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Transition Metal Chemistry
Journal Prestige (SJR): 0.306  Citation Impact (citeScore): 1 Number of Followers: 6  Hybrid journal (It can contain Open Access articles)ISSN (Print) 1572-901X - ISSN (Online) 0340-4285 Published by Springer-Verlag  [2469 journals]
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- Asymmetrically tetra-substituted phthalocyanine derivatives: synthesis,
photophysical and photochemical properties-
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Abstract: Abstract The syntheses of highly soluble asymmetrically substituted metal free and zinc phthalocyanine derivatives bearing three 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy) and one 4-(2-(benzo[d]thiazol-2-yl)phenoxy) groups or bearing one 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy) and three 4-(2-(benzo[d]thiazol-2-yl)phenoxy) groups were reported for the first time in this study. The successful synthesis of phthalocyanines was achieved through the common statistical condensation method utilizing two different phthalonitriles named as 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy)phthalonitrile and 4-(2-(benzo[d]thiazol-2-yl)phenoxy)phthalonitrile. The asymmetrical phthalocyanines were characterized by spectroscopic methods. Moreover, the aggregation behavior, photophysical and photochemical properties of the substituted A3B type asymmetrical metal free and Zn (II) phthalocyanines were investigated in DMF. The asymmetrical Zn (II) phthalocyanine complexes produced highly singlet oxygen and appropriate fluorescence behavior in DMF suggesting that they can be suitable candidates as Type II photosensitizers in photodynamic therapy (PDT) applications.
PubDate: 2022-05-16
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- Advances in value-added aromatics by oxidation of lignin with transition
metal complexes-
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Abstract: Abstract Lignin is the second most abundant component in biomass, considered as the most abundant and available renewable source of aromatics in Nature. The depolymerization of lignin presents a sustainable way for producing value-added aromatic chemical platforms. Among all the transformation strategies, the catalytic oxidation transformation of lignin toward the production of highly functionalized aromatic chemicals is an efficient way for high-value chemicals. Herein, we review various transition metal complexes used for the effective transformation of lignin and lignin model compounds to aromatic building blocks, which involves metal porphyrins, metal salens, vanadium complexes, methyltrioxo rhenium and other highly elaborated complexes. The corresponding mechanisms are included. Based on the catalytic systems, challenges and future directions are discussed.
PubDate: 2022-04-13
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- Synthesis, characterization and antileishmanial activity of copper(II) and
zinc(II) complexes with diamine ligands-
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Abstract: Abstract A new set of copper- and zinc-diamine (N-alkylated (L1) and N,N'-dialkylated (L2)) complexes, [Cu(L1)2(NO3)2] (1), [Cu(L1)2(Cl)2].5H2O (2), [Cu(L2)2(NO3)2] (3), [Cu(L2)2(Cl)2] (4), [Zn(L1)2(C2H3O2)2] (5), [Zn(L1)2(Cl)2] (6), [Zn(L2)2(C2H3O2)2] (7), [Zn(L2)2(Cl)2] (8) were prepared by a reaction of the N-alkylated (L1) and N,N'-dialkylated (L2) with their respective copper and zinc salts under mild conditions. The metal complexes were fully characterized by physicochemical and spectroscopic methods. All new metal compounds exhibited significant biological activity against Leishmania amazonensis promastigotes when compared to the free ligands (L1 and L2).
PubDate: 2022-03-28
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- A family of 1D coordination polymers based on Ln–Cu 15-metallacrown-5
units with two topological sorting: syntheses, structures, and
single-chain magnet behaviour-
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Abstract: Abstract Three one-dimensional coordination polymers based on Ln–Cu 15-metallacrown-5 units were self-assembled via covalent bonds between pyrazine hydroxamic acid ligands and Cu atoms in the adjacent MC units. Due to the presence of different coordination anion ligands, complexes TbIII (1) and GdIII (2) show zig-zag-like topological structures, while complex DyIII (3) displays wheatear-like topological structure. The frequency dependence of the out-of-phase reveals that complexes 1 and 2 show slow relaxation of the magnetization, and complex 3 displays single-chain magnet behaviour.
