induces red-shift of the complexes 1(Zn), 1b(Zn) and 1c(Zn) in absorption and emission spectra. These results were confirmed by density-functional theory (DFT) and time-dependent DFT (TDDFT) molecular orbital calculations. Moreover, single crystal structure of simple salicylaldiminato Zn(II) complex 1’b(Zn) was compared to that of the corresponding pyrene-type salicylaldiminato complex 1b(Zn).
... [23] Ni-triazole complexes have been also used as catalysts for the polymerization of olefins, showing an efficiency comparable to Schiff base complexes. [24,25] In this work, we considered the use of triazole moiety as complexing element for designing a novel electrochemical label that offers better stability and hydrolysis resistance in aqueous solution than Schiff base complexes. The new synthesized bistriazole ligand and its corresponding copper complex were characterized through their crystallographic structures, electronic properties (UV-vis and EPR) and electrochemical activities. ...
The bis‐triazole ligand and its corresponding copper complexes were synthesized and characterized for the first time and proposed as new labels for the development of electrochemical aptasensors. The bis‐triazole ligand was prepared from methyl 1,6‐heptadiyne‐4‐carboxylate and 2‐(azidomethyl)phenol using classical CuAAC in presence of different copper salts. The X‐ray structure of bis‐triazole showed a symmetry center (C1). UV‐Vis and X‐band EPR spectra showed that the coordination capacity of the bis‐triazole ligand was improved in the presence of triethylamine due to deprotonation of the triazole and phenolate moieties. After complexation with copper, the obtained complex was successfully attached to an anti‐estradiol aptamer through thiol‐maleimide coupling, and the resulting labelled aptamer was immobilized on a carbon screen‐printed electrode by carbodiimide coupling. The electrochemical response of the resulting sensor was shown to decrease in the presence of estradiol, demonstrating that the developed complexes can be applied for the development of aptasensors.
... The key characteristic of BIANs as strong p-acceptor molecules is their ability to reversibly accept up to four electrons, and reversibly exchange electrons with the coordinated metal, which can trigger redox based chemical processes. The BIANs have been extensively studied in olefin polymerization reactions [15][16][17][18][19][20][21][22][23][24] and have been shown to be catalytically active in many other organic transformations [25][26][27][28][29][30][31][32][33][34][35][36]. In addition, a reversible metal-to-ligand electron transfer (redox isomerism or valence tautomerism) has been established in such metal complexes [3,7,8,10]. ...
... In a recent work, we have synthesised a series of tetradentate chelated a-diimine nickel(II) complexes [NiBr 2 (ArN@C(An)-C(An)@NAr)] (where Ar = 2-(1-benzyl-1H-1,2,3-triazol-4-yl)phenyl (1), 2-(1-(1-phenylethyl)-1H-1,2,3-triazol-4-yl)phenyl (2), 2-(1-phenyl-1H-1,2,3-triazol-4-yl)phenyl (3); An = acenaphthenic backbone), as represented in Scheme 1, and preliminary tests showed that complexes 1-3 are precatalysts for the polymerization of norbornene and styrene when activated with MAO [18]. Further studies on the polymerization of norbornene catalyzed by 1-3/MAO systems concluded that it follows a coordination addition mechanism [19]. ...
... Methylaluminoxane (MAO) of the type PMAO-IP (7 wt.% Al) was purchased from AkzoNobel. The nickel precatalysts [NiBr 2 (ArN@C(An)-C(An)@NAr)] (where Ar = 2-(1-benzyl-1H-1,2,3-triazol-4-yl)phenyl (1), 2-(1-(1-phenylethyl)-1H-1,2, 3-triazol-4-yl)phenyl (2), and 2-(1-phenyl-1H-1,2,3triazol-4-yl)phenyl (3); An = acenaphthenic backbone) were prepared as reported in a previous publication [18]. The deuterated solvent 1,1,2,2-tetrachloroethane-d 2 was dried by storage over 4 Å molecular sieves and degassed by the freeze-pump-thaw method. ...
... phenyl-1H-1,2,3-triazol-4-yl)phenyl (3); An ¼ acenaphthenic backbone), as represented in Scheme 3. [23] Preliminary testing of complexes 1-3 revealed they were inactive in the metal-catalysed homopolymerisation of ethylene and 1-hexene, but active in the addition homopolymerisation of norbornene and of styrene, when activated with MAO. Particularly, in the case of norbornene, high catalytic activities and molecular weights were obtained in the production of polynorbornenes. ...
