Chloro Species Research Articles

Dual Antimicrobial-Anticancer Potential, Hydrolysis, and DNA/BSA Binding Affinity of a Novel Water-Soluble Ruthenium-Arene Ethylenediamine Schiff base (RAES) Organometallic

The need for a systematic approach in developing new metal-based drugs with dual anticancer-antimicrobial properties is emphasized by the vulnerability of cancer patients to bacterial infections. In this context, a novel organometallic assembly was designed, featuring ruthenium(II) coordination with p-cymene, one chlorido ligand, and a bidentate neutral Schiff base derived from 4-methoxybenzaldehyde and N,N-dimethylethylenediamine. The compound was extensively characterized in both solid-state and solution, employing single crystal X-ray diffraction, nuclear magnetic resonance, infrared, ultraviolet–visible spectroscopy, and density functional theory, alongside Hirshfeld surface analysis. The hydrolysis kinetic was thoroughly investigated, revealing the important role of the chloro-aqua equilibrium in the dynamics of binding with deoxyribonucleic acid and bovine serum albumin. Notably, the aqua species exhibited a pronounced affinity for deoxyribonucleic acid, engaging through electrostatic and hydrogen bonding interactions, while the chloro species demonstrated groove-binding properties. Interaction with albumin revealed distinct binding mechanisms. The aqua species displayed covalent binding, contrasting with the ligand-like van der Waals interactions and hydrogen bonding observed with the chloro specie. Molecular docking studies highlighted site-specific interactions with biomolecular targets. Remarkably, the compound exhibited wide spectrum moderate antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, coupled with low micromolar cytotoxic activity against human colorectal adenocarcinoma cells and significant activity against human leukemic monocyte lymphoma cells. The presented findings encourage further development of this compound, promising avenues for its evolution into a versatile therapeutic agent targeting both infectious diseases and cancer.

Effect of current density and pH on the electrochemically generated active chloro species for the rapid mineralization of p-substituted phenol

The aim of present study is increasing the degradation and mineralization of 4-chlorophenol (4-CP) during electrochemical oxidation with Ti/RuO2 anodes. Innovatively, the evolution of chlorine-related species and the formations of various inorganic ions were investigated by electrolytic analysis in order to set up whether the formation and consumption of these byproducts associated with either chemical or electrochemical reactions. The effect of operating parameters such as current density, solution pH, treatment time, and electrolyte concentration has been studied. The formation of Cl2, chlorite (ClO2−), and chlorate (ClO3−) were detected by adding the known concentration of Cl− ions at different pH and current densities. Concentration trends of active chloro-species indicate that the degradation of 4-CP and chemical oxygen demand (COD) removal was formed maximum at pH 6 and j of 225.2 Am−2 in presence of 0.0085 M NaCl. Thus, the 4-CP degradation mainly depends on the radicals and active chlorine formation and a mineralization mechanism was proposed based on intermediates byproducts formation such as catechol, hydroquinone, 1, 4-benzoquinone, and organic acids identify by using the GC-MS and HPLC analysis at the optimum treatment condition. Total organic carbon (TOC) at different pH and current density, mass balance analysis of carbon and inorganic species formation were determined at the optimum treatment conditions of 4-CP. The degradation kinetic of 4-CP was followed the pseudo-first order kinetic model during the each parameters optimization. Specific energy consumption and current efficiency were also used to identify the technical feasibility of the process.

Controlled Relay Process to Access N-Centered Radicals for Catalyst-free Amidation of Aldehydes under Visible Light

<h2>Summary</h2> Nitrogen-centered radicals have attracted increasing attention as a versatile reactive intermediate for diverse C–N bond constructions. Despite the significant advances achieved in this realm, the controllable formation of such species under catalyst-free conditions remains highly challenging. Here, we report a new relay process involving the slow <i>in situ</i> generation of a photoactive <i>N</i>-chloro species via C–N bond formation, which subsequently enables mild and selective access to N-centered radicals under visible light conditions. The utility of this approach is demonstrated by the conversion of aldehydes to amides, employing <i>N</i>-chloro-<i>N</i>-sodio carbamates as a practical amidating source. This synthetic operation obviates the need for catalysts, external oxidants, and coupling reagents that are typically required in related processes, consequently allowing high functional group tolerance and excellent applicability for late-stage functionalization.

