Stephen O. Ojwach

Stephen O. Ojwach
University of KwaZulu-Natal | ukzn · School of Chemistry and Physics

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95
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Publications

Publications (95)
Article
Selective extraction of water-bound metal cations through chelating agents is investigated. Reactions of 2,6-pyridinedimethanol (L1) with Cu(NO3)2.3H2O, Zn(NO3)2.6H2O and Cd(NO3)2.4H2O produced complexes [Cu(L1)2] (1), [Zn(L1)2] (2), and [Cd2(μ-NO3)(L1)2] (3), respectively. The solid-state structures of 1, 2, and 3 confirmed that L1 coordinates in...
Article
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The phenoxy-amino ligands 2-(((2-(diethylamino)ethyl)amino)methyl)phenol (L1) and 2-(((2-mercaptoethyl)amino)methyl)-phenol (L2) were studied as model chelating agents for liquid-liquid extraction of copper(II), zinc(II), cadmium(II), and lead(II) cations from water using dichloromethane-water biphasic system. The relative affinities of these chela...
Article
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Reactions of N-(benzo[d]thiazol-2-yl)pyrazine-2-carboxamide (HL1) and N-(1H-benzo[d]imidazol-2-yl)- pyrazine-2-carboxamide (HL2) ligands with Ru(PPh3)3ClH(CO) and Ru(PPh3)3(CO)2H2 precursors afforded the respective organo-carboxamide ruthenium(II) complexes [Ru(II)(CO)Cl(PPh3)2L1] (Ru1), [Ru(II)(CO)- H(PPh3)2L1] (Ru2), [Ru(II)(CO)Cl(PPh3)2L2] (Ru3)...
Article
The metal complexes [Fe(L1)2] (Fe1); [Fe(L2)2] (Fe2); [Fe(L3)2] (Fe3); [Co(L1)2] (Co1); [Co(L2)2] (Co2); [Co(L3)3] (Co3); [Ni(L1)2] (Ni1); [Ni(L2)2] (Ni2) and [Ni(L3)3] (Ni3); where L = 2,4-dibromo-6-((pyridin-2-ylimino)methyl)phenol (L1H), 2,4-dibromo-6-(((4-methylpyridin-2-yl)imino)methyl)phenol (L2H) and 2,4-dibromo-6-((quinolin-8-ylimino)methyl...
Article
Reactions of 2-[{(2-hydroxyethyl)imino}methyl]phenol (L1) and 2-[1-{2-(diethylamino)ethylimino}ethyl]phenol (L3) with copper(II) nitrate yielded monometallic complexes [CuNO3(L1)] (1) and [CuNO3(L3)] (2), respectively. The solid-state structures of 1 and 2 confirmed the κ³-O,N,O’ and κ³-O,N,N’ tridentate binding mode of L1 and L3, respectively. The...
Article
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Reactions of ligands (E)-N′-(2,6-diisopropylphenyl)-N-(4-methylpyridin-2-yl)benzimidamide (L1), (E)-N′-(2,6-diisopropylphenyl)-N-(6-methylpyridin-2-yl)benzimidamide (L2), (E)-N′-(2,6-dimethylphenyl)-N-(6-methylpyridin-2-yl)benzimidamide (L3), (E)-N′-(2,6-dimethylphenyl)-N-(4-methylpyridin-2-yl)benzimidamide (L4), and (E)-N-(6-methylpyridin-2-yl)-N′...
Article
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The syntheses and characterization of fish scale biochar magnetic composites (FSB@Fe3O4) and their applications in the removal of indigo carmine dye from effluents are described. Preparation of the fish scale biochar magnetic composites, FSB@400 °C-Fe3O4, FSB@600 °C-Fe3O4, and FSB@800 °C-Fe3O4, was done following the chemical co-precipitation metho...
