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Cooperative Effects of Aniline with DMSO in Ru II Complexes: Tuning the Reactivity for Ring‐Opening Metathesis Polymerization
Author(s) -
Martins Daniele M.,
Maia Pedro I. S.,
CarvalhoJr Valdemiro P.,
LimaNeto Benedito S.
Publication year - 2019
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.201900887
Subject(s) - chemistry , romp , norbornene , ring opening metathesis polymerisation , metathesis , dicyclopentadiene , polymerization , monomer , ruthenium , norbornadiene , medicinal chemistry , aniline , polymer chemistry , reactivity (psychology) , ring opening polymerization , catalysis , polymer , organic chemistry , medicine , alternative medicine , pathology
The complex cis,fac ‐[RuCl 2 (DMSO–O)(DMSO–S) 3 ] [ 1 ] reacted with aniline (NH 2 Ph) under reflux to produce the complex trans , cis , cis ‐[RuCl 2 (DMSO–S) 2 (NH 2 Ph) 2 ] [ 2 ], whereas at room temperature the resulting complex was cis,fac ‐[RuCl 2 (DMSO–S) 3 (NH 2 Ph)] [ 3 ]. The complexes were characterized by FTIR, EPR, 1 H and 13 C NMR, electronic spectra, and the crystal structure of 2 was determined by single X‐ray crystallography. The influence of NH 2 Ph and DMSO as ancillary ligands in the new complexes was then evaluated for ring‐opening metathesis polymerization (ROMP) of norbornene (NBE), norbornadiene (NBD), and dicyclopentadiene (DCPD) in presence of ethyl diazoacetate (EDA) with different [monomer]/[Ru] molar ratios. Homopolymers of NBE with molecular weights in the order of magnitude of 10 5 g.mol –1 and insoluble polymers in CHCl 3 from NBD and DCPD were obtained in different yields depending of the starting complex, reaction time (5 and 30 min), and temperature (25 and 50 °C). Valorous results were obtained for polyNBD, polyDCPD, and copolymerizations from NBE with NBD or DCPD using the new complexes, affording higher yields than with 1 . In conclusion, beneficial effects are observed when DMSO and the weak σ‐donor NH 2 Ph ligands are arranged in the same coordination sphere of Ru(II) pre‐catalysts for ROMP.