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Cycloheptyl-fused N,N,N'-chromium catalysts with selectivity for vinyl-terminated polyethylene waxes: thermal optimization and polymer functionalization.

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journal contribution
posted on 2019-04-08, 14:27 authored by Chuanbing Huang, Yongfeng Huang, Yanping Ma, Gregory A. Solan, Yang Sun, Xinquan Hu, Wen-Hua Sun
Five chromium(iii) chloride complexes, [2-{(Ar)N[double bond, length as m-dash]CMe}-9-{N(Ar)}C10H10N]CrCl3 (Ar = 2,6-Me2C6H3Cr1, 2,6-Et2C6H3Cr2, 2,6-i-Pr2C6H3Cr3, 2,4,6-Me3C6H2Cr4, 2,6-Et2-4-MeC6H2Cr5), each chelated by a sterically and electronically different cycloheptyl-fused N,N,N'-bis(imino)pyridine, have been synthesized by the reactions of CrCl3(THF)3 with the corresponding ligand (L1/L1'-L5/L5'). The molecular structure of Cr2 highlights both the steric properties exerted by the inequivalent N-2,6-ethylphenyl groups and the puckering of the fused cycloheptyl ring; a distorted octahedral geometry is conferred about the metal center. On activation with methylaluminoxane (MAO) or modified MAO (MMAO), Cr1-Cr5 displayed their optimal activity for ethylene polymerization at temperatures between 70 and 80 °C with the least sterically demanding Cr1 proving the most productive (1.44 × 107 g (PE) per mol (Cr) per h). The polyethylenes formed are of low molecular weight (Mw range: 0.66-3.56 kg mol-1) with narrow molecular weight distributions and display high levels of end-group unsaturation. Furthermore, the amenability of these vinyl-terminated polyethylenes to undergo functionalization via epoxidation has been demonstrated.

Funding

This work was supported by the National Natural Science Foundation of China No. 21871275. GAS thanks the Chinese Academy of Sciences for a President's International Fellowship for Visiting Scientists.

History

Citation

Dalton Transactions, 2018, 47 (38), pp. 13487-13497

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Chemistry

Version

  • AM (Accepted Manuscript)

Published in

Dalton Transactions

Publisher

Royal Society of Chemistry

eissn

1477-9234

Acceptance date

2018-08-30

Copyright date

2018

Available date

2019-08-31

Publisher version

https://pubs.rsc.org/en/Content/ArticleLanding/2018/DT/C8DT03052A#!divAbstract

Notes

Electronic supplementary information (ESI) available: CCDC 1858340 (Cr2). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8dt03052a;The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.

Language

en

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