Synthesis and Structural Characterization of ... - Jacobs University

Chapter 4
Unpublished Results
Few examples in literature on mixed incorporation of lanthanides and d-transition metal
ions into POMs (also known as 3d-4f heterometalic POMs) are known. 11-15 Krebs et al.
successfully synthesized [((VO) 2 Dy(H 2 O) 4 K 2 (H 2 O) 2 Na(H 2 O) 2 )(α-B-AsW 9 O 33 ) 2 ] 8− , which is
constructed from two trilacunary Keggin anions, two VO 2+ and one Dy 3+ ion forming a
sandwich-type structure with C 2v symmetry. 11 Kögerler et al. reported two compounds, 12
[(CH 3 ) 2 NH 2 ] 6 H 2 [{α-P 2 W 16 O 56 (OH) 2 }{Ce IV Mn IV 6O 9 (O 2 CCH 3 ) 8 }]·20H 2 O and K 36 Na 11 [{α-
P 2 W 15 O 56 } 6 {Ce 3 Mn 2 (μ 3- O) 4 (μ 2- OH) 2 } 3 (μ 2- OH) 2 (H 2 O) 2 (PO 4 )]·106H 2 O, which were
synthesized by interaction of the high oxidation state heterometallic
clusters[CeMn 6 O 9 (O 2 CCH 3 ) 9 (NO 3 )(H 2 O) 2 ] and [Ce IV 3 Mn IV 2 O 6 (OH) 2 ] 6+ respectively with the
tri-vacant Wells-Dawson phosphotungstate [α-P 2 W 16 O 56 ] 12− . 12 Mialane’s group synthesized
polyanions containing Cu(II) and Ln(III) cations by reaction of the [A-α-SiW 9 O 34 ] 10− unit with
the Cu(II) acetate and Ln(NO 3 ) 3 . 13 As well, Wang et al. have been synthesizing several
polyanions containing 3d-transition metal centers and having lanthanide cations as linkers
between the different POM units. 14 They also reported the synthesis of a polyanion based 3d-
4f heterometallic aggregate, constructed from three {α-AsW 9 O 38 } fragments bridged by three
{Fe-(μ 3- O) 3 -Ce} heterometalic clusters. 14c Reinoso et al. reported [{Ce(H 2 O) 2 } 2 Mn 2 (B-α-
GeW 9 O 34 ) 2 ] 8- polyanion constituting the first example of a heterometallic 3d-4f cluster related
to the Weakley-type dimeric structure, and it contains Ce III 2Mn III 2O 20 rhomblike moiety. 15
Therefore, the cyclic phophotungstate P 8 W 48 represented for us a good candidate towards
synthesis of new heterometallic polyanion. As mentioned above, P 8 W 48 is known to interact
with both 3d-transition metals and lanthanides. Furthermore, a paramagnetic 3d metal oxocluster
interacting with paramagnetic lanthanide centers is an interesting combination for
magnetic interactions. Therefore, we decided to study the formation of the known Fe 16 P 8 W 48 ,
previously reported by our group, in the presence of lanthanides. This has resulted in the
synthesis and structural characterization of the europium(III) and gadolinium(III)-coupled 16-
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