Article
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Treatments of N-(pyridin-2-ylmethyl)pyrazine-2-carboxamide (L1), N-(quinolin-8-yl)pyrazine-2-carboxamide (L2), N-(quinolin-8-yl)picolinamide (L3) and N-(quinolin-8-yl)quinoline-2-carboxamide (L4) with [PdCl2(NCMe)]2 afforded the corresponding Pd(ii) complexes, [Pd(L1)Cl] (PdL1); [Pd(L2)Cl] (PdL2); [Pd(L3)Cl] (PdL3); and [Pd(L4)Cl] (PdL4) in moderat...
Article
The syntheses and characterization of fish scale biochar magnetic composites (FSB@Fe3O4) and their applications in the removal of indigo carmine dye from effluents are described. Preparation of the fish scale biochar magnetic composites, FSB@400 °C-Fe3O4, FSB@600 °C-Fe3O4, and FSB@800 °C-Fe3O4, was done following the chemical co-precipitation metho...
Article
Reactions of Fe3O4 magnetic nanoparticles supported ligands, phenol((triethoxysilyl)propylimino)ethyl ([email protected]3O4) and phenol((triethoxysilyl)propylimino)methyl ([email protected]3O4) with appropriate metal salts afforded the respective immobilized complexes [email protected]3O4, [email protected]3O4, [email protected]3O4, [email protecte...
Article
Reactions of the ligands; sodium 4-hydroxy-3-((phenylimino)methyl)benzenesulfonate (L1), sodium 3-(((2,6-dimethylphenyl)imino)methyl)-4-hydroxybenzenesulfonate (L2) and sodium 3-(2,6-diisopropylphenyl)imino)methyl)-4-hydroxybenzenesulfonate (L3) with Pd(OAc)2 afforded the respective palladium(II) complexes [Pd(L1)2] (PdL1), [Pd(L2)2] (PdL2) and [Pd...
Article
Treatment of ligands (S)-1-phenyl-N-(1-(pyridin-2-yl)ethylidene)ethanamine (L1), (R)-1-phenyl-N-(1-(pyridin-2-yl)ethylidene)ethanamine (L2), (S)-1-phenyl-N-((pyridin-2-yl)methylene)ethanamine (L3), (R)-1-phenyl-N-((pyridin-2-yl)methylene)ethanamine (L4), (S)-N-(2-(diphenylphosphino)benzylidene)-1-phenylethanamine (L5), and (R)-N-(2-(diphenylphosphi...
Article
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Chiral (pyridyl)imine Fe(II) complexes, [Fe(L1)3]²⁺[PF6⁻]2, (Fe1), [Fe(L2)3]²⁺[PF6⁻]2, (Fe2), [Fe(L3)3]²⁺[PF6⁻]2 (Fe3), and [Fe(L4)3]²⁺[PF6⁻]2 (Fe4) were synthesised by reactions of synthons (S-)-1-phenyl-N-(pyridine-2-yl) ethylidine)ethanamine (L1), (R-)-1-phenyl-N-(pyridine-2-yl) ethylidine) ethanamine (L2), (S)-1-phenyl-N-(pyridine-2-yl methylen...
Article
Five imino-pyridine Ni(II) complexes: [{Ni(L1)Cl2}2] Ni1; [{Ni(L2)Cl2}2] Ni2; [{Ni(L3)Cl2}2] Ni3; [{Ni(L4)Cl2}2] Ni4 and [Ni(L5)2Cl2] Ni5 derived from ligands 2,6-diisopropyl-N-[(pyridin-2-yl) methylene] aniline (L1); 2,6-diisopropyl-N-[(pyridin-2-yl) ethylidene]aniline (L2); 2,6-dimethyl-N-[(pyridin-2-yl) methylene] aniline (L3); 2,6-dimethyl-N-[(...
Article
Reactions of (pyridyl)imine ligands: 2,6-diisopropyl-N-[(pyridine-2-yl)methylene]aniline (L1), 2,6-diisopropyl-N-[(pyridine-2-yl)ethylidene]aniline (L2), 2,6-dimethyl-N-[(pyridine-2-yl)methylene]aniline (L3), 2,6-dimethyl-N-[(pyridine-2-yl)ethylidene]aniline (L4) and N-[(pyridine-2-yl)methylene]aniline (L5) with FeCl2 salt afforded the correspondin...
