Search

AcAc (β‐acetylacetonate) are among the first ligands ever to be studied. They form stable complexes with most metals. During the 1960s, their sulfur derivatives were introduced, including AcSac (β‐thioketonate), SacSac (β‐dithioketonate) and SacNac (β‐thioketoiminate). These derivatives exhibit contrasting reactivity, stereochemical, magnetic and spectral properties to their formed complexes. Sulfur ligand‐based complexes were at their pinnacle in the early 1970s, but their fell into disuse, due to the lack of methodologies for obtaining them and the absence of synthetic tools for their structural modification. As an effort to promote the study and application of these sulfur‐ligands; this review will address their history, the properties they bring to the metal centers and their potential applications. [ABSTRACT FROM AUTHOR]

A new type of trans‐dichloro‐Ir(III) complexes derived from non‐symmetrical NacNac‐type ligands was unexpectedly obtained as the main reaction product from the former ligands and the dimeric species [Ir(COD)Cl2]. One equivalent of LH was reacted with an excess of [Ir(COD)Cl]2 in dichloromethane or toluene as solvent and at room temperature. The general formula of the product is [IrCl2(COD)L] and was isolated as a sole product instead of the expected Ir(I) compound [Ir(COD)L]; all the new Ir(III) were prepared in high yields as microcrystalline solids. They were all stable under laboratory atmosphere, lasting for weeks in solution and for months in solid state. The structure of each compound was examined by 1D and 2D nuclear magnetic resonance (NMR) and high‐resolution mass spectrometry (HRMS). Complex 1k was selected for an X‐ray diffraction study. Finally, an evaluation was made of the catalytic activity of all complexes in the transfer hydrogenation reaction of ketones and imines. [ABSTRACT FROM AUTHOR]

Reaction of Ni(CO)4 in toluene at room temperature with one equivalent of GaAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) and GaL (L = HC[C(Me)N(C6H3-2,6-iPr2)]2) formed the mono-substituted Ni(CO)3(GaAr′) (1) and Ni(CO)3(GaL) (3), respectively. Compound 1 decomposed under reduced pressure or upon heating in toluene to give the new cluster species Ni4(CO)7(GaAr′)3 (2). Reaction of 3 with a second equivalent of GaL in toluene at 95 °C afforded the disubstituted complex Ni(CO)2(GaL)2 (4). All the compounds were characterized by IR, 1H and 13C{1H} NMR spectroscopy and X-ray crystallographic studies were undertaken to elucidate the structures of the complexes 2, 3 and 4.The reaction of Ni(CO)4 with GaAr′ affords [Ni(CO)3(GaAr′)] (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) which readily decomposes to the new nickel carbonyl cluster [Ni4(CO)7(GaAr′)3].

Here in, we report a rollover iridacycle complex cis-[Ir(κ2-C–N-L1)(κ2-N–N-L1)Cl2], which can be easily obtained as yellow solid, through the reaction of two equivalents of new 2-(6-bromopyridin-2-yl)imidazo[1,2-a]pyridine (L1) type ligand and IrCl3 in dimethylformamide at 70 °C for a week. Rollover complex have an unusual κ2-C–N-cyclometallated ligand fragment, which involves the C–H bond activation reaction in remote position on bromo-pyridine, with a second one in classic κ2-N–N-donor mode. The structure of both compounds was studied by NMR, IR, and high-resolution mass spectrometry. Rollover complex UV/Vis absorption spectrum showed a dominating π–π* absorption band at 350 nm. Excitation at 385 nm gave a narrow emission band with maximum at 541 nm, which was associated to ligand-centred emission. The ligand shows antiproliferative activities against breast cancer lines. Density Functional Theory (DFT) calculations suggest that the rollover C–H bond activation occurs after a first κ2-N–N coordination during the complexation of the second ligand and is supported by DMF molecules. [ABSTRACT FROM AUTHOR]

The article titled "Cover Feature: AcSac, SacSac, and SacNac, the Forgotten Sulfur-Based Ligands and their Reactivity in the Formation of Main and Transition Metal Complexes" explores the use of sulfur-based ligands in the synthesis of p-block and transition metal compounds. The authors highlight the re-emergence of this chemistry in recent years, particularly through the use of Lawesson's reagent as a mild sulfur-source for ligand synthesis. The article draws parallels between the beauty of monarch butterflies and geothermal sulfurated waters to the efforts of spreading this chemistry to different research fields. For more information, readers can refer to the review by J. Rangel-Garcia, C.E. Rivas, O. Serrano, and C. Cristobal. [Extracted from the article]