Effects of dissolved gases on partial anodic passivation phenomena at copper microelectrodes immersed in aqueous NaCl

Anodic passivation for copper exposed to aqueous NaCl (model seawater) is rate limited by diffusion of a poorly soluble Cu(I) chloro species. As a result, a protective layer of CuCl forms on copper metal (with approx. 1 μm thickness) that is then put under strain at more positive applied potentials with explosive events causing current spikes and particulate product expulsion. In this report, the mechanism for this explosive film rupture and particle expulsion process is shown to occur (i) in the absence of underlying anodic gas evolution, and (ii) linked to the presence/nature of gaseous solutes. The film rupture event is proposed to be fundamentally dependent on gas bubble nucleation (triggered by the release of interfacial stress) with surface tension effects by dissolved gases affecting the current spike pattern. Oxygen O2, hydrogen H2, and helium He suppress current spikes and behave differently to argon Ar, nitrogen N2, and carbon dioxide CO2, which considerably enhance current spikes. Vacuum-degassing the electrolyte solution results in behaviour very similar to that observed in the presence of helium. The overall corrosion rate for copper microelectrodes is compared and parameters linked to passivation and corrosion processes are discussed.

An Electrochemical Study of Divalent Ytterbium Species in NaCl–KCl and NaCl–KCl–Cscl Based Melts

A usual oxidation state of rare earth metals in chloride melts is +3. A number of lanthanides (particularly europium, ytterbium, samarium, and thulium) can also form thermodynamically stable ions in the oxidation state +2. Ln(II)/Ln(III) redox processes are normally investigated employing transient electrochemical techniques where the formation of Ln(II) ions is limited to the near electrode surface layer. The present work was aimed at studying the reduction of Yb(III) ions in the bulk of the melt and assessing the stability of Yb(II) chloro species in molten chloride media. The experiments were carried out in the melts based on NaCl–KCl–CsCl eutectic and NaCl–KCl equimolar mixtures at 550–850 and 700–850 oC, respectively, employing stationary and transient electrochemistry and high temperature spectroscopy methods. Concentration of ytterbium in the melt was varied from 1 to 10 wt. %. Ytterbium(II)/(III) formal standard redox potentials were obtained from the results of electrochemistry measurements (cyclic voltammetry and potentiometry). Electronic absorption spectra of Yb(II) species were recorded both in molten and quenched electrolytes. Reduction of Yb(III) to Yb(II) can be achieved by shifting the equilibrium of the reaction YbCl6 3– + Cl– ↔ YbCl6 4– + ½ Cl2 to the right by lowering partial pressure of chlorine in the atmosphere above the melt. Here, zirconium, as a metal with high affinity for chlorine, was used as a getter. The reduction process was followed by measuring the absorption spectra. As the reaction proceeded, the color of the melt changed from colorless of YbCl6 3– to brown. Analysis of the resulting melts showed that the mean oxidation state of ytterbium was below three, the value depended on temperature, duration of the reduction and melt composition. Increasing temperature or reduction time expectedly resulted in a greater degree of reduction. Ytterbium(III) can also be reduced with a suitable reductant and hydrogen was chosen here as an example. Sparging the melt containing Yb(III) ions with hydrogen resulted in decreasing mean oxidation state of ytterbium: YbCl6 3– + Cl– + ½ H2 ↔ YbCl6 4- + HCl. The course of the reduction process was followed by measuring the redox potential. The efficiency of hydrogen as a reducing agent was comparable to the thermal decomposition in the presence of zirconium getter. Hydrogen reduction was also a very convenient way of preparing the melts with a low Yb(II) content for spectroscopy measurements. Another way of reducing Yb(III) to Yb(II) is electrolysis: YbCl6 3– + e– ↔ YbCl6 4-. In a series of preliminary experiments Yb(II)/Yb(III) redox potentials were determined from the results of cyclic voltammetry measurements. Reduction of Yb(III) to Yb(II) was carried out by potentiostatic electrolysis under an inert (argon) or a reducing (hydrogen) atmosphere with and without agitating the melt. The lowest mean oxidation state of ytterbium in the melt thus obtained was 2.33 showing that two thirds of Yb(III) could be reduced to Yb(II). Acknowledgement. This work was supported by the Ministry of Education and Science of the Russian Federation (project No. 4.5062.2017/8.9).