Article
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This work reports the use of homogeneous and silica immobilized palladium(II) complexes of ligands (2-phenyl-2-((3(triethoxysilyl)propyl)imino)ethanol) (L1), (4-methyl-2-((3(triethoxysilyl)propyl)imino)methyl)phenol) (L2), [L1-MCM-41] (L1im), and [L2-MCM-41] (L2im) as catalysts in molecular hydrogenation of alkenes, alkynes and functionalized benze...
Article
New concepts and various strategies are being explored to improve the cytotoxicity of metal-based complexes. One of those strategies is to fine-tune the substitution kinetics of metallo-drugs to limit competive substitution, and hence maximise delivery to the cellular targets, DNA or proteins. To date, it appears there is a missing link in understa...
Article
Reactions of 2,6-bis(benzimidazol-2-yl)pyridine (L1), 2,6-bis(benzoxazol-2-yl)pyridine (L2), and 2,6-bis(benzothiazol-2-yl)pyridine (L3) with [Pd(NCMe)2Cl2] in the presence of NaBF4 afforded the corresponding Pd(II) complexes, [Pd(L1)Cl]BF4, PdL1; [Pd(L2)Cl]BF4, PdL2; [Pd(L3)Cl]BF4, PdL3; respectively, while reaction of bis[(1H-benzimidazol-2-yl)me...
Article
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In the paper by MacNeil et al. [ IUCrData , (2020), 5 , x200040], the address of the second author is incorrect.
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New examples of the very rare class of iridium(I) Fischer carbene complexes (FCCs) are reported from the facile transmetalation from group 6 FCCs. Postcomplexation modification of either the carbene ligand or the ancillary coligands results in a tunable IrI metal center, for unprecedented application as a (pre)catalyst in a benchmark transfer hydro...
Article
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In the title complex, [NiCl 2 (C 12 H 9 N 3 ) 2 ]·H 2 O, a divalent nickel atom is coordinated by two 2-(pyridin-2-yl)-1 H -benzimidazole ligands in a slightly distorted octahedral environment defined by four N donors of two N , N ′-chelating ligands, along with two cis -oriented anionic chloride donors. The title complex crystallized with a water...
Article
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(Pyrazolyethyl)pyridine palladium (II)complexes have been structurally characterized and found to give active catalysts in themethoxycarbonylation of higher olefins to mainly linear esters. The catalyticactivities of the complexes were mainly controlled by nature of the acidpromotor, phosphine derivative and olefin chain length. DFT studies establi...
Article
Reactions of 2-[(2-hydroxyethyl)imino]methyl]phenol (L1H), 2-[1-[(2-hydroxyethyl)imino]ethyl]phenol (L2H) and 2-[{[(2-diethylamino)ethyl]imino}methyl]phenol (L3H) with CoCl2 and FeCl2 salts produced the metal complexes [Co(L1)2] (Co1), [Fe(L1)2] (Fe1), [Co(L2)2] (Co2), [Fe(L)2] (Fe2), [Co2(L3H)2Cl4)] (Co3) and [Fe2(L3H)2Cl4] (Fe3), respectively. Mo...
Article
Reactions of 2-methoxy-N-((pyridin-2-yl)methylene)ethanamine (L1), 2-((pyridin-2-yl)methyleneamino)ethanol (L2) and 3-methoxy-N-((pyridin-2-yl)methylene)propan-1-amine (L3) ligands with either [PdCl2(COD)] or [PdCl(Me)(COD)] produced the corresponding monometallic complexes [PdCl2(L1)] (1), [PdClMe(L1)] (2), [PdCl2(L2)] (3) and [PdCl2(L3)] (4). The...
