Co Complexes Research Articles

Reaction of a Nitrosyl Complex of Co(II)-porphyrin with Hydrogen peroxide: Formation of a Porphyrin Radical Cation.

A nitrosyl complex of Co(II)-porphyrinate, [CoII(TTMPP2-)(NO)], 1, [TTMPPH2 = 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl)porphyrin] having {Co(NO)}8 configuration has been synthesized and characterized spectroscopically as well as structurally. Complex 1 in dichloromethane:acetonitrile (1:4, v/v) solution at -40 °C reacts with hydrogen peroxide (H2O2) to result in the corresponding nitrite (NO2-) complex, [CoIII(TTMPP2-)(NO2-)], 2. The formation of a Co(III)-peroxynitrite intermediate is presumed in this reaction based on the characteristic phenol ring nitration test. From spectroscopic studies, formation of [CoIV=O] species followed by a Co(III)-porphyrin radical complex was observed during the course of the reaction.

Pyrazinamide-based Co(II), Ni(II) and Cu(II) complexes: DFT exploration of structure, reactivity properties and in silico ADMET profiles.

In this paper, we present a theoretical study on the complexation of Co(II), Ni(II), and Cu(II) with a pyrazinamide ligand (PZA), which plays an important role in the treatment of tuberculosis and has biological and pharmacological benefits. It is a hybrid organic/inorganic material involving coordination between a metal ion and PZA ligand containing different coordination sites. This allows it to have different binding modes with metal ions and, therefore, provides a versatile ability to coordinate with metals. This study aimed to optimize the structures of the [M(PZA)2Cl2] complexes using density functional theory (DFT) at the B3LYP/6-311G + (d,p) level and the M06-2X functional is a high-nonlocality functional of double the amount of nonlocal exchange 2X. Various properties, including geometrical parameters, natural bonding orbital (NBO) to determine atomic charges, HOMO-LUMO energies, electronic properties, reactivity (ELF, LOL), NCI-RDG, and molecular electrostatic potential (MEP) on the surfaces of key metal-PZA complexes were determined and described. The AIM method has also been used to examine the chemical bonds. Furthermore, an in silico analysis aiming to explore the ADMET profiles of the compounds under investigation revealed promising aqueous solubility, oral bioavailability and gastrointestinal absorption, in addition to favorable druglikeness non-toxic and non-carcinogenic characteristics. The DFT method was carried out using Gaussian 09 software and GaussView 5.0. Avogadro software was used to define the geometry of the complexes. The Multiwfn program was used to produce scatter plots of the reduced density gradient (RDG), non-covalent interactions (NCI), ELF, LOL, and to define the parameters selected for the topological analysis of the BCPs using Bader's AIM.

Formally Zerovalent Bis(arene) Germylene Complexes of Zirconium and Hafnium.

Tetrachlorides of zirconium- and hafnium form adducts (2,3) with an intramolecular germylene phosphine Lewis pair. Two electron reduction treating the adducts with [MesNacnacMg]2 gives the low valent metal complexes (4, 5) featuring η6-Trip coordination at the Zr(II) and Hf(II) metal atom. Reduction of the M(II)-complexes gives the zerovalent metal complexes of zirconium (6) and hafnium (7), which have been structurally characterized. Two arene moieties and the germylene exhibit metal coordination. Puckered coordination of a P-phenyl unit was observed for both derivatives 6 and 7. Four electron reduction of a reaction mixture of metal tetrachloride with the germylene-phosphine Lewis pair also gives the zerovalent complexes in good yield. Carbonyl complexes were synthesized treating the reduced metal complexes with carbon monoxide. Dimethylbutadiene shows a reaction with an arene moiety and the coordinated germylene ligand of the zerovalent complexes. A cyclohexadienyl and a triorganogermate ligand are formed. For zirconium this reaction is reversible at room temperature.

Metalized Borylene in Boron-Gold Carbonyl Complexes: Infrared Spectra and Theoretical Calculations.

