395656-19-6Relevant academic research and scientific papers
Process for the preparation of (co)polymers of conjugated dienes in the presence of a catalytic system comprising a bis-imino-pyridine complex of cobalt
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, (2016/11/14)
Process for the preparation of (co)polymers of conjugated dienes which comprises polymerizing at least one conjugated diene in the presence of a catalytic system comprising at least one bis-imino-pyridine complex of cobalt having general formula (I): wherein: R2 and R3, equal to or different from each other, represent a hydrogen atom; or they are selected from linear or branched C1-C20 preferably C1-C15, alkyl groups, optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; R1 and R4, different from each other, represent a hydrogen atom; or they are selected from linear or branched C1-C20 preferably C1-C15, alkyl groups, optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; arylalkyl groups; or R1 and R2 can be optionally bound to each other to form, together with the other atoms to which they are bound, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted with linear or branched C1-C20, preferably C1-C15, alkyl groups, said cycle optionally containing other heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorous, selenium; or R3 and R4, can be optionally bound to each other to form, together with the other atoms to which they are bound, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted with linear or branched C1-C20, preferably C1-C15, alkyl groups, said cycle optionally containing other heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorous, selenium; R5, R6 and R7, equal to or different from each other, represent a hydrogen atom, or they are selected from linear or branched C1-C20, preferably C1-C15, alkyl groups, optionally halogenated, cycloalkyl groups optionally substituted; aryl groups optionally substituted; arylalkyl groups; or R5 and R6, can be optionally bound to each other to form, together with the other atoms to which they are bound, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted with linear or branched C1-C20, preferably C1-C15, alkyl groups, said cycle optionally containing other heteroatoms such as, for example, oxygen, -sulfur, nitrogen, silicon, phosphorous, selenium; or R6 and R7, can be optionally bound to each other to form, together with the other atoms to which they are bound, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted with linear or branched C1-C20, preferably C1-C15, alkyl groups, said cycle optionally containing other heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorous, selenium; X1 and X2, equal to or different from each other, represent a halogen atom such as, for example, chlorine, bromine, iodine; or they are selected from linear or branched C1-C20, preferably C1-C15, alkyl groups, —OCOR8 groups or —OR8 groups wherein R8 is selected from linear or branched C1-C20/preferably C1-C15, alkyl groups.
Oligomerisation of ethylene to linear α-olefins by new Cs- and C1-symmetric [2,6-bis(imino)pyridyl]iron and -cobalt dichloride complexes
Bianchini, Claudio,Mantovani, Giuseppe,Meli, Andrea,Migliacci, Fabio,Zanobini, Fabrizio,Lasehi, Franco,Sommazzi, Anna
, p. 1620 - 1631 (2007/10/03)
A new family of Cs- and C1-symmetric 2,6-bis(imino)pyridyl ligands has been synthesised. These ligands, which differ from their known counterparts in the contemporaneous presence of alkyl and aryl substituent at the ketimine nitrogen atoms, form stable, five-coordinate complexes with FeCl2 and COC12. All ligands and catalysts have been fully characterised both in the solid state and in solution. A single-crystal X-ray analysis of [CoCl2-{2-[CMe=N-(2,6- dimethylphenyl)]6-(CMe=N-C6H11)C5H3 N}]·H2O shows the metal centre to adopt a highly distorted square-pyramidal geometry. In combination with methylaluminoxane (MAO), both iron and cobalt compounds act as effective and selective (> 99%) catalysts for the oligomerisation of ethylene to a Schulz-Flory distribution of α-olefins, with the α factor ranging from 0.61 to 0.91. The iron catalysts exhibit TOFs as high as 7.105 mol C2H4 (mol of cat × h)-1 and are much more active than their cobalt analogues. Experiments at different ethylene pressures with the iron catalysts showed that both the propagation rate and the chain transfer rate are first order in ethylene pressure. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2003.