PubDate: 2022-03-24
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- Synthesis, characterization, and electrochemistry of SNS cobalt(II)
tridentate complexes-
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Abstract: Abstract The preparation of two cobalt(II) complexes that contain a tridentate ligand with sulfur, nitrogen, and sulfur donor atoms is described. The tridentate ligand precursors are based on bis-imidazole or bis-triazole moieties. The complex based on a bis-imidazole precursor was green in color and was prepared in 93.3% yield. The complex based on a bis-triazole precursor was blue-green in color and was prepared in 69.8% yield. Single-crystal structures of both complexes were obtained. Both complexes contain [BF4]− as the counter-anion. Based on the single-crystal structure, the molecular geometry around the cobalt(II) center is distorted tetrahedral. EPR spectra were obtained for both complexes at 4 K. Each complex has axial symmetry for its electron density and each cobalt(II) complex has S = 3/2. For the complex based on a bis-imidazole precursor, the UV–Vis peaks were observed at 696 nm, 629 nm, 585 (sh) nm, and 375 (sh) nm. For the complex based on bis-triazole, UV–Vis peaks were observed at 681, 613, 570, 243, 239, 236, 233, 230, 227, and 210 nm. Cyclic voltammetry spectra were obtained for both complexes. Both the ligand precursor and the cobalt(II) complexes are redox active. All of the redox waves were irreversible.
PubDate: 2022-03-22
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- Synthesis, characterization and catalytic transfer hydrogenation
properties of Ru(II) complexes-
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Abstract: Abstract Three half-sandwich Ru(II) complexes with the general formulae of [Ru( \(\eta\) 6-p-cymene)(L)Cl2] (where L: 2a (diethyl-4-aminobenzylphosphonate), 2b (4-aminoethylbenzoate) and 2c (4-methoxybenzylamine) containing an aniline ligands were synthesized and their structures were characterized. The Crystal structure of complex [Ru( \(\eta\) 6-p-cymene)(2c)Cl2] was investigated by single crystal X-ray diffraction studies. Each Ru(II) ion in both complexes is coordinated with a 6-p-cymene nitrogen atom, two chloride and aniline derivatives. This results in a distorted piano-stool geometry. The catalytic performances of the complexes were investigated in transfer hydrogenation reactions. The complexes catalyze the transfer hydrogenation of cyclohexanone and 2-hexanone in the presence of a base. For 2-hexanone to 2-hexanol reduction, complex [Ru( \(\eta\) 6-p-cymene)(2a)Cl2] showed the highest conversion rate (at the end of 6 h) with 97% conversion. The complexes were found to be more active catalysts in the transfer hydrogenation of cyclohexanone than that of 2-hexanone.
PubDate: 2022-02-12
DOI: 10.1007/s11243-021-00488-y
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- Stereoselective homo- and co-polymerization of lactides and
ε-caprolactone catalysed by highly active racemic zinc(II) pyridyl
complexes-
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Abstract: A series of Zn(II) chlorido complexes (1′–5′) supported by N,N′-bidentate N-(pyridin-2-ylethyl)amine ligands have been synthesized. Zn(II) alkyl and alkoxy complexes 1′-Me–5′-Me and 1′-OBn–5′-OBn were synthesized in situ by first reacting complexes 1′–5′ with methyl lithium and subsequently with benzyl alcohol. Both species 1′-Me–5′-Me and 1′-OBn–5′-OBn showed excellent catalytic activity in ring-opening polymerization (ROP) of cyclic esters with the alkoxyl species performing better. The ROP reactions exhibited pseudo-first-order kinetics with respect to monomer concentration. Polymer molecular weights increased as ligand steric hindrance decreased and they lie between 3096 and 8837 g mol−1 and relatively high molecular weight distributions with dispersity (Ð) values ca. 2 were observed. The poly(rac-lactide) polymers were predominantly heterotactic, while poly(ʟ-lactides) formed were largely isotactic. All polymerization reactions proceeded through coordination insertion mechanism followed by hydrolysis of the metal. Notably, the stereogenic centres of the ligand skeleton influenced control of polymer stereochemistry. Random copolymerization of ε-caprolactone (ε-CL) and lactides (LA) resulted in block gradient copolymers. The sequential addition of lactides after ε-CL gave diblock PCL-b-PLA, and reversing monomer addition did not form any copolymer. Graphical abstract
PubDate: 2022-02-11
DOI: 10.1007/s11243-022-00493-9
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- N3/4-pyridinyl Schiff base copper(II) benzoate complexes: synthesis,
crystal structures and ring-opening polymerization studies-
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Abstract: Abstract Five benzoate complexes of copper(II) were synthesized by the reaction of N-donor Schiff base ligands with copper(II) acetate and benzoate co-ligands. All complexes were characterized by physicochemical, spectroscopic techniques and single-crystal X-ray diffraction studies. Crystal structure analysis revealed mononuclear complexes Cu(C6H5COO)2(L1)2·H2O (1) with a square pyramidal geometry and Cu(Me-C6H5COO)2(L2)2·2H2O (3) with a distorted octahedral geometry around the Cu(II) center. Three other complexes [Cu(C6H5COO)2(L2)]2·(2), [Cu(Me-C6H5COO)2(L3)]2·(4) and [Cu(C6H5COO)2(L4)]2·(5) all adopted a paddlewheel conformation in which the two Cu(II) centers each have a square pyramidal geometry. All complexes were found to be active as catalyst in ring-opening polymerization of ɛ-caprolactone (ε-CL), yielding low molecular weight polymers of about 2200 g mol−1 to 3870 g mol−1. The activity of complex 4 increased with the addition of different alcohol co-initiators except in t-butanol where a reduction was obtained arguably due to steric hindrance.