Electronic Absorption Spectra of Uranium(V) Species in Fused Alkali Chlorides

Alkali chloride based melts can be used in pyrochemical reprocessing various types of spent nuclear fuels, especially those of fast neutron reactors. There is a possibility of refabricating uranium oxide or mixed uranium-plutonium oxide fuel by electrodeposition of UO2 or (U,Pu)O2 from chloride melts containing uranyl (or a mixture of uranyl and plutonyl) ions. At high temperatures uranyl chloro species undergo decomposition yielding UO2 + ions and finally UO2. Increasing temperature and lowering partial pressure of chlorine in the atmosphere above the melt shifts the equilibrium towards the decomposition products. In fact, uranium(V) ions are often present in uranyl-containing melts and, if unaccounted for, result in increased current efficiency of UO2 electrodeposition process. Electronic absorption spectroscopy allows a convenient method for detecting and measuring concentration of uranium(V) in uranyl-containing electrolytes. Absorption spectra of uranium(V) species in fused salts were reported over fifty years ago but still remain the least studied especially from the quantitative side concerning molar absorption (extinction) coefficient values. Uranium(V), f 1-electron configuration, absorbs in the visible region of the spectrum and the spectra have there two broad bands with the maxima around 620 and 775 nm not overlapping with the absorption of uranium(VI) ions, Fig. These bands correspond to two f–f transitions in UO2Cl4 3– complex ion, i.e., φ5u → 3π1u and φ5u → 3π3u. The aim of the present work was studying the effect of temperature and cationic melt composition on the absorption spectra of uranium(V) ions and determining molar absorption coefficients. The measurements were performed in individual alkali chlorides and their mixtures of various compositions including LiCl, CsCl, LiCl–KCl, LiCl–KCl–CsCl, NaCl–KCl, NaCl–CsCl. The temperature range varied from 350 to 850 oC depending on the melt. Uranium(V) ions were obtained in situ by reducing uranium(VI) ions with hydrogen. Uranium dioxide was also produced but no soluble uranium(IV) species in the melt were detected. After recording the spectrum a sample of the melt was taken and analyzed for the total uranium concentration and the mean uranium oxidation state which always was between five and six. From that, concentration of U(V) and V(VI) ions in the melt were calculated and U(V) extinction coefficients determined. The results obtained allow determination of U(V) concentration in technological electrolytes. Acknowledgement. This work was supported by the Ministry of Education and Science of the Russian Federation (project No. 4.5062.2017/8.9). Fig. Electronic absorption spectra of LiCl–KCl based melts containing U(VI) ions (line 1) and a mixture of U(VI) and U(V) ions at a 3 : 2 ratio (line 2). Total uranium concentration 0.038 mol/l, T = 550 oC. Figure 1

Base-free non-noble-metal-catalyzed hydrogen generation from formic acid: scope and mechanistic insights.

The iron-catalyzed dehydrogenation of formic acid has been studied both experimentally and mechanistically. The most active catalysts were generated in situ from cationic Fe(II) /Fe(III) precursors and tris[2-(diphenylphosphino)ethyl]phosphine (1, PP3 ). In contrast to most known noble-metal catalysts used for this transformation, no additional base was necessary. The activity of the iron catalyst depended highly on the solvent used, the presence of halide ions, the water content, and the ligand-to-metal ratio. The optimal catalytic performance was achieved by using [FeH(PP3 )]BF4 /PP3 in propylene carbonate in the presence of traces of water. With the exception of fluoride, the presence of halide ions in solution inhibited the catalytic activity. IR, Raman, UV/Vis, and EXAFS/XANES analyses gave detailed insights into the mechanism of hydrogen generation from formic acid at low temperature, supported by DFT calculations. In situ transmission FTIR measurements revealed the formation of an active iron formate species by the band observed at 1543 cm(-1) , which could be correlated with the evolution of gas. This active species was deactivated in the presence of chloride ions due to the formation of a chloro species (UV/Vis, Raman, IR, and XAS). In addition, XAS measurements demonstrated the importance of the solvent for the coordination of the PP3 ligand.