Article
Treatment of 2-phenyl-2-((3(triethoxysilyl)propyl)imino)ethanol (L1) and 4-nitro-2-((3(triethoxysilyl)propyl)imino)methyl)phenol (L2) with MCM-41 support afforded the respective immobilized ligands (L1im) and (L2im). Reactions of synthons L1, L2, L1im and L2im with either FeCl2·4H2O or CoCl2 led to the formation of their respective homogeneous and...
Article
In this perspective, we present a systematic account, using recent reports, on tandem olefin oligomerization and Friedel-Crafts alkylation reactions of preformed ethylene oligomers catalyzed by iron, cobalt, nickel and palladium complexes. Special attention is accorded to pyrazolyl-based metal complexes, which appear to be the most abundant in the...
Article
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The immobilization of 2-phenyl-2-((3(tryethoxysicyl)propyl)imino)ethanol (HL1) and 4-methyl-2-(((3(triethoxysilyl)propyl)imino)methyl)phenol (HL2) on MCM-41 afforded the respective ligands HL1-MCM-41 (HL3) and HL2-MCM-41 (HL4). The treatment of complexes Pd(L1)2 and Pd(L2)2 with MCM-41 afforded the immobilized complexes (Pd(L1)2)-MCM-41 (1) and (Pd...
Article
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The reactions of substituted (benzimidazolylmethyl)amines ligands (L1–L3) with ZnEt2 in the presence of either BnOH or t-BuOH afforded the corresponding Zn(II) metal alkoxides [Zn(L1)(OBn)]2 (1), [(Zn(L2)(OBn)]2(2), [Zn(L3)(OBn)]2 (3), [Zn(L2)(t-BuO)]2 (4), respectively. Complexes 1–4 formed effective initiators in the ring-opening polymerization (...
Article
Reactions of 2-(2-methoxyethylimino)ethyl)phenol (HL1), 2-(2-hydroxyethylimino)ethyl)phenol (HL2), 2-(2-aminoethylimino)ethyl)phenol (HL3) and 2-(2-hydroxyethylimino)methyl)phenol (HL4) with [PdCl2(COD)] afforded the neutral palladium complexes [PdCl2(HL1)] (1), [PdCl2(HL2)] (2), [PdCl2(HL3)] (3), [PdCl2(HL4)] (4) respectively. Treatment of complex...
Article
A series of (benzoimidazol-2-ylmethyl)amine palladium(II) complexes have been employed as catalysts in the homogeneous hydrogenation of alkenes and alkynes under mild conditions. A correlation between the catalytic activity and the nature of the ligand was established. Kinetic studies of the hydrogenation reactions of styrene established pseudo-fir...
Article
Reactions of 2-bromo-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (L1), 2,6-di (1H-pyrazol-1-yl) pyridine (L2) and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (L3) with RuCl3·3H2O led to the formation of their respective metal complexes [RuCl3(L1)] (1), [RuCl3(L2)] (2) and [RuCl3(L3)] (3). Solid state structure of complex 3 established the formation...
Article
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Reactions of N-(1H-benzoimidazol-2-ylmethyl-2-methoxy)aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl-2-bromo)aniline (L2) with p-TsOH, Pd(AOc)2 and two equivalents of PPh3 or PCy3 produced the corresponding palladium complexes, [Pd(L1)(OTs)(PPh3)] (1), [Pd(L2)(OTs)(PPh3)] (2) and [Pd(L1)(OTs)(PCy3)] (3), respectively, in good yields. The new palla...
Preprint
A series of (benzoimidazol-2-ylmethyl)amine palladium(II) complexes have been employed as catalysts in the homogenous hydrogenation of alkenes and alkynes under mild conditions. A correlation between the catalytic activity and the nature of the ligand was established. Kinetic studies of the hydrogenation reactions of styrene established pseudo-firs...
