James Darkwa

• BSc(Hons), Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; PhD, University of New Brunswick, Fredericton, Canada.
• Professor at Botswana Institute for Technology Research and Innovation

A series of Schiff‐base rhodium(I) complexes (C1–C8) chelating N^O salicylaldimine and naphthaldimine ligands have been synthesized and characterized. These complexes were evaluated for their ability to catalyse the isomerization and hydroformylation of terminal (1‐octene and 1‐decene) and internal olefins (1, 2‐, 3‐, and 4‐octene) to linear and br...

We present the synthesis, characterization, and catalytic activities of four bis(pyrazolyl)nickel(II) complexes (1–4) in the hydrogenation of 1‐octene. Characterization techniques, such as Fourier‐transform infrared spectroscopy, electrospray ionization‐mass spectrometry, elemental analysis, single‐crystal X‐ray diffraction, and density functional...

Developing effective catalysts that can selectively hydrogenate C=C bonds in biodiesel samples is vital as it tackles the major problem of oxidative stability, which greatly limits the utilization of biodiesel as an alternative fuel. In this work, Co, Ni, and Pd catalysts stabilized with the bidentate nitrogen ligands N-(3-(triethoxysilyl)propyl)py...

The Africa Capacity-Building Initiative is a Royal Society programme funded by the former UK Department for International Development to develop collaborative research between scientists in sub-Saharan Africa and the UK. Initially, four institutions were involved in the Chem4Energy consortium: Cardiff University in the UK and three African partners...

Biodiesel from renewable sources offers an attractive alternative to conventional diesel fuel and partial hydrogenation of free-fatty acid methyl esters (FAME) is one way to improve this renewable fuel. We have used the mononuclear pyrazolyl nickel(ii) and palladium(ii) complexes, [NiBr2(L1)] (1), [NiBr2(L2)] (2), [NiBr2(L3)] (3), [PdCl2(L1)] (4),...

The search for renewable sources of energy has resulted in the focus of the use of biomass and biomass-derived platform chemicals for the generation of energy. One such chemical—furfuryl alcohol—which has several industrial applications can be obtained from furfural via hydrogenation using catalysts. Novel N^S (pzyraolyl-thio) and N^Se (pyrazolyl-s...

Widespread consumption of fossil resources yielding waste CO2 has reached an all-time high and this poses an environmental threat that is contributing to global warming and climate change. Using CO2 as a C1 source may serve as an avenue to convert waste to valuable platform chemicals such as formates. This manuscript reports on the design and synth...

The burning of fossil fuels to meet energy demands has increased carbon dioxide (CO2) in the atmosphere, causing global warming and associated climate change. Therefore, new materials are being developed to capture CO2 effectively, limit its impact on the environment, and store and/or utilise it as an abundant C1 building block. In this study, we i...

Background: Glyco disulfide gold nanoparticles (GDAuNPs) were prepared by three methods: direct, photochemical irradiation and ligand substitution. Glyco disulfide acted as reducing and capping agents of gold ions, to produce AuNPs GD1–GD16. Results: Shorter chains of glyco disulfides (n = 1 and 2) offered monodispersed and stable GDAuNPs in physio...

Recent efforts in addressing the environmental problems have involved using CO2 as a cheap and nontoxic C1 source. Iridium catalysts with bidentate ligands are excellent catalysts for CO2, especially if these complexes possess proton-responsive OH or NH groups. Here-in we report the synthesis of novel Ir half-sandwich complexes with N^N bidentate t...

Hydrogenation of CO2 to products such as formic acid has gained attention in recent times as one of the means of addressing the environmental impact of CO2 as well as H2 storage. Herein we report the synthesis of a tetrazolyl ligands bearing PS bonds which undergoes a PS heterolysis during complexation with [PdCl2(MeCN)2] resulting in the accidenta...

Monomers derived from renewable sources are of great interest to drive sustainable polymer chemistry. Herein, bio-based furfural, glycerol and lactic acid were used as building blocks to prepare methacrylate monomers via simple transesterification reactions in high yield and purity. The monomers were polymerized and co-polymerized by employing a fr...

1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L) reacts with [Cu(OAc)2] and C6H5COOH, 4-OH-C6H4COOH, 2-Cl-C6H4COOH and (3,5-NO2)2-C6H3COOH to afford the copper complexes [Cu2(C6H5COO)4(L)2] (1), [Cu2(4-OH-C6H4COO)4(L)2] (2), [Cu2(2-Cl-C6H4COO)4(L)2] n (3) and [Cu{(3,5-NO2)2-C6H3COO}2L] n (4) which are characterised by IR, mass spectrometry, ele...

