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Abstract: Well-defined PNNCN pincer ruthenium complexes bearing both strong phosphine and weak oxazoline donors were developed. These easily accessible complexes exhibit significantly better catalytic activity in transfer hydrogenation of ketones compared to their PN3P analogs. These reactions proceed under mild and base-free conditions via protonation–deprotonation of the ‘NH’ group in the aromatization–dearomatization process. [Copyright &y& Elsevier]

Abstract: A dearomatized complex [RuH(PN3P)(CO)] (PN3P N, N′-bis(di-tert-butylphosphino)-2,6-diaminopyridine) (3) was prepared by reaction of the aromatic complex [RuH(Cl)(PN3P)(CO)] (2) with t-BuOK in THF. Further treatment of 3 with formic acid led to the formation of a rearomatized complex (4). These new complexes were fully characterized and the molecular structure of complex 4 was further confirmed by X-ray crystallography. In complex 4, a distorted square-pyramidal geometry around the ruthenium center was observed, with the CO ligand trans to the pyridinic nitrogen atom and the hydride located in the apical position. The dearomatized complex 3 displays efficient catalytic activity for hydrogen transfer of ketones in isopropanol. [Copyright &y& Elsevier]

Abstract: Several non-metallocene-type titanium(IV) complexes containing phenoxy-phosphine or thiophenoxy-phosphine ligands of type, (2-R 1-4-R 2-6-PPh2-C6H2X)2TiCl2 (2a: X = O, R 1 = R 2 = t-Bu; 2b: X = O, R 1 = R 2 = cumyl; 2c: X = S, R 1 = SiMe3, R 2 = H) have been synthesized by treating TiCl4 with the corresponding ligands 2-R 1-4-R 2-6-PPh2-C6H2XH in the presence of n-BuLi. The complexes 2a–c were investigated as the catalysts for ethylene with 1-hexene and/or polar alkenes copolymerizations. The catalytic activity and the comonomer incorporation were highly dependent upon catalyst and reaction conditions employed. Among these complexes, 2a can not only promote ethylene/1-hexene living copolymerization at room temperature, but also can utilize ethylene with methyl 10-undecenoate copolymerization. [Copyright &y& Elsevier]