Incorporation of Sulfate or Selenate Groups into Oxotellurates(IV): III. Compounds with Magnesium or Zinc

Article abstract of DOI:10.1002/zaac.201700017

The mixed oxochalcogenate compounds Mg₂(SO₄)(TeO₃)(H₂O), Mg₃(SO₄)(TeO₃)(OH)₂(H₂O)₂, Zn₂(SeO₄)(TeO₃), and Zn₄(SO₄)(TeO₃)₃ were obtained under hydrothermal conditions (210 °C, autogenous pressure). Structure analyses using single-crystal X-ray data revealed tellurium in all four compounds to be present in oxidation state +IV, whereas sulfur or selenium atoms exhibit an oxidation state of +VI. In the crystal structures of the two magnesium compounds, [MgO₅(H₂O)] octahedra [Mg₂(SO₄)(TeO₃)(H₂O) structure, isotypic with the Co and Mn analogues] or [MgO₄(OH)₂] and [MgO₄(OH)₂(H₂O)₂] octahedra [Mg₃(SO₄)(TeO₃)(OH)₂(H₂O)₂structure, novel structure type] as well as trigonal-pyramidal TeO₃^2– anions make up metal oxotellurate sheets, which are bridged by SO₄^2– anions. The polar crystal structure of Zn₂(SeO₄)(TeO₃) is isotypic with Zn₂(MoO₄)(TeO₃) and consists of [ZnO₄] tetrahedra, [ZnO₆] octahedra, SeO₄^2– and TeO₃^2– anions as principal building units that are connected into a framework structure. Such a structural arrangement, with basically the same coordination polyhedra as in Zn₂(SeO₄)(TeO₃) but with SO₄^2– instead of SeO₄^2– anions, is also found in the tellurium-rich compound Zn₄(SO₄)(TeO₃)₃ that crystallizes in a novel structure type.

Full text of DOI:10.1002/zaac.201700017

Journal of Inorganic and General Chemistry
DOI: 10.1002/zaac.201700017
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
Incorporation of Sulfate or Selenate Groups into
Oxotellurates(IV): III. Compounds with Magnesium or Zinc
Matthias Weil*[a] and Mahdi Shirkhanlou[a]
Abstract. The mixed oxochalcogenate compounds Mg2(SO4)(TeO3)- ture, novel structure type] as well as trigonal-pyramidal TeO32– anions
(H2O), Mg3(SO4)(TeO3)(OH)2(H2O)2, Zn2(SeO4)(TeO3),
and make up metal oxotellurate sheets, which are bridged by SO42– anions.
Zn4(SO4)(TeO3)3 were obtained under hydrothermal conditions The polar crystal structure of Zn2(SeO4)(TeO3) is isotypic with
(210 °C, autogenous pressure). Structure analyses using single-crystal Zn2(MoO4)(TeO3) and consists of [ZnO4] tetrahedra, [ZnO6] octahe-
X-ray data revealed tellurium in all four compounds to be present in dra, SeO42– and TeO32– anions as principal building units that are con-
oxidation state +IV, whereas sulfur or selenium atoms exhibit an oxid- nected into a framework structure. Such a structural arrangement, with
ation state of +VI. In the crystal structures of the two magnesium
compounds, [MgO5(H2O)] octahedra [Mg2(SO4)(TeO3)(H2O) struc-
basically the same coordination polyhedra as in Zn2(SeO4)(TeO3) but
with SO4 instead of SeO4 anions, is also found in the tellurium-
2–
2–
ture, isotypic with the Co and Mn analogues] or [MgO4(OH)2] and rich compound Zn4(SO4)(TeO3)3 that crystallizes in a novel structure
[MgO4(OH)2(H2O)2] octahedra [Mg3(SO4)(TeO3)(OH)2(H2O)2 struc- type.
Introduction
Experimental Section
Synthesis: Selenic acid was prepared by oxidizing SeO2 in aqueous
solution with an H2O2/HNO3 mixture. Zinc selenate pentahydrate was
prepared by dissolving basic zinc carbonate in an excess of selenic acid
and the solution evaporated nearly until dryness. The obtained product
was recrystallized from water and checked by powder X-ray diffraction
for purity. All other chemicals were used from commercial sources.