Bimetallic catalytic systems, especially heterogeneous bimetallic catalytic systems, have been shown to be effective catalysts for CO2 hydrogenation as a result of synergistic effects. Here‐in we report the synthesis of bimetallic Ir−Ir, Ir−Sn and a novel five‐membered heteroatomic Ir−Sn tetrazole complex. These complexes were obtained as a result...

We have prepared several pyrazolyl palladium and nickel complexes ([(L1)PdCl2](1), [(L2) PdCl2](2), [(L3) PdCl2](3), [(L1) NiBr2](4), [(L2) NiBr2](5) and [(L3) NiBr2](6)) by reacting 3,5-dimethyMH-pyrazole (L1), 3,5-di-ferf-butyl-1ZÏ-pyrazole (L2) and 5-ferrocenyl-1Zf-pyrazole(L3) with [PdCl2(NCMe)2] or [NiBr2(DME)] to afford mononuclear palladium...

A rise in atmospheric CO2 levels, following years of burning fossil fuels, has brought about increase in global temperatures and climate change due to the greenhouse effect. As such, recent efforts in addressing this problem have been directed to the use of CO2 as a non-expensive and non-toxic single carbon, C1, source for making chemical products....

Hydrogenation of CO2 to formate serves as a means of H2 storage. By utilizing robust, electron-rich and bulky N∧N bidentate tetrazolylpyridyl ligands, we have prepared CO2 hydrogenation iridium(III) and palladium(II) catalyst precursors (3–7) that operate in water as a solvent. In situ1H NMR spectroscopic data obtained when the hydrogenation cataly...

The development of both chemotherapeutic drug resistance as well as adverse side effects suggest that the current chemotherapeutic drugs remain ineffective in treating the various types of cancers. The development of new metallodrugs presenting anti-cancer activity is therefore needed. Ruthenium complexes have gained a great deal of interest due to...

Pyrazolyl compounds 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl-amine) (L1), 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyl-amine (L2), and 2-(3-phenyl-5-(trifluoromethyl)-1H-pyrazol-1-yl)ethyl-amine (L3) were reacted with a mixture of zinc(II) acetate and 3,5-dinitrobenzoic acid to form the bidentate complexes [(2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)-ethyl-a...

A series of new Schiff-base rhodium(I) water-soluble complexes (C1-C3), were prepared and characterized. These complexes served as catalyst precursors for the hydroformylation of 1-octene and resulted in excellent substrate conversions (>98%) with 100% chemoselectivities to aldehydes, under mild conditions. Notably, good regioselectivities towards...

Glyco-gold nanoparticles (AuNPs) in aqueous dispersions were prepared by two approaches, namely direct reduction and ligand substitution methods. In the direct method, potassium salts of glyco thiols, with the general formula (C6H11O6)NH(CH2) n CH2SK (where L1, n = 1; L2, n = 2; L3, n = 3, L4, n = 4; L5, n = 5), were used as reducing and capping a...

The hydrogenation of carbon dioxide (CO 2) to formic acid is of great importance due to its useful properties in the chemical industry. In this work, we have prepared a novel metal-organic framework (MOF), JMS-1, using bipyridyl dicarboxylate linkers, with molecular formula [La 2 (bpdc) 3 (DMF) 3 ] n. Network analysis of JMS-1 revealed a new 7-conn...

The industrial process of hydroformylation or the oxo process has been used for many years in the production of aldehydes from alkenes. Different metals have been used as efficient catalysts for hydroformylation, in which linear and branched aldehydes are the products obtained; therefore, the development of new catalysts for hydroformylation with h...

The creative use of ligand design to fine‐tune catalytic properties of metal complexes has been the exciting aspect of this project … Read more about the story behind the cover in the Cover Profile and about the research itself in the Full Paper by J. Darkwa, B. C. E. Makhubela et al.. image John Wiley & Sons, Ltd.

Novel multidentate pyridyl‐aminophosphinite (L1) and pyridyl‐phosphoramidite (L2) ligands of N^P^P^N‐donor system have been synthesized via a series of simple steps. The ligands are symmetrical and as a result, their reactions with [Ru(p‐cymene)Cl2]2 and [Ru(benzene)Cl2]2 lead to the formation of four monodentate bimetallic complexes (1–4) that ret...