Electrochemical degradation of a real textile wastewater using β-PbO2 and DSA® anodes

Abstract The electrochemical degradation of a real textile effluent was carried out using Ti–Pt/β-PbO2 and Ti/Ti0.7Ru0.3O2 (DSA®) anodes in a filter-press flow cell, in the presence and absence of chloride ions, varying the pH (3, 7, 11) and temperature (25 °C and 45 °C) of the effluent, and monitoring the removal of its turbidity and chemical oxygen demand (COD). The best experimental conditions for turbidity and COD removal were attained in neutral and basic conditions, independently of temperature. Higher COD removal values were attained with the Ti–Pt/β-PbO2 anode, as a consequence of its higher oxidation power; the electric charge applied per unit volume of effluent significantly decreased in the presence of chloride ions, when instantaneous current efficiencies as high as 0.5 were attained in the initial electrooxidation stages. Under these conditions, the electric energy consumption necessary to oxidize the real textile effluent was as low as 50 kW h m−3. The use of chloride ions enabled higher COD removal efficiencies using the Ti–Pt/β-PbO2 and DSA® anodes than a purely mass-transport controlled process due to indirect oxidation processes mediated by the active chloro species.

Highly Selective Colorimetric Detection of Hydrochloric Acid Using Unlabeled Gold Nanoparticles and an Oxidizing Agent

We report a colorimetric system for the detection of HCl in aqueous environments using unlabeled gold nanoparticle (AuNP) probes. This nonaggregation-based detection system relies on the ability of chloro species to cause rapid leaching of AuNPs in an aqueous dispersion containing a strong oxidizing agent, such as HNO(3) or H(2)O(2). The leaching process leads to remarkable damping of the surface plasmon resonance peak of the AuNP dispersion. This method works only with AuNPs of a particular size (∼30 nm diameter). It is highly selective for HCl over several common mineral acids, salts, and anions. This simple and cost-effective sensing system provides rapid and simple detection of HCl at concentrations as low as 500 ppm (far below the hazard limit) in natural water systems.

Redox and spectral behaviour of copper (II)-chloro and bromo complexes in some nonaqueous solvents

The redox behaviour of 3 × 10-3 M each of CuCl2.2H2O and CuBr2.H20 have been investigated at Platinum (Pt) electrode and 1 × 10-3 M CuCl2.2H20 at glassy carbon (GCE) electrode in dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetonitrile (AN) and ethanol/0.1 M tetrabutylammonium perchlorate (TBAP) using cyclic voltammetry. For CuCl2 System, Epc1 and E0 are more positive, ∆Ep is smaller and Ipa1/Ipc1 is > at GCE than at Pt electrode, exception being ethanol where opposite trend is observed. In ethanol, two reduction steps c1/a1 due to Cu2+/ Cu+ couple while a2/c2 due to Br-/Br2 couple are observed in CuBr2system. The electron paramagnetic resonance (EPR) features of copper (II) chloro species in DMF and DMSO show splitting of the gII in frozen solution. For frozen CuBr2 system, the spectral features in DMF, DMSO and ethanol are characterized by four small peaks in the gII and one g^ signal as found for CuCl2in ethanol. However, splitting of the gII peak occurs in AN which was not observed in similar solvent for CuCl2. Key words: Redox, spectral, voltammograph, EPR, nonaqueous, cupric halide.

A Cationic AgI(PNPtBu) Species Acting as PNP Transfer Agent: Facile Synthesis of Pd(PNPtBu)(alkyl) Complexes and Their Reactivity Compared to PCPtBu Analogues

The straightforward synthesis of cationic complex 1, [Ag(PNPtBu)]BF4 (PNPtBu = 1,2-bis[(di-tert-butylphosphino)methyl]pyridine), and its facile transmetalating properties toward gold and palladium are described. The corresponding Au complex [Au(PNPtBu)]2(BF4)2 (2) exists as a dimer in the solid state, as deduced by X-ray crystallography. The transmetalating properties were expanded to include the formation of Pd-alkyl species. Reaction of 1 with 0.5 equiv of Pd(allyl)(μ-Cl) dimer led to clean formation of the [Pd(PNPtBu)(η1-allyl)]BF4 complex 3. The analogous cationic methyl (4), cyanophenyl (5), and chloro species (6) could also be prepared in good yields from appropriate Pd precursors via this transmetalation methodology. The molecular structures for complexes 3−5 were established by X-ray crystallography. Reaction of complexes 4 and 6 with NaN(SiMe3)2 led to deprotonation and dearomatization of the PNP backbone with formation of the neutral Pd species 7 and 8, which can be regarded as the diphosphino-m...

