Fiche publication
Date publication
septembre 2012
Auteurs
Membres identifiés du Cancéropôle Est :
Pr HIBERT Marcel
Tous les auteurs :
Ako AM, Alam MS, Mameri S, Lan YH, Hibert M, Stocker M, Muller P, Anson CE, Powell AK
Résumé
A structural analogue of the previously reported record-high-spin (S = 83/2) mixed-valence [Mn19] coordination cluster [MnIII12MnII7(mu 4-O)8(mu 3-?1-N3)8(HLMe)12(MeCN)6]Cl2 center dot 10MeOH center dot MeCN (1) {H3LMe = 2,6-bis(hydroxymethyl)-4-methylphenol} was prepared in which the methyl group at the 4-position on the phenyl ring was replaced by a methoxy group to give the compound [Et3NH]2[MnIII12MnII7(mu 4-O)8(mu 3-?1-N3)7.4(mu 3-Cl)(0.6)(HLOMe)12(MeOH)6]Cl4 center dot 14MeOH (2). Single-crystal X-ray diffraction analysis of 2 confirms that the molecular structure motif found for 1, comprising two supertetrahedral {MnIII6MnII4} units sharing a common MnII vertex, was retained. Magnetic susceptibility measurements on 2 show that the ferromagnetic spin structure, which results in the maximum ST = 83/2 spin ground state for 1, is largely robust with respect to the change in ligand substituent in 2. Molecules of compounds 1 and 2 were deposited onto highly oriented pyrolytic graphite (HOPG) substrates and were investigated by scanning tunneling microscopy (STM) andcurrent imaging tunneling spectroscopy (CITS). By usingextremely dilute solutions (109 mol?L1), one-dimensionalarrangements as well as isolated single molecules of [1]Cl-2 center dot 10MeOH center dot MeCN were observed with STM topography, generally at the step edges or at defects of the HOPG surfaces, while small groups of molecules of 2 were observed. The size of the individual molecules was consistent with the X-ray crystallographic data. In the CITS images of the single molecules, a strong tunneling current contrast was observed at the positions of the metal ions.
Référence
. 2012 Sep;26:4131-40.
