title: Assignment and conformational investigation of asymmetric phenylindenylidene ruthenium complexes bearing N,O-bidentate ligands.
abstract: The NMR conformational study of three asymmetric phenylindenylidene ruthenium complexes 4.1-4.3, is presented. Complete (1)H and (13)C assignments could be obtained for 4.1-4.3 in benzene solution from multiple 2D homonuclear and heteronuclear NMR techniques. Our NMR analysis shows that each complex exists as a 55:45 mixture of two rotational isomers in slow exchange on the NMR chemical shift timescale. They are shown to be related by a 180 degrees flip of the indenylidene ligand along the Ru=CR bond. Both rotational isomers can be discriminated by means of NOEs contacts between the various ligands coordinating to the Ru. By matching these stereospecific assignments to the chemical shift, a chemical shift based fingerprint of the isomers that may allow straightforward assignment of future asymmetric phenylindenylidene ruthenium complexes is proposed.
authors.affiliation: Department of Organic Chemistry, Ghent University, Krijgslaan 281 (S4), B-9000 Ghent, Belgium. Pieter.Hendrickx@UGent.Be
authors.forename: P M S
authors.initials: PM
authors.lastname: Hendrickx
authors.forename: R
authors.initials: R
authors.lastname: Drozdzak
authors.forename: F
authors.initials: F
authors.lastname: Verpoort
authors.forename: J C
authors.initials: JC
authors.lastname: Martins