The search for cobalt single-molecule magnets: A disk-like (CoCo6II)-Co-III cluster with a ligand derived from a novel transformation of 2-acetylpyridine
Φόρτωση...
Ημερομηνία
Συγγραφείς
Kitos, A. A.
Efthymiou, C. G.
Papatriantafyllopoulou, C.
Nastopoulos, V.
Tasiopoulos, A. J.
Manos, M. J.
Wernsdorfer, W.
Christou, G.
Perlepes, S. P.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Elsevier
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Polyhedron
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
The initial employment of 2-acetylpyridine, (py)(Me)CO, in Co cluster chemistry is reported, and the synthesis, crystal structure, and full magnetic study of [Co-7(OH)(6)(L)(6)](ClO4)(3)center dot 1.6H(2)O (1.1.6H(2)O) are described: L- is the anion of 2-(pyridine-2-yl)pentane-2-ol-4-one, (py)(Me)C(CH2COCH3)(O)(-), formed in situ through a crossed-aldol reaction in acetone under strongly basic conditions. The reaction of Co(ClO4)(2)center dot 6H(2)O, (POMe)CO and (NBu4OMe)-O-II (1:1:1.2) in acetone at room temperature under aerobic conditions affords 1.1.6H(2)O in 35% yield. The mixed-valent cation possesses a wheel-shaped (or disk-like) structural motif comprising a central octahedral Co-III atom linked to six peripheral distorted octahedral Co-II atoms by six mu(3)-OII- groups: the six Co-II atoms on the rim are held together by six eta(1):eta(1):eta(1):mu(2).L- ligands and the oxygen atoms of the hydroxo groups. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on 1. The dc magnetic study of 1 shows a decline in the product chi(T)(M) with decreasing T. The observation of out-of phase (chi ''(M)) ac susceptibility signals below similar to 4 K suggests that the CoIIICo6II complex may be a single molecule magnet, and this was confirmed by single-crystal magnetization vs. dc field sweeps down to 0.04 K that exhibited hysteresis. The study reveals that each complex cation is a weak single-molecule magnet, but that there are also intermolecular interactions (also confirmed crystallographically) to create a 3D ordered lattice: this still gives some hysteresis at 5 K. (C) 2011 Elsevier Ltd. All rights reserved.
Περιγραφή
Λέξεις-κλειδιά
cobalt single-molecule magnets, crossed-aldol reaction, heptanuclear (coco6iii)-co-ii clusters, ligands transformations, magnetic properties, 2-(pyridine-2-yl)pentane-2-olate-4-one, ligand, high-spin molecules, manganese carboxylate chemistry, mixed-valence cobalt(ii/iii), 2-pyridyl ketone oxime, di-2-pyridyl ketone, coordination polymer, crystal-structures, ground-state, mn-cluster, complexes
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000298522800006
http://ac.els-cdn.com/S0277538711000957/1-s2.0-S0277538711000957-main.pdf?_tid=69a02f66-3636-11e3-a0e8-00000aacb361&acdnat=1381909488_11c6532f82feac2e4246624bded1d628
http://ac.els-cdn.com/S0277538711000957/1-s2.0-S0277538711000957-main.pdf?_tid=69a02f66-3636-11e3-a0e8-00000aacb361&acdnat=1381909488_11c6532f82feac2e4246624bded1d628
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας