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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]

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]

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]

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.)