title: Quinone-annulated N-heterocyclic carbene-transition-metal complexes: observation of pi-backbonding using FT-IR spectroscopy and cyclic voltammetry.
abstract: A new N-heterocyclic carbene architecture comprising a 1,4-naphthoquinone annulated to 1,3-dimesitylimidazolylidene (NpQ-NHC) was synthesized in two high yielding steps from commercially available starting materials. The free NpQ-NHC was characterized (solution and solid-state) and was used to synthesize various Rh and Ag complexes that ranged in pi-electron density. Enabled by the quinone moiety, the pi-systems of these complexes were analyzed using infrared spectroscopy and cyclic voltammetry. In contrast to previous reports, pi-backbonding was found to be non-negligible and was directly influenced by the metal's electronic character.
authors.affiliation: Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Sanderson
authors.forename: Justin W
authors.initials: JW
authors.lastname: Kamplain
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Bielawski
mesh_terms: D004563:Electrochemistry; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011809:Quinones / Q000737:chemistry*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013237:Stereoisomerism; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D006571:Heterocyclic Compounds; D006838:Hydrocarbons; D009942:Organometallic Compounds; D011809:Quinones; D028561:Transition Elements; C030011:carbene; D008697:Methane