Isostructural diamagnetic cobalt(III) and paramagnetic nickel(III) dithiolene complexes with an extended benzenedithiolate core [CpM(bdtodt)] (M = Co and Ni)

The isostructural diamagnetic [CpCo(bdtodt)] and paramagnetic [CpNi(bdtodt)] (Cp = η⁵-cyclopentadienyl, bdtodt:benzo[1,3]dithiol-2-one-5,6-dithiolato) complexes were prepared by starting from the corresponding bis(dithiocarbonate): benzo[1,2-d;4,5-d′]bis[1,3]dithiole-2,6-dione. Both Co and Ni complexes are isostructural and crystallize in the orthorhombic system, space group Pbca. The formally M^III (16-electron for Co^III and 17-electron Ni^III) complexes were investigated by X-ray structure analyses and exhibit the same two-legged piano-stool geometry. The CV of the radical [CpNi(bdtodt)] resulted in well-defined reversible reduction and oxidation waves. On the other hand, oxidation of [CpCo(bdtodt)] leads to dimerization in CH₂Cl₂ or reaction in the more coordinating CH₃CN solvent. The absorption maximum (λ_max) of [CpNi(bdtodt)] (741 nm) showed a more red shift compared with [CpCo(bdtodt)] (595 nm) in dichloromethane solution. The structural similarities, and electrochemical, spectroscopic and magnetic differences between various [CpCo(dithiolene)] and [CpNi(dithiolene)] complexes are further analyzed.     

Syntheses and reactivities of azido coordinated CpCo(dithiolene) complexes

Azido coordinated dithiolene complexes [CpCo(N₃){S₂C₂(CO₂Me)₂}(S-CHR¹R²)], where R¹, R² = H (4a); R¹ = H, R² = SiMe₃ (4b); R¹ = H, R² = CO₂Et (4c), were synthesized by the reactions of the corresponding Cl⁻ coordinated precursors [CpCo(Cl){S₂C₂(CO₂Me)₂}(S-CHR¹R²)] (3a-3c) with sodium azide. The Cl⁻ coordinated complex 3d (R¹, R² = CO₂Me) did not produce any N₃⁻ coordinated complexes but formed the CR¹R²-bridged alkylidene adduct [CpCo{S₂C₂(CO₂Me)₂}(CR¹R²)] (2d; R¹, R² = CO₂Me). The structure of 4a was determined by X-ray diffraction study. In the molecular structure of 4a, the coordinated N₃⁻ ligand and CHR¹R² group were located at the same side with respect to the dithiolene ring (syn form), although the corresponding Cl⁻ precursor (3a; R¹, R² = H) was anti form. A structural conversion of syn/anti was conceivable during the Cl⁻/N₃⁻ ligand exchange. Thermal (80 °C) and photochemical reactions (Hg lamp) of 4a-4c were performed. Among them, 4c was relatively well reacted compared with the others to form the CR¹R²-bridged alkylidene adduct (2c; R¹ = H, R² = CO₂Et), followed by a formal HN₃ elimination, and the reaction also produced non-adduct of the cobalt dithiolene complex [CpCo{S₂C₂(CO₂Me)₂}] (1). The electrochemical 1e⁻ reduction of 4c underwent a formal N₃⁻ ligand elimination, and successive second reduction caused the CHR¹R² group elimination or reformed the CR¹R²-bridged alkylidene adduct 2c.     

Two near-UV and visible chromophores of CpCo(Dithiolene) complexes with pyridinium-dicyanomethylide group