Borylenes (:B-R), built on a single B-R bond between boron and another nonmetallic atom or group,are a heated subject of special interest due to their intriguing transition-metal-mimicking reactivity, but the relative lack of understanding for the electronic structure and chemical bonding of transition metal borides leads to lingering neglect of metalized borylenes (:B-M) based on covalent B-M bonding. Here we use infrared photodissociation spectroscopy in combination with density functional calculations to study the geometric structure and chemical bonding of boron-gold carbonyl complex cations. The structure and bonding analyses demonstrated that the BAu(CO)3+ and BAu2(CO)4+ complexes can be described as bis-carbonyl-trapped borylene adducts. While the metal-rich BAu3(CO)4+ complex represents an unusual multicenter-bond-stabilized borylene cation with excellent σ-acidity and π-backbonding capability for CO activation, featuring Cs symmetry with a quasi-T-shaped BAu3+ core. It is manifested that BAu3+ presents greater amphoteric reactivity and improved stability compared to BAu1,2+ due to the presence of the three-center-two-electron Au-B-Au bond. This study discloses a conceptually new platform for accessing reactive metalized borylenes by exploiting the boron-mediated multicenter-bond stabilization strategy and using more bench-stable and ubiquitous metal carbonyl fragments as starting materials, thus providing a broader opportunity for the design of novel chemical structures and catalysts.

Heavy Pentaisopropylcyclopentadienyltriylenes and their Heterobimetallic Complexes.

A series of triylenes of the heavy group 13 elements gallium, indium and thallium, carrying the pentaisopropylcyclopentadienyl ligand is reported. The compounds were characterized in solution and in the solid-state and their donor ligand properties in heterobimetallic complexes were investigated, whereby a series of tungsten carbonyl complexes was isolated. Furthermore, a new synthetic route towards a previously described lithium-aluminum heterobimetallic dimetallocene is reported, which also enabled the isolation of a heterobimetallic polydecker of lithium and gallium.

Bridging Carbonyl and Carbyne Complexes of Weak-Field Iron: Electronic Structure and Iron-Carbon Bonding.

Carbon monoxide inhibited forms of nitrogenases have carbonyl (CO) and carbide (C4-) bridges, which are common in synthetic iron complexes with strong-field ligand environments but rare in iron sites with weak-field ligand environments analogous to the enzyme. Here, we explore the fundamental bonding description of bridging CO in high-spin iron systems. We describe the isolation of several diiron carbonyls and related species, and elucidate their electronic structures, magnetic coupling, and characteristic structural and vibrational parameters. These high-spin iron complexes exhibit equivalent π-backbonding abilities to low-spin iron complexes. Sequential reduction and silylation of a formally diiron(I) bridging CO complex ultimately gives a formally diiron(IV) bridging carbyne complex. Despite the large range of formal oxidation states across this series, X-ray absorption spectroscopy and density functional theory calculations indicate that the electron density at the iron sites does not change. Thus, the [Fe(μ-CO)]2 core undergoes redox changes at the bridging carbonyls rather than the metal centers, rendering the metal's formal oxidation state misleading. The ability of the Fe2C2 core to easily shift charge between the metals and the ligands has implications for nitrogenases, and for other multinuclear systems for redox catalysis.

Hydrogen‐Bonded Complexes of HPN⋅ and HNP⋅ Radicals with Carbon Monoxide

AbstractPhosphorus mononitride (PN) is a carrier of phosphorus in the interstellar medium. As the simplest derivatives of PN, the radical species HPN⋅ and HNP⋅ have remained elusive. Herein, we report the generation, characterization, and photochemistry of HPN⋅ and HNP⋅ in N2‐matrix at 3 K. Specifically, HPN⋅ was formed as a weakly bonded complex with CO in the matrix by 254 nm photolysis of the novel phosphinyl radical HPNCO⋅. The ⋅NPH−CO complex is extremely unstable, as it undergoes spontaneous isomerization to the lower‐energy isomer ⋅PNH−CO through fast quantum mechanical tunneling (QMT) with a half‐life of 6.1 min at 3 K. Upon further irradiation at 254 nm, the reverse conversion of ⋅PNH−CO to ⋅NPH−CO along with dehydrogenation to yield PN was observed. The characterization ⋅NPH−CO and ⋅PNH−CO with matrix‐isolation IR spectroscopy is supported by D, 15N, and 13C isotope labeling and quantum chemical calculations at the XYGJ‐OS/AVTZ level of theory, and the mechanism by hydrogen atom tunneling is consistent with multidimensional instanton theory calculations.