Article
Full-text available
Reactions of (benzimidazolylmethyl)amine ligands N-((1H-benzo[s]imidazol-2-yl)methyl)-2,6-dimethylaniline (L1), N-((1H-benzo[d]imidazol-2-yl)methyl)-2,6-diisopropylaniline (L2), and N-((1H-benzo[d]imidazol-2-yl)methyl)-2,4,6-trimethylaniline (L3) with Mg(n Bu) 2 in the presence of either benzyl alcohol (BnOH) or tert-butyl alcohol (t-BuOH) afforded...
Article
Reactions of N-(1H-benzimidazol-2-ylmethyl)-2-analine (L1), N-(1H-benzimidazol-2-ylmethyl)-2-bromoanaline (L2), N-(1H-benzimidazol-2-ylmethyl)-2-methoxyanaline (L3) and N-(1H-benzimidazol-2-ylmethyl)-2-phenolanaline (L4) with the appropriate nickel(II) salts afforded the respective complexes [Ni(L1)Br2] (1), [Ni(L2)Br2] (2), [Ni(L3)NiBr2] (3), [Ni(...
Article
Condensation reactions of 2-aminoethanol with the appropriate aldehyde gave ligands 2-[1-[(2-hydroxyethyl)imino]ethyl]phenol (L1) and 2-[(2-hydroxyethyl)imino] methyl]phenol (L2) respectively. Subsequent reductions of L1 and L2 with NaBH4 afforded the corresponding amine ligands 2-[1-[(2-hydroxyethyl)amino]ethyl]phenol (L3) and 2-{[(2-hydroxyethyl)...
Article
Compounds 2-[1-(3,5-dimethylpyrazol-1-yl)ethyl]pyridine (L1) and 2-[1-(3,5-diphenylpyrazol-1-yl)ethyl]pyridine (L2) were obtained in a three-step procedure which involved the reduction of acetylpyridine using NaBH4, chlorination of the alcohol intermediate using SOCl2 and subsequent reaction with appropriate pyrazoles. Reactions of L1 and L2 with N...
Article
Metal complexes have been used as catalysts in alkene transformation reactions to produce alcohols, esters, and organic acids as potential raw materials for the manufacture of detergents, perfumes, and other fine chemicals. Herein, we report the use of palladium(II) and ruthenium complexes as efficient catalyst precursors for the methoxycarbonylati...
Article
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This paper describes the synthesis of (pyridyl)benzoazole Zn(II) and Cu(II) complexes and their applications as catalysts in ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). Reactions of 2-(3-pyridyl)-1H-benzimidazole (L1), 2-(2-pyridyl)-1H-benzothiazole (L2) and 2-(2-pyridyl)-1H-benzimidazole (L3) with Zn(II) and Cu(II) acetates produce...
Article
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Reactions of (3,5-dimethylpyrazolylmethyl)pyridine (L1) and (3,5-diphenylpyrazolylmethyl)pyridine (L2) with either [PdCl2(NCMe)2] or [PdClMe(COD)] afforded the respective neutral palladium complexes, [PdCl2(L1)] (1), [PdCl2(L2)] (2) and [PdClMe(L1)] (3). Treatment of complex 1 with equimolar amounts of PPh3 or PPh3/NaBAr4 produced the corresponding...
Article
A series of iron(ii) and nickel(ii) complexes chelated by 2-pyrazolyl(methyl)pyridine (L1), 2,6-bis(pyrazolylmethyl)pyridine (L2), and 2,6-bis(pyrazolyl)pyridine (L3) ligands have been investigated as transfer hydrogenation (TH) catalysts for a range of ketones. Nine chelates in total were studied: [Ni(L1)Br2] (1), [Ni(L1)Cl2] (2), [Fe(L1)Br2] (3),...
Article
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Four bis(pyrazolyl)pyridine Zn(II) and Cu(II) carboxylate complexes have been structurally elucidated and used as initiators in the ring-opening polymerization (ROP) of ε-carprolactone (ε-CL). Reactions of bis(3,5-dimethyl-pyrazol-1-yl)pyridine (L1) with the appropriate Zn(II) and Cu(II) carboxylates afforded the corresponding complexes; [Zn(L1)(C6...