PubDate: 2022-02-04
DOI: 10.1007/s11243-022-00494-8
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- An investigation into luminescent phenoxo-bridged heterobimetallic
copper(II)–calcium(II)/strontium(II)-based bis(salamo)-like complexes-
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Abstract: Two luminescent hetero-trinuclear complexes [Cu2Ca(L)(µ2-NO3)2] (1) and [{Cu2Sr(L)(µ2-NO3)(ƞ2-NO3)}2]·2EtOH·H2O (2) have been prepared by a flexible bis(salamo)-based ligand (H4L) with Cu(NO3)·3H2O and M(OAc)2·nH2O (M(II) = Sr, n = 2; Ca, n = 1), respectively. The structural characterizations were performed by physicochemical and spectroscopic methods. Two penta-coordinate Cu(II) atoms of complex 1 are sited at the N2O2-donor coordination environments of the (L)4− moiety, while tetra- and penta-coordinate Cu(II) atoms in complex 2 are also located in the N2O2 cavities of the (L)4− unit. Ca(II) and Sr(II) atoms are located in various O8 and O9 cavities, respectively. In the solid state, infinite 3D supra-molecular structures are formed in complexes 1 and 2 through the abundant intermolecular hydrogen bonds and π···π interactions. These interactions were quantitatively analyzed by Hirshfeld surface analyses. DFT calculations and fluorescence properties showed that complexes 1 and 2 have stable chemical properties and good luminescence properties. Graphical abstract Two hetero-trinuclear complexes [Cu2Ca(L)(µ2-NO3)2] (1) and [{Cu2Sr(L)(µ2-NO3)(ƞ2-NO3)}2]·2EtOH·H2O (2) have been synthesized and characterized structurally. Two penta-coordinate Cu(II) atoms in complex 1 are located in the N2O2 cavities of the (L)4− unit, while tetra- and penta-coordinate Cu(II) atoms in complex 2 are also located in the N2O2 cavities of the (L)4− unit. There are eight and nine oxygen donor atoms coordinating to the Ca(II) and Sr(II) atoms. Infinite 3D supra-molecular structures are formed in complexes 1 and 2 through the intermolecular hydrogen bonds and π···π stacking interactions.
PubDate: 2022-01-27
DOI: 10.1007/s11243-021-00489-x
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- Mononuclear copper(II) complexes of the macrolide antibiotics tylosin and
tilmicosin-
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Abstract: Abstract The 16-membered macrolide antibiotics tylosin (HTyl) and tilmicosin (HTilm) react with Cu(II) to form isostructural mononuclear complexes of composition [CuL2] (L = Tyl− (1), Tilm− (2)). Reactions take place in aqueous alkaline solutions, at molar metal-to-ligand ratio ranging from 1:10 to 1:2. The coordination species obtained were characterized by physico-chemical and spectroscopic methods. Experimental data and quantum chemical calculations revealed that the copper atom is placed in a square-planar environment and the main chromophore unit is of composition [CuN2O2]. The complexes consist of two ligand monoanions acting in a bidentate coordination mode via the tertiary nitrogen atom and the deprotonated hydroxyl group of the mycaminosyl substituent. The antibacterial assay of the macrolides and their mononuclear copper(II) complexes 1–2 against Gram-positive microorganisms demonstrated that the new coordination compound of tilmicosin exhibits enhanced activity compared to that of the parent ligand.