The geometric structures, vibrational frequencies and redox properties of the actinyl coordination complexes ([AnO2(L)n]m; An = U, Pu, Np; L = H2O, Cl−, CO32−, CH3CO2−, OH−) in aqueous solution, studied by density functional theory methods

The geometric and electronic structures of the aqua, chloro, acetato, hydroxo and carbonato complexes of U, Np and Pu in both their (VI) and (V) oxidation states, and in an aqueous environment, have been studied using density functional theory methods. We have obtained micro-solvated structures derived from molecular dynamics simulations and included the bulk solvent using a continuum model. We find that two different hydrogen bonding patterns involving the axial actinyl oxygen atoms are sometimes possible, and may give rise to different An-O bond lengths and vibrational frequencies. These alternative structures are reflected in the experimental An-O bond lengths of the aqua and carbonato complexes. The variation of the redox potential of the uranyl complexes with the different ligands has been studied using both BP86 and B3LYP functionals. The relative values for the four uranium complexes having anionic ligands are in surprisingly good agreement with experiment, although the absolute values are in error by approximately 1 eV. The absolute error for the aqua species is much less, leading to an incorrect order of the redox potentials of the aqua and chloro species.

Photo-hydrogen-evolving activity of chloro(terpyridine)platinum(ii): a single-component molecular photocatalyst

[PtCl(terpy)]Cl x 2 H(2)O (terpy = 2,2':6',2''-terpyridine) (1Cl x 2 H(2)O) is the first example serving as a bifunctional system promoting both photosensitization and hydrogenic activation as an H(2)-evolving catalyst in aqueous media in the presence of a sacrificial electron donor (EDTA) under visible-light illumination. The rate of H(2) formation has turned out to be quadratic to the concentration of 1, suggesting that a bimolecular path determines the overall reaction rate for the photoinduced H(2) formation. It is suggested that the bimolecular mechanism operates at the photosensitization process through the formation of the so-called (3)MMLCT excited state and thus formed dinuclear photosensitizer itself provides a site for the hydrogenic activation (MMLCT = metal-metal-to-ligand charge transfer). The stability of the complex during the photolysis was successfully confirmed by ESI-TOF mass spectrometry. The photolysis was carried out in both the absence and the presence of mercury to rule out the formation of colloidal platinum. The rate of H(2) evolution considerably decreases when the photolysis was carried out by using acetate, propionate, or phosphate as a buffer reagent instead of MES (MES = 2-morpholinoethanesulfonic acid), which was used in typical experiments. The major chemical species in MES, acetate, propionate, and phosphate buffer solutions were respectively ascertained to be [PtCl(terpy)](+), [Pt(acetato)(terpy)](+), [Pt(propionato)(terpy)](+) and [Pt(H(2)PO(4))(terpy)](+) by ESI-TOF mass spectrometry. It is concluded that the original chloro species (i.e., [PtCl(terpy)](+)) plays a crucial role in the photochemical H(2) formation. The saturation kinetics for the H(2) formation with regard to the EDTA concentration was observed, revealing that the dimer of 1 (i.e., (1)(2)(2+)) and the dianionic form of EDTA form an ion-pair adduct to facilitate the electron injection from EDTA during the photochemical processes.

