Jump to main content
Jump to site search


Mono-oxo molybdenum(VI) and tungsten(VI) complexes bearing chelating aryloxides: synthesis, structure and ring opening polymerization of cyclic esters

Author affiliations

Abstract

The 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-tert-butylphenol) L1H2, respectively. Use of in situ generated [Mo(O)(Ot-Bu)4] with two equivalents of L1H2 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 L1H2 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 (L2H4) 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 L2H4 with [W(O)(Ot-Bu)4]. Similar reaction of p-tert-butylcalix[4]areneH4 (L3H4) 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 L3H4 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.

Graphical abstract: Mono-oxo molybdenum(vi) and tungsten(vi) complexes bearing chelating aryloxides: synthesis, structure and ring opening polymerization of cyclic esters

Back to tab navigation

Supplementary files

Publication details

The article was received on 17 Nov 2018, accepted on 23 Dec 2018 and first published on 27 Dec 2018


Article type: Paper
DOI: 10.1039/C8DT04566F
Citation: Dalton Trans., 2019, Advance Article
  •   Request permissions

    Mono-oxo molybdenum(VI) and tungsten(VI) complexes bearing chelating aryloxides: synthesis, structure and ring opening polymerization of cyclic esters

    Z. Sun, Y. Zhao, T. J. Prior, M. R. J. Elsegood, K. Wang, T. Xing and C. Redshaw, Dalton Trans., 2019, Advance Article , DOI: 10.1039/C8DT04566F

Search articles by author

Spotlight

Advertisements