The Front Cover shows a picturesque sunrise in the savanna grassland of Africa signifying a new dawn with the opportunity to develop a sustainable future, where the environment is not negatively impacted by the growing demand for chemicals. The soil is rich with minerals that can be formed into interesting chemical structures with catalytic propert...

The conversion of CO2 into valuable chemicals has been of major interest because it is cheap and readily available. The concept of reducing CO2 pollution via its utilization into valuable products has inspired us to synthesise novel 4,4'-((1Z)-butane-2,3-diylidenebis(azanylylidene))dibenzoic acid (L) metal complexes {[(L)RuII] (C1), [(L)RhIII] (C2)...

Background Triazoles are a class of aza-heterocycles with broad spectrum of biological importance. The synthetic tunability of the triazole moiety allows for the development of new pharmacophores with applications as drugs to contend with the burden of cancer. Objective In this study, we aimed to develop a series of N-aryltriazole and N-acridinylt...

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...

Recent progress in carbon–carbon cross-coupling reactions has resulted in the discovery of highly active catalysts for carrying out such transformations. However, due to the wide array of applications of the products from cross-coupling reactions, there is the need to design suitable catalysts that permit the practical and economical synthesis of t...

Pyrazole-containing compounds have been used in recent times as ligands to stabilize metal complexes used as pre-catalysts in cross-coupling reactions. With various substituents at various positions in the pyrazole ring, the overall electrophilic and steric properties of the metal complexes can be fine-tuned. Herein, we report the synthesis of bulk...

New Ru(II) complexes (1 and 2) of 4-(diphenylphosphino)benzoic acid (L1) and 3-(diphenylphosphino)propanoic acid (L2) have been synthesized and reacted with Zn(OAc)2 to form hexanuclear complexes (3 and 4) containing four Ru(II) and two Zn(II) centres. The four ruthenium complexes were formed through coordination of Ru to a phosphine, while the pho...

57Fe Mössbauer spectroscopy has been used to study electronic dispersions in complexes of Fe, Co, Ni and Pd anchored on 3-ferrocenyl-5-methylpyrazolylmethylenepyridine and 3-ferrocenylpyrazolylmethylenepyridine ligands. Mössbauer spectroscopy shows that pyrazolyl-derivatizing of ferrocene increases the electron-density at the Fe-centre as well as f...

Palladium complexes of ferrocenylpyrazolylpyridine and ferrocenylpyrazolylamine were synthesised and screened as pre-catalysts (1–4) for olefin polymerisation. The pre-catalysts 1–4 on activation with EtAlCl2 in the presence of ethylene with chlorobenzene or hexane as solvent were highly active with 1 being the most active, with an activity of 360...

Macro(meso) porous polymer materials were prepared via a modified TIPS method using reagent grade polymers mixtures; polyacrylonitrile (PAN) and polyvinylpyridine-co-styrene (PVPS). Reaction conditions such as concentration, temperature and the solvents used were found to affect the morphology of the polymer materials formed. The use of low heat fo...

Pyrazolylethylphosphinite compounds, L1 (2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenlyphosphinite) and L2 (2-(3,5-di-tert-butyl-1H-pyrazol-yl)ethyldiphenylphosphinite) were reacted with the palladium(II) precursors [PdCl(CH3)(COD)] and [PdCl2(NCCH3)2] resulted in the formation of five novel complexes, produced from disproportionation reaction and h...

The methoxycarbonylation of selected 1-alkenes catalyzed by various neutral and cationic palladium(II) complexes, containing mixed N^N^X (X = O and S) tridentate ligands 2-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-6-(phenoxymethyl)pyridine (L1), 2-[(3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl]-6-(phenoxymethyl)pyridine (L2), 2-[(3,5-dimethyl-1H-pyrazol-1...

Compounds (2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L1), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L2), and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L3) were prepared using the synthetic routes reported in literature. These compounds were reacted with [NiCl2(DME)2] or [NiBr2(DME)2] under approp...

Several novel thiocarbohydrate phosphinogold(I) complexes were prepared via the reaction of n-gluconamidoalkyl thiol (L1–L7) {where L1–L4 = n-gluconamidoalkyl thiol (n = 1–4), L5–L7 = acetylated n-gluconamidoalkyl thiol (n = 1–3)} with the gold precursors [AuCl(PPh3)], [Au2Cl2(dppe)], [Au2Cl2(dppp)] and [Au2Cl2(dppb)], leading to the new gold(I) co...