A determining factor in the crystal chemistry of oxo-
tellurates(IV)[1,2] is the presence of the 5s2 lone electron pair
at the tellurium(IV) atom that – in the majority of cases – is
stereochemically active.[3] The shapes of the resulting oxo-
tellurate(IV) anions, with coordination numbers of the TeIV
atom ranging from three to five, are considered to have signifi-
cant influence for a possible formation of non-centrosymmetric
crystal structures, a precondition for non-linear optical or other
interesting physical properties.[4]
In recent projects we have investigated the incorporation of
tetrahedral sulfate or selenate anions into metal oxotellurate-
(IV) frameworks with the objective to use these building units
as spacers and to obtain new phases with non-centrosymmetric
crystal structures. For this purpose we have originally chosen
systems with divalent metal ions having large radii (Hg, Cd,
Ca, Sr, and Pb), that were reacted hydrothermally with precur-
sors of TeIV and SVI or SeVI.[5–7] The goal of the current pro-
ject was to investigate whether sulfate or selenate anions can
also be incorporated under hydrothermal conditions into
oxotellurates(IV) of metals with smaller ions, resulting in non-
centrosymmetric structures. For this purpose, we chose magne-
sium and zinc, and succeeded in the preparation and structural
characterization of four new double salts with composition
Hydrothermal syntheses were conducted in sealed Teflon containers
(capacity ca. 5–10 mL) in steel autoclaves at autogenous pressure at
210 °C for one week. Experimental details are described elsewhere.[7]
Magnesium and zinc compounds in form of their oxides, chlorides,
sulfates or selenates were mixed in stoichiometric amounts with TeO2.
For batches starting from oxides or chlorides, concentrated selenic acid
(ca. 80 wt%) or sulfuric acid (ca. 94 wt%) were added; for some ex-
periments KOH or NaOH were also added to ensure slightly basic
conditions. The solid products were filtered off, washed subsequently
with mother liquor, water and ethanol. Representative results of the
hydrothermal experiments are gathered in Table 1.
Powder X-ray Diffraction (PXRD): Samples of the bulk material
were ground, fixed with small amounts of petroleum jelly on silicon
wafers and measured with Cu-Kα1,2 radiation in Bragg-Brentano
geometry on a PANalytical X’PertPro system.
Thermogravimetry: The samples were heated in alumina crucibles in
a stream of argon (10 mL·min–1) with a heating rate of 10 K·min–1 in
the temperature interval 30–1000 °C with a Netzsch TG F3 Tarsus
system.
Mg2(SO4)(TeO3)(H2O),
Mg3(SO4)(TeO3)(OH)2(H2O)2,
Zn2(SeO4)(TeO3), and Zn4(SO4)(TeO3)3.
* Prof. Dr. M. Weil
Single Crystal Diffraction and Structure Analysis: Crystals were
pre-selected under a polarizing microscope. Indexing procedures of
selected single crystals revealed unknown unit cells for some crystals.
Intensity data of these crystals were measured either at room tempera-
ture (Siemens SMART) or at –173 °C in a stream of cold nitrogen
(Bruker APEX-II). Data strategies were optimized with APEX2[8]
using φ- and ω-scans and with SMART[8] using ω-scans. Intensity data
were integrated with SAINT[8] and absorption corrections were applied
E-Mail: Matthias.Weil@tuwien.ac.at
[a] Institute for Chemical Technologies and Analytics
Division Structural Chemistry
TU Wien
Getreidemarkt 9/164-SC
1060 Vienna, Austria
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201700017 or from the au-
thor.
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ARTICLE
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Table 1. Details of representative experiments for phase formation studies in the systems M/X/Te/O/(H) (M = Mg, Zn; X = Se, S) performed
under hydrothermal conditions.
