Vanadium Complexes Derived from O,N,O-tridentate 6-bis(o-hydroxyalkyl/aryl)pyridines: Structural Studies and Use in the Ring-Opening Polymerization of ε-Caprolactone and Ethylene Polymerization
نویسندگان
چکیده
Interaction of [VO(OiPr)3] with 6-bis(o-hydroxyaryl)pyridine, 2,6-{HOC(Ph)2CH2}2(NC5H3), LH2, afforded [VO(OiPr)L] (1) in good yield. The reaction LNa2, generated in-situ from LH2 and NaH, [VCl3(THF)3] led to the isolation [VL2] (2) which pyridyl nitrogen atoms are cis; a regioisomer 3∙2THF, trans, was isolated when using [VCl2(TMEDA)2]. 2,6-bis(o-hydroxyalkyl)pyridine {HOC(iPr)2CH2}2(NC5H3), L1H2, [VO(OR)3] (R = nPr, iPr) led, following work-up, [VO(OR)L1] nPr (4), iPr (5)). Use bis(methylpyridine)-substituted alcohol (tBu)C(OH)[CH2(C5H3Me-5)]2, L2H, Et, [VO(μ-O)(L2)]2 (6). Complexes 1 6 have been screened for their ability act as pre-catalysts ring opening polymerization (ROP) ε-caprolactone (ε-CL), δ-valerolactone (δ-VL), rac-lactide (r-LA) compared against known catalyst [Ti(OiPr)2L] (I). 1, 4–6 were also catalysts ethylene (in presence dimethylaluminium chloride/ethyltrichloroacetate). For ROP ε-CL, toluene solution, conversions low moderate, affording molecular weight products, whilst melts, systems more active higher polymers. δ-VL, run melts conversions, but case r-LA, all exhibited (<10%) except (<54%) I (<39%). In polymerization, highest activity (8600 Kg·mol·V−1bar−1h−1) by dichloromethane, high weight, linear polyethylene at 70 °C. 4 5, contain propyl-bearing chelates, activities somewhat lower (≤1500 Kg·mol·V−1bar−1h−1), found be inactive.
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ژورنال
عنوان ژورنال: Catalysts
سال: 2023
ISSN: ['2073-4344']
DOI: https://doi.org/10.3390/catal13060988