Tetracyanoethylene oxide (TCNEO) reacted with [CpCo(dithiolene)] (Cp = η⁵-cyclopentadienyl) complexes having 4-pyridyl or 3-pyridyl group to undergo a dicyanomethylation to the nitrogen atom on the pyridyl group. The reaction of [CpCo(S₂C₂(⁴Py)₂)] (1) with TCNEO formed both the monodicyanomethylated [CpCo(S₂C₂(⁴Py)(⁴Py-C(CN)₂))] (1a) and bisdicyanomethylated [CpCo(S₂C₂(⁴Py-C(CN)₂)₂)] (1b). [CpCo(S₂C₂(²Py)(⁴Py))] (2) reacted with TCNEO to give [CpCo(S₂C₂(²Py)(⁴Py-C(CN)₂))] (2a) but no dicyanomethylation occurred on the 2-pyridyl group. 2 reacted with excess TCNEO to form the only dicyanomethylated acetylene derivative ²Py-CC-(⁴Py-C(CN)₂) (2c), followed by a dissociation of the CpCoS₂ fragment. The monodicyanomethylated [CpCo(S₂C₂(ⁿPy-C(CN)₂)(2-thienyl))] (n = 4 (4a) or 3 (5a)) complexes were also prepared from [CpCo(S₂C₂(ⁿPy)(2-thienyl))] (n = 4 (4) or 3 (5)) and TCNEO. 1b was structurally characterized by X-ray diffraction study. The all dicyanomethylated [CpCo(dithiolene)] complexes showed the dithiolene LMCT absorption in the range of 605-644 nm (ε = 7000-9200 M⁻¹ cm⁻¹) and very strong absorption due to their pyridinium-dicyanomethylide moieties in near-UV region (e.g. 1b: λ_max = 470 nm, ε = 43,400 M⁻¹ cm⁻¹). The CV of the all dicyanomethylated complexes exhibited two reduction waves. The first reduction is due to Co^III/Co^II and the second one is due to the reduction of the pyridinium-dicyanomethylide moiety. The reduced 1b⁻ is stable enough for several minutes according to the visible spectroelectrochemical measurement. The ESR spectrum of 1b⁻ indicated eight hyperfine splittings due only to the interaction with the nuclear spin of cobalt (I = 7/2).     

CpCo(dithiolene) complexes of highly flexible oxddt ligand with two different Z-shaped and U-shaped structures

[CpCo(oxddt)] complex (2, oxddt = o-xylenediyldithioethylene-1,2-dithiolate, Cp = η⁵-cyclopentadienyl) was obtained from o-xylenediyldithioethylene-1,3-dithiol-2-one (OC(oxddt)) (1). 2 further reacted with diazoalkanes (N₂CHR) to form some alkylidene-bridged adducts [CpCo(CHR)(oxddt)] (R = H (3a), SiMe₃ (3b)). Adduct 3a further reacted with protic acids (HX) to give some S-methylated adducts [CpCo(X)(oxddt)(S-Me)] (X = Cl (4a), OCOCF₃ (4c)), followed by the Co-C bond cleavage in the three-membered cobaltathiirane ring. Two different Z-shaped and U-shaped molecular structures were observed by X-ray diffraction studies. In the former structure (Z), the dithiolene and o-xylylene planes are located at almost parallel position each other, and in the latter structure (U), both planes are not parallel but the o-xylylene moiety is located closer to the dithiolene plane than the Z-shaped one. The Z-shaped structure involves 1 and 2. The U-shaped structure involves 3a, 3b, 4a and 4c. Complex 1 showed a one-dimensional chain through intermolecular π-π interaction in the crystal. Complex 2 had a dimeric interaction between dithioethylenedithiolate moieties (S₂C₂S₂) in the oxddt. The SiMe₃ group in 3b was placed at an exo-position with respect to the cobaltadithiolene ring due to a steric hindrance from the U-shaped oxddt ligand. In 4a, the X and Me groups are located at the opposite side of the dithiolene plane (anti-form) but in 4c, both groups are presented at the same side of the dithiolene plane (syn-form). The NMR analysis of 4a in solution indicated existence of both anti- and syn-isomers (7:1).     