Amounts of starting materials and stoichiometric ratios
Phases determined by X-ray powder diffraction
of the bulka)
(Additional) phases determined by sin-
gle-crystal X-ray diffraction
Strong acidic media (phases crystallized from solution after hydrothermal experiment)
MgO 0.13 g, TeO2 0.10 g, H2SO4 1 mL;
Te2O3(SO4)[16]
Te2O3(SO4)
MgO:TeO2:H2SO4 = 5:1:Ͼ10
ZnO 0.15 g, TeO2 0.10 g, H2SO4 1 mL;
ZnO:TeO2:H2SO4 = 3:1:Ͼ10
MgO 0.13 g, TeO2 0.10 g, H2SeO4 1 mL;
MgO:TeO2:H2SeO4 = 5:1:Ͼ8
ZnO 0.15 g, TeO2 0.10 g, H2SeO4 1 mL;
ZnO:TeO2:H2SeO4 = 3:1:Ͼ8
ZnSO4·H2O[17], Te2O3(SO4)
Te2O3(SO4)
H6TeO6
[18]
H6TeO6
H6TeO6, ZnSeO4·H2O[19]
Slightly basic media (pH ≈ 9–10; phases obtained directly after hydrothermal experiment)
Mg2(SO4)(TeO3)(H2O)b)
[20]
MgCl2·2H2O 0.38 g, TeO2 0.18 g, H2SO4 0.3 mL,
Mg2Te3O8[15], MgTe2O5
NaOH 0.09 g;
MgCl2·2H2O:TeO2:H2SO4:NaOH = 2.5:1:2:2
MgSO4·7H2O 0.38 g, TeO2 0.10 g, KOH 0.07 g;
MgSO4·7H2O:TeO2:KOH = 2.5:1:2
b)
Mg2Te3O8
Mg3(SO4)(TeO3)(OH)2(H2O)2
Mg2Te3O8,
Mg2(SO4)(OH)2 (caminite)[21]
K2Mg3(OH)2(SO4)3·2H2O[22]
Zn2(SeO4)(TeO3)b)
,
ZnO 0.106 g, TeO2 0.136 g, H2SeO4 0.2 mL, KOH 0.076 g; Zn2Te3O8[23], TeO2[24], ZnO[25]
ZnO:TeO2:H2SeO4:KOH = 1.6:1:1:1.6
ZnSeO4·5H2O 0.47 g, TeO2 0.10 g, KOH 0.07 g;
ZnSeO4·5H2O:TeO2:KOH = 2.5:1:2
Zn2Te3O8
Zn2(SeO4)(TeO3)b)
Zn3(TeO3)3(SO4)b)
Zn2(SeO4)(TeO3)b)
Zn3(TeO3)3(SO4)b)
ZnSO4·7H2O 0.36 g, TeO2 0.10 g, KOH 0.07 g;
ZnSO4·7H2O:TeO2:KOH = 2:1:2
a) Main phases appear first, minor phases last in terms of semi-quantitative phase analysis. For all batches additional reflections were present
that could not be assigned to known phases or the new phases given in the right column. b) This work.
with SADABS.[8] The crystal structures were solved by direct methods
and refined using the SHELXTL program package.[9]
The hydrogen atoms of the water molecule in the structure of
Mg2(SO4)(TeO3)(H2O) were clearly discernible from a difference map
Table 2. Details of data collections and structure refinements.
Mg2(SO4)(TeO3)(H2O)
Mg3(SO4)(TeO3)(OH)2(H2O)2
Zn2(SeO4)(TeO3)
Zn4(SO4)(TeO3)3
MR
338.30
414.64
449.30
884.34
Crystal size /mm3
Temperature /°C
Diffractometer
Radiation; λ /Å
Crystal color; form
Space group (no.)
Formula units, Z
a /Å
0.08ϫ0.10ϫ0.12
–173
Bruker APEX-II
0.009ϫ0.009ϫ0.280
–173
Bruker APEX-II
0.02ϫ0.06ϫ0.25
23
Siemens SMART
0.06ϫ0.12ϫ0.22
–173
Bruker APEX-II
Mo-Kα; 0.71073
colorless, parallelepiped
Pbcm (57)
4
7.4239(3)
10.1841(5)
8.3958(4)
90
634.77(5)
5.220
3.540
2.74–35.15
–12 Յ h Յ 12
–16 Յ k Յ 16
–13 Յ l Յ 13
41730
colorless, needle
Pnma (62)
4
9.8038(7)
6.0940(5)
15.2895(11)
90
913.46(12)
3.743
3.015
2.47–30.21
–13 Յ h Յ 13
–8 Յ k Յ 8
–21 Յ l Յ 21
27973
colorless, lath
P21 (4)
2
5.1889(9)
8.1373(12)
7.1710(12)
101.465(5)
296.74(8)
19.018
colorless, bar
P21/c
4
15.7405(9)
5.1943(3)
13.9917(8)
101.3320(14)
1121.67(11)
16.359
b /Å
c /Å
β /°
V /Å3
μ /mm–1
X-ray density /g·cm–3
Range θmin – θmax
Range
5.028
5.237
2.90–31.42
–7 Յ h Յ 7
–11 Յ k Յ 11
–10 Յ l Յ 10
4627
2.97–37.99
–26 Յ h Յ 26
–8 Յ k Յ 8
–23 Յ l Յ 23
35830
Measured reflections
Independent reflections
1484
1467
1902
3785
Obsserved reflections [I Ͼ 2σ(I)] 1382
1112
1866
3566
Ri
0.0453
0.117
0.027
0.047
Absorption correction
Transmission coefficients
Tmin; Tmax
SADABS
0.609;
0.747
SADABS
0.650;
0.746
SADABS
0.439;
0.746
SADABS
0.281;
0.747
Number of parameters
Difference electron density
67
95
101
191
0.76 [0.67, O5];
1.54 [1.00, Te1];
–1.75 [0.61, Te1]
–
0.0437
0.1025
1.34 [0.89, Te];
–1.01 [0.96, O2]
0.070(11)
0.0198
0.0456
1.018
2.63 [0.65, Te3];
–2.07 [0.46, Te3]
–
0.0271
0.0716
max; min / e–·Å–3 (dist. /Å, atom) –1.10 [1.23, Te1]
Flack parameter
R [F2 Ͼ 2σ(F2)]
wR2 (F2 all)
GooF
–
0.0173
0.0314
1.186
1.102
1.201
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Table 3. Selected interatomic distances /Å and angles /° as well as results of bond valence sum calculations /v.u., with coordination partners for
oxygen atoms in parentheses.