PubDate: 2022-01-20
DOI: 10.1007/s11243-022-00491-x
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- Synthesis, crystal structure, and photocatalytic property of
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Abstract: A new heterometallic calcium‒titanium oxo cluster formulated as [Ca2Ti8(μ3-O)8(AcO)2(OiPr)2(BA)16]·4H2O (BA = benzoate) was synthesized and structurally characterized by single-crystal X-ray diffraction analysis. The cluster core contains a crown-ether-like Ti8O8 ring with two Ca atoms embedded in it. Due to the unique {Ti8Ca2O8} core structure and the coordination with sixteen bridging benzoate ligands, this cluster exhibits high structural stability in aqueous solutions with a wide pH range. Photocatalytic experiments for the degradation of methyl orange demonstrate the high photocatalytic activity and good recycling stability of the cluster. Graphical abstract
PubDate: 2022-01-19
DOI: 10.1007/s11243-021-00487-z
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- Manganese(II)-based coordination polymer as a bi-responsive luminescent
sensor for highly selective detection of picric acid and CrO42− ion-
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Abstract: A novel luminescent coordination polymer (CP) {Mn(H2abtc)(DMF)(H2O)2·2H2O}n (1), (H4abtc = 3,3′,5,5′-azobenzenete-tracarboxylic acid), has been successfully prepared by the solvothermal reaction of H4abtc and MnCl2·4H2O, which has been further characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis (TGA), infrared (IR) spectrum and powder X-ray diffraction (PXRD). 1 can serve as a potential dual response luminescence sensor for picric acid (PA) and CrO42− via luminescence quenching with good selectivity and sensitivity. The quenching behavior of PA toward 1 can be ascribed to the combined effects of electron and resonance energy transfer mechanisms. And the quenching phenomenon of CrO42− to 1 can be explained by the electron transfer mechanism. Graphical abstract A novel luminescent Mn(II)-based coordination polymer 1 has been successfully prepared. 1 can serve as a potential dual response luminescence sensor for Picric acid (PA) and CrO42− with good selectivity and sensitivity.
PubDate: 2022-01-18
DOI: 10.1007/s11243-022-00492-w
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- 6-Membered cyclopalladated complex of 1-N-ferrocenylmethylindazole and its
catalytic activity in cross-coupling Suzuki reactions-
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Abstract: Abstract The new organometallic derivatives 1-N- and 2-N-ferrocenylmethylindazoles (1 and 2) were synthesized as ligand precursors. Direct cyclopalladation of 1 using different palladating agents (Li2PdCl4, Na2PdCl4, Pd(OAc)2/LiCl) followed by the addition of PPh3 led to the 6-membered palladacycle 3. The structures of new ferrocene ligand precursors 1 and 2 and CN cyclopalladated complex 3 were characterized by physicochemical and spectroscopic methods. The single-crystal X-ray analysis of 3 indicated a boat conformation of the 6-membered palladacycle. The obtained bimetallic complex 3 appeared to be an active precatalyst in the Suzuki reactions of aryl bromides with phenylboronic acid.
PubDate: 2022-01-16
DOI: 10.1007/s11243-021-00486-0
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- Nickel(II) and cobalt(II) complexes with
4,5-dichloro-isothiazole-3-carboxylic acid and 1,10-phenanthroline:
synthesis, crystal structures and cytotoxicity-
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Abstract: Abstract In this study, Ni(II) and Co(II) complexes [Co(H2O)2L2] (1), [Ni(H2O)2L2] (2), [Co(phen)L2] (3), [Ni(phen)L2]·2H2O·EtOH (4·2H2O), and [Ni(phen)2(H2O)L]·L·2H2O (5), where L—4,5-dichloro-isothiazole-3-carboxylate anion and phen—1,10-phenanthroline are reported. All complexes have been characterized by physicochemical and spectroscopic methods. Mass spectrometry and UV–Vis spectroscopy have been used to show the behavior of complexes in ethanol solution and phosphate buffer saline. Crystal structures of mononuclear complexes 1, 4 and 5 have been determined by single-crystal X-ray diffraction. In the structure of 4, mononuclear units have been found to form infinite zigzag chains due to the presence of Cl•••Cl non-covalent interactions which can be regarded as halogen bonding. All complexes have been screened in vitro for their cytotoxic activity against Hep2 cancer cell line. The complexes obtained showed no activity (IC50 > 50 µM) in comparison with structurally related Cu(II) complex [Cu(phen)(H2O)L2] exhibiting dose-dependent toxicity comparable to that of cisplatin (IC50 = 3.06 ± 0.07 µM (Cu(II) complex), IC50 = 9.2 ± 0.5 µM (cisplatin)). DNA binding constants were determined using absorption titration: Cu(II), Ni(II) and Co(II) complexes possessed similar DNA binding efficacy (Kb ~ 104).