Synthesis,structure and physical properties of nickel bis(dithiolene) complexes with different cations

A series of new complexes of multi-sulfur 1,2-dithiolene ligands, [Ru(bipy)₃][Ni(L)₂]₂ (bipy?=?2,2′-bipyridine; L?=?pddt (6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate), dddt (5,6-dihydro-1,4-dithiin-2,3-dithiolate)), have been synthesized and characterized. One typical complex, [Ru(bipy)₃][Ni(pddt)₂]₂·2H₂O (1), crystallized in an acentric space group of P2₁2₁2₁, with the cell dimensions of a?=?8.634(1), b?=?14.560(1), c?=?49.889(5)?Å, α?=?β?=?γ?=?90°, and Z?=?4. It consists of alternating columns of cations and anions along the a direction. The structure was refined by full matrix least squares methods to R ₁?=?0.0340, wR ₂?=?0.0670. Magnetic studies on [Ph₂Cr][Ni(dddt)₂] are also reported.     

Formations and electrochemical behavior of mononuclear and binuclear molybdenum dithiolene complexes with nitrosyl ligands: Evidence for the formation of a coordinatively unsaturated species [CpMo(NO)(dithiolene)]

The one-pot reaction of [Cp^∗Mo(NO)(CO)₂] with elemental sulfur and dimethyl acetylenedicarboxylate (C₂Z₂ (Z = COOMe)) gave the [2+2] cycloadduct of the mononuclear molybdenum dithiolene complex [Cp^∗Mo(NO)(S₂C₂Z₂)(C₂Z₂)] (1), and some binuclear complexes:[Cp^∗Mo(NO)(S₂C₂Z₂)]₂ (2), [Cp^∗₂Mo₂(NO)₂S₂(S₂C₂Z₂)] (3) and [Cp^∗Mo(NO)S₂]₂ (4).The reaction of [Cp^∗Mo(NO)(Cl)(μ-Cl)]₂ with OC{S₂C₂(COOMe)₂} in the presence of sodium methoxide also produced complex 2 and the paramagnetic Cp^∗Mo bisdithiolene complex [Cp^∗Mo(S₂C₂Z₂)₂] (5, Z = COOMe).The structures of complexes 1-5 were determined by X-ray crystal structure analysis.The nitrosyl ligands of complexes 1-4 showed a linear coordination to the molybdenum center (the Mo-N-O bond angles = 169-174°), and their N-O bond lengths were 1.17-1.20 Å.In the binuclear complexes 2-4, two nitrosyl ligands were placed at cis-position.Complexes 1 and 2 were characterized by cyclic voltammetry and spectroelectrochemistry (visible and IR). The electrochemical reduction of the dimeric complex 2 formed the monomeric dithiolene complex[Cp^∗Mo(NO)(S₂C₂Z₂)]⁻ (X⁻) whose lifetime was several minutes. When the anion X⁻ was electrochemically oxidized, the coordinatively unsaturated species X was generated, but it was immediately dimerized to afford the original dimeric complex 2. The reduction of the complex 1 included the elimination of the bridged DMAD moiety (C₂Z₂) to give the anion X⁻.     

Reactivity and electrochemical behavior of ruthenium dithiolene complexes with coordinatively unsaturated metal centers: cycloaddition and dimerization reactions

The novel ruthenium dithiolene complexes [(arene)Ru{S₂C₂(COOMe)₂}] (arene = C₆H₆ (1a), C₆H₄(Me)(iPr) (1b), C₆Me₆ (1c)) were synthesized. The equilibrium between complex 1a and the corresponding dimer [(C₆H₆)Ru{S₂C₂(COOMe)₂}]₂ (1a′) was confirmed in solution. The reaction of complex 1a with dimethyl- or diethylacetylene dicaboxylate gave the alkene-bridged adducts [(C₆H₆)Ru{S₂C₂(COOMe)₂}{C₂(COOR)₂}] (R = Me (2a), Et (3a)) as [2 + 2] cycloaddition products formally. The reactions of complex 1a with diazo compounds also gave the alkylidene-bridged adducts [(C₆H₆)Ru{S₂C₂(COOMe)₂}(CHR)] (R = H (4a), SiMe₃ (5a), COOEt (6a)) as [2 + 1] cycloaddition products. The electrochemical behavior of complex 1a was investigated. The reductant of complex 1a was a stable species for several minutes. The oxidant of complex 1a was very unstable; the cation 1a⁺ formed was immediately converted to the corresponding cationic dimer 1a′⁺. The cationic dimer 1a′⁺ was stable for several minutes, and it was rapidly and quantitatively converted to the neutral complex 1a when it was reduced.     