In this work, we describe a serendipitous self-assembly synthesis of non-symmetrical CNN–platinacycle pincer complexes, with an early formation and detection of hydride species. The synthesis involves a formal C–H bond activation, with an earlier C–N bond formation via C–Br bond excision, instead of the expected rollover cyclometalated complex. According to our experimental results, the nature of the Pt(II)-starting material, having cyclooctene (COE), tetrahydrothiophene (THT) or Cl as co-ligands, does not affect the reaction pathway, and the best yields are achieved using stochiometric amounts of K2PtCl4, and the appropriate Schiff base ligand and aniline, at 70 °C for three days. Structures of platinacycle complexes have been supported by UV/Vis, IR, NMR and ESI-MS experiments, although specific ions formed in the ionization source were affected by the solvent used for compound solubilization/dilution. [ABSTRACT FROM AUTHOR]

The article explains the mechanisms of the iridium mediated isomerization of pyridine to form its 2-carbene tautomer.

A study describes the transformation of 2-substituted pyridines into the respective carbene tautomers in an iridium mediated process that involves formally a 1,2-H shift from carbon to nitrogen. The increased bulkiness of the 2-substituted pyridines destabilizes the N-adduct by F-strain, while the isomeric carbene structures do not suffer from this kind of steric repulsion.

Rationale: Quantification of small molecules by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) is challenging yet attractive, due to micro‐scale procedural simplicity, high throughput and lack of memory effects. Since these features are important while analyzing trace elements in quality control schemes, MALDI‐TOFMS was used for the determination of copper (Cu) and lead (Pb) in tequila with quantification carried out by partial least squares regression (PLS2) and by univariate calibration (UC). Methods: In the proposed procedure, Bi(III) was added as internal standard (IS), diethyldithiocarbamate complexes were formed (pH 7.4) and extracted into chloroform; after solvent evaporation and re‐constitution in acetonitrile, the sample was co‐crystallized with α‐cyano‐4‐hydroxycinnamic acid on a steel target. From the acquired mass spectra, UC was performed using IS‐normalized signals of the monoisotopic ions of analytes, and the m/z range 350–513 was used for PLS2. Accuracy was tested by recovery experiments and by inductively coupled plasma (ICP)‐MS analysis. Results: When compared with direct analyte signal measurements, application of IS yielded enhanced analytical performance using either UC or PLS2; the method quantification limits were: 11.1 μg L−1, 23.4 μg L−1 for Cu and 89.8 μg L−1, 97.1 μg L−1 for Pb, respectively. In tequila, MALDI‐TOFMS and ICP‐MS provided consistent results for Cu (165–2599 μg L−1); Pb was not detected in any sample by MALDI‐TOFMS, yet recoveries obtained after standard addition were indicative of acceptable accuracy (400 μg L−1 Pb added; recoveries: 91.2–108% for UC and 98.8–120% for PLS2). Conclusions: New experimental evidence has been provided supporting the inclusion of trace metals quantification within a range of MALDI‐TOFMS applications. Slightly better results were obtained for UC as compared with PLS2 yet both methods can be recommended for testing the compliance of Cu and Pb levels with Official Mexican Norm. Of note, while using PLS2, there is no need for signal integration nor for IS normalization. [ABSTRACT FROM AUTHOR]

In this work, the synthesis and reactivity of seven-membered palladacycles are described, and a novel bi-pyridine synthesis in a catalytic pathway is reported. Neophyl-palladacycle(i) reacts with an excess of 2-Br-pyridine, giving the desired new binuclear seven-membered palladacycle (1) and unexpectedly, a bipyridine complex, [Pd(BiPy)Br2]. ESI-HRMS experiments show that fragmentation of the Pd–Br bond in 1 can take place producing unusual two coordinated Pd(ii) molecular ions, [Pd(NeoPyR)]+. [ABSTRACT FROM AUTHOR]

The synthesis of four rhodium(II) paddlewheel complexes bearing axial aromatic amines and coumarin ligands, with formula [Rh2(OAc)4(L)2] (L = NH2Mesityl (1), NH2Dip (2), NH2Couma (3), coumarin (4)), prompted by microwave irradiation, was carried out successfully. All of the complexes were characterized by the melting point, elemental analysis, NMR, IR, and UV/Visible spectroscopy. Additionally, the structure of complexes 1-2 and 4 was corroborated by single-crystal X-ray diffraction. Cyclic voltammetry, ESI-MS, and tandem MS analyses were carried out in compound 1 for gaining further insight into its stability. Finally, a DFT study shows that complexes 1–4 are the thermodynamic products, having as intermediates complexes 1′–4′ which, under our experimental conditions, cannot be isolated. [ABSTRACT FROM AUTHOR]