Mg2(SO4)(TeO3)(H2O)
Zn2(SeO4)(TeO3)
Mg1
Mg1
Mg1
Mg1
Mg1
Mg1
S1
S1
S1
Te1
Te1
–
–
–
–
–
–
–
–
–
–
–
O3
O4
O4
O6
O1
O5
O6
O2
O5
O3
O4
2.0453(10)
2.0515(12)
2.0638(11)
2.0860(11)
2.1118(9)
2.2229(11)
1.4667(11) (2ϫ) Zn2
1.4844(15)
1.4938(16)
1.8499(15)
Zn1
Zn1
Zn1
Zn1
Zn2
Zn2
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
O5
O7
O4
O1
O6
O5
O3
O7
O4
O2
O3
O6
O1
O2
O4
O5
O7
O2
1.925(3)
1.941(3)
1.958(3)
2.067(3)
2.032(3)
2.043(3)
2.046(3)
2.104(3)
2.180(3)
2.398(3)
1.635(3)
1.638(3)
1.643(3)
1.652(3)
1.864(3)
1.870(3)
1.897(3)
2.533(3)
Zn2
Zn2
Zn2
1.8715(10) (2ϫ) Se
Se
Se
Se
Te
Te
Te
Te
D–H···A
O1–H1···O2
D–H
0.82(3)
H···A
D···A
рD–H···A
162(3)°
1.79(3) 2.5816(12)
Mg1 2.04, S1 5.94, Te1 4.07, O1 (2 Mg; H atoms not considered) 0.65,
Zn1 1.96, Zn2 1.98, Se1 5.94, Te 3.93 (CN 3), 4.16 (CN 4), O1 (Zn, Se)
O2 (S) 1.46, O3 (2 Mg, Te) 2.18, O4 (2 Mg, Te) 2.08, O5 (2 Mg, S) 1.90, 1.86, O2 (Se, and long bonds to Zn and Te considered) 1.82, O3 (Zn, Se)
O6 (Mg, S) 1.88.
1.91, O4 (2 Zn, Te) 2.14, O5 (2 Zn, Te) 2.29, O6 (Zn, Se) 1.91, O7 (2 Zn,
Te) 2.11.
Mg3(SO4)(TeO3)(OH)2(H2O)2
Mg1
Mg1
Mg1
Mg1
Mg1
Mg1
Mg2
Mg2
Mg2
Mg2
Mg2
S1
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
O1H
O2H
O3
O4
O2
2.038(4)
2.055(4)
2.069(4)
2.072(4)
2.097(4)
2.114(4)
2.015(6)
2.062(6)
2.096(10) (2ϫ)
2.127(4) (2ϫ)
2.199(10) (2ϫ)
1.467(5)
1.467(4) (2ϫ)
1.496(5)
O1H
O1H
O2H
O2H
O2H
···
···
···
···
···
O2H
O3
O1WA
O3
2.744 (7)
2.696 (6) (2ϫ)
2.821 (10) (2ϫ)
2.835 (6) (2ϫ)
2.924 (11)
O1WB
O1
O2H
O1H
O1WB
O3
O1WA
O5
O2
O1
O3
O4
O1WA
O1WA
O1WA
O1WA
O1WA
O1WB
O1WB
O1WB
···
···
···
···
···
···
···
···
O5
O1WA
O3
O1WB
O4
O5
2.740 (11)
2.76 (2)
2.786 (11)
2.797 (17)
2.983 (12)
2.808 (11)
2.823 (11)
3.000 (11)
S1
S1
Te1
Te1
1.853(4) (2ϫ)
1.860(5)
O5
O1H
Mg1 2.15, Mg2 2.00, S 6.00, Te1 4.17, O1H (3 Mg) 1.16, O2H (3 Mg) 1.17, O1 (S, 2 Mg) 2.05, O2 (S, Mg) 1.87, O3 (Te, 2 Mg) 2.07, O4 (Te, 2 Mg)
2.09, O5 (S) 1.53, O1WA (Mg) 0.26, O2WB (Mg) 0.34.