Radical CpNi(dithiolene) and CpNi(diselenolene) complexes: Synthetic routes and molecular properties

The formally Ni(III) d⁷ radical organometallic complexes formulated as [CpNi(dithiolene)] can be prepared by different routes involving different CpNi sources such as the Ni^(I) [CpNi(CO)]₂, the Ni^(II) [Cp₂Ni] or [CpNi(cod)]⁺ or the Ni^(III) [Cp₂Ni]⁺ complexes. As dithiolene precursors, the naked dithiolate, the mono- as well as bis-(dithiolene) metal complexes were investigated. The highest yields are generally associated with an appropriate redox match, that is a CpNi^(II) precursor with a formally Ni^(IV) [Ni(dithiolene)₂]⁰ complex, or a CpNi^(III) precursor with a formally Ni^(III) [Ni(dithiolene)₂]^? complex. The structural, electrochemical and spectroscopic (UV–vis–NIR, EPR) properties of more than twenty complexes are described and compared, with the help of DFT calculations. They all exhibit a small optical gap with a low-energy absorption band in the Near Infra-Red region, between 700 and 1000 nm. The smaller electrochemical and optical gap found in the [CpNi(dmit)] and [CpNi(dddt)] complexes is correlated with an extensive delocalisation of the spin density in these complexes, while the other members of the series are characterized with a larger and sizeable spin density on the cyclopentadienyl ring.     

Hydrogen bonding interaction of CpCo(Dithiolene) complex with monocyclic 2-pyridonyl substituent and unexpected formation of dithiolene-fused tricyclic pyridone derivative

One-pot reaction of [CpCo(CO)₂], elemental sulfur with some heterocycle-substituted alkynes (R-CC-HET) produced [CpCo(dithiolene)] complexes with ²PyOBn (2), with both ²PyOBn and 2-hydroxy-2-propyl groups (C(OH)Me₂) (5), both ²Py and C(OH)Me₂ (8), both ⁴Py and C(OH)Me₂ (11), and with ⁴Py substituent (13). A deprotection of benzyl group (Bn) from 2 with trimethylsilyl iodide formed [CpCo(dithiolene)] with 2-pyridonyl substituent (3). Heating reaction of 8 without any base resulted in the C(OH)Me₂ group elimination to form the 2-pyridylethylenedithiolate complex (9), but 11 underwent only dehydration at the C(OH)Me₂ under heating. While the preparation of 5, the benzyl free complex (6) was obtained as a main product. 6 has a dithiolene-fused tricyclic pyridone skeleton. The structures of 3, 5, 6, 8, and 11 were determined by X-ray diffraction studies. Intramolecular OH?N(²Py) hydrogen bondings are found in 5 and 8, and an intermolecular OH?N(⁴Py) one is found in 11 at solid state. In the 2-pyridonyl complex 3, intermolecular NH?O and CH(dithiolene)?O hydrogen bondings are observed. 8 showed an intermolecular Cp?Cp face-to-face interaction. The tricyclic complex 6 exhibited lower energy electronic absorption (λ_max = 668 nm) compared with the others (λ_max = 562-614 nm), due to an extended π-conjugation of aromatic cobaltadithiolene ring.     

Rare direct imidation of aromatic metallacycle by reaction of CpCo(dithiolene) complex with N-halosuccinimide