Synthesis and Structure of Rhenium and Manganese Carbonyl Complexes Bearing a Thiosaccharinate Ligand

AbstractThe reactions of [M2(CO)8(NCMe)2] (M=Re, Mn) with thiosaccharin (tsacH) have been investigated. TsacH reacts with [Re2(CO)8(NCMe)2] at room temperature to furnish [Re2(CO)8(μ‐H)(μ‐sac‐κN,S)] (1) and [Re(CO)5(sac‐κS)] (2), while a similar reaction with [Mn2(CO)8(NCMe)2] affords only [Mn(CO)5(sac‐κS)] (3). The dinuclear 1 contains a bridging tsac ligand coordinated to both rhenium centers using the nitrogen and thiocarbonylic sulfur atoms, while the tsac ligand is bonded to the metal center only through the sulfur atom in mononuclear 2 and 3. The molecular structures of 1–3 have also been determined by X‐ray crystallography.

Observation of Aromatic B13(CO)n+ (n = 1-7) as Boron Carbonyl Analogs of Benzene.

CO as a typical σ-donor is one of the most important ligands in chemistry, while planar B13+ is experimentally known as the most prominent magic-number boron cluster analogous to benzene. Joint gas-phase mass spectroscopy, collision-induced dissociation, and first-principles theory investigations performed herein indicate that B13+ reacts with CO successively under ambient conditions to form a series of boron carbonyl complexes B13(CO)n+ up to n = 7, presenting the largest boron carbonyl complexes observed to date with a quasi-planar B13+ core at the center coordinated by nCO ligands around it. Extensive theoretical analyses unveil both the chemisorption pathways and bonding patterns of these aromatic B13(CO)n+ monocations which, with three delocalized π bonds well-retained over the slightly wrinkled B13+ moiety, all prove to be boron carbonyl analogs of benzene tentatively named as boron carbonyl aromatics (BCAs). Their π-isovalent B12(CO)n (n = 1-6) complexes with a quasi-planar B12 coordination center are predicted to be stable neutral BCAs.

Bismuth Bound to Transition Metals: Visible-Light-Induced Olefin Coordination, Reductive Elimination, and Oxidative Addition.

A series of dibenzobismepinyl (C14H10Bi) substituted transition metal complexes of the type [(C14H10Bi)M(CO)x(L)] (M = Mn, Co, Fe) was prepared in salt elimination reactions from a halobismepine and sodium metallates. Irradiation of these complexes with visible light has been investigated, aiming at the elimination of one carbonyl ligand and the concomitant coordination of the bismepine's olefin moiety to the transition metal center. The resulting complexes of the type [{κ2C,κ1Bi-(C14H10)Bi}M(CO)x-1(L)] (M = Co, Fe) have been isolated and fully characterized. When two dibenzobismepinyl units are positioned in the coordination sphere of an iron carbonyl complex fragment, reductive elimination / oxidative addition events of the dibismuthane (C14H10Bi)2 have been shown to be relevant. The analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, elemental analysis, single-crystal X-ray diffraction analysis, UV/Vis spectroscopy, IR spectroscopy and (TD)-DFT calculations.

Crystal structure of the heterometallic complex of Co(II) and Nd(III) with phenanthroline

A new heterometallic complex of CoII and NdIII with phenathroline [Co(Рhen)3][Nd(NO3)5(H2O)][Nd(NO3)4(H2O)2]H2O was synthesized for the first time by the self-assembly method. The crystal structure of the complex was determined by X-ray crystallography. The compound is an anion-cation complex and crystallizes in the monoclinic space group P21/n with unit cell parameters a=12.4251(4) Å, b=11.7206(3) Å, c=36.5374(12) Å, ==900, =90.581(3)0. In the crystalline phase, the complex is in the form of a crystal hydrate with a composition of 1:1. The anionic part of the complex consists of two nitrate hydrated NdIII complexes: [Nd(NO3)5(H2O)]2– and [Nd(NO3)4(H2O)2]–, in which the coordination number of neodymium is 11 and 10, respectively. The [Co(Phen)3]3+ ion is a cationic part of the complex in which the CoII atom has a distorted CoN6 octahedral environment, bidentately coordinating three phenanthroline molecules. Due to intermolecular hydrogen bonds (N–HO, O–HO), a three-dimensional supramolecular architecture is formed in the crystal, in which the polymer layers are packed parallel along the crystallographic axis a.