PubDate: 2022-01-12
DOI: 10.1007/s11243-021-00490-4
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- Diarylazooxime complex of cobalt(III): synthesis, structure, ligand redox,
DFT calculations and spectral characteristics-
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Abstract: By using a multifunctional diarylazooxime ligand LNOH 1, incorporating electron deficient azo chromophore in conjunction with a pendant π-electron-rich naphthyl group, the trans dichloro bis complex of type [CoIII(LNOH)(LNO−)Cl2] 2 has been synthesized. The structure of the chelate has been determined by X-ray crystallography, thereby authenticating the presence of oxime-oximato hydrogen bond within the coordinated moiety. The stability of this complex is attributed to intra-molecular hydrogen bonding as well as due to strong Phπ–Phπ stacking interactions. The complex has been characterized by several spectroscopic techniques, and their electrochemical properties have been reported. These are further complemented by theoretical studies in the form of DFT and TDDFT. The visible excitation for the complex arises from mainly mixed singlet manifold 1ILCT and 1LLCT transitions. Graphical abstract
PubDate: 2022-01-12
DOI: 10.1007/s11243-021-00485-1
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- Inorganic–organic hybrids assembled by flexible multidentate linker:
design, structure and luminescence-
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Abstract: Abstract Three coordination complexes, [Cu(L1)(2,2–bipy)]2n·3nH2O (1), [Cu(L1)(2,2–bipy)2]·xH2O (2: x = 3.5 and 3: x = 5), were synthesized by reactions of the flexible ligand 1,1´-methylenebis(5-methyl-pyrazole-4-carboxylic acid) (H2L1) and coligands 2,2'–bipyridyl (2,2-bipy) with Cu(OAc)2·H2O in different reaction condition, respectively. The structures of these complexes were established by elemental analysis, IR and single-crystal X-ray diffraction analysis. Complex 1 possessed a one-dimensional (1D) chainlike structure, (L1)2− group exhibited trans-configuration and coordinated to Cu(II) ions by carboxylate O atoms in µ2–k:O,O′; k:O′′′,O′′′ mode. In the similar subjectival structure of 2 and 3, (L1)2− anions also presented trans-configuration, but only one carboxylate group chelated to a Cu(II) ion, and the other carboxylate group remains free in a deprotonated form. The 1D chains in 1 were further assembled to a 3D supramolecular architecture via intermolecular C–H···O hydrogen bond. The mononuclear zwitterionic complexes 2 and 3 are further assembled into a 2D/3D supramolecular architecture by intermolecular hydrogen bonds and π···π interaction. The thermal and photoluminescent properties of 1–3 in the solid state have also been investigated.
PubDate: 2021-12-01
DOI: 10.1007/s11243-021-00475-3
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- ADT-Type [FeFe]-hydrogenase biomimics featuring monodentate phosphines:
formation, structures, and electrocatalysis-
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Abstract: Abstract To further develop the diiron subsite biomimics of [FeFe]-hydrogenases, two new diiron azadithiolate (adt) complexes Fe2(μ-adtNPh)(CO)5(Ph2PX) (X = NHBut, 1 and P(O)Ph2, 2) featuring monodentate phosphines were unexpectedly produced by the Me3NO-induced decarbonylating reactions of all-CO diiron precursor Fe2(μ-adtNPh)(CO)6 (A, adtNPh = (SCH2)2NPh) with different aminodiphosphines (Ph2P)2NR (R = But and C6H4Cl-p) in MeCN at ambient temperature. The as-obtained complexes 1 and 2 have been fully characterized by means of elemental analysis, FT-IR, (1H, 31P) NMR spectroscopies and further confirmed by X-ray crystallography. At the same time, the electrochemical and electrocatalytic behaviors of 1 and 2 have been studied and compared in the absence or presence of acetic acid (HOAc) as a proton source by cyclic voltammetry (CV), suggesting that they can be considered as the active biomimetic electrocatalysts for proton reduction to hydrogen (H2).