Zn4(SO4)(TeO3)3
Zn1
Zn1
Zn1
Zn1
Zn1
Zn1
Zn2
Zn2
Zn2
Zn2
Zn3
Zn3
Zn3
Zn3
Zn3
Zn3
Zn4
Zn4
Zn4
Zn4
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
O8
O8
O12
O6
O3
O1
O11
O4
O7
O10
O7
O2
O11
O9
O10
O13
O9
O2
O3
O5
2.015(3)
2.037(3)
2.066(3)
2.144(3)
2.207(2)
2.325(3)
1.945(3)
1.974(3)
1.975(2)
2.007(3)
2.003(3)
2.014(3)
2.072(3)
2.109(3)
2.128(3)
2.465(3)
1.962(2)
1.967(3)
1.973(2)
1.997(3)
Te1
Te1
Te1
Te1
Te2
Te2
Te2
Te2
Te3
Te3
Te3
S1
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
O3
O8
O2
O6
O7
O11
O9
O13
O13
O4
O10
O1
1.867(3)
1.880(3)
1.891(2)
2.587(2)
1.888(2)
1.907(3)
1.909(2)
2.347(3)
1.841(3)
1.867(3)
1.901(2)
1.469(3)
1.481(3)
1.484(3)
1.484(3)
S1
S1
S1
O12
O5
O6
Zn1 1.96, Zn2 1.93, Zn3 2.03, Zn4 1.93, Te1 3.91 (CN3; 4.10 CN4), Te2 3.68 (CN3; 4.05; CN4) Te3 4.02, S1 5.92, O1 (S, Zn) 1.71, O2 (Te, 2 Zn)
2.19, O3 (Te, 2 Zn) 2.09, O4 (Te, Zn) 1.83, O5 (S, Zn) 1.92, O6 (S, Zn) 1.76 (S, Zn + long Te) 1.96, O7 (Te, 2 Zn) 2.20, O8 (Te, 2 Zn) 2.15, O9
(Te, 2 Zn) 2.03, O10 (Te, 2 Zn) 1.99, O11 (Te, 2 Zn) 2.10, O12 (S, Zn) 1.85, O13 (Te) 1.44 (Te, long bond Te, long bond Zn) 1.94.
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and were refined freely. The oxygen atom of the water molecule in the
tions at ca. 40 °C for several days, colorless crystalline masses
structure of Mg3(SO4)(TeO3)(OH)2(H2O)2 is disordered relative to a
mirror plane and was refined with two statistically occupied sites
(O1WA and O1WB), for which no restraints were applied during
refinement. Hydrogen atom positions in the structure of
Mg3(SO4)(TeO3)(OH)2(H2O)2 could not be located reliably and hence
were excluded from the model. Nevertheless, bond valence sum calcu-
lations (BVS), for which bond valence parameters of Brese and
O’Keeffe[10] or Brown[11] were used, clearly revealed the oxygen atoms
belonging to water molecules or OH groups.
were obtained that were separated by filtration. Identified
phases are compiled in Table 1; novel phases were not ob-
tained under these conditions. The stronger oxidation power of
selenic acid led to an oxidation of TeIV to yield telluric acid,
whereas use of sulfuric acid yielded Te2O3(SO4)[16] without
changing the oxidation state of tellurium. Basic conditions (pH
9–10) on the other hand are beneficial for formation of mixed
oxochalcogenate phases, as was already shown for other sys-
tems M/Se/Te/O (M = Hg,[5] Cd, Ca, Sr,[6] Pb[7]). For M = Mg,
Zn, four new double salts with compositions Mg2(SO4)(TeO3)-
(H2O), Mg3(SO4)(TeO3)(OH)2(H2O)2, Zn2(SeO4)(TeO3), and
Zn4(SO4)(TeO3)3 were obtained, albeit in the majority of cases
with low yields and as parts of multi-phase products. Except
for Zn4(SO4)(TeO3)3 that could be prepared as a single-phase
product (see Figure S1, Supporting Information), optical in-
spection of the reaction products under a polarizing micro-
scope revealed multi-phase formation for all batches. These
findings were confirmed by subsequent single crystal and pow-
der X-ray diffraction of the bulk (Table 1). Apart from the
identified phases, additional weak reflections were present in
the diffraction pattern of all batches that could not be assigned
to any known phase(s).
