TY - JOUR

T1 - Vanadium complexes derived from oxacalix[6]arenes

T2 - structural studies and use in the ring opening homo-/co-polymerization of ε-caprolactone/δ-valerolactone and ethylene polymerization

AU - Xing, Tian

AU - Prior, Timothy J.

AU - Elsegood, Mark R.J.

AU - Semikolenova, Nina V.

AU - Soshnikov, Igor E.

AU - Bryliakov, Konstantin

AU - Chen, Kai

AU - Redshaw, Carl

N1 - Funding Information: We thank the China Scholarship Council (CSC) for a PhD Scholarship to TX. The EPSRC Mass Spectrometry Service (Swansea, UK) and the EPSRC National X-ray Crystallography Service (Southampton) are thanked for data collection. CR also thanks the EPSRC (grant EP/S025537/1) for financial support and the British Council for funding a workshop in Novosibirsk. We also thank Dr Orlando Santoro for useful discussion. NVS and IES thank the Ministry of Science and Higher Education of Russia (#AAAA-A17-117041710085-9), and Dr. M. A. Matsko for the GPC measurements. Publisher Copyright: © The Royal Society of Chemistry 2020. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/1/21

Y1 - 2021/1/21

N2 - Reaction of Na[VO(tBuO)4] (generatedin situfrom VOCl3and NaOtBu) withp-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 isolatedviathe use of [VO(OnPr)3]. Reaction of L1H6with [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 L1H6afforded the product [VO(L2)]2·4MeCN (8·4MeCN) (L2= 2-(p-CH3-C6H4NCH)-4-tBu-C6H2O-6-CH2)-4-tBuC6H2OH) in which L1has 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 complexes1to8exhibited 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 ofrac-lactide. In the case of ethylene polymerization, complexes3,5and7exhibited highest activity when screened in the presence of dimethylaluminium chloride/ethyltrichloroacetate; the activity of4was much lower. The products were highly linear polyethylene withMwin the range 74-120 × 103Da.

AB - Reaction of Na[VO(tBuO)4] (generatedin situfrom VOCl3and NaOtBu) withp-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 isolatedviathe use of [VO(OnPr)3]. Reaction of L1H6with [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 L1H6afforded the product [VO(L2)]2·4MeCN (8·4MeCN) (L2= 2-(p-CH3-C6H4NCH)-4-tBu-C6H2O-6-CH2)-4-tBuC6H2OH) in which L1has 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 complexes1to8exhibited 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 ofrac-lactide. In the case of ethylene polymerization, complexes3,5and7exhibited highest activity when screened in the presence of dimethylaluminium chloride/ethyltrichloroacetate; the activity of4was much lower. The products were highly linear polyethylene withMwin the range 74-120 × 103Da.

UR - http://www.scopus.com/inward/record.url?scp=85098214745&partnerID=8YFLogxK

U2 - 10.1039/d0cy01979h

DO - 10.1039/d0cy01979h

M3 - Article

AN - SCOPUS:85098214745

VL - 11

SP - 624

EP - 636

JO - Catalysis Science and Technology

JF - Catalysis Science and Technology

SN - 2044-4753

IS - 2

ER -