The aromatic [CpCo(S₂C₂(R)(H))] (R = Ph, Me, 9-phenanthryl, H) complexes reacted with N-halosuccinimides (NXS; X = Cl, Br, I) in carbon tetrachloride at room temperature to undergo the N-succinimide substitution reaction on the dithiolene ring, but no halogenated dithiolene complex was obtained. The imidation products [CpCo(S₂C₂(R)(N-sccinimide))] were yielded up to 64% where X = I and R = 9-phenanthryl. The reaction of [CpCo(S₂C₂(Ph)(H))] with N-bromophthalimide (NBP) also gave the imidation product [CpCo(S₂C₂(Ph)(N-phthalimide))]. This is the rare direct imidation reaction to an aromatic metallacycle by NXS. The reaction of [CpCo(S₂C₂H₂)] (R = H) with NIS afforded the double imidation product. One by-product in this reaction was the dithiolene-dithiolene homo-coupling product [CpCo(S₂C₂(R))]₂ (R = Ph, Me, 9-phenanthryl). The microwave-enhanced (MW) reactions were attempted in the carbon tetrachloride solution. Although the solution temperature increased up to only 43 °C by MW irradiation, the imidation reaction worked with short reaction time.     

Formations and structures of cobalt dithiolene complexes with nitrogen group-substituted cyclopentadienyl ligands

The cobalt dithiolene complex with the sulfonylamide-substituted Cp ligand [(C₅H₄-NHTs)Co{S₂C₂(COOMe)₂}] (1, Ts = p-SO₂C₆H₄Me) reacted with TsOH · H₂O to give [(C₅H₄-NH₂)Co{S₂C₂(COOMe)(H)}] (2), [(C₅H₄-NHTs)Co(S₂C₂H₂)] (3) and [(C₅H₄-NHTs)Co{S₂C₂(COOMe)(H)}] (4). Complex 1 was dissolved in a basic aqueous solution, and the anion reacted with Me₂SO₄ to form the N-methylated product [{C₅H₄-N(Me)Ts}Co{S₂C₂(COOMe)₂}] (5); the carboxylic acid complex [{C₅H₄-N(Me)Ts}Co{S₂C₂(COOMe)(COOH)}] (6) formed by a base hydrolysis. The X-ray crystal structures of complexes 4-6 and the methylsulfonylamide-substituted Cp complex [(C₅H₄-NHMs)Co{S₂C₂(COOMe)₂}] (7, Ms = SO₂Me) were determined. In the crystal structures of complexes 4 and 7, intermolecular hydrogen bondings of NH?O (ca. 2.1 Å) and NH?S (ca. 3.1 Å) were observed. Complex 6 showed the OH?O intermolecular hydrogen bonding (ca. 1.6 Å) of COOH moiety between two molecules, and these two molecules were assembling each other. Complexes 5 and 6 showed an intramolecular π-π interaction between the aromatic cobaltadithiolene and benzene rings, and complex 5 also has intermolecular π-π interactions between two benzene rings, and between two cobaltadithiolene rings.     

Syntheses,crystal structures,and electrochemical characterizations of two octahedral iron(III) complexes with Schiff base of pyridoxal and aminoguanidine

This article presents the synthesis, physico-chemical, in particular voltammetric, characteristics of two iron(III) complexes with pyridoxal aminoguanidine (PLAG), [Fe(PLAG)Cl₂(H₂O)]Cl (1) and [Fe(PLAG)₂](NO₃)₃ (2). As expected, the zwitterion of the chelate ligand is coordinated tridentate through oxygen of phenol and nitrogen atoms of azomethine and imino groups of the aminoguanidine fragment. In both complexes, Fe(III) is distorted octahedral. [Fe(PLAG)₂](NO₃)₃ (2) is the first bis(ligand) complex with this ligand. Cyclic voltammetric characteristics of the ligand and complexes were studied in DMF in the presence of TBAP or LiCl as supporting electrolytes. The complexes are unstable in this solvent, especially in the presence of an excess of chloride, thus forming several reducible species whose stabilities and behaviors were characterized.     