Details of the data collections and structure refinements are listed in
Table 2. Selected bond lengths and angles are compiled in Table 3,
together with the results of BVS calculations. A complete list of bond
length including symmetry codes to generate symmetry-related sites is
given as Supporting Information. Drawings of structural details were
produced using the program ATOMS.[12]
Further details of the crystal structures investigations may be obtained
from the Fachinformationszentrum Karlsruhe, 76344 Eggenstein-
Leopoldshafen, Germany (Fax: +49-7247-808-666; E-Mail:
crysdata@fiz-karlsruhe.de,
http://www.fiz-karlsruhe.de/request-for-
deposited-data.html) on quoting the depository numbers CSD-
432345 [Mg2(SO4)(TeO3)(H2O)], CSD-432392 [Mg3(SO4)(TeO3)-
(OH)2(H2O)2], CSD-432346 [Zn2(SeO4)(TeO3)], and CSD-432381
[Zn4(SO4)(TeO3)3].
Supporting Information (see footnote on the first page of this article):
Detailed list of selected bond lengths and angles including symmetry
codes; X-ray powder diffraction pattern of Zn4(SO4)(TeO3)2; Thermo-
gravimetric measurement of Zn4(SO4)(TeO3)2.
Crystal Structures
Mg2(SO4)(TeO3)(H2O)
The compound crystallizes with four formula units in the
centrosymmetric space group Pbcm and is isotypic with its Co
Results and Discussion
To the best of our knowledge, double salts of magnesium or and Mn analogues.[26] The asymmetric unit contains one Mg
zinc in combination with oxotellurate(IV) and oxochalco- site in a general position 8e, one S and one Te site on a mirror
genate(VI) anions are unknown. Our first approaches with re- plane (4d), six O sites, two of which in general positions (8e;
spect to the preparation of such compounds were simple co- O4, O6), three on a mirror plane (4d, O2, O3, O5), and one
precipitation reactions in aqueous solutions. For this purpose on a twofold rotation axis (4c; O1), as well as one H site in a
we used a concentrated solution of magnesium (zinc) sulfate general position. The principal building units are one
or selenate in excess, to which a half-concentrated solution of [MgO5(H2O)] octahedron, one trigonal-pyramidal TeO32–, and
2–
sodium oxotellurate(IV) was slowly added. In all reactions one tetrahedral SO4 anion, all with bond lengths and angles
white precipitates formed which were left in the mother liquor distributions characteristic for their respective configura-
overnight. As revealed by PXRD, in the case of ZnSO4 tions.[1,2,27–29] Individual [MgO5(H2O)] octahedra are con-
or ZnSeO4 + Na2TeO3, amorphous solids had formed, whereas densed by sharing two edges (O3···O5; O4···O4Ј; Ј denotes the
in the case of MgSO4 or MgSeO4 + Na2TeO3, a mixed symmetry-related counterpart) into zigzag chains running par-
sodium
magnesium
oxotellurate
with
composition allel to [001]. Individual chains are linked along [010] by shar-
Na2Mg(TeO3)2·3H2O was obtained as revealed by isotypism ing water molecules (O1) into undulating layers extending par-
with the hexagonal Na2M(TeO3)2·3H2O structures (M = Co, allel (100).
