Formation of Ho-III trinuclear clusters and Gd-III monodimensional polymers induced by ortho and para regioisomers of pyridyl-functionalised beta-diketones: synthesis, structure, and magnetic properties

Andrews, Philip C., Deacon, Glen B., Frank, René, Fraser, Benjamin H., Junk, Peter C., Maclellan, Jonathan G., Massi, Massimiliano, Moubaraki, Boujemaa, Murray, Keith S., and Silberstein, Morry (2009) Formation of Ho-III trinuclear clusters and Gd-III monodimensional polymers induced by ortho and para regioisomers of pyridyl-functionalised beta-diketones: synthesis, structure, and magnetic properties. European Journal of Inorganic Chemistry, 2009 (6). pp. 744-751.

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View at Publisher Website: http://dx.doi.org/10.1002/ejic.200801006
 
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Abstract

Reaction of GdCl3(H2O)6 and 1,3-bis(pyridin-4-yl)propane-1,3-dione in methanol with an excess of triethylamine produced a monodimensional polymeric chain [Gd(p-dppd)3(H2O)]∞, whereas treatment of HoCl3(H2O)6 with 1,3-bis(pyridin-2-yl)propane-1,3-dione yielded a trinuclear cluster [Ho3(o-dppd)3(μ3-OH)2(H2O)4Cl2]Cl2. The compounds were characterised by elemental analysis, IR spectroscopy and magnetism, and their structures were investigated by X-ray crystallography. The 8.20-μB magnetic-moment value of the polymeric [Gd(p-dppd)3(H2O)]∞, between 300 and 20 K, and the magnetisation isotherms (2–20 K; fields 0–5 T), are in agreement with essentially uncoupled single-ion Gd3+ f7 centres, a small decrease in μeff below 20 K being indicative of zero-field splitting. A temperature-dependent dc-susceptibility and magnetisation investigation of the trinuclear (triangular) [Ho3(o-dppd)3(μ3-OH)2(H2O)4Cl2]Cl2 revealed that spin-orbit and ligand-field effects on the Ho3+ centres, leading to thermal depopulation of Zeeman levels and consequent decreases in μeff values with decreasing temperature, are occurring rather than weak intra-cluster antiferromagnetic coupling. Frequency- and temperature-dependent ac-susceptibility studies on this homometallic Ho3+ cluster did not show clear evidence for slow magnetisation reversal, characteristic of single-molecule magnetism (SMM), and this contrasts with such behaviour recently reported, elsewhere, for a Dy3+ triangle having the same core structure but with different chelating {O,O} ligands.

Item ID: 29695
Item Type: Article (Research - C1)
ISSN: 1099-0682
Keywords: beta-diketonate ligands, coordination polymers, cluster compounds, molecular magnets, ketones, N,O ligands, chelates
Funders: Australian Research Council (ARC), Bayer Schering Pharma
Date Deposited: 02 Oct 2013 10:34
FoR Codes: 03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030202 f-Block Chemistry @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%
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