Four new (pyrazol-1-yl)phenylmethanone ligands and their palladium (II) complexes were synthesized and characterized by various analytical techniques. The electronic properties of substituents on the phenyl ring of the ligand have significant effects on the structures as well as the catalytic properties of the complexes toward ethylene oligomerizat...

Solvent-free conversion of bio-derived levulinic acid (LA) to γ-valerolactone (GVL) has been achieved by new pyrazolylphosphite and pyrazolylphosphinite ruthenium(II) complexes as catalyst precursors, using both formic acid and molecular hydrogen as hydrogen sources. The reactions were very efficient at moderate temperatures of 100 to 120 °C. With...

The new compounds and potential ligands 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiphenlyphosphinite (L1), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L2), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl-diethylphosphite (L3) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L4) were prepared from the reaction of (3,5-(disubsti...

Treatment of human immunodeficiency virus (HIV) is currently complicated by increased prevalence of co-infection with Mycobacterium tuberculosis. The development of drug candidates that offer the simultaneous management of HIV and tuberculosis (TB) would be of great benefit in the holistic treatment of HIV/AIDS, especially in sub-Saharan Africa whi...

This is a short perspective on palladium catalyzed polymerization of phenylacetylene that lead to much lower molecular weight poly(phenylacetylene)s (Mw 3 000–60 000 Da) in contrast to polymers made from rhodium and iridium catalyzed reactions (Mw > 100 000 Da). It looks at the effects of ligands on both polymer molecular weight and microstructure;...

HIV infection is known for replicating in proliferating CD+ T-cells. Treatment of these cells with cytostatic (anti-proliferation) compounds such as hydroxyurea interferes with the cells’s ability support HIV replication. Combinations of such cytostatic compounds with proven anti-retroviral drugs (like ddI) are known as virostatic, and have been sh...

Five new iron(III) 1-hexene polymerisation catalysts were prepared from the reactions of 2,4-di-tert-butyl-6-(2-(1H-imidazol-4-yl)ethylimino)methylphenol (L1), or 4-tert-butyl-6-(2-(1H- imidazol-4-yl)ethylimino)methylphenol (L2) or 2,4-di-tert-butyl-6-[(2-pyridin-2-yl-ethylimino)-methyl-phenol (L3) with anhydrous iron(II) halides to form [FeCl2(L1)...

Compounds L1-L6 (3-ferrocenylpyrazole (L1), 3-ferrocenyl-5-methylpyrazole (L2), 3-ferrocenylpyrazolyl-methylenepyridine (L3), 3-ferrocenyl-5-pyrazolyl-methylenepyridine (L4), 3-ferrocenylpyrazolyl-ethylamine (L5) 3-ferrocenyl-5-pyrazolyl-ethylamine (L6)) reacted with [NiBr2(DME)] or [NiCl2.6H2O] to give the mononuclear nickel complexes [NiBr2(1-L1...

The bis(pyrazole)zinc(II) benzoate complexes bis(3,5-diphenylpyrazole)zinc(II) benzoate (1), bis(3,5-diphenylpyrazole)zinc(II) 3,5-dinitrobenzoate (2), bis(3,5-diphenylpyrazole)zinc(II) 4-hydroxybenzoate (3), and bis(3,5-di-ferf-butylpyrazole)zinc(II) 2-chlorobenzoate (4) were synthesized from the reaction of 3,5-diphenylpyrazole (LI) or 3,5-di-fer...

Advances in nanotechnology have led to the fabrication of nano-constructs of organic or inorganic origins with well-defined structures, surface properties, and can be made to respond to physical or chemical stimuli. These nano-constructs can provide a shift in the way diagnostic and therapeutic drugs are delivered to achieve target specificity and...

Technological advances that allow deeper penetration in live tissues, such as the development of confocal and the generation of ever-new fluorophores that facilitate bright labeling of cells and tissue components have made imaging of vertebrate model organisms efficient and highly informative. Recently, high luminescence, single-excitation narrow e...