Zn).[13] The diffraction patterns of the precipitates showed
The tellurium atoms are situated between the chains and
broad peaks indicating a rather poor crystallinity of the materi- have a bridging function, with two atoms (O4, O4Ј) to one
als; refined lattice parameters[14] on the basis of the chain and O3 to the neighboring chain, thus forming a metal
Na2Co(TeO3)2·3H2O structure model[13] in space group P63/m oxotellurate(IV) layer 2ϱ[Mg2O3(H2O)(TeO3)]4–. The lone elec-
2–
are a = 9.415(2), c = 7.719(2) Å, and V = 592.5(3) Å3 at room tron pair of the trigonal-pyramidal TeO3 anion points in the
temperature. Reacting the obtained product in the mother opposite direction relative to the water molecule towards the
liquor under the same hydrothermal conditions as described in open space of this arrangement. Adjacent 2ϱ[Mg2O3(H2O)-
more detail above led to single phase formation of spiroffite- (TeO3)]4– layers are linked by the sulfur atoms along [100],
type Mg2Te3O8.[15]
whereby an individual sulfur atom shares two oxygen atoms
Attempts for crystal growth under hydrothermal conditions with one layer (O6, O6Ј) and one oxygen atom (O5) of the
in strong acidic media with excessive acid resulted in colorless other layer (Figure 1). Atom O2 completes the tetrahedral co-
solutions in all cases. After partial evaporation of these solu- ordination of the sulfur atom and is exclusively bonded to the
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latter. Its rather low bond valence sum of 1.46 valence units
The resulting 2ϱ[Mg3O3TeO3(OH)2(H2O)2]4– layers (Fig-
can be readily explained by its additional role as an acceptor ure 2) are connected along [001] by sulfur atoms. Three oxy-
of a rather strong hydrogen bond involving the water molecule gen bonding partners of the sulfur atom originate from the
[O···O distance: 2.5816(12) Å, OH···O angle: 162(3)°].
layers (two, O2, O2Ј, from one and one, O1, from the other
layer), the forth oxygen atom (O5) being solely bonded to the
sulfur atom (Figure 3). The displacement parameters of this
oxygen atom show no conspicuous features, making it highly
Figure 1. The crystal structure of Mg2(SO4)(TeO3)(H2O) in a projec-
tion along [001]. [MgO6] octahedra are turquoise, SO42– anions orange
2–
and TeO3 anions red. Displacement ellipsoids are drawn at the 90%
probability level.
Figure 2. The 2ϱ[Mg3O3TeO3(OH)2(H2O)2]4– layer in the crystal struc-
ture of Mg3(SO4)(TeO3)(OH)2(H2O)2 in a projection along [001]. Col-
our codes are as in Figure 1; oxygen atoms belonging to OH groups
are green, and those of water molecules (only the average position of
the disordered water molecule is shown) are lilac. Displacement ellip-
soids are drawn at the 97% probability level.
Mg3(SO4)(TeO3)(OH)2(H2O)2
Two Mg sites, one Te, one S, and nine O sites are present
in the asymmetric unit of Mg3(SO4)(TeO3)(OH)2(H2O)2 that
crystallizes with four formula units in the space group Pnma.
Except one of the Mg sites, the disordered O sites belonging
to the water molecule and two O sites on general positions
(8d), all other sites are located on mirror planes (4c). Both
Mg2+ cations in this novel structure type exhibit a distorted
octahedral environment. Mg1 is bound to four O atoms and
two cis-disposed OH groups, whereas Mg2 is bound to two
oxygen atoms, two cis-disposed OH groups and two trans-
disposed water molecules, with Mg–O distances ranging from
2.038(4) to 2.199(10) Å. The [Mg1O4(OH)2] octahedra share
edges O1···O4 and OH1···OH2 to make up infinite chains ex-
tending along [010]. These chains are bridged by
[Mg2O2(OH)2(H2O)2] octahedra through corner-sharing of
O2H and edge-sharing of O3···O1H and their symmetry-re-
lated counterparts, giving rise to a fused system of six-mem-
bered rings. The rings are organized into a corrugated layer
extending parallel (001), whereby each of the two OH groups
(O1H, O2H) is bonded to three Mg2+ cations, the correspond-
ing bond lengths being the shortest of the two octahedra. The
open space of the ring system is occupied above and below
the ring plane by tellurium atoms, which are bonded to three
oxygen atoms of the ring in the shape of slightly distorted
trigonal prisms. The positions of the tellurium atoms alternate
(along [100]) in an up and down mode, with the lone electron
pair pointing away from the layer.
Figure 3. The crystal structure of Mg3(SO4)(TeO3)(OH)2(H2O)2 in a
projection along [010]. Color codes are as in Figure 1 and Figure 2.
Displacement ellipsoids are drawn at the 97% probability level.
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probable that it is hydrogen-bonded to the disordered water (Figure 4) that can be rationalized as being composed of sheets
stacked along [001]. The first sheet comprises of alternately
assembled rows of [ZnO6] octahedra and SeO4 anions (Fig-
ure 5a); the second sheet is made up from likewise alternating
molecules at medium strengths (OW···O5 distances: 2.74–
2.82 Å), in agreement with the rather low bond valence
parameter of 1.53 v.u. for O5. Other interpolyhedral O···O dis-
tances (Table 2) involving the OH groups and water molecules
both as donor and acceptor atoms as well as framework oxygen
atoms (O3, O4) as acceptor atoms point to a rather complex
hydrogen-bonding network of medium to weak strengths
(O···O distances between 2.7 and 3.0 Å). The various possibil-
ities for hydrogen bonding interactions deem it possible that
the hydrogen atoms are disordered over several sites which
might be the reason why a reliable localization of hydrogen
atoms was not possible from difference maps on the basis of
the current diffraction data.
