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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]

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 first goal of this work was to explore the feasibility of diaryl-mercury species as the synthetic precursors of triaryl-gallium species GaAr* 3 (where Ar*= pH, 4; Ar*= 3,5-difluorophenyl, 5; and Ar*= 3,5-trifluoromethylphenyl, 6). Expecting that 4–6 behave as Lewis acids of different strength, the second purpose was to use them for the synthesis of either rollover or classic cyclometallated Ga compounds. Three analogous diaryl-mercury HgAr* 2 species, 1–3, were successfully synthesized. The structures of compounds 2 and 3 were confirmed by gas chromatography - mass spectrometry experiments. Additionally, compound 3 was analyzed through X-ray diffraction; in the crystal structure obtained, π-stacking interactions were observed. The only Ga compound synthesized was GaPh 3 , 4, because the presence of fluorine-containing groups in meta-position caused sublimation of the respective mercury diaryl compounds, impeding their reaction with gallium. The attempts toward the synthesis of the rollover or classic cyclometallated compounds in the reaction of 4 with bipyridine-, pyrazole- or benzo-imidazole- type ligands have failed. On the other hand, under the experimental conditions applied, water traces favored formation of the solid aryl-Ga cluster containing twelve Ga atoms [Ga 12 ], whereas the above-mentioned ligands were quantitatively recovered in the solution. The identity of aryl-gallium cluster was confirmed by electrospray ionization - high resolution mass spectrometry. Although Ga cluster was not expected, it is considered an important finding of this work, owing to the variety of possible applications and still limited data available on the synthesis and structural characterization of such compounds. [Display omitted] [ABSTRACT FROM AUTHOR]