4th EucheMs chemistry congress

Poster Session 1
s992
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - inorganic Chemistry
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MuLtinuCLeAr MAnGAneSe-ContAininG
PoLyoxotunGStAteS:SyntheSiS, StruCture,
And CAtALytiC CAPACity
r. AL-oweini 1 , B. BASSiL 1 , u. Kortz 1
1 Jacobs University, School of Engineering and Science,
Bremen, Germany
Inorganic compounds are generally known to be formed
from atoms of a metallic nature as their intrinsic building units.
Polyoxometalates (POMs) are discrete, nano-sized metal-oxo
anions of high oxidation state early transition metals,
predominantly VV , NbV , TaV , MoVI , and WVI . 1a They are adaptable
structures with natural properties in nano-sized dimensions, shape,
charge density and surface reactivity due to the flexibility of their
chemical composition, charge, and counterions. [1] Such properties
render POMs highly desirable for magnetic, electronic, and
catalytic studies amongst others. [2, 3]
Polyanions containing several paramagnetic d-block ions are
of interest for oxidation catalysis applications. In particular
manganese-containing polyanions are important here, and very
recently our group has reported the synthesis and magnetic
properties of a new member, the Mn -containing polyanion
19
[Mn II
19 (OH) 12 (SiW 10 O 37 ) 6 ]34- {Mn 19 }. [4] To date only a few
high-nuclearity, mixed-valence polytungstates have been
prepared, usually based on reactions of MnII - and MnO , or the
4
well-known {Mn }, with lacunary polytungstate precursors.
12
We have investigated the reactivity of {Mn } with lacunary
12
heteropolytungstates. This approach has enabled us to synthesize
the polyanions [Mn III
3 (OH) 3 (H 2 O) 3 SiW 9 O 34 ]4- {Mn 3 -Keggin},
[Mn III
3 MnIV (CH 3 COO) 3 SiW 9 O 37 ] 6- {Mn 4 }, [Mn III
3 (H 2 O) 5 (PW 9 O 34 ) 2 ]9-
{Mn 3 -Knoth}, and [Mn III
6 MnIV
4 O 4 (OH) 12 (H 2 O) 12 (AsW 9 O 34 ) 4 ]22-
{Mn 10 }, which were all characterized by single-crystal XRD,
electrochemical studies, TGA, and IR spectroscopy.
These compounds have tremendous potential in electro- and
oxidation-catalysis.
references:
1. a) M. T. Pope, A. Müller, Angew. Chem. Int. Ed. Engl.
1991, 30, 34–48;
b) Chem. Rev. 1998, 98, 1–390 (Special Issue on
Polyoxometalates; Ed.: C. L. Hill);
2. Kortz, U., Müller, A., van Slageren, J., Schnack, J., Dalal,
N.S., and Dressel, M. Coord. Chem. Rev. 2009, 253,
2315–2327;
3. Eur. J. Inorg. Chem. 2009, 34 (Issue dedicated to
Polyoxometalates; Guest Ed.: U. Kortz);
4. B. S. Bassil, M. Ibrahim, R. Al-Oweini, M. Asano, Z. Wang,
J. van Tol, N. S. Dalal, K.-Y. Choi, R. Ngo Biboum,
B. Keita, L. Nadjo, U. Kortz, Angew. Chem. Int. Ed.,
2011, 50, 5961–5964.
Keywords: Polyoxometalates; Oxidation; Homogeneous
catalysis; Manganese; Magnetic properties;
4 th EucheMs chemistry congress
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hiGh-nuCLeArity, MAGnetiC
MetAL-oxo ASSeMBLieS StABiLized By
heteroPoLytunGStAteS
B. BASSiL 1 , S. S. MAL 1 , M. iBrAhiM 1 , u. Kortz 1
1 Jacobs University, Chemistry, Bremen, Germany
Lacunary heteropolytungstates are known to act as inorganic
multidentate ligands with oxygen atom donors at the lacunary
sites. [1] The combination of 3d transition metals with lacunary
heteropolutungstates is part of the TMSP (Transition
Metal-Substituted Polyoxometalates) subclass. Recently, a
growing interest started to show in TMSP’s comprising high
nuclearity (>10) metal-oxo cage complexes with paramagnetic
centers, due to their potential to exhibit Single
Molecular Magnet (SMM) behavior. [2] Interaction of the
wheel-shaped 48-tungsto-8-phosphate [H P W O ] 7 8 48 184 33- ({P W }) 8 48
with copper(II) and iron (III) formed the 20-copper(II)- and
16-iron(III)-containing species {Cu P W } and {Fe P W }
20 8 48 16 8 48
respectively, which correspond to the parent lacunary
precursor {P W } encapsulating a [Cu Cl(OH) (H O) ] 8 48 20 24 2 12 9- and a
[Fe (OH) (H O) ] 16 28 2 4 20+ core. [3] Interaction of the trilacunary
nonatungstosilicate [SiW O ] 9 34 10- ({SiW }) with manganese(II) and
9
its phosphate analogue [PW O ] 9 34 9- ({PW }) with cobalt(II) ions
9
in basic phosphate buffer formed the 19-manganese(II)- and
16-cobalt(II)-containing species {Mn Si W } and {Co P W }
19 6 60 16 4 36
respectively, corresponding to a sheet-like [Mn (OH) ] 19 12 26+ core
stabilized by six [SiW O ] 10 37 10- units and a tetrahedrally arranged
[Co (OH) (PO ) ] 16 12 4 4 8+ core stabilized by four {PW } units. 9 [4]
references:
1. Eur. J. Inorg. Chem. 2009, 34 (Issue dedicated to
Polyoxometalates; Guest Ed.: U. Kortz).
2. U. Kortz, A. Müller, J. van Slageren, J. Schnack,
N.S. Dalal, M. Dressel, Coord. Chem. Rev. 2009, 253, 2315.
3. a) S. S. Mal, U. Kortz, Angew. Chem. Int. Ed. 2005, 44, 3777
b) S. S. Mal, M. H. Dickman, U. Kortz, A. M. Todea,
A. Merca, H. Bögge, T. Glaser, A. Müller, S. Nellutla,
N. Kaur, J. van Tol, N. S. Dalal, B. Keita, L. Nadjo,
Chem. Eur. J. 2008, 14, 1186
4. a) B.S. Bassil, M. Ibrahim, R. Al-Oweini, M. Asano,
Z. Wang, J. van Tol, N. S. Dalal, K.-Y. Choi, U. Kortz,
Angew. Chem. Int. Ed. 2011, 50, 5961
b) M. Ibrahim, Y. Lan, B. S. Bassil, Y. Xiang, A. K. Powell,
U. Kortz, Angew. Chem. Int. Ed. 2011, 50, 4708
Keywords: Polyoxometalates; Transition metals; Magnetic
properties;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc