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Chelating η 6 ‐Arene‐η 1 ‐carbene Ligands in Ruthenium Complexes
Author(s) -
Özdemir Ismail,
Demir Serpil,
Çetinkaya Bekir,
Toupet Loïc,
Castarlenas Ricardo,
Fischmeister Cédric,
Dixneuf Pierre H.
Publication year - 2007
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.200601189
Subject(s) - chemistry , carbene , ruthenium , romp , ligand (biochemistry) , medicinal chemistry , metathesis , norbornene , ether , chelation , polymer chemistry , catalysis , polymerization , organic chemistry , biochemistry , polymer , receptor
Abstract N‐Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC‐η 6 ‐arene ligand have been prepared and evaluated as precursors for ring opening metathesis polymerization (ROMP). The reaction of [RuCl 2 ( p ‐cymene)] 2 with electron‐rich olefins of the bis(imidazolinylidene) type containing at least one arylmethyl‐ N chain (aryl: 2,4,6‐trimethylphenyl, 3,4,5‐trimethoxyphenyl) selectively leads, upon heating, to ruthenium(II) complexes 2 containing a chelating bridged carbene η 6 ‐arene ligand. The reaction of complexes containing an additional ROCH 2 CH 2 N group with AgOTf leads to ionic complexes 5 with a tridentate trifunctional carbene/arene/ether ligand. The X‐ray structure of[RuCl 2 {η 1 ‐CN(CH 2 {η 6 ‐C 6 H 2 Me 3 ‐2,4,6})CH 2 CH 2 N(CH 2 {C 6 H 2 (OMe) 3 ‐3,4,5})}] ( 2c ) and that of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand that provides ten electrons, [RuCl{η 1 ‐CN(CH 2 {η 6 ‐C 6 H 2 Me 3 ‐2,4,6})CH 2 CH 2 N(CH 2 CH 2 OCH 3 )}][CF 3 SO 3 ] ( 5e ), have been determined. The precursors 2 in the presence of AgOTf and propargyl alcohol, in order to produce an allenylidene initiator, and complexes 5 in the presence of propargyl alcohol lead to ROMP of norbornene. It is shown that initial chloride abstraction is required and that the catalyst activity is increased by using mesityl–ruthenium precursors and coordinated branched ether complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)