Two Isostructural Layered Lanthanide(III) Complexes: Syntheses,Structures, Magnetic and Luminescent Properties

Two N'-(2-hydroxybenzylidene)pyridine N-oxide-carbohydrazide (H₃L)-based coordination complexes with the formula [Ln₂(DMF)₂(OAc)₂(HL)₂]_n (Ln = Dy for 1 and Eu for 2 ) were solvothermally synthesized. Crystal structures, thermal stabilities, magnetic and luminescent properties of the two complexes were fully investigated. Both complexes are isomorphic two-dimensional layers with centrosymmetric {Ln₂} subunits extended by doubly deprotonated HL^2– connectors. Complex 1 with highly anisotropic Dy^III spin exhibits slightly frequency-dependent magnetic relaxations under zero dc field with an effective energy barrier of ca. 6.84 K. Eu^III-based complex 2 displays only one weak fluorescent emission around 532 nm with the absence of characteristic emission of Eu^III ion. These results provide helpful hints of the hydrazide Schiff-functionalized organic ligands on the function modulations of the resulting Ln complexes.     

Syntheses,crystal structures,electrochemical studies,and antioxidant activities of zinc(II) and copper(II) complexes with bis(2-benzimidazolyl) aniline derivatives

Two ligands, bis(benzimidazol-2-ylmethyl) aniline (bba) and bis(N-methyl-benzimidazol-2-ylmethyl) aniline (Mebba), and their transition metal complexes [Zn(bba)(Br)₂]·2DMF (1) and [Cu(Mebba)(Br)₂]·2DMF (2) have been synthesized and characterized by elemental analyses, molar conductivities, UV–vis spectra, IR spectra, NMR spectroscopy, and X-ray crystallography. The structure around Zn(II) can be described as distorted tetrahedral. Complex 2 can be described as distorted trigonal bipyramidal. Cyclic voltammograms of 2 indicate a quasireversible Cu²⁺/Cu⁺ couple. Additionally, the antioxidant activities of the free ligands and their complexes were determined by the superoxide and hydroxyl radical scavenging methods in vitro. Complexes 1 and 2 possess potent hydroxyl radical scavenging activity and better than standard antioxidants such as vitamin C and mannitol. Complex 2 possesses excellent superoxide radical activity.     

Synthesis, structure, catalytic transfer hydrogenation and biological activity of cyclometallated ruthenium(III)2-(arylazo)phenolate complexes

A series of mononuclear organoruthenium complexes of the type [RuX(PPh₃)₂(L)] (X = Cl or Br; L = 2-(arylazo)phenolate ligand) have been synthesized from the reaction of five 2-(arylazo)phenol ligands with ruthenium(III) precursors, viz. [RuCl₃(PPh₃)₃] and [RuBr₃(PPh₃)₂(CH₃OH)] in benzene under reflux. In all these reactions, the 2-(arylazo)phenolate ligand replaces one triphenylphosphine molecule, two chlorides or bromides and one methanol from the precursors leading to five-membered cyclometallated species. The 2-(arylazo)phenol ligands behave as dianionic tridentate C, N, O donors and coordinated to ruthenium by dissociation of the phenolic proton and the phenyl proton at the ortho position of the phenyl ring. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-Vis and EPR spectral data. These complexes are paramagnetic and shows intense d-d and charge transfer transitions in chloroform. The solution EPR spectrum of the complex 7 in dichloromethane at 77 K shows rhombic distortion around the ruthenium ion. The structural conformation of the complex 1 has been carried out by X-ray crystallography. The redox behavior of the complexes has been investigated by cyclic voltammetry and the potentials are observed with respect to the electronic nature of substituents (R) in the 2-(arylazo) phenolate ligands. These complexes catalyze transfer hydrogenation of benzophenone to benzhydrol with up to 99.5% in the presence of i-prOH/KOH. Further, these complexes have shown great promise in inhibiting the growth of both Gram +ve and Gram −ve bacteria, viz. Staphylococcus aureus NCIM 2079 and Escherichia coli NCIM 2065 and fungus Candida albicans NCIM 3102.     