The bis(silyl)triazene compound 2,6-(Me3Si)2-4-Me-1-(NNNC4H8)C6H2 ( 4) was synthesized by double lithiation/silylation of 2,6-Br2-4-Me-1-(NNNC4H8)C6H2 ( 1). Furthermore, 2,6-bis[3,5-(CF3)2-C6H3]-4-Me-C6H2-1-(NNNC4H8)C6H2 derivative 6 can be easily synthesized by a C,C-bond formation reaction of 1 with the corresponding aryl- Grignard reagent, i.e., 3,5-bis[(trifluoromethyl)phenyl]magnesium bromide. Reactions of compound 4 with KI and 6 with I2 afforded in good yields novel phenyl derivatives, 2,6-(Me3Si)2-4-MeC6H2I and 2,6-bis[3,5-(CF3)2C6H3]-4-MeC6H2I ( 5 and 7, resp.). On the other hand, the analogous m-terphenyl 1,3-diphenylbenzene compound 2,6-bis[3,5-(CF3)2C6H3]C6H3I ( 8) could be obtained in moderate yield from the reaction of (2,6-dichlorophenyl)lithium and 2 equiv. of aryl- Grignard reagent, followed by the reaction with I2. Different attempts to introduce the tBu (Me3C) or neophyl (PhC(Me)2CH2) substituents in the central ring were unsuccessful. All the compounds were fully characterized by elemental analysis, melting point, IR and NMR spectroscopy. The structure of compound 6 was corroborated by single-crystal X-ray diffraction measurements. [ABSTRACT FROM AUTHOR]

Thereaction of dinuclear complex [IrCl(COD)]2(COD =1,5-cyclooctadiene) with 1 equiv of 1,3-dimesitylpropane-1,3-dione(H-AcacBiMs) and an excessof triethylamine in benzene or dichloromethane at room temperatureresults in the formation of β-diketonate complex [Ir(AcacBiMs)(COD)], 1. Further, compound 1reacts with an equivalentof H-AcacBiMsin dichloromethaneunder atmospheric conditions to give the new complex with the formula[cis-Ir(AcacBiMs)2(COE-OH)], 2(COE-OH = σ,π-hydroxyenediyl),through a formal insertion of a hydroxyl group into a COD ring. Allcompounds were characterized by melting point, analytical data, andIR and NMR spectroscopy. Additionally, an X-ray crystallographic studywas undertaken to corroborate the structure of both complexes. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of LiArMe6 [ArMe6 C6H3-2,6(C6H2-2,4,6-Me3)2] with InCl, [In(InI4)], InCl in the presence of LiI, or ‘GaI’ in toluene solution resulted in the isolation of the 1,2-diaryl-1,2-dihalogen derivatives [{InCl(ArMe6)}2]2 (1), [{InI(ArMe6)}2]2 (2), [{In4Cl2I2(ArMe6)4}] (3), and [{GaI(ArMe6)}2] (4). The indium derivatives 1–3 were isolated as tetrametallic complexes formed via the almost symmetric bridging by four halides of two In–In bonded, ArMe6In–InArMe6 moieties. In 1, the In4Cl4 core features almost parallel In–In units, linked by four almost symmetrically bridging chlorides. This yields a structure formed from two folded In2Cl2 rings, and two six-membered In4Cl2 boat-shaped rings that have common In–Cl edges. The structures of 2 and 3 also feature two ArMe6InInArMe6 units bridged by four halides. However, there is a large torsion angle between the two In–In vectors, so that the In4I4 (2) and In4Cl2I2 (3) cores are formed from four five-membered In3I2 (2) or In3ClI (3) rings. Compound 4 has a simple Ga–Ga bonded dimeric structure, in which the gallium atoms are three coordinated, being bonded to each other as well as to an iodine and an ArMe6 ligand. All the compounds were characterized by 1H and 13C {1H} NMR spectroscopy, and by X-ray crystallography. The structural differences between the gallium and indium derivatives is probably a result of the larger size and greater Lewis acidity of the indium centers. [Copyright &y& Elsevier]

Abstract: The nickel (0) compound Ni(COD)(GaAr′)2 (Ar′ = C6H3–2,6-(C6H3-2,6-i-Pr2)2), 1, was synthesized by the reaction of Ni(COD)2 (COD = 1,5-cyclooctadiene) with (GaAr′)2. Compound 1 reacted with ethylene at 25 °C and at 1 atm pressure to give the bimetallic cluster [Ni2(GaAr′)2(η1:η1-μ2-C2H4)], 2, through the incorporation of one molecule of ethylene and displacement of COD. The structure of 2 featured an unusual Ni2Ga2C2 core bicyclic structure in which the C2H4 moiety bridges the Ga···Ga edge of a Ga2Ni2 tetrahedron. The galliums each carry an η1-bonded Ar′ substituent which complexes the nickel atom by an η6–π interaction with one of its flanking Ar’ rings. [Copyright &y& Elsevier]