Synergistic solvent extraction system composed of bis(pyridin-2-ylmethyl) dodecan-1-amine and dinonylnaphthalene for enhanced selective extraction of nickel and cobalt

Simultaneous recovery of Ni and Co from Fe(III) and Al is a critical challenge in hydrometallurgical processes. Recognized solvent extraction systems often struggle with selectivity and effective performance in mixed metal ion environments. Herein, a new synergistic solvent extraction (SSX) system comprised of a novel pyridine analog, N,N-bis(pyridin-2-ylmethyl) dodecan-1-amine (BPMDA), and dinonylnaphthalene sulfonic acid (DNNSA) with tributyl phosphate as phase modifier is introduced. The SSX system demonstrates high extraction performance achieving >90% for Ni and >97% for Co in a single-stage extraction process, with high selectivity. Under optimal conditions, the selectivity sequence is observed as Co2+ (>97%) > Ni2+ (>90%) > Mn2+ (<20%) > Fe3+ (<10%) > Mg2+ (<5%) > Al3+ (<2%) > Ca2+ (<1%). Spectroscopic analysis evidences the preferential binding of BPMDA with Ni and Co in the presence of DNNSA, concurrently achieving a significant reduction in the co-extraction of Fe(III) and Al. The selective complexation of Ni and Co using the SSX system offers a highly efficient and selective approach for their extraction, with promising potential for applications in recovery-based processes.

Anchoring of boron halides BX (X: F, Cl, and Br) on transition metal (M: Cr, Mo, W) carbonyl complexes M(CO)5 (M: Cr, Mo, W): structure, bonding, and energy decomposition studies based on theoretical calculations

Anchoring of boron halides BX (X: F, Cl, and Br) on transition metal (M: Cr, Mo, W) carbonyl complexes M(CO)5 (M: Cr, Mo, W): structure, bonding, and energy decomposition studies based on theoretical calculations

Carbon Nanoparticle Oxidation by NO2 and O2: Chemical Kinetics and Reaction Pathways.

Carbon nanoparticle interactions with gases are central to many environmental and technical processes, but the underlying reaction kinetics and mechanisms are not well understood. Here, we investigate the oxidation and gasification of carbon nanoparticles by NO2 and O2 under combustion exhaust conditions. We build on a comprehensive experimental data set and use a kinetic multilayer model (KM-GAP-CARBON) to trace the uptake and release of gas molecules alongside the temporal evolution of particle size and surface composition. The experimental results are captured by a model mechanism that involves different types of carbon atoms (edge/plane-like) and the formation of a reactive oxygen intermediate (activated CO complex) as the rate-limiting step. A transition between distinct chemical regimes driven by NO2 at lower temperatures and O2 at higher temperatures is reflected by an increase in the observable activation energy from 60 kJ/mol to 130 kJ/mol. We derive energy profiles for three alternative reaction pathways that involve uni- or bimolecular decomposition of reactive oxygen intermediates.

Synthesis of some new transition metal complexes derived from tellurated formazanes

A novel series of organotellurium compounds based on formazane derivatives with a general formula of ArTeBr3 4 and Ar2TeBr2 5 [Ar = 2-[{4-hydroxy-3-methoxyphenyl}{4-nitrophenyldiazenyl}methylene amino]-5-nitrophenyl] were synthesized by refluxing mercurated formazane derivative ArHgCl with TeBr4 in two different mole ratios of 1:1 and 2:1, respectively, in dry dioxane solvent under an argon atmosphere. Compounds ArTeBr3 and Ar2TeBr2 were then reduced by the action of an ethanolic solution of hydrazine hydrate to obtain Ar2Te2 6 and Ar2Te 7, respectively. The ligand properties of bis(2-[{4-hydroxy-3-methoxy phenyl}{4-nitrophenyl diazenyl}methylene amino]-5-nitrophenyl) telluride (7) were examined toward several metal ions through its reaction with K2PtCl4, PdCl2 · 2 H2O, K2PtCl6, RhCl3 · 3 H2O, CoCl3 · 6 H2O and NiCl2, respectively. These compounds were characterized by FTIR, UV-Vis,1H and 13C{1H} NMR spectroscopy and mass spectrometry as well as by elemental analysis, thermal analysis, magnetic susceptibility and molar conductivity. The identification of the synthesized complexes 8-13 proved that the complexes of Pt(II), Pd(II) and Ni(II) have square pyramidal geometries and are diamagnetic, while the complexes of Pt(IV), Rh(III) and Co(III) have octahedral shapes with the same magnetic behavior. The telluride 7 behaves as a neutral pentadentate ligand.