Ru(III) complexes containing 3,5-pyrazole dicarboxylic acid and triphenylphosphine/triphenylarsine: Synthesis, characterization and catalytic activity

New hexa-coordinated Ru(III) complexes of the type [Ru(H₂Pzdc)(EPh₃)₃X₂] have been synthesized by reacting 3,5-pyrazole dicarboxylic acid (H₃Pzdc) with the appropriate starting complexes [RuX₃(EPh₃)₃] (where X = Cl or Br; E = P or As). The ligand behaves as a bidentate monobasic chelate. All the complexes have been characterized by analytical and spectroscopic (IR, electronic and EPR) data. Single-crystal X-ray analysis of the complex [Ru(H₂Pzdc)(PPh₃)₂Cl₂]·C₆H₆·C₂H₅OH revealed that the coordination environment around the ruthenium center consists of an NOP₂Cl₂ octahedron. The planar ligand occupies the equatorial position along with two chlorine atoms, while the triphenylphosphine groups occupy the axial positions. The electrochemical behavior of the new complexes was studied using cyclic voltammetry. The new mononuclear ruthenium complexes are capable of acting as catalysts for the oxidation of alcohols.     

Synthesis,characterization, and electrocatalysis of a dinuclear cobalt(III) thioxanthate complex

This study reports on the synthesis, characterization, and performance of a new dinuclear cobalt(III) thioxanthate complex of [Co₂(μ-SC₂H₄OH)₂(HOC₂H₄SCS₂)₄] as an electrocatalyst for trichloroacetic acid (TCA) and bromate reduction. Its structure was characterized by X-ray crystallography and elemental analysis. The structure contains two different anions of 2-sulfanylethanol thioxanthate and 2-sulfanylethanol. The electrochemical behavior and the electrocatalysis of the cobalt complex bulk-modified carbon paste electrode have been studied by cyclic voltammetry. It shows good electrocatalytic activities toward the reduction of TCA and bromate. The values for the detection limit and the sensitivity are 0.06 µmol L^?1 and 19.40 µA µmol L^?1 for TCA detection and 0.01 µmol L^?1 and 177.6 µA µmol L^?1 for bromate detection, respectively. This modified electrode exhibits good reproducibility, high stability, low detection limit and technical simplicity, and allows a possibility for rapid preparation, which is important for practical applications.     

Ketiminate supported aluminum(III) complexes: Synthesis, characterization and reactivity

The reaction of LLi, (L = [RNC(Me)CHC(Me) = O] (R = C₂H₄NEt₂)), with AlCl₃ at −78 °C forms the mono-ketiminate product, LAlCl₂, 1, while the same reaction at 0 °C affords the bis-ketiminate complex, [{(LH)₂AlCl}(Cl₂)], 2, Reduction of 1 with Li^o, K^o or Mg^o yielded an unusual dimeric aluminum(III) species, [L′AlCl]₂, 3, where C-C coupling of the ligand backbone is observed.     

New type dithiolene complex based on 4,5-(1,4-dioxane-2,3-diyldithio)-1,3-dithiol ligand: Synthesis,experimental and theoretical investigation

A new Nickel complex with an extended multisulfur dithiolene ligand Ni(edodddt)₂ (edodddt = 2,3,4α,8α-tetrahydro-dithiine [2,3-b] [1,4] dioxo-6,7-dithiolene) has been synthesized and characterized by electrochemical measurements, IR, UV–Vis and NMR spectroscopy. Its crystal structure was resolved by X-ray diffraction on a single crystal. DFT calculations were made in order to compare the results with the experimental findings and gain an insight of the properties of this new dithiolene complex.     

(n‐Bu4N)2[Au(mnt)2]: Synthese,Struktur‐ und EPR‐Untersuchungen eines stabilen,mononuklearen AuII‐Komplexes

The reaction of [Au^III(mnt)₂]^? with (n‐Bu₄N)[BH₄] in acetone leads to the formation of [Au^II(mnt)₂]^2?, which is the second stable mononuclear Au^II complex characterized by X‐ray structure analysis. (n‐Bu₄N)₂[Au^II(mnt)₂] crystallizes triclinic, P (a = 904.24(5), b = 989.55(5), c = 1627.35(10) pm, α = 92.040(7), β = 94.937(7), γ = 107.220(6)°, Z = 1) with two molecules acetone per unit cell. The anion is planar. From EPR investigations using single crystals of (n‐Bu₄N)₂[Au^II(mnt)₂] the g tensor components were derived. Information about magnetic exchange interactions were obtained from line width analyses.