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Aharonovich S.,Institute of Catalysis Science and Technology | Botoshansky M.,Institute of Catalysis Science and Technology | Tumanskii B.,Institute of Catalysis Science and Technology | Nomura K.,Nara Institute of Science and Technology | And 2 more authors.
Dalton Transactions | Year: 2010

Salt metathesis of (2,6-xylylimido) vanadium trichloride (1) with the unsolvated or the TMEDA lithium p-Et benzamidinate complexes (2 and 3, respectively, in 1:2 V:Li molar ratio) yields bis[N,N'-bis(trimethylsilyl) p-Et benzamidinate](2,6-xylylimido)VCl (4) as dark brown, diamond-shaped crystals. When equimolar amounts of complexes 1 and 2 are reacted, a mixture of the bis (4) and mono (5) imidovanadium amidinates results. A similar mixture is also obtained by a ligand metathesis reaction of the bis amidinate complex 4 and complex 1. When the synthesis of the mono amidinate 5 is attempted with the TMEDA lithium amidinate complexes 3 or the 3-pyridyl derivative (7) (in 1:1 V:Li molar ratio) a redox reaction takes place to produce (κ2- TMEDA)(2,6-xylylimido)VIVCl2 (6) as crystalline, mustard-yellow plates. The activity of complex 4 in ethylene polymerization was negligible with MAO or MAO\(CPh3)+[B(C6F 5)4]- as co-catalysts. © 2010 The Royal Society of Chemistry. Source


Aharonovich S.,Institute of Catalysis Science and Technology | Botoshansky M.,Institute of Catalysis Science and Technology | Waymouth R.M.,Stanford University | Eisen M.S.,Institute of Catalysis Science and Technology
Inorganic Chemistry | Year: 2010

Unlike the reaction of LiNTMS2· TMEDA (TMS = SiMe 3; TMEDA = tetramethylethylenediamine) with 2-cyanopyridine, which results in the nearly exclusive formation of the amidinate, (Me 3SiNC6F5)Li · TMEDA (1) reacts with 2-cyanopyridine in toluene to yield quantitatively the lithium pyridyltetrafluorobenzimidazolate complex [C6F4N 2C(2-C5H4N)]Li · TMEDA (3). In this work, the reactivity of complex 1 toward aromatic nitriles Ar-CN (Ar = Ph, o-OMeC6H4, C6F5, 2-pyridyl) was examined. Whereas complex 1 fails to react with o-methoxybenzonitrile, its reaction with benzonitrile or pentafluorobenzonitrile gives triphenyl-1,3,5- triazine (4) or the hexacoordinate lithium polymer [LiN(4-NCC6F 4)(C6F5) · THF · TMEDA] n (7), respectively. When 1 is reacted with 2-cyanopyridine in tetrahydrofuran (THF), the benzimidazolate coordination polymer {[C 6F4N2C(2-C5H4N)]Li · THF}n (5) is obtained. Herein we discuss how this diverse chemoselectivity in the reaction of the examined lithium N-silylated amides LiNRTMS · TMEDA (R = TMS, C6F5) with nitriles is influenced by the electronic properties of the nitrile or amide substituents and by the ability of these substituents to interact with the lithium or silicon atoms. Further, we present the syntheses and structures of zirconium tris(pyridyltetrafluorobenzimidazolate) chloride (10) and zirconium bis(dimethylamido)(pyridyltetrafluorobenzimidazolate) chloride · THF (11) complexes. These complexes, the first prepared zirconium mono-and tris(benzimidazolate)s, were crystallographically characterized and examined in the polymerization of propylene with methyl aluminoxane (1:1000 Zr/Al molar ratio). © 2010 American Chemical Society. Source


Aharonovich S.,Institute of Catalysis Science and Technology | Botoshanski M.,Institute of Catalysis Science and Technology | Rabinovich Z.,Institute of Catalysis Science and Technology | Waymouth R.M.,Stanford University | Eisen M.S.,Institute of Catalysis Science and Technology
Inorganic Chemistry | Year: 2010

Lithium N,N′-bis(trimethylsilyl)heterocyclic amidinate complexes with 3- and 4-pyridyl and 3-furyl carbon substituents were prepared by addition of the corresponding nitriles to LiN(SiMe3)2 (LiNTMS 2) solution. In the presence of N,N,N′, N′ tetramethylethylene diamine (TMEDA), both pyridyl amidinates crystallize as coordination polymers with an amidinate-Li-pyridyl backbone. The 4-pyridyl derivative (7) creates a linear polymer with amidinate-Li-TMEDA units as side chains, whereas the 3-pyridyl polymer (6) has a two-dimensional (2D) network structure in which TMEDA serves as a cross-linker. Solvation of the reaction mixture of 3-furonitrile and LiNTMS2 with TMEDA affords the monomeric 3-furyl amidinate Li TMEDA complex (3). Crystals of the Li2O complex {[3-furyl-C-(NTMS)2Li]4 · Li2O) · C7H8 (4) are obtained from toluene by partial hydrolysis of the unsolvated 3-furyl amidinate (2). Degradation of the polymer (7) to monomeric units can be achieved by solvation in toluene or by reaction with TMS2NLi · TMEDA that affords crystals of the complex (NTMS2Li · [4-C5H4N-C(NTMS) 2Li · TMEDA]}2 · (NTMS2Li · TMEDA) (8). The formation of these aggregates can be rationalized by directed substitution of TMEDA with pyridyl moieties and by the laddering principle. © 2009 American Chemical Society. Source


Rabinovich E.,Institute of Catalysis Science and Technology | Aharonovich S.,Institute of Catalysis Science and Technology | Botoshansky M.,Institute of Catalysis Science and Technology | Eisen M.S.,Institute of Catalysis Science and Technology
Dalton Transactions | Year: 2010

Salt metathesis of ThCl4·3THF with N,N′- bis(trimethylsilyl)-2-pyridyl-lithium-TMEDA (1) yields bis(N,N′- bis(trimethylsilyl)-2-pyridylamidinate) thorium-chloride (μ-Cl) 2Li(TMEDA) (2) (60% isolated yield) and tris(N,N′- bis(trimethylsilyl)-2-pyridylamidinate) thorium monochloride (3) (10% isolated yield). The latter compound is the first crystallographically characterized tris(amidinate) thorium complex. The bis pyridyl amidinate thorium (2) displays a unique reactivity towards the dual-site cyclo-oligomerization of ε-caprolactone, which produces two fractions of macrocyclic oligo-esters with extremely narrow (1.01-1.06) polydispersity. A mechanism for the dual-site oligomerization reaction is proposed based on kinetic, poisoning, and 1H NMR studies. © The Royal Society of Chemistry 2010. Source

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