title: Square-planar ruthenium(II) complexes: control of spin state by pincer ligand functionalization.
abstract: Functionalization of the PNP pincer ligand backbone allows for a comparison of the dialkyl amido, vinyl alkyl amido, and divinyl amido ruthenium(II) pincer complex series [RuCl{N(CH2 CH2 PtBu2 )2 }], [RuCl{N(CHCHPtBu2 )(CH2 CH2 PtBu2 )}], and [RuCl{N(CHCHPtBu2 )2 }], in which the ruthenium(II) ions are in the extremely rare square-planar coordination geometry. Whereas the dialkylamido complex adopts an electronic singlet (S=0) ground state and energetically low-lying triplet (S=1) state, the vinyl alkyl amido and the divinyl amido complexes exhibit unusual triplet (S=1) ground states as confirmed by experimental and computational examination. However, essentially non-magnetic ground states arise for the two intermediate-spin complexes owing to unusually large zero-field splitting (D>+200 cm(-1) ). The change in ground state electronic configuration is attributed to tailored pincer ligand-to-metal π-donation within the PNP ligand series.
authors.affiliation: Department Chemie und Pharmazie, Universität Erlangen-Nürnberg, Egerlandstr. 1, 91058 Erlangen (Germany).
authors.forename: Bjorn
authors.initials: B
authors.lastname: Askevold
authors.forename: Marat M
authors.initials: MM
authors.lastname: Khusniyarov
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kroener
authors.forename: Klaus
authors.initials: K
authors.lastname: Gieb
authors.forename: Paul
authors.initials: P
authors.lastname: Müller
authors.forename: Eberhardt
authors.initials: E
authors.lastname: Herdtweck
authors.forename: Frank W
authors.initials: FW
authors.lastname: Heinemann
authors.forename: Martin
authors.initials: M
authors.lastname: Diefenbach
authors.forename: Max C
authors.initials: MC
authors.lastname: Holthausen
authors.forename: Veacheslav
authors.initials: V
authors.lastname: Vieru
authors.forename: Liviu F
authors.initials: LF
authors.lastname: Chibotaru
authors.forename: Sven
authors.initials: S
authors.lastname: Schneider
mesh_terms: D000478:Alkylation; D000577:Amides / Q000737:chemistry; D002070:Butadienes / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D012428:Ruthenium / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D000577:Amides; D002070:Butadienes; D056831:Coordination Complexes; D014753:Vinyl Compounds; D012428:Ruthenium; C031763:1,3-butadiene
keywords: NMR spectroscopy; computer chemistry; ligands; magnetic properties; ruthenium