Bond distances are not always what they appear to be: discovery and un-discovery of the longest Cr(v)N triple bond

The coordination chemistry of CrCl3 with three pentadentate ligands having the [1,4,7]-triazacyclononane-1,4-diacetato motif have been investigated. The new resulting six-coordinate Cr(iii)-chloro species react cleanly with sodium azide to form the corresponding azido species, which undergo photolysis under irradiation at 419 nm in acetonitrile-water solution to form Cr(v)-nitrido species that are partially hydrolyzed to their corresponding Cr(III)-hydroxo counterparts. Five of these Cr complexes have been characterized by X-ray crystallography. The hydroxo and nitrido species co-crystallize complicating crystal structural refinement. What at first appeared to be the longest Cr[triple bond, length as m-dash]N triple bond distance yet observed (1.66 A) was found after re-refinement to be an artifact of positional disorder of the Cr atoms of 73% nitrido and 27% hydroxo species. The re-refined Cr[triple bond, length as m-dash]N bond distance is estimated as 1.58 A, which agrees well with the observed Cr[triple bond, length as m-dash]N stretching frequency of 971 cm-1 found by IR spectroscopy. UV-vis data for the "nitrido" complexes suggest that they are all three partially hydrolyzed. These results emphasize the care that must be taken in the characterization of compounds that may co-crystallize with structurally similar analogs.

Spectroelectrochemical Study of Neptunium in Molten LiCl-KCl Eutectic

Neptunium behaviour in an LiCl-KCl eutectic melt at 723 K was studied using spectroelectrochemistry. Cathodic reduction of neptunium(IV)-containing melts led to the formation of Np(III) ions and then neptunium metal. Electronic absorption spectra of Np(IV) and Np(III) chloro species in LiCl-KCl melt were recorded and resolved into individual Gaussian bands. The nature of neptunium complex ions in the melt is discussed.

Tungsten Chemistry in Alkali Chloride Melts

Speciation of tungsten in alkali chloride melts (based on NaCl-2CsCl, NaCl-KCl and 3LiCl-2KCl mixtures) was studied between 550 and 750◦C using electronic absorption spectroscopy. OnlyW(IV) and W(V) chloro and oxychloro species can be stabilized under the conditions studied. Tungsten(IV) chloride ions are very sensitive to oxide/hydroxide impurities present in the melt. Anodic dissolution ofWmetal at anodic current densities in the range of 0.005 - 0.1 A/cm2 produces only [WCl6]2− ions that can be electrochemically (on a glassy carbon anode) oxidized to [WCl6]−. Small amounts of oxide ions present in the melt result in a gradual conversion of W(IV) chloro species intoW(IV) oxychloro species. In the presence of O2 in the atmosphere [WCl6]2− is oxidized into the tungsten(V) species [WOCl5]2−. Dissolution of tungsten hexachloride, WCl6, in an NaCl-2CsCl melt initially yields [WCl6]2− (due to disproportionation). Reaction of metallic tungsten with Pd(II)-containing melts results in the formation of [WCl6]2− species. The main spectroscopic parameters of [WCl6]2− and [WCl6]− complex ions were calculated.

Arthromyces ramosus peroxidase produces two chlorinating species

We previously reported that the hemes of horseradish peroxidase (HRP) and Arthromyces ramosus peroxidase (ARP) undergo vinyl and meso-carbon modifications when the enzymes oxidize chloride ion. Here we demonstrate for ARP that, although both modifications exhibit the same pH profile with an optimum at ∼pH 4.0, monochlorodimedone suppresses the vinyl but not meso-carbon modifications. Furthermore, meso-chlorination occurs when ARP reacts with exogenous HOCl, implicating an Fe(III)–O–Cl intermediate in the reaction. These results establish that (a) the chloro species involved in meso-modification differs from that which reacts with the vinyl groups, (b) equilibration of the vinyl modifying species (HOCl) into the medium occurs more rapidly than vinyl group modification, and (c) the oxidation of chloride by ARP produces two reactive species: HOCl, which adds to the heme vinyl but not meso-positions, and a distinct second species that adds to the meso-carbon.