Article
Zinc(II) complexes of (benzoimidazolyl)amine ligands, N-(1H-benzoimidazol-2-ylmethyl)aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl)-2-bromoaniline (L2), [Zn-2(L-1)(2)(OBz)(4)] (1), [Zn-2(L-2)(2)(OBz)(4)] (2) and [Zn(L1)(2)(OAc)(2)] (3) have been employed in the ring-opening polymerization of lactides. The complexes were found to form active catal...
Article
Reactions of (2-(2-pyridyl)benzimidazole (L1), 2-(2-pyridyl)benzothiazole (L2) and 2-(2-pyridyl)benzoxazole (L3) with either [PdCl2(NCMe)2] or [PdClMe(COD)] produced complexes [(PdCl2(L1)] (1), [(PdCl2(L2)] (2), [(PdCl2(L3)] (3) and [(PdClMe(L1)] (4) in good yields. Treatment of 1 with PPh3 gave the cationic complex [(Pd(L1)ClPPh3]Cl (5), while rea...
Article
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Treatment of N,N′-bis(2,6-dimethylphenyl)formamidine (L1), N,N′-bis(2,6-diisopropylphenyl)formamidine (L2), and N,N′-dimesitylformamidine (L3) with Zn(OAc)2·2H2O or Cu(OAc)2·H2O produced the corresponding Zn(ii) and Cu(ii) N,N′-diarylformamidine complexes [Zn3(L1)2(OAc)6] (1), [Zn2(L2)2(OAc)4] (2), [Zn2(L3)2(OAc)4] (3) and [Cu2(L2)2(OAc)4] (4), res...
Article
Reductions of imine compounds 2-methoxy-N-(1-(pyridin-2-yl)ethylidene)ethanamine (L1), 2-methoxy-N-((pyridin-2-yl)methylene)ethanamine (L2), N,N-diethyl-N-((pyridin-2-yl)methylene)ethane-1,2-diamine (L3) and 2-((pyridin-2-yl)methyleneamino)ethanol (L4) using NABH4 produced their corresponding amine analogues N-(2-methoxyethyl)-1-(pyridin-2-yl)ethan...
Article
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We report the synthesis, molecular structures and applications of bis(pyrazolylmethyl)pyridine Zn(II) and Cu(II) complexes in the ring-opening polymerization (ROP) of ε-carprolactone (ε-CL). Reactions of bis(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine (L1) with the appropriate Zn(II) and Cu(II) carboxylates afforded the corresponding complexes; [Zn(L1...
Article
The (imino)pyridine ligands bearing pendant arms 2-methoxy-N-(1-(pyridin-2-yl)ethylidene)ethanamine (L1), 2-methoxy-N-((pyridin-2-yl)methylene)ethanamine (L2), 3-methoxy-N-((pyridin-2-yl)methylene)propan-1-amine (L3), N,N-diethyl-N-((pyridin-2-yl)methylene)ethane-1,2-diamine (L4), and N-((6-bromopyridin-2-yl)methylene)-2-methoxyethanamine (L5) were...
Article
Reactions of N-(1H-benzoimidazol-2-ylmethyl)-2-methoxy aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl)-2-bromo aniline (L2) with either [PdCl2(COD)] or [PdClMe(COD)] afforded the neutral palladium complexes [PdCl2(L1)] (1), [PdClMe(L1)] (2) and [PdClMe(L2] (3), respectively. Treatment of 2 and 3 with one equivalent of PPh3 in the presence of NaBAr...
Article
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The kinetics, mechanism and polymer microstructure studies of ring-opening polymerization (ROP) of lactides (LA) by Zn(II) and Cu(II) complexes of (pyrazolylmethyl)pyridine ligands, 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 2-(3,5-diphenylpyrazol-1-ylmethyl)pyridine (L2) is described. The complexes [Zn(Ac)2(L1)] (1), [Cu(Ac)2(L1)] (2), [Z...