Synthesis, characterization and biological studies of transition metal complexes of dehydroacetic acid Schiff bases derived from 3-aminomethyl pyridine

The solid metal complexes of Cu (II), Ni (II), Fe (III), Co (II), Mn (II) and Cd (II) with DHA Schiff base ligand derived from DHA and aromatic primary amine 3-aminomethyl pyridine were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–VIS, 1HNMR and XRD), magnetic susceptibility measurement, thermogravimetric analysis and differential thermal analysis (TGA/DTA) and investigated for biological activities like anti-bacterial, ant-fungal, antioxidant and anticancer activity. The structure of synthesized DHA Schiff base ligand and all metal complexes were confirmed by spectroscopic methods, stability of complexes was studied by TGA/DTA. DHA Schiff base ligand and all metal complexes were found to be biologically active.

Novel Co(II), Cu(II) and Zn(II) complexes derived from thiazole containing Schiff base ligands: Green synthesis, antimicrobial and anti-cancer studies

Six novel metal complexes of Co(II), Cu(II), and Zn(II) were synthesized using a microwave-assisted method. These complexes were derived from Schiff base ligands prepared through the condensation of 4-(p-fluorophenyl)-5-methyl-2-aminothiazole with 3-methoxysalicyldehyde (L1) and 2-hydroxynaphthaldehyde (L2). Characterization techniques, including UV–vis, IR, NMR, and HR-MS confirm the tridentate nature of Co(II), Zn(II), and bidentate nature of Cu(II) complexes. Elemental and thermogravimetric analysis showed 1:2 (M:L) stoichiometry in metal complexes. Meanwhile, magnetic susceptibility and powder X-ray diffraction express the geometry and crystal systems of complexes. The antimicrobial analysis of the synthesized compounds indicates Cu(II) complexes have greater potency against gram-positive bacterial and fungal strains while Zn(II) complexes show a greater zone of inhibition against gram-negative bacterial strains. Moreover, MIC values of the most potent complexes [Cu(L2)2] and [Zn(L2)2] range from 190 to 375 µg/mL. Furthermore, ligands and their complexes have been tested for anticancer potential against MDA-MB 231 and A549 cell lines by MTT assay. [Zn(L1)2] and [Zn(L2)2] complexes were found to have potent activity with IC50 values of 16.7 µM, 24.1 µM, and 8.7 µM, 13.4 µM respectively on MDA-MB-231 and A549 cell lines compared to other complexes and parent ligands. Molecular docking study performed using the PyRx 0.8 program against EGFR (PDB: 5XGM) showed strong binding interactions which supports the experimental results.

Selective Oxidative Scission of Olefins to Aldehydes Enabled by Ruthenium Complexes Containing Salicylaldimine Ligands

ABSTRACTTreatment of Ru3(CO)12 with salicylaldimine ligands [ArNCH(3‐tBuC6H3OH) [ArC6H5 (L1H); 4‐OMeC6H4 (L2H); 4‐MeC6H4 (L3H); 2,4,6‐Me3C6H2 (L4H); 4‐ClC6H4 (L5H); 4‐BrC6H4 (L6H)] in refluxing toluene afforded six bis‐ligand mononuclear ruthenium carbonyl complexes [ArNCH(3‐tBuC6H3O)]2Ru(CO)2 1a–1f in good yields. All of the Ru(II) complexes were characterized using IR, NMR, and elemental analysis. The molecular structures of complexes 1a, 1b, 1e, and 1f were further confirmed through X‐ray diffraction analysis. Additionally, the catalytic performance of these complexes was investigated in the oxidation of olefins to aldehydes, using TBHP as the oxidant in refluxing trichloromethane. With 1.0 mol% catalyst loading, these ruthenium complexes displayed high reactivity and good functional‐group compatibility, selectivity providing the corresponding oxidation product aldehydes in 73%–94% yields.

