A series of nitrile-modified N-heterocyclic carbene (NHC) complexes of Ir(III) (2a−e) and Ru(II) (3a−d) have been prepared by transmetallation of [IrCp*Cl 2 ] 2 and [RuCl 2 (pcymene)] 2 forming an in situ NHC−Ag complex. The structures of all complexes were characterized by 1 H NMR, 13 C NMR, and Fourier transform infrared (FT-IR) spectroscopies. And the structures were clearly elucidated by performing X-ray diffraction studies on 2b, 3a, and 3c single crystals. The complexes of NHC− Ir(III) (2a−e) and NHC−Ru(II) (3a−d) were investigated in the N-alkylation reaction of aniline derivatives with benzyl alcohols to form N-benzyl amines and in the N-methylation reaction of aniline derivatives with methanol. Both reactions were performed in solvent-free media. The Ir(III) complexes (2a−e) were found to perform essentially better than similar Ru(II) complexes (3a−d) in the N-alkylation and N-methylation reactions. Among the Ir(III) complexes (2a−e), the best results were obtained with 2b. The catalytic mechanisms of both reactions were revealed by 1 H NMR study. Formation of Ir-hydride species was observed for both reactions. This new report provides useful information to evaluate the activity of complexes and the differences in sensitivity between the NHCs.

The size distributions of microcapsules are important in determining the surface area over which the contents of the microcapsules are released. The size distribution is generally not normal around the mean, but biased toward smaller capsule sizes, forming a mode around some characteristic diameter. In order to assess the factors effective in determining this characteristic drop size, size distribution analyses were carried out photographically at each stage of the complex coacervation process. In addition, the emulsion drop size distributions were investigated as a function of stirring rate, stirring time and phase ratio. The results agreed qualitatively with the theory of isotropy but were an order of magnitude smaller. This theory is valid for Newtonian liquids. Elongational stresses could be operative with large-sized macromolecules and a mechanism was proposed based on variation of elongational stresses with velocity and rates of extension. Elongational viscosities measured for the gelatin solutions supported the proposed mechanism.

Through the strategy of water soluble N‐heterocyclic carbene (NHC) ligand, Pd‐catalyzed reactions were developed in aqueous media. Therefore, four new piperidoimidazolinium salts (1a‐d) consisting of sulfonate (a), esther (b, c) and carboxylic acid (d) functionalities and their water‐soluble Pd‐NHC complexes (2a‐d) were synthesized. The new compounds were characterized by elemental analysis, FTIR, TGA, UV–vis and NMR spectroscopy. The catalytic activities of water soluble Pd‐NHC complexes (2a‐d) were investigated using the Suzuki‐Miyaura (S‐M) reaction and the reduction of nitroarenes. We found that the water‐soluble polar or ionic groups on piperidoimidazolin‐2‐ylidine had an effect on the catalytic activity. The water‐soluble catalyst can be recycled efficiently and reused six times with only a very slight loss of catalytic activity.

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A series of piperidoimidazolinium salts which differ in the chain lengths (butyl, octyl, dodecyl, octadecyl) and their Pd-N-heterocyclic carbene complexes with pyridine were synthesized and characterized using elemental analysis and spectroscopic methods. The effects of these ligands on catalyst activation and the performance of the complexes were studied in Suzuki-Miyaura reactions of arylboronic acid with aryl chlorides. The complex with the ligand having the longest chain length was found to be most active. The results demonstrated that the length of the alkyl chain of the piperidoimidazolin-2-ylidene controlled the dispersion and composition of the nanoparticles and it affected the catalytic activity. The impact of alkyl chain length of piperidoimidazolin-2-ylidene on the Suzuki-Miyaura reactions of arylboronic acid with aryl halides was systematically investigated.