title: Rare-earth dichloro and bis(alkyl) complexes supported by bulky amido-imino ligand. Synthesis, structure, reactivity and catalytic activity in isoprene polymerization.
abstract: A monoanionic amido-imino ligand system [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)](-) was successfully employed for the synthesis of monomeric dichloro [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]LnCl2(THF)2 (Ln = Y, 2Y; Lu, 2Lu) and bis(alkyl) [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]Ln(CH2SiMe3)2(THF) (Ln = Y, 4Y; Lu, 4Lu) species of yttrium and lutetium. Dichloro complexes 2Y and 2Lu turned out to be unstable in aromatic solvents. The ligand symmetrization reaction in the case of 2Y affords the yttrium complex coordinated by dianionic [(2,6-iPr2C6H3)NC(=CH2)C(=CH2)N(C6H3-2,6-iPr2)](2-) ligand, (2,6-iPr2C6H3)N=C(Me)C(Me)=N(C6H3-2,6-iPr2) and YCl3. On the contrary, bis(alkyl) species 4Y and 4Lu are rather stable and do not undergo such a transformation or thermal decomposition. The treatment of complex 4Y with DME resulted in C-O bond cleavage and the formation of a dimeric methoxy-alkyl species {[(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]Y(CH2SiMe3)(μ-OMe)}2 (5). The ternary systems 4Ln/AliBu3/borate (borate = [HNMe2Ph][B(C6F5)4] and [CPh3][B(C6F5)4]; molar ratio 1 : 10 : 1) performed high catalytic activity in isoprene polymerization and ability to convert into polymer 1000-5000 equivalents of isoprene in 20-120 min with quantitative conversion. The obtained polyisoprenes possessed high molecular weights (2.9 × 10(4)-4.1 × 10(4)) and moderate polydispersities (2.14-3.52). Predominant 3,4-regioselectivity (up to 78%) was observed.
authors.affiliation: G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod Tropinina str., 49, Russia.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Kissel
authors.forename: Dmitry M
authors.initials: DM
authors.lastname: Lyubov
authors.forename: Tatyana V
authors.initials: TV
authors.lastname: Mahrova
authors.forename: Georgy K
authors.initials: GK
authors.lastname: Fukin
authors.forename: Anton V
authors.initials: AV
authors.lastname: Cherkasov
authors.forename: Tatyana A
authors.initials: TA
authors.lastname: Glukhova
authors.forename: Dongmei
authors.initials: D
authors.lastname: Cui
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Trifonov
mesh_terms: D000577:Amides / Q000737:chemistry*; D002070:Butadienes / Q000737:chemistry*; D002384:Catalysis; D045782:Hemiterpenes / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008674:Metals, Rare Earth / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010420:Pentanes / Q000737:chemistry*; D058105:Polymerization
chemical_list: D000577:Amides; D002070:Butadienes; D045782:Hemiterpenes; D007097:Imines; D008674:Metals, Rare Earth; D009942:Organometallic Compounds; D010420:Pentanes; C005059:isoprene