Ti(IV)-Tris(phenolate) catalyst systems for the ring-opening Copolymerization of cyclohexene oxide and carbon dioxide
Author(s)
Type
Journal Article
Abstract
Titanium(IV) complexes of amino-tris(phenolate) ligands (LTiX, X = chloride, isopropoxide) together with bis(triphenylphosphine)iminium chloride (PPNCl) are active catalyst systems for the ring-opening copolymerization of carbon dioxide and cyclohexene oxide. They show moderate activity, with turnover frequency values of ∼60 h–1 (0.02 mol % of catalyst, 80 °C, 40 bar of CO2) and high selectivity (carbonate linkages >90%), but their absolute performances are lower than those of the most active Ti(IV) catalyst systems. The reactions proceed with linear evolution of polycarbonate (PCHC) molar mass with epoxide conversion, consistent with controlled polymerizations, and evolve bimodal molar mass distributions of PCHC (up to Mn = 42 kg mol–1). The stoichiometric reaction between [LTiOiPr] and tetraphenylphosphonium chloride, PPh4Cl, allows isolation of the putative catalytic intermediate [LTi(OiPr)Cl]−, which is characterized using single-crystal X-ray diffraction techniques. The anionic titanium complex [LTi(OR)Cl]− is proposed as a model for the propagating alkoxide intermediates in the catalytic cycle.
Date Issued
2020-05-11
Date Acceptance
2020-02-01
Citation
Organometallics, 2020, 39 (9), pp.1619-1627
ISSN
0276-7333
Publisher
American Chemical Society
Start Page
1619
End Page
1627
Journal / Book Title
Organometallics
Volume
39
Issue
9
Copyright Statement
© 2020 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY)
License, which permits unrestricted use, distribution and reproduction in any medium,
provided the author and source are cited http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html.
License, which permits unrestricted use, distribution and reproduction in any medium,
provided the author and source are cited http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html.
License URL
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000535187200018&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Chemistry, Inorganic & Nuclear
Chemistry, Organic
Chemistry
GROUP-4 COMPLEXES
METAL-COMPLEXES
ALTERNATING COPOLYMERIZATION
ALKOXIDE INITIATORS
TRIANIONIC AMINE
CO2
POLYMERIZATION
EPOXIDES
ZIRCONIUM
TITANIUM
Publication Status
Published
Date Publish Online
2020-02-11