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A series of bis(oxazoline) rare-earth metal dialkyl complexes [(L)Ln(CH2SiMe3)2(THF)n] (L = L1 (dimethyl-substituted bis(oxazoline) ligand), Ln = Y (1-Y), Lu (1-Lu), Sc (1-Sc), n = 1; L = L2 (phenyl-substituted bis(oxazoline) ligand), Ln = Y (2-Y), Lu (2-Lu), Sc (2-Sc), n = 2) was successfully prepared. NMR spectroscopy and X-ray diffraction indicated that all the complexes ligated with a C2 symmetric bis(oxazoline) and two trimethylsilylmethyl ligands. In the presence of borate and triisobutyl aluminium, these complexes exhibited high catalytic activity for the polymerization of isoprene, yielding the polymer with high cis-1,4-regularity (up to 99.9%) and high molecular weight. Moreover, these ternary catalytic systems also served as efficient initiators for the polymerization of polar ortho-methoxystyrene. However, atactic polymers in all the cases were isolated despite the C2 symmetric geometry of bis(oxazoline) ligands. [ABSTRACT FROM AUTHOR]

A series of rare-earth metal bis(alkyl) complexes have been prepared via protonolysis reactions of tris(aminobenzyl) complexes (Ln(CH2C6H4N(Me)2-o)3) with phosphine-functionalized amidinated ligands (DippNCN(CH2)nPPh2, n = 2 (L1-H) and n = 3 (L2-H)). The X-ray diffraction of P2-Sc (DippNCN(CH2)3PPh2Sc(CH2C6H4N(Me)2-o)2) showed the un-coordination of the diphenylphosphine group due to the inherent saturation of the central metal ion. In conjunction with [Ph3C][B(C6F5)4], all the rare-earth metal complexes showed a high catalytic activity for the polymerization of 1,3-conjugated dienes (isoprene, β-myrcene and β-farnesene), affording highly 3,4-regular polymers (up to 100% 3,4-) with high molecular weight and narrow molecular weight distribution. After the abstraction of the alkyl moiety –CH2C6H4N(Me)2-o of P1-Sc by [Ph3C][B(C6F5)4], the species with the coordination of the diphenylphosphine group to the central metal probably formed, as shown in the 31P NMR spectra and DFT calculation results, and it might serve as the true active species in the 3,4-selective polymerization of 1,3-conjugated dienes. [ABSTRACT FROM AUTHOR]

The reliance of both our life and industry on fossil resource and the alarming accumulation of polymeric materials in the environment have presented huge challenges to sustainable society. Nowadays, utilization of renewable monomers as building blocks for polymeric materials has emerged as a hot topic and increasingly gained attention from chemists. As a class of biomass with abundance and low cost, terpenes are typical hydrocarbon‐rich natural compounds, and some of them, such as myrcene and farnesene, are inherently suitable for coordination polymerization. In this review, we focus on the rare‐earth metal catalyzed highly regio‐ and stereoselective polymerization of bio‐based conjugated dienes, especially the ones from terpene‐derived compounds with or without modifications. This review also discusses the future direction on the modification of these bio‐based conjugated dienes. [ABSTRACT FROM AUTHOR]

A series of binuclear rare‐earth metal complexes based on the ligands containing bis(phosphinophenyl)amido‐PNP unit are successfully synthesized. All the ligands and the corresponding binuclear complexes are fully characterized by NMR spectra (1H, 13C, and 31P). In conjunction with [Ph3C][B(C6F5)4], all the binuclear complexes exhibited high catalytic activity and high cis‐1,4‐selectivity (>99%) toward the polymerization of 1,3‐conjugated dienes (isoprene, β‐myrcene and β‐farnesene) with excellent livingness at room temperature or even 80 °C. [ABSTRACT FROM AUTHOR]

A series of bis(oxazoline) rare-earth metal dialkyl complexes [(L)Ln(CH 2 SiMe 3 ) 2 (THF) n ] (L = L1 (dimethyl-substituted bis(oxazoline) ligand), Ln = Y (1-Y), Lu (1-Lu), Sc (1-Sc), n = 1; L = L2 (phenyl-substituted bis(oxazoline) ligand), Ln = Y (2-Y), Lu (2-Lu), Sc (2-Sc), n = 2) was successfully prepared. NMR spectroscopy and X-ray diffraction indicated that all the complexes ligated with a C 2 symmetric bis(oxazoline) and two trimethylsilylmethyl ligands. In the presence of borate and triisobutyl aluminium, these complexes exhibited high catalytic activity for the polymerization of isoprene, yielding the polymer with high cis -1,4-regularity (up to 99.9%) and high molecular weight. Moreover, these ternary catalytic systems also served as efficient initiators for the polymerization of polar ortho -methoxystyrene. However, atactic polymers in all the cases were isolated despite the C 2 symmetric geometry of bis(oxazoline) ligands.