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Lithium Quinolyl‐Amidinates Efficiently Promoting Ring‐Opening Polymerization of ε‐Caprolactone: Synthesis and 7 Li NMR Spectroscopic Studies
Author(s) -
Rajendran Natesan Mannangatti,
Xi Yanxia,
Zhang Wenjuan,
Sun Yang,
Sun WenHua
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201700135
Subject(s) - chemistry , nuclear magnetic resonance spectroscopy , lithium (medication) , ring opening polymerization , polymerization , spectroscopy , ring (chemistry) , aniline , crystallography , crystal structure , polymer chemistry , stereochemistry , organic chemistry , polymer , medicine , physics , quantum mechanics , endocrinology
Lithium complexes ( Li1 – Li5 ) of tridentate quinolyl‐amidinate scaffolds were successfully synthesized in high yields and characterized by 1 H NMR spectroscopy and multinuclear solution 7 Li NMR spectroscopy. The molecular structures of representative complexes Li2 and Li3 were established by single‐crystal X‐ray diffraction analysis, indicating two four‐coordinate lithium atoms connected through two amidinate units. Interestingly, one Li atom is coordinated exclusively by the four N atoms of the quinolyl‐amidinate moieties, whereas the other Li atom is coordinated by the amino N atoms of the aminoquinolyl moieties, as well as the N atoms of the aniline moieties. These complexes were found to be highly active towards the ring‐opening polymerization of ε‐caprolactone, in both the absence and presence of benzyl alcohol as a co‐initiator. The mechanistic studies associated with these polymerizations were performed by 1 H NMR spectroscopy and 7 Li NMR spectroscopy.