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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]

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]

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]