Vanadium Complexes Derived from Oxacalix[6]arenes: Structural Studies and Use in the Ring Opening
Homo-/co-polymerization of ε-Caprolactone/δ-Valerolactone and Ethylene Polymerization
Full article
| Общее |
Language:
Английский,
Genre:
Full article,
Status:
Published,
Source type:
Original
|
| Journal |
Catalysis Science & Technology
|
| Output data |
Year: 2020,
DOI:
10.1039/D0CY01979H
|
| Authors |
Xing Tian
1
,
Prior Timothy J.
1
,
Elsegood Mark R.J.
2
,
Semikolenova Nina V.
3
,
Soshnikov Igor E.
3,4
,
Bryliakov Konstantin
3,4
,
Chen Kai
1,5
,
Redshaw Carl
1
|
| Affiliations |
| 1 |
Plastics Collaboratory, Department of Chemistry, University of Hull
|
| 2 |
Chemistry Department, Loughborough University
|
| 3 |
Boreskov Institute of Catalysis
|
| 4 |
Novosibirsk State University
|
| 5 |
Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology
|
|
Funding (3)
|
1
|
Federal Agency for Scientific Organizations
|
0303-2016-0009
|
|
2
|
China Scholarship Council
|
|
|
3
|
Engineering and Physical Sciences Research Council
|
EP/S025537/1
|
Reaction of Na[VO(tBuO)4] (generated in situ from VOCl3 and NaOtBu) with p-tert-butyltetrahomodioxacalix[6]areneH6 (L1H6) afforded, after work-up (in MeCN), the mixed-metal complex [(VO)2(μ-O)Na2(L1)(MeCN)4]·5(MeCN) (1·5MeCN), whilst the oxo complex {[VO]4L1} (2·6MeCN) was isolated via the use of [VO(OnPr)3]. Reaction of L1H6 with [V(Np-CH3C6H4)(OtBu)3] afforded the complex {[V(Np-CH3C6H4)]2L1} (3·7MeCN·0.5CH2Cl2). Use of similar methodology afforded the imido complexes {[V(Np-RC6H4)]2L1} (R = OMe (4); CF3 (5); Cl (6); F (7)); on one occasion, reaction of [V(Np-CH3C6H4)(OEt)3] with L1H6 afforded the product [VO(L2)]2·4MeCN (8·4MeCN) (L2 = 2-(p-CH3-C6H4NCH)-4-tBu-C6H2O-6-CH2)-4-tBuC6H2OH) in which L1 has been cleaved. For comparative catalytic ring opening polymerization (ROP) studies, the known complexes [VOL3] (L3 = oxacalix[3]arene) (I), [V(Np-CH3-C6H4)L3]2 (II), [Li(MeCN)4][V2(O)2Li(MeCN)(L6H2)2] (L6H6 = p-tert-butylcalix[6]areneH6) (III) and [(VO)2L8H] (L8H8 = p-tert-butylcalix[8]areneH8) (IV) have also been prepared. ROP studies, with or without external alcohol present, indicated that complexes 1 to 8 exhibited moderate to good conversions for ε-Cl, δ-VL and the co-polymerization thereof. Within the imido series, a positive influence was observed when electron withdrawing substituents were present. These systems afforded relatively low molecular weight products and were also inactive toward the ROP of rac-lactide. In the case of ethylene polymerization, complexes 3, 5 and 7 exhibited highest activity when screened in the presence of dimethylaluminium chloride/ethyltrichloroacetate; the activity of 4 was much lower. The products were highly linear polyethylene with Mw in the range 74–120 × 103 Da.