Graphical abstract Neutral and cationic nickel, palladium and platinum complexes containing a new N,N,S-tridentate ligand have been prepared and characterized. The structure of the ligand and eight complexes was determinate by X-ray crystallographic analysis. Ligand can be both mono- or di-deprotonated under mild reaction conditions. Studies in Heck reaction and antiproliferative activities are reported. Abstract Organometallic and coordination nickel, palladium and platinum complexes, neutral and cationic, with general formula [M(κ3-SacNac)X] and [M(κ3-SacNac)L′][BPh 4 ] (where M = Ni, Pd and Pt, X = Me, Cl, 1 – 6 ; M = Ni, X = N 3 , SMe, 7 – 8 ; M = Pd, X = I, 13 ; M = Ni and Pd, L′ = PPh 3 , 9 – 10 ; M = Ni and Pt, X = PMe 3 , dmso, 11 – 12) containing a new SacNac N,N,S-tridentate ligand [C 6 H 5 (S)CCH 2 C(N-CH 2 CH 2 NHC 6 H 5)CH 3 ] were synthetized and obtained as microcrystalline solids. Compounds 2 – 13 were fully characterized by elemental analysis, IR, 1D and 2D NMR spectroscopy. The structure of the ligand and eight complexes was determined by X-ray crystallographic analysis. The ligand can be both mono- or bi-deprotonated under mild reaction conditions. Results in Heck reaction and antiproliferative activities are reported. [ABSTRACT FROM AUTHOR]

Gallium (Ga) ion-doped TiO 2 (Ga-TiO 2 ) nanocomposite with small particle size (9-10 nm) and high surface area (104 m 2 /g) has been easily synthesized via sol-gel method at low temperature by using low-valent GaI as a doping precursor. The structural and morphological characterization of Ga-TiO 2 was carried out with standard analytical and spectroscopic techniques. Ga doping into the TiO 2 matrix inhibited a phase transformation from anatase to rutile (photocatalytically inactive) form, even at a higher temperature of 750 °C. Finally, Ga-TiO 2 nanocomposite showed high photocatalytic activity and exhibited 97% degradation of acid violet 63 dye within 60 min. The dye degradation rate constant was calculated as 1.6 × 10 -1 and 1.4 × 10 -1 min -1 under UV and white light irradiation, respectively, which is higher, as compared to the previously reported Ga-TiO 2 composites to date.

Herein, three novel Pt(ii) complexes with formula [ trans -Pt(Br-PyBenz-X)(Cl) 2 (DMSO)] (1-3) having Br-pyridylbenz-(imida, oxa or othia)-zole (L 1-3 ) derivatives as potential bidentate ligands, under an unusual κ 1 -N-coordination mode are reported. All compounds were obtained straightforwardly via reaction of corresponding L PB1-3 and [Pt(Cl) 2 (DMSO) 2 ] (DMSO = dimethyl sulfoxide), at 100 °C in acetonitrile, respectively. 1-3 complexes were characterized by analytical and spectroscopic data: melting point, FT-IR, Raman, UV/Vis and NMR experiments. Cyclic voltammetry studies show an irreversible two-electron process at -0.50 and -0.51 V, which was ascribed to the Pt(ii)/Pt(iv) couple, for complexes 2 and 3. The crystal structure of complex 2 was elucidated by single-crystal X-ray diffraction, where the platinum atom exhibits a square plane geometry, where L PB2 adopts an unusual mono-coordinated mode via an N-κ 1 -benzoxazole ring. According to DFT calculations the first N-coordination exchanging one DMSO molecule is favourable, while the second N-coordination is highly impeded., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

C-Br bond activation followed by a C-C coupling reaction of the 2-bromo-pyridyl unit of [1-phenyl-2-(6-bromopyridin-2-yl)-benzoimidazole] was performed by Pd(CH(2)CMe(2)-o-C(6)H(4))(η(4)-COD). Two new seven membered palladacycles were obtained. A combined experimental and theoretical DFT study elucidates the mechanism for this reaction.

The Ir(III) compound Tp(Ms'')Ir(N2), that contains a pentadentate, doubly metalated 3-mesityl substituted tris(pyrazolyl)borate ligand, induces the cleavage of C-H and C-Cl bonds of CH2Cl2 to yield a highly electrophilic chlorocarbene Ir=C(H)Cl complex.