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Adsorption of [Mn 19 ] Aggregates with S = 83/2 onto HOPG Surfaces
Author(s) -
Ako Ayuk M.,
Alam Mohammad Sahabul,
Mameri Samir,
Lan Yanhua,
Hibert Marcel,
Stocker Michael,
Müller Paul,
Anson Christopher E.,
Powell Annie K.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200420
Subject(s) - chemistry , crystallography , highly oriented pyrolytic graphite , valence (chemistry) , molecule , scanning tunneling microscope , hydroxymethyl , substituent , crystal structure , single crystal , stereochemistry , graphite , nanotechnology , materials science , organic chemistry
A structural analogue of the previously reported record‐high‐spin ( S = 83/2) mixed‐valence [Mn 19 ] coordination cluster [Mn III 12 Mn II 7 (μ 4 ‐O) 8 (μ 3 ‐η 1 ‐N 3 ) 8 (HL Me ) 12 (MeCN) 6 ]Cl 2 · 10MeOH · MeCN ( 1 ) {H 3 L Me = 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 [Et 3 NH] 2 [Mn III 12 Mn II 7 (μ 4 ‐O) 8 (μ 3 ‐η 1 ‐N 3 ) 7.4 (μ 3 ‐Cl) 0.6 (HL OMe ) 12 (MeOH) 6 ]Cl 4 · 14MeOH ( 2 ). Single‐crystal X‐ray diffraction analysis of 2 confirms that the molecular structure motif found for 1 , comprising two supertetrahedral {Mn III 6 Mn II 4 } units sharing a common Mn II vertex, was retained. Magnetic susceptibility measurements on 2 show that the ferromagnetic spin structure, which results in the maximum S T = 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 (10 –9 mol L –1 ), one‐dimensionalarrangements as well as isolated single molecules of [ 1 ]Cl 2 · 10MeOH · 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.