... The nickel precatalysts [NiBr 2 (ArN ¼ C(An)-C(An) ¼ NAr)] (where Ar ¼ 2-(1benzyl-1H-1,2,3-triazol-4-yl)phenyl 1, 2-(1-(1-phenylethyl)-1H-1,2,3-triazol-4-yl)phenyl 2, 2-(1-phenyl-1H-1,2,3-triazol-4-yl)phenyl 3; An¼ acenaphthenic backbone) were prepared as reported in a previous publication. [23] The deuterated solvents 1,1,2,2tetrachloroethane-d 2 was dried by storage over 4 Å molecular sieves and degassed by the freeze-pump-thaw method, and stored under nitrogen. ...
... It was demonstrated that complexes 1-3 possess octahedral geometries around the metal centres and are stereochemically non-rigid, being their coordination configurations variable, as displayed in Scheme 6. [23] The pendant labile triazolyl groups can adopt different coordination orientations with respect to the acenaphthene-adiimine plane (Scheme 6). ...
A series of three recently synthesised tetradentate chelated alpha-diimine nickel complexes of the type [NiBr2(Ar-BIAN)] (where Ar = 2-(1-R-1H-1,2,3-triazol-4-yl)phenyl; R = benzyl 1, 1-phenyl-ethyl 2, phenyl 3) are used as precatalysts for the polymerisation of norbornene. When activated with MAO, 1-3 are highly active catalysts for the production of high molecular weight polynorbornene (e. g., 1.39 x 10(7) g PNB mol Ni-1 . h(-1)). The catalytic activity and polymer molecular weight increase markedly with the initial concentration of norbornene, but both parameters decrease with the reaction time. The characterisation of the poly-norbornenes by NMR, GPC/SEC, X-ray diffraction, and DSC/TGA leads to the assignment of a structure typical of a polynorbornene originated by a coordination vinyl addition mechanism.
The study of transition metal complexes linked with 1,2,3-triazoles has gained significant attention due to their potential as effective catalysts in various chemical reactions. The 1,2,3-triazole moiety has been proven to be an excellent ligand in metal complex catalysis, primarily because of its unique electronic and steric properties. The ability to tune these properties through modifications to the triazole ligand allows for precise control over the reactivity and selectivity of the metal complex. This review provides a critical assessment of the recent advances made in the development of 1,2,3-triazolyl ligated transition metal complexes and their uses in catalysis with emphasis on how structural variation impacts on the catalytic performances of these complexes.
Five dinuclear copper(I) complexes of the type [Cu{κ N ,κ N’ -5-R-NC 4 H 2 -2-C(H)=N(2,6- i Pr 2 C 6 H 3 )}] 2 ( 1a - e ; R = 2,4,6- i Pr 3 C 6 H 2 ( a ), R = 2,6-Me 2 C 6 H 3 ( b ), R = 3,5-(CF 3 ) 2 C 6 H 3 ( c ), R = 2,6-(MeO) 2 C 6 H 2 ( d ), R = CPh 3 ( e )) were...
In the present report, three mononuclear azo-aromatic complexes of Co(II), 1-3, and an imine-based Co(II) complex, 4, were synthesized through a reaction of respective amine-functionalized pincer-like ligands, HL1-4, with CoCl2·6H2O in the ligand-to-metal ratio of 1 : 1. All the complexes, 1-4, were thoroughly characterized using various physicochemical characterization techniques, single-crystal X-ray structure determination, and density functional theory (DFT) calculations. Complexes 1-4 were explored for the catalytic styrene polymerisation reaction separately in the presence of modified methyl aluminoxane (MMAO). All the complexes, 1-4, are indeed active for the polymerisation of styrene under mild conditions at room temperature upon activation with MMAO. Among the azo-aromatic complexes 1-3, complex 3 is the most efficient. The activity of the imine complex 4 is poor compared to those of the azo-aromatic complexes 1-3. The weight average molecular weight (Mw) of the isolated polystyrene ranges from 32.9 to 144.0 kg mol-1, with a polydispersity index (Đ) in the range of 1.1-1.8. Microstructural analysis of the isolated polymer from complexes 1-4 was carried out by 13C NMR spectroscopy, infrared spectroscopy, and powder X-ray diffraction studies. Their thermal properties were scrutinized by differential scanning calorimetry and thermogravimetric analysis. These studies have shown the atactic and amorphous nature of the polymers. The mechanical strength of the polymers was measured by a nanoindentation technique which has shown the good plastic/soft nature of the polymers.