Article
Reactions of 2-bromo-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (L1) and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (L2) with NiCl2 and NiBr2 led to the formation of their respective metal complexes [NiCl2(L1)] (1), [NiBr2(L1)] (2) and [NiBr2(L2)] (3) in moderate to high yields. The complexes were characterized using elemental analyses, mass spect...
Article
Reactions of 2-(chloromethyl)-6((3,5-dimethyl-1H-pyrazol-1-yl)methyl)pyridine (L1) and 2-(chloromethyl)-6-((3,5-diphenyl-1H-pyrazol-1-yl)methyl)pyridine (L2) with NiCl2, NiBr2, CoCl2 and FeCl2 led to the formation of their respective metal complexes [NiCl2(L1)] (1), [NiBr2(L1)] (2), [CoCl2(L1)] (3), [FeCl2(L1)] (4), [NiBr2(L2)] (5), and [CoCl2(L2)1...
Article
The title compound, [CoCl2(C15H12N2)2]·0.5CH2Cl2, was crystallized from a binary mixture of dichloromethane and hexane and a dimeric supramolecular structure was isolated. The CoII centre exhibits a distorted tetrahedral geometry, with two independent pyrazole-based ligands occupying two coordination sites and two chloride ligands occupying the thi...
Article
Compounds N-(1H-benzimidazol-2-ylmethyl)aniline (L1), N-(1H-benzimidazol-2-ylmethyl)-2-bromoaniline (L2), and N-(1H-benzimidazol-2-ylmethyl)-2-aminothiophenol (L3) react with ZnII and CuII carboxylates to form complexes [Zn2(L1)2(OBn)4] (1), [Zn2(L2)2(OBn)4] (2), [Zn2(L3)2(OBn)4] (3), [Cu2(L2)2(OBn)4] (4), [Zn(L1)2(OAc)2] (5), [Zn(L2)2(OAc)2] (6) a...
Article
The synthesis and structural characterization of ruthenium complexes supported by 2-(2-pyridyl)benzoazole ligands and their evaluation as catalysts in the transfer hydrogenation of ketones are reported. Reactions of 2-(2-pyridyl)benzoimidazole (), 2-(2-pyridyl)benzothiazole () and 2-(2-pyridyl)benzoxazole () with RuCl3·3H2O produced the correspondi...
Article
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The structural and kinetic studies of polymerization reactions of ε-caprolactone (ε-CL) using (pyrazolylmethyl)pyridine Cu(ii) and Zn(ii) complexes as initiators is described. Reactions of 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine () and 2-(3,5-diphenylpyrazol-1-ylmethyl)pyridine () with Zn(Ac)2·2H2O or Cu(Ac)2·2H2O produced the corresponding comp...
Article
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Three ligands, 1,2-bis(3,5-dimethylpyrazol-1-ylmethyl)benzene (L1), 1,3-bis(3,5-dimethylpyrazol-1-ylmethyl)benzene (L2) and 1,4-bis(3,5-dimethylpyrazol-1-ylmethyl)benzene (L3), were reacted with either nickel(II) chloride or nickel(II) bromide to produce four nickel complexes, Ni(L1)Br2 (1), Ni(L1)Cl2 (2), Ni(L2)Br2 (3), Ni(L1)Br2 (4). The complexe...
Article
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Article
Reactions of two equivalents of {3,5-(dimethylpyrazol-1-yl)-4-methoxy-1-carbonyl}benzene (L1), {3,5-(dimethylpyrazol-1-yl)-4-ethoxy-1-carbonyl}benzene (L2), {3,5-(dimethylpyrazol-1-yl)-4-hexyloxy-1-carbonyl}benzene (L3), and {3,5-(dimethylpyrazol-1-yl)-4-dodecycloxy-1-carbonyl}benzene (L4) with one equivalent of [Pd(NCMe)2Cl2] produced the correspo...