Unsymmetric Ir2 and RhIr Dinuclear Complexes Supported by a Linear Tetraphosphine meso-dpmppp, Showing High Reactivity for O2, H2, and HCl.

Unsymmetric dinuclear Ir(I) complexes, [Ir2Cl2(L)(meso-dpmppp)] (L = XylNC (1aIr2), tBuNC (1bIr2), CO (1cIr2)), were synthesized using meso-Ph2PCH2P(Ph)(CH2)3P(Ph)CH2PPh2 (meso-dpmppp), which supports cis-P,P (M1) and trans-P,P (M2) metal sites, and exhibited high reactivity for O2, H2, and HCl. The IrRh heterodinuclear complexes, [M1M2Cl2(L)(meso-dpmppp)] (1xM1M2) (M1M2 = IrRh, RhIr; L = XylNC, CO (x = a, c)), were also synthesized and used together with the Rh2 complexes (1a,cRh2) to elucidate the role of each metal site. For the reactions of O2, 1aIr2 and 1aRhIr showed higher reactivity than those of 1aIrRh and 1aRh2, giving η2-peroxide complexes [{M1Cl2}{M2(η2-O2)(XylNC)}(meso-dpmppp)] (2aIr2, 2aRhIr), from which O2 would not dissociate. All the CO complexes 1cM1M2 (M1, M2 = Ir or Rh) showed no reactivity for O2. In the reactions with H2, 1aIr2 reacted with H2 to give the dihydride complex, [{IrCl2}{Ir(H)2L}(meso-dpmppp)] (11aIr2) and the tetrahydride complex, [{Ir(H)Cl2}(μ-H){Ir(H)2L}(meso-dpmppp)] (12aIr2), while 1aRhIr gave the dihydride complex, and 1aIrRh and 1aRh2 gave no hydride complexes. Reactions of 1a,cM1M2 with HCl afforded the dihydride complexes, [{IrCl3}(μ-H){Ir(H)Cl(XylNC)}(meso-dpmppp)] (14aIr2), [{Ir(H)Cl2}(μ-H){M2Cl2(L)}(meso-dpmppp)] (M2 = Ir, L = CO (15cIr2); M2 = Rh, L = XylNC (15aIrRh), CO (15cIrRh)), and [{Rh(H)Cl2}(μ-Cl){Ir(H)Cl(XylNC)}(meso-dpmppp)] (18aRhIr), the structures varying depending on M1 and M2 as well as L.

Group 7 carbonyl complexes of a PNN-heteroscorpionate ligand.

A series of rhenium and manganese carbonyl complexes of a heteroscorpionate ligand with an atypical N2P-donor set has been prepared to better understand their electronic and CO releasing properties. Thus, the ligand, pz2TTP, with an a,a-bis(pyrazol-1-yl)tolyl group decorated with an ortho-situated di(p-tolyl)phosphanyl reacts with carbonyl group 17 reagents to give [fac-(κ2NP-pz2TTP)Re(CO)3Br], 1, and [fac-(κ3N2P-pz2TTP)M(CO)3](OTf = O3SCF3), 2-M (M = Re, Mn), if care is taken during the preparation of the manganeses derivative. When heated in CH3CN, 2-Mn slowly transforms to [fac,cis-(κ3N2P-pz2TTP)Mn(CO)2(NCCH3)](OTf), 3-Mn. In contrast, the corresponding 3-Re can only be prepared from 2-Re using Me3NO; pure 3-Mn can also be prepared by this method. Experimental and density functional calculations at the M06L/Def2-TZVP/PCM(CH3CN) level show that the replacement of a carbonyl with an acetonitrile solvent decreases the oxidation potential by around 0.8 V per carbonyl released, making decarbonylated species potent reductants. At the same time, the electronic spectrum broadens and undergoes a red-shift, making dicarbonyl complexes more susceptible to photo-initiated decarbonylation reactions than tricarbonyls. When 2-Mn or 3-Mn are irradiated in with 390 nm LED light in aerated solutions, [trans-Mn(pz2TTP = O)2](OTf)2, 4, along with insoluble manganese oxides are rapidly formed.