Bis(pyrazole)-palladium(II) and nickel(II) halide complexes, [(pz)2PdCl2] (1), [(3,5-Me2pz)2PdCl2] (2), [(3,5-tBu2pz)2PdCl2] (3), [(3,5-Ph2pz)2PdCl2] (4), [(3-CF3,5-Phpz)2PdCl2] (5),[(pz)4NiBr2] (6), [(3,5-Me2pz)2NiBr2] (7), [(3,5-tBu2pz)2NiBr2] (8), [(3,5-Ph2pz)2NiBr2] (9) and [(3-CF3,5-Phpz)2NiBr2] (10), were investigated as catalysts for ethylen...

Neutral chloromethylpalladium(ii) complexes, [Pd(Cl)(CH3)(L)] () with ligands κ(2)-N^S-2-((3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl)-6-(phenylthiomethyl)pyridine (), κ(2)-N^S-2-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-6-(phenylthiomethyl)pyridine (), κ(2)-N^Se-2-((3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl)-6-(phenylselanylmethyl)pyridine (), κ(2)-N^Se...

Reactions of L1-L6 (3-ferrocenylpyrazolyle (L1), 3-ferrocenyl-5-methylpyrazolyle (L2) 3-ferrocenylpyrazolyl-methylenepyridine (L3) and 3-ferrocenyl-5-methylpyrazolylmethylene-pyridine (L4), 3-ferrocenylpyrazolylethylamine (L5) and 3-ferrocenyl-5-methylpyrazolylethyl-amine (L6)) with [PdCl(Me) (cod)] formed the mononuclear complexes [PdCl(Me) (κ1-L1...

The reaction of Zn(OAc)2 with 3-ferrocenylpyrazol-1-ylmethylenepyridine (L1), 3-ferrocenyl-5-methylpyrazol-1-ylmethylenepyridine (L2), 3-ferrocenylpyrazol-1-ylethylamine (L3) and 3-ferrocenyl-5-pyrazol-1-ylethylamine (L4) afford the corresponding zinc complexes [Zn(CH3COO)2(L1)] (1), [Zn(CH3COO)2(L2)] (2), [Zn(CH3COO)2(L3)] (3), and [Zn(CH3COO)2(L4...

EXECUTIVE SUMMARY South Africa’s National Research Foundation (NRF) is the nation’s premier research funding agent. It promotes and supports research in all fields of knowledge with a view to fostering high-level human capital development. As an independent government agency, it provides services to the country’s research community, especially at H...

Several bio-friendly carbohydrate disulfides and thiocarbohydrates have been synthesized via the reaction of D-(+)-gluconic acid δ-lactone with aminoalkylthiols, leading to n-gluconamidoalkyldisulfides {di-(2-gluconamidoethyl)disulfide (L1), di(3-gluconamidopropyl)disulfide (L2), di(4-gluconamidobutyl) disulfide (L3) and (2-gluconamidoethyl)thiol (...

Label free impedance technology enables the monitoring of cell response patterns post treatment with drugs or other chemicals. Using this technology, a correlation between the lipophilicity of metal complexes and the degree of cytotoxicity was observed. Au(L1)Cl (1), AuPd(L1)(SC4H8)Cl3 (1a) and Au(L2)Cl (2) [L1 = diphenylphosphino-2-pyridine; L2 =...

A series of discrete chromium(III) precatalysts, {[Cr(κ 3‐L1)] (1a.7H2O), {[Cr(κ 3‐L2)] (2a.5H2O), {[Cr(κ 3‐L3)] (3a.6H2O), {[Cr(κ 3‐L4)] (4a.10H2O), {[Cr(κ 3‐L5)] (5a.4H2O) and in‐situ‐generated chromium(III) precatalysts {[Cr(κ 3‐L1)] (1b), {[Cr(κ 3‐L2)] (2b), {[Cr(κ 3‐L3)] (3b), {[Cr(κ 3‐L4)] (4b), {[Cr(κ 3‐L5)] (5b) bearing 2,4‐di‐tert‐butyl‐6‐...

In this study statistical glyco-dithiocarbamate (DTC) copolymers were synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) and subsequently used to prepare glyconanoparticles and conjugated glyconanoparticles with the anti-cancer drug, gold(I) triphenylphosphine. These glyconanoparticles and the corresponding conjug...

The reaction of 2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (), 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol () or 4-tert-butyl-2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol () with iron(ii) precursors produced either iron(ii) or iron(iii) complexes, depending on the nature of the anions in the iron(ii) precur...