PubDate: 2021-12-01
DOI: 10.1007/s11243-021-00482-4
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- Nickel(II) complexes with mono(imino)pyrrole ligands: preparation,
structure, DFT calculation and catalytic behavior-
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Abstract: Abstract In recent years, a variety of novel late transition metal catalysts have been used for polymerization of methyl methacrylate (MMA); in order to study the effects of fine-tuning of catalyst structure on polymerization of MMA, we synthesized a series of mono(imine)pyrrole ligands (L1–L5) with different substituents in the same position using microwave reactions. Then, the ligands were directly coordinated with NiCl2·6H2O through liquid-phase reaction method to prepare the Ni(II) complexes (1–4). All the compounds were characterized by spectroscopic methods, and compounds L1, L3, L5 and 2 were characterized by X-ray crystallography. The results showed that the structures of the three ligands were mono(imine)pyrrole Schiff base structure. Complex 2 contains two molecular ligands’ structure and a Ni(II) atom to form a standard square plane geometry. The total molecular energy and other data for each Ni(II) complex were obtained by Gaussian 09 calculation program. The negative total molecular energy indicated the structures of complexes were relatively stable. Additionally, the bond parameters were in good agreement with X-ray single-crystal diffraction data. With the aid of azodiisobutyronitrile (AIBN), the synthesized Ni(II) complexes were used in the polymerization of MMA. By comparing the Ni(II) catalysts with different structures, we found catalytic activities were in a sequence of 4 > 1 > 2 > 3, which indicated the stronger electron-withdrawing ability of the substituent, the better catalytic activity of catalyst for MMA. We also studied the effects of polymerization temperature and time on catalytic performance, the optimum activity (11.71 × 104 g mol−1·h−1) was obtained at 100℃ and 10 h, and the polymer with relatively narrow molecular weight distribution (PDI = 1.91) and large molecular weight (Mn = 36.10 × 104 g mol−1) was obtained under the same condition.
PubDate: 2021-12-01
DOI: 10.1007/s11243-021-00478-0
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- Synthesis, crystal structures, luminescence and magnetic property of two
complexes based on 5-nitroisophthalic acid-
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Abstract: Abstract Based on 5-nitroisophthalic acid (5-H2nip) and bis(4-pyridyl)amine (dpa), the complexes {[Cd6(5-nip)6(dpa)4]·EtOH}n (1) and [Co5(5-nip)2(dpa)2(OH)2(SO4)2(H2O)2]n (2) have been synthesized and characterized by elemental analysis, single-crystal X-ray diffraction, IR spectroscopy, thermal gravimetry analysis, fluorescence and magnetic susceptibility. The carboxylate groups of the 5-nip2− adopt three different bridging modes [bis(chelate-bidentate), bis(bidentate) and bis(monodentate)]. The 5-nip2− anions and dpa play as linkers, which connect Cd(II) or Co(II) ions to form the three-dimensional structures of 1 and 2. Moreover, 1 exhibits intense solid-state luminescence emissions centered at 402 nm at room temperature, which mainly originates from the intraligand π–π* transitions of 5-nip2−. Magnetic susceptibility measurement indicates that 2 shows antiferromagnetic interactions between the Co(II) ions.
PubDate: 2021-11-30
DOI: 10.1007/s11243-021-00484-2
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- Synthesis and ethylene oligomerization behavior of trinuclear nickel
complex with phosphorus dendrimer-
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Abstract: Abstract A phosphorus dendrimer with multiple amino groups was synthesized via a two-step reaction with phosphonitrilic chloride trimer and 4-acetamidophenol. The trinuclear nickel complex was subsequently prepared with the phosphorus dendrimer and nickel chloride hexahydrate as starting materials. The structures of the phosphorus dendrimer and the trinuclear nickel complex were characterized by physicochemical and spectroscopic methods. The trinuclear nickel complex based on the phosphorus dendrimer was evaluated as catalyst precursor for ethylene oligomerization using methylaluminoxane (MAO) as an activator. Under the conditions of 0.5 h, 0.9 MPa, 25 °C and Al/Ni molar ratio of 700, the catalytic activity of the trinuclear nickel complex showed a maximum value of 2.31 × 105 g/(mol Ni h), and the oligomerization products were mainly low-carbon olefins (C4 and C6). The ligand structure and the coordination mode showed notable variations in the catalytic activities and the product distribution due to the influence of electronic and steric effects. The catalytic activity of the nickel complex based on the ligand with an aryl backbone was superior to the nickel complex based on the ligand with an alkyl backbone.
PubDate: 2021-11-18
DOI: 10.1007/s11243-021-00483-3
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