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Octametallic and Hexadecametallic Ferric
Wheels**
Press, London, 1973, pp. 143 160; c) For
a review of stemona
Leigh F. Jones, Andrei Batsanov, Euan K. Brechin,*
David Collison,* Madeleine Helliwell, Talal Mallah,
Eric J. L. McInnes, and Stergios Piligkos
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Et2O, 2 h; e) oxalyl chloride, DMSO, NEt3. Sulfone 2 was synthesized
from 1,3-propanediol in 84% overall yield by the following sequence:
a) NaH, BnBr, DMF, 24 h; b) CBr4, PPh3, CH2Cl2; c) 1-phenyl-1H-
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[20] M. W. Rathke, J. Am. Chem. Soc. 1970, 92, 3222 3223.
[21] CCDC 185839 and 185840 contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge via
Crystallographic Data Centre, 12, Union Road, Cambridge CB21EZ,
UK; fax: (þ 44)1223-336-033; or deposit@ccdc.cam.ac.uk).
The synthesis of paramagnetic molecular clusters has
become an area of intense research since the discovery that
such molecules can act as nanoscale magnets below a critical
temperature.[1,2] Such single-molecule magnets (SMMs) are
promising new materials for data storage and quantum
computing, which exhibit not only magnetization hysteresis
but also display quantum tunneling of magnetization and
quantum phase interference.[3,4] In order to function as a SMM
a molecule must possess the combination of a large spin and
large, easy-axis-type anisotropy. The first SMM was
[Mn12O12(O2CMe)16(H2O)4] (™Mn12∫), and since its prepara-
tion a number of molecules have been reported as new
members of this family.[5 9] An intriguing class of cluster in this
respect is the ™molecular wheel∫. Most even-membered
wheels are antiferromagnetic and characterized by S ¼ 0
ground states, however, this is not the case for the reported
™Ni12∫ and ™Cr10∫ wheels.[10,11] Indeed ™Ni12∫ was recently
reported as the first example of a Ni SMM.[10] Although
compounds with S ¼ 0 ground states cannot function as
SMMs, they represent ideal model systems for the study of
1D magnetic materials, quantum effects, and magnetic
anisotropy. To this end, molecular wheels and metallocycles
with 6, 8, 10, 12, 18, and 24 metal ions have been reported.[12]
We have chosen to investigate the use of the pro-ligand 1,1,1-
tris(hydroxymethyl)ethane (H3thme) in the synthesis of novel
transition metal clusters, and herein report the synthesis and
initial magnetic properties of two new FeIII clusters, the first
unsupported octametallic and hexadecametallic ferric wheels
(unsupported in the sense that there are no central metal ions
present). The H3thme ligand has been successfully used in
vanadium chemistry[13] but has been sparingly employed for
other transition metal complexes.[14]
[*] Dr. E. K. Brechin, Dr. D. Collison, L. F. Jones, Dr. M. Helliwell,
Dr. E. J. L. McInnes, S. Piligkos
Department of Chemistry
The University of Manchester
Oxford Road, Manchester, M13 9PL (UK)
Fax : (þ 44)161-275-4616
E-mail: euan.k.brechin@man.ac.uk
Dr. A. Batsanov
Department of Chemistry
University Science Laboratories
South Road, Durham DH13LE (UK)
Prof. T. Mallah
Universitÿ Paris-Sud, Bat. 420
Laboratoire de Chimie Inorganique, UMR CNRS 8613
91405 Orsay (France)
[**] This work was supported by the EPSRC (UK), Lloyd©s of London
Tercentenary Foundation, and the European Community (contract
HPRN-CT-1999-00012/TMR network ™MolNanoMag∫).
Supporting information for this article is available on the WWW under
4318
¹ 2002 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0044-8249/02/4122-4318 $ 20.00+.50/0
Angew. Chem. Int. Ed. 2002, 41, No. 22