The poly(pyrazol-1-ylmefhyl)benzenes L1-L5 react with [PdCl 2(NCMe)2] or [PdClMe(COD)] to form dinuclear palladium complexes [{PdClX(3,5-Me2pzCH2)2-1,2-C 6H4}2] (X = Cl (1), Me (2)), [{PdCl 2(3,5-Me2pzCH2)2-1,3-C 6H4}2] (3), palladium complexes [{Pd 2(μ-Cl)2Me2(3,5Me2pzCH 2)2-1,3-C6H4}] (4), [{Pd 2(μ-Cl)2X2(3,5-Me2pzCH 2)2-1,4-C6H4}] (X = Cl (5), M...

Reactions of [PdCl2(NCMe)2] with the ferrocenylpyrazolyl compounds: 3-ferrocenyl-1H-pyrazole-5-carboxylate (), ethyl-1-(2-bromoethyl)-3-ferrocenyl-1H-pyrazole-5-carboxylate (), ethyl-1-(2-bromoethyl)-5-ferrocenyl-1H-pyrazole-3-carboxylate (), 3-ferrocenylpyrazolyl-methylenepyridine () and 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine () at room...

Introduction: Carbohydrates are key participants in many biological processes including reproduction, inflammation, signal transmission and infection. Their biocompatibility and ability to be recognized by cell-surface receptors illustrate their potential therapeutic applications. αYet, they are not ideal candidates because they are complex and te...

The World Bank’s forecast for Africa’s economic growth for 2013 is 4.8%, at a time when most regions in the world have very low or negative growth of their economies. In fact, if one removes South Africa from this forecast, growth is expected to be 6% in Sub-Saharan Africa; yet Sub-Saharan Africa hardly features when it comes to Global Chemistry Re...

The pyrazolylamine ligands, 2-(3,5-dimethyl-1H-pyrazol-1-yl)-N-(pyridin-2-ylmethyl)ethan-amine (L1a), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)-N-(pyridin-2-ylmethyl)ethan-amine (L2a), 2-(3,5-dimethyl-pyrazol-1-yl)-ethyl-(1H-pyrrol-2-ylmethyl)-amine (L3a), 2-(3,5-di-tert-butyl-pyrazol-1-yl)-ethyl-(1H-pyrrol-2-ylmethyl)-amine (L4a), were prepared by red...

The reactions of potassium salts of the dithiocarbamates L {where L = pyrazolyldithiocarbamate (L1), 3,5-dimethylpyrazolyldithiocarbamate (L2), or indazolyldithiocarbamate (L3)} with the gold precursors [AuCl(PPh3)], [Au2Cl2(dppe)], [Au2Cl2(dppp)], or [Au2Cl2(dpph)] lead to the new gold(I) complexes [AuL(PPh3)] (1-3), [Au2L2(dppe)] (4-6), [(Au2L2)(...

In (η⁶-p-cymene)(difluorophosphinato-κO){2-[(1H-pyrazol-1-yl)methyl-κN²]pyridine-κN}ruthenium(II) 0.85-hexafluoro­phosphate 0.15-tetrafluoroborate, [Ru(PO2F2)(C10H14)(C9H9N3)](PF6)0.85(BF4)0.15, (I), the [PO2F2]⁻ ligand exhibits positional disorder due to one F atom and one O atom sharing the same two positions related by a mirror reflection across...

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...

The anti-tumor activity of organo-gold compounds is a focus of research from the last two decades. A variety of gold stabilizing ligands such as vitamins, xanthanes have been prepared and explored for their 'chelating effect' as well as for their anti-tumor activity. Dithiocarbamates (DTC) represent an active and important class of gold chelating l...

Electrospun polystyrene fibres incorporating potassium salts of pyrazole-1-carbodithioate and imidazole-1-carbodithioate were employed as sorbents for heavy metals from aqueous environments. The equilibrating time, initial metal concentra-tions and sorbent mass for optimal adsorption were 40 min, 5 mg/ℓ and 8 mg, respectively. The optimal pH for me...

A series of tridentate (O^N^N) and bidentate (N^N) iron, cobalt and nickel complexes were prepared from {2,4-di-tert-butyl-6-[(2-(3,5-RR-pyrazol-1-yl-ethylimino)methyl]-phenol}, R = H (L1), Me (L2), Ph (L3), [(3,5-di-tert-butyl-2-ethoxy-benzylidene)-[2-(3,5-dimethyl-pyrazol-1-yl)-ethyl]amine (L4), and (4-(4-tert-butyl-benzylidene)-[2-(3,5-dimethyl-...

