A zwitterionic nickel(II) catalyst has been discovered to display an initial catalytic activity comparable to that of cationic palladium catalysts for alternating copolymerization of carbon monoxide and ethylene. This demonstrates the absence of a severe dormant state in the present zwitterionic system, in contrast to the cationic nickel(II) catalysts. However, the highly active catalyst is short-lived. Stoichiometric decomposition of the catalyst under carbon monoxide suggests that the insufficient stability of the tetraphenylborate motif in the ligand framework with respect to electrophilic attack is likely a culprit for catalyst deactivation. P alladium-catalyzed alternating copolymerization of alkene and carbon monoxide is a highly efficient method for synthesis of aliphatic polyketones. 1−5 Simple members in this family, such as the terpolymer of CO, ethylene, and propylene, possess a plurality of desirable materials properties and are attractive semicrystalline engineering thermoplastics suitable for a variety of applications. 6,7 Since the initial attempts by Shell and BP in the 1990s, efforts of large-scale production of the aliphatic polyketones have continued. However, one of the shortcomings of the current technology is the necessity of using the expensive palladium metal as the catalyst.Nickel is the first metal discovered to catalyze CO−ethylene copolymerization but is generally far inferior to palladium and has not been as widely studied. The cationic palladium catalysts in the commercial processes typically have activities of ∼6000 g (g of Pd) −1 h −1 (grams of polyketone per gram of palladium per hour) and productivities of 10 6 g (g of Pd) −1 (grams of polyketone per gram of palladium). 2 The nickel analogues of the cationic palladium catalysts are less productive and less active than the latter by several orders of magnitude. 8,9 Brookhart and his co-workers have shown from a mechanistic viewpoint that the difference between cationic Ni and Pd catalysts is the involvement of five-coordinate intermediates in the nickel system. 10 The 18-electron, 5-coordinate chelate intermediate A reacts with ethylene very slowly and may be a resting state that severely impedes the catalytic process. If the 5-coordinate resting state could be eliminated, theoretical work predicted that the cationic nickel catalysts should be more active than the cationic palladium catalysts. 11,12 Neutral nickel compounds with anionic N,O-and P,Ochelating ligands are isoelectronic with the cationic compounds and should be less Lewis acidic. 13,14 These compounds as catalyst precursors are known to catalyze the alternating copolymerization of CO and ethylene. The neutral arylnickel-(II) compounds with anionic N,O-chelating ligands appear rather active, but an induction period of at least 45 min under copolymerization conditions is required before any copolymer is produced. 14a The activities of these catalysts have not been rigorously examined. Their reported productivity (∼3000 g (g of Ni) −1 ) is significantly lower than that o...

Two novel heterocyclic ligands, 2-[(5-fluoro-1,3-benzothiazol-2-yl)amino]naphthalene-1,4-dione (HL 1 ) and 2-[(5-methyl-1,3-benzothiazol-2-yl)amino]naphthalene-1,4-dione (HL 2 ), and their Pd(II), Ni(II) and Co(II) complexes were prepared and characterized using 1 H NMR, 13 C NMR, infrared and UV-visible spectroscopic techniques, elemental analysis, magnetic susceptibility, thermogravimetry and molar conductance measurements. The infrared spectral data showed that the chelation behaviours of the ligands towards the transition metal ions were through one of the carbonyl oxygen and deprotonated nitrogen atom of the secondary amine group. Molar conductance results confirmed that the complexes are non-electrolytes in dimethylsulfoxide. The geometries of the complexes were deduced from magnetic susceptibility and UV-visible spectroscopic results. Second-order perturbation analysis using density functional theory calculation revealed a stronger intermolecular charge transfer between ligand and metal ion in [NiL 1 (H 2 O) 2 (CH 3 COO-)] and CoL 1 compared to the other complexes. The in vitro antibacterial activity of the compounds against some clinically isolated bacteria strains showed varied activities. [NiL 1 (H 2 O) 2 (CH 3 COO-)] exhibited the best antibacterial results with a minimum inhibitory concentration of 50 μg mL −1 . The molecular interactions of the compounds with various drug targets of some bacterial organisms were established in a bid to predict the possible mode of antibacterial action of the compounds. The ferrous ion chelating ability of the

In this study, a novel bidentate ligand containing oxime, hydrazone, and indole moieties and its BF2+‐bridged transition metal complexes [Ni(II), Cu(II), and Co(II)] were synthesized and their cytotoxic activities against prostate and breast cancer cells were investigated. The vic‐dioxime ligand bearing indole–hydrazone side groups was synthesized by reacting antiglyoximehydrazine (GH2) with 3‐methoxy indole. The ligand forms mononuclear complexes with a metal‐to‐ligand ratio of 1:2 with M = Co(II)(H2O)2, Ni(II), and Cu(II). These metal complexes were then reacted with BF3(C2H5)2O to obtain BF2+‐bridged transition metal complexes. The Co(II) complex of the ligand is proposed to be octahedral with water molecules as axial ligands, whereas the Ni(II) and Cu(II) complexes are proposed to be square planar. Spectral studies showed that the ligand bonded to the metal ion in a neutral bidentate fashion through the azomethine nitrogen atom and the imine oxime group. Structural assignments are supported by a combination of 1H nuclear magnetic resonance (NMR), 13C NMR, Fourier‐transform infrared, LC/MS, elemental analyses, and magnetic susceptibility testing. For determining the cytotoxic effects of the novel anticancer products, cancer cells were cultured. The antiproliferative effects were determined using the MCF‐7 breast cancer and PC‐3 prostate cancer cell lines. The antiproliferative effects of the products were analyzed and their apoptotic or necrotic effects were determined with the Hoechst/propidium iodide double staining method in both cancer cell lines. Paclitaxel was used as the positive control (1 μm). The results indicated that the newly synthesized compounds are effective on both cell lines between concentrations of 5 and 40 μm and show their effects by apoptotic mechanisms. Besides, these products were found to be more effective on the MCF‐7 cell line. The cytotoxic efficiency of the newly synthesized products was more than that of paclitaxel (depending on concentration), which is a chemotherapeutic agent used in cancer therapy.

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