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Reactions of 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L2) and 2-(3,5-ditertbutylpyrazol-1-ylmethyl)pyridine (L3) with either Zn(NO3) or Cd(NO3) produced monometallic complexes [Zn(NO3)2(L2)] (1), [Zn(NO3)2(L3)] (2), [Cd(NO3)2(L2)] (3) and [Cd(NO3)2(L3)] (4). In the solid state structures of complexes 1, 3 and 4, L2 and L3 ligate to the zinc and...
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Reactions of imino-pyridyl ligands, (2-pyridyl-2-thiophenemethyl)imine (L1) and (2-pyridyl-2- thiopheneethyl)imine (L2) with NiBr2(DME) gave the corresponding complexes [Ni(L1)Br2] (1) and [Ni(L2)Br2] (2) in good yields. Treatment of 1 and 2 with one equivalent of 2-hydroxythiophenol resulted in the displacement of the bromide ligands to form the n...
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The title compound, C 21 H 17 N 3 , crystallizes with the phenyl ring in the 3-position coplanar with the pyrazole ring within 4.04 (5)°, whereas the phenyl ring in the 5-position forms a dihedral angle of 50.22 (3)° with the pyrazole ring. There is no ambiguity regarding the position of pyridine N atom, which could have exhibited disorder between...
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The coordination chemistry and cationic binding properties of 2,6-bis(pyrazol-1- ylmethyl)pyridine (L1), 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L2), and 2,6-bis(3,5- ditertbutylpyrazol-1-ylmethyl)pyridine (L3) with zinc(II) and cadmium(II) have been investigated. Reactions of L2 with zinc(II) and cadmium(II) nitrate or chloride salts prod...
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Chlorpyrifos ethyl was found to be widely distributed in water and sediment in Lake Naivasha. Higher levels were reported in sediment (11.2-30.0 ng g(-1) dry weight (dw) in wet season than in dry season (4.7-17.4 ng g(-1) dw). The mean concentration of chlorpyrifos ethyl in water in wet season ranged between 8.8 and 26.6 μg L(-1) and decreased to b...
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Five pyrazolyl and imidazolyl compounds, 2,4-di-tert-butyl-6-[2-pyrazol-1- yl-ethylimino-methyl]-phenol (L1), 2,4-di-tert-butyl- 6-{[2-(3,5-dimethyl- pyrazol-1-yl)-ethylimino]-methyl}-phenol (L2), 2,4-di-tert-butyl-6-{[2-(1H- imidazol-4-yl)-ethylimino]- methyl}-phenol (L3), 4-tert-butyl-2-{[2-(1H- imidazole-4-yl)-ethylimino]-methly}-phenol (L4) and...
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Five pyrazolyl and imidazolyl compounds, 2,4-di-tert-butyl-6-[2-pyrazol-1-yl-ethylimino-methyl]-phenol (L1), 2,4-di-tert-butyl-6-{[2-(3,5-dimethyl-pyrazol-1-yl)-ethylimino]-methyl}-phenol (L2), 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]methyl}-phenol (L3), 4-tert-butyl-2-{[2-(1H-imidazole-4-yl)-ethylimino]-methly}-phenol (L4) and 2-{[2-...
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Complexes of 2-((3,5-dimethyl)-1H-pyrazol-1-ylmethyl)pyridine (L1), 2-((3,5-ditert-butyl-1H-pyrazol-1-yl)methyl)pyridine (L2), 2-((3,5-diphenyl)-1H-pyrazol-1-yl)methyl)pyridine (L3), 2-((3,5-bis(trifluoromethyl)-1H-pyrazol-1-ylmethyl)pyridine (L4) and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)methyl)pyridine (L5) with cobalt(II), iron(II) and nickel(II)...
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In the title compound, [RhCl(3)(C(12)H(12)N(2)O)]center dot CH(2)Cl(2), the Rh(III) atom shows a slightly distorted octahedral geometry being coordinated by two N atoms and one O atom from the 2,2 '-(oxydimethanediyl)dipyridine ligand and three Cl atoms. Two Cl atoms adopt a trans arrangement to the two pyridyl N atoms, while the third Cl atom and...