Leaching of an oxide gold ore with chloride/hypochlorite solutions

An oxide gold ore was subjected to chloride/hypochlorite leaching at room temperature. The effects of three factors, including Ca(OCl) 2 vs. NaOCl, OCl − concentration, and HCl concentration on gold leaching performance were investigated. Due to formation of CaOCl + complex in solution and hence less reactivity, calcium hypochlorite produces a sluggish gold leaching kinetics, taking twice the time (46 h) to achieve maximum gold recovery of 58% compared to sodium hypochlorite. 10 g/L of total initial hypochlorite species in solution produces reasonable gold recoveries. The amount of added HCl and hence the initial pH was found to have a major effect on gold leaching kinetics and maximum gold recovery. A high level of 9 g/L of added HCl causes HClO to be very reactive, producing very fast kinetics, reaching 67% gold extraction in 4 h. It also causes a faster consumption of hypochlorous acid, through catalytic decomposition (by NiO and CuO) and disproportionation. Hypochlorous acid reactions with sulfide and ferrous content of ore proceed very slowly in the pH range of 4–11. Gold–chloro complexes are strongly adsorbed on quartz component of ore. To minimize this undesirable adsorption of gold–chloro species, the aging time must be limited to a few hours only.

Various Coordination Modes of the Bis(di(o-N,N-dimethylanilinyl)phosphino)methane Ligand in Mononuclear and Binuclear Complexes of Group 8 and Group 9 Metals

The synthesis and characterization of a series of compounds involving the bis(di(o-N,N-dimethylanilinyl)phosphino)methane (dmapm) ligand are described. The mononuclear complexes [MCl(CO)(P,N-dmapm)] (M = Rh, Ir) have a square-planar geometry in which the dmapm ligand chelates via a phosphine functionality and an adjacent amino group. The carbonyl ligand lies opposite the amine, while the chloro ligand is trans to the phosphine. The related complex [RhI(CO)(P,N-dmapm)] has also been prepared. All compounds are highly fluxional by at least three independent processes, as discussed for the rhodium-chloro species. A diiridium complex, [Ir(2)Cl2(CO)2(P,N,P',N'-dmapm)], and the closely related rhodium/iridium analogue, [RhIrCl2(CO)2(P,N,P',N'-dmapm)], have been prepared in which the metals are bridged by the diphosphine group while an amino group at each end of the diphosphine is also coordinating to each metal on opposite faces of the MIrP2 plane (M = Ir or Rh). For the Ir2 species, the carbonyl and chloro groups are again shown to be opposite the amine and phosphine functionalites, respectively. The mononuclear complex [Ru(CO)3(P,P'-dmapm)] has also been prepared. In contrast to the mononuclear species of rhodium and iridium, the dmapm group chelates the ruthenium center through both phosphorus atoms, occupying one axial and one equatorial site of Ru in a distorted trigonal bipyramidal geometry. Reaction of this Ru species with 1/2 equiv of the complexes [RhClL2]2 (L2 = COD, (C2H4)2, (CO)2) yields the unstable Rh/Ru product [RhRuCl(CO)3(P,N,P',N'-dmapm)].

Solvation of uranyl(II) and europium(III) cations and their chloro complexes in a room-temperature ionic liquid. A theoretical study of the effect of solvent "humidity".

We report a molecular dynamics study of the solvation of the UO2(2+) and Eu3+ cations and their chloro complexes in the [BMI][PF6][H2O] "humid" room-temperature ionic liquid (IL) composed of 1-butyl-3-methylimidazolium+ and PF6- ions and H2O in a 1:1:1 ratio. When compared to the results obtained in dry [BMI][PF6], the present results reveal the importance of water. The "naked" cations form UO2(H2O)5(2+) and Eu(H2O)9(3+) complexes, embedded in a shell of 7 and 8 PF6- anions, respectively. All studied UO2Cln(2-n) and EuCln(3-n) chloro complexes remain stable during the dynamics and coordinate additional H2O molecules in their first shell. UO2Cl4(2-) and EuCl6(3-) are surrounded by an "unsaturated" water shell, followed by a shell of BMI+ cations. According to an energy component analysis, the UO2Cl4(2-) and EuCl6(3-) species, intrinsically unstable toward dissociation, are more stable than their less halogenated analogues in the IL solution, due to the solvation forces. The different chloro species also interact better with the humid than with the dry IL, which hints at the importance of solvent humidity to improve their solubility. Humidity markedly modifies the local ion environment, with major consequences as far as their spectroscopic properties are concerned. We finally compare the aqueous interface of [BMI][PF6] and [OMI][PF6] ionic liquids, demonstrating the importance of imidazolium substituents (N-butyl versus N-octyl) to the nature of the interface and miscibility with water.