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Issue 40, 2010
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Synthesis and structural and magnetic characterisation of cobalt(ii) complexes of mixed phosphonate-antimonate ligands

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Abstract

The polynucleating oxygen donor ligands, [(SbAr)4O2(PhPO3H)4(PhPO3)4] 1 and [(SbAr)2O(HO3PtBu)6] 2, based on condensation of p-chlorophenylstibonic acid (ArSbO3H2) and phosphonic acids, were used to prepare polymetallic cobalt(II) complexes. Reaction of 1 with cobalt acetate under solvothermal conditions produces three different types of polymetallic cobalt complexes. With LiOMe/pyridine as base in MeOH a dinuclear cobalt cage, [Co2(SbAr)4O4(O3PPh)4(OMe)4py2] 3, is formed, with four Sb(II) and two Co(II) centres bridged by μ3-oxides and phosphonates. The pyridine in the structure can be replaced by 3-picoline 4, 4-picoline 5, quinoline 6, 1,2-diazole 7, 4-phenylpyridine 8, 4-ethyl pyridine 9 and methanol 10. Using pyrazine (pyz) instead of pyridine under the same conditions a polymer, [Co2(SbAr)4O4(O3PPh)4(OMe)4(C4H4N2)]n11, is formed. A similar 1D-polymer forms with 4,4′-bipyridyl-ethylene 12 in place of pyrazine. With Et3N/pyridine as base in MeCN a tetranuclear cobalt cage, [Co4(SbAr)5O9(O3PPh)6(py)4] 13, with five Sb(II) centres forming a “bowtie” and bridging to four Co(II) centres by phosphonates and μ3-oxides, is formed. The reaction of 2 with cobalt acetate using LiOMe/pyridine as base in methanol, under solvothermal conditions, produces a dinuclear Co(II) complex, [Co2(SbAr)2(O3PtBu)3O2(OMe)2(py)2] 14, with two CoII and two Sb centres at the vertices of a distorted tetrahedron. Magnetic measurements on selected number of these cobalt cages are reported.

Graphical abstract: Synthesis and structural and magnetic characterisation of cobalt(ii) complexes of mixed phosphonate-antimonate ligands

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Article information


Submitted
17 May 2010
Accepted
07 Jul 2010
First published
03 Sep 2010

Dalton Trans., 2010,39, 9588-9597
Article type
Paper

Synthesis and structural and magnetic characterisation of cobalt(II) complexes of mixed phosphonate-antimonate ligands

S. Ali, C. A. Muryn, F. Tuna and R. E. P. Winpenny, Dalton Trans., 2010, 39, 9588
DOI: 10.1039/C0DT00482K

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