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Molybdenum (Vi) imido complexes derived from chelating phenols: synthesis, characterization and ɛ-caprolactone rop capability
journal contribution
posted on 2015-12-03, 13:27 authored by Yahya Al-Khafaji, Timothy J. Prior, Mark ElsegoodMark Elsegood, Carl RedshawReaction of the bulky bi-phenols 2,2′-RCH[4,6-(t-Bu)2C6H2OH]2 (R = Me L1MeH2, Ph L1PhH2) with the bis(imido) molybdenum(VI) tert-butoxides [Mo(NR1)(NR2)(Ot-Bu)2] (R1 = R2 = 2,6-C6H3-i-Pr2; R1 = t-Bu, R2 = C6F5) afforded, following the successive removal of tert-butanol, the complexes [Mo(NC6H3i-Pr2-2,6)2L1Me] (1), [Mo(NC6H3i-Pr2-2,6)2L1Ph] (2) and [Mo(Nt-Bu)(μ-NC6F5)(L1Me)]2 (3). Similar use of the tri-phenol 2,6-bis(3,5-di-tert -butyl-2-hydroxybenzyl)-4-methylphenol (L2H3) with [Mo(NC6H3i-Pr2-2,6)2(Ot-Bu)2] afforded the oxo-bridged product [Mo(NC6H3i-Pr2-2,6)(NCMe)(μ-O)L2H]2 (4), whilst use of the tetra-phenols α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-p- or -m-xylene L3pH4/L3mH4 led to {[Mo(NC6H3i-Pr2-2,6)2]2(μ-L3p)} (5) or {[Mo(NC6H3i-Pr2-2,6)2]2(μ-L3m)} (6), respectively. Similar use of [Mo(NC6F5)2(Ot-Bu)2] with L3pH4 afforded, after work-up, the complex {[Mo(NC6F5)(Ot-Bu)2]2(μ-L3p)}·6MeCN (7·6MeCN). Molecular structures of 1, 2·CH2Cl2, 3, 4·6MeCN, 6·2C6H14, and 7·6MeCN are reported and these complexes have been screened for their ability to ring open polymerize (ROP) ε-caprolactone; for comparative studies the precursor complex [Mo(NC6H3i-Pr2-2,6)2Cl2(DME)] (DME = 1,2-dimethoxyethane) has also been screened. Results revealed that good activity is only achievable at temperatures of ≥100 °C over periods of 1 h or more. Polymer polydispersities were narrow, but observed molecular weights (Mn) were much lower than calculated values.
History
School
- Science
Department
- Chemistry
Published in
CatalystsVolume
5Issue
4Pages
1928 - 1947Citation
AL-KHAFAJI, Y. ... et al, 2015. Molybdenum (Vi) imido complexes derived from chelating phenols: synthesis, characterization and ɛ-caprolactone rop capability. Catalysts, 5 (4), pp. 1928 - 1947.Publisher
MDPI / © The authors.Version
- VoR (Version of Record)
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This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/Publication date
2015Notes
This is an open access article published by MDPI and distributed under the Creative Commons Attribution License (CC BY 4.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.eISSN
2073-4344Publisher version
Language
- en