title: Alkali-Metal-Mediated Magnesiations of an N-Heterocyclic Carbene: Normal, Abnormal, and "Paranormal" Reactivity in a Single Tritopic Molecule.
abstract: Herein the sodium alkylmagnesium amide [Na4Mg2(TMP)6(nBu)2] (TMP=2,2,6,6-tetramethylpiperidide), a template base as its deprotonating action is dictated primarily by its 12 atom ring structure, is studied with the common N-heterocyclic carbene (NHC) IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. Remarkably, magnesiation of IPr occurs at the para-position of an aryl substituent, sodiation occurs at the abnormal C4 position, and a dative bond occurs between normal C2 and sodium, all within a 20 atom ring structure accommodating two IPr(2-). Studies with different K/Mg and Na/Mg bimetallic bases led to two other magnesiated NHC structures containing two or three IPr(-) monoanions bound to Mg through abnormal C4 sites. Synergistic in that magnesiation can only work through alkali-metal mediation, these reactions add magnesium to the small cartel of metals capable of directly metalating a NHC.
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK).
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Martínez-Martínez
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK).
authors.forename: M Ángeles
authors.initials: MÁ
authors.lastname: Fuentes
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK).
authors.forename: Alberto
authors.initials: A
authors.lastname: Hernán-Gómez
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK).
authors.forename: Eva
authors.initials: E
authors.lastname: Hevia
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK).
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kennedy
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK). r.e.mulvey@strath.ac.uk.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Mulvey
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK).
authors.forename: Charles T
authors.initials: CT
authors.lastname: O'Hara
keywords: alkali metals; carbenes; crown compounds; magnesium; metalation