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Mono-oxo molybdenum(VI) and tungsten(VI) complexes bearing chelating aryloxides: synthesis, structure and ring opening polymerization of cyclic esters
journal contribution
posted on 2019-01-18, 10:10 authored by Ziyue Sun, Yanxia Zhao, Timothy J. Prior, Mark ElsegoodMark Elsegood, Kuiyuan Wang, Tian Xing, Carl RedshawThe mono-oxo aryloxide complexes [M(O)(L1
)2] (M = Mo (1·hexane), W(2·2MeCN)) have been prepared
from [Mo(O)(Cl)4] or [W(O)(Ot-Bu)4] and two equivalents of the di-phenol 2,2’-ethylidenebis(4,6-di-tertbutylphenol) L1
H2, respectively. Use of in situ generated [Mo(O)(Ot-Bu)4] with two equivalents of L1
H2
also led to the isolation of 1·2MeCN. In the presence of adventitious oxygen, attempts to generate in situ
[Mo(O)(Ot-Bu)4] and reaction with one equivalent of L1
H2 afforded the bi-metallic complex [Mo(O)(L1
)
(μ-O)Li(THF)(MeCN)]2·2MeCN (3·2MeCN). Use of the tetra-phenol α,α,α’,α’-tetrakis(3,5-di-tert-butyl-2-
hydroxyphenyl)-p-xyleneH4 (L2
H4) with [Mo(O)(Oi-Pr)4] led to the isolation of {[Mo(O)]L2
}2 (4), whilst the
analogous tungsten complex {[W(O)]L2
}2 (5) was isolated from the reaction of L2
H4 with [W(O)(Ot-Bu)4].
Similar reaction of p-tert-butylcalix[4]areneH4 (L3
H4) with [Mo(O)(Oi-Pr)4] afforded ([Mo(O)
L3
(NCMe)]·3MeCN (6). Modifications of known routes were employed to access complexes
[W(Cl)2L3
]·3.5MeCN (7·3.5MeCN) and [W(O)L3
(NCMe)] (8), whilst use of [WO(Ot-Bu)4] with L3
H4 unexpectedly afforded [W(Ot-Bu)2L3
]·MeCN (9·MeCN). The molecular crystal structures for 1–9 are reported, and
the ability of these complexes to act as catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL), δ-valerolactone (δ-VL) and ω-pentadecalactone (ω-PDL) has been investigated. The molybdenum complexes 1 and 4 were the best performers for ε-Cl and δ-VL, but all complexes exhibited poor
control and were also inactive toward the ROP of PDL.
History
School
- Science
Department
- Chemistry
Published in
Dalton TransactionsVolume
48Issue
4Pages
1454-1466Citation
SUN, Z. ... et al., 2019. Mono-oxo molybdenum(VI) and tungsten(VI) complexes bearing chelating aryloxides: synthesis, structure and ring opening polymerization of cyclic esters. Dalton Transactions, 48 (4), pp.1454-1466.Publisher
© Royal Society of Chemistry (RSC)Version
- AM (Accepted Manuscript)
Publisher statement
This paper was accepted for publication in the journal Dalton Transactions and the definitive published version is available at https://doi.org/10.1039/c8dt04566fAcceptance date
2018-12-23Publication date
2018-12-27ISSN
1477-9226eISSN
1477-9234Publisher version
Language
- en