The pyrazolyl pyridylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]pyridin-2-ylmethyleneimine (L1) and [2-(3,5-di-tert-butylpyrazol-1-yl)ethyl]pyridin-2-ylmethyle-neimine (L2) and pyrazolyl thienylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]thiophen-2-ylmethyleneimine (L3), [2-(3,5-di-tert-butyl-pyrazol-1-yl)ethyl]thiophen-2-ylmethyle-neimi...

Electrospun polystyrene fibres incorporating potassium salts of pyrazole-1-carbodithioate and imidazole-1-carbodithioate were employed as sorbents for heavy metals from aqueous environments. The equilibrating time, initial metal concentra-tions and sorbent mass for optimal adsorption were 40 min, 5 mg/ℓ and 8 mg, respectively. The optimal pH for me...

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[PtCl2(dppe)] (dppe = 1,2-bis(diphenylphosphino)ethane) reacts with pyrazol-1-yl- (L1), 3,5-dimethylpyrazol-1-yl- (L2), and indazol-1-yl- (L3) dithiocarbamate to form [Pt(L1)2(dppe)] (1), [Pt(L2)2(dppe)] (2) and [Pt(L3)2(dppe)] (3). These complexes readily transform into [Pt(S2CO)(dppe)] (4) in chloroform and dichloromethane at room temperature. St...

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...

The title compound, [PdCl2(C21H17N3)], is a member of a sequence of Pd, Pt and Co dichloride complexes bearing polysubstituted (pyrazol-1-ylmeth­yl)pyridine ligands. It is shown that there is a correlation between the steric bulkiness of the bidentate (pyrazol-1-ylmeth­yl)pyridine ligands and the Pd—Npyrazole distances, i.e. the larger the ligand,...

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...

The synthesis of series of 1,2,1′ substituted bis(diphenylphosphino)- ruthenocenyl (1–4) and ferrocenyl cis-platinum(II) (5–7) and gold(I) (8–12) complexes are described. Crystal structures of 2 and 4, as well as 5, 6 and 10 confirm the molecular geometry of these ligands and their metal complexes. Preliminary investigation of four gold complexes a...

A high-yield, solvent-free approach to the synthesis of 1,3,5-trisubstituted pyrazoles is reported. Four compounds, (3,5-di-tert-butyl-1H-pyrazole, (2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol were readily prepared by solvent-free condensation of the appropriate dike...

The title compound, C38H30N4, a potentially mono- and bidentate ligand, does not seem to form palladium complexes similar to other poly(pyrazol-1-ylmeth­yl)benzenes due to the large steric size of the phenyl substituents on the pyrazole rings. The pyrazole rings have a 21.09 (5)° angle between their mean planes and exhibit a trans-like geometry in...

The angles within the benzene ring in the title compound, C30H49N3O, ranging from 116.34 (16) to 124.18 (16)°, reflect the presence of electron-donating and electron-withdrawing substituents. The angles at the two electron-donating tert-butyl substituents are smaller than 120°, at the electron-withdrawing eth­oxy substituent larger than 120°, and a...

In the title compound, [PdCl2(C7H13N3)]·CH2Cl2, the 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanamine ligand chelates the PdII atom via two N atoms forming a six-membered ring resulting in a distorted square-planar metal coordination environment, highlighted by N—Pd—Cl angles of 172.63 (8) and 174.98 (9)°. In addition to N—H⋯Cl hydrogen bonds creating inf...

A series of palladium(II) and platinum(II) complexes ([PdCl2(J003)] (1), [PdCl2(W001)] (2), [PtCl2(J003)] (3) and [PtCl2(W001)] (4), where J003 = the Josiphos ligand (R)-1-[(S)-2-diphenylphosphino)ferrocenyl]ethyldicyclohexylphosphine and W001 = the Walphos ligand (R)-1[(R)-2-(2′-diphenylphosphinyl)ferrocenyl]ethyldo(bis-3,5-trifluoromethylphenyl)p...

A detailed description of the crystal structure solution and refinement of a pseudo-merohedrally twinned crystal of an organometallic complex is presented as a guide to the handling of similar non-routine challenging crystal structures. The interpretation of the signs of twinning and the logic behind the selection of the correct space group are exp...