2–
Zn2(SeO4)(TeO3)
Zn2(SeO4)(TeO3) crystallizes with Z = 2 in the polar space
group P21 and is isotypic with Zn2(MoO4)(TeO3) and
Zn2(MoO4)(SeO3).[4] All atoms are located on general posi-
tions. Zn1 is tetrahedrally coordinated and Zn2 octahedrally,
Figure 4. The crystal structure of Zn2(SeO4)(TeO3) in a projection
both coordination polyhedra being considerably distorted. Zn1 along [100]. [ZnO6] octahedra are turquoise, [ZnO4] tetrahedra light-
2–
2–
blue, SeO4 anions orange, and TeO3 anions red. Displacement el-
lipsoids are drawn at the 74% probability level.
shows three similar Zn–O bond lengths of about 1.94 Å and
one longer bond of 2.07 Å, with angles ranging from 93–123°;
Zn2 has three similar short Zn–O bonds (2.04 Å), two interme-
diate bonds (2.11–2.17 Å), and one long bond (2.40 Å). The
O–Zn–O angles range from 74–118° for cisoid and from 146–
163° for transoid bonds. The [Zn2O6] octahedron shows a
higher distortion than the two corresponding polyhedra in the
isotypic Zn2(MoO4)(SeO3) and Zn2(MoO4)(SeO3) struc-
tures,[4] where the bond lengths range from 1.986(3)–2.227(3)
and 2.016–2.155(5) Å, respectively. The angular distortions of
2–
the SeO4 anion are small (range 107–112°) and all Se–O
bonds are very similar, with the mean value of 1.642 Å in very
good agreement with literature data.[29]
The tellurium(IV) atom can be described as [3+1] coordi-
nated, with three short bonds around 1.88 Å (trigonal-pyrami-
dal configuration) and one considerably longer bond around
2.53 Å (bisphenoidal configuration). Whereas a consideration
of the long Te–O bond has no high relevance for the tel-
lurium(IV) atom itself (the bond valence sum increases from
3.93 v.u. considering only the three short bonds to 4.16 v.u. if
the long bond is also taken into account), it appears to be im-
portant for the remote O2 atom. This atom shows the longest
Se–O bond and is also bonded to the Zn2+ cation at the longest
distance. Hence the contributions of the long Zn–O and
Te–O bonds, equivalent to 0.15 v.u. and 0.23 v.u., respectively,
cannot be ignored and participate to the saturation of
this oxygen atom. However, for the following description
2–
Figure 5. The sheets in the crystal structure of Zn2(SeO4)(TeO3),
viewed in a projection along [103]. Color code and displacement ellip-
soids are as in Figure 4. (a) The sheet composed of [ZnO6] polyhedra
the trigonal-pyramidal configuration for the TeO3 anion is
used.
In the crystal structure the principal building units are linked
through common corners into a three-dimensional framework TeO3 anions.
2–
and SeO4 anions; (b) the sheet composed of [ZnO4] polyhedra and
2–
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2–
rows of [ZnO4] tetrahedra and TeO3 anions, whereby the
lone electron pairs of the tellurium(IV) atoms are alternately
oriented in an up and down fashion for every row, pointing
towards the empty space (Figure 5b). The two types of sheets
are linked by edge- and corner-sharing of individual polyhedra
2–
2–
with TeO3 and SeO4 anions remaining isolated from each
other.
Zn4(SO4)(TeO3)3
All sites (four Zn, one S, three Te, and 13 O) in this centro-
symmetric structure (Z = 4, P21/c) are located on general posi-
tions of this novel structure type. Just like in the Zn2(SeO4)-
(TeO3) structure, the Zn2+ cations display different coordina-
tion numbers, with two of them (Zn1, Zn3) in octahedral and
two (Zn2, Zn4) in tetrahedral coordination. The octahedral co-
ordination spheres are considerably distorted, showing two no-
ticeable longer bonds for Zn1 [2.207(2) and 2.325(3) Å] and
one longer bond for Zn3 [2.465(3) Å], while both tetrahedral
coordination spheres display a rather uniform bond lengths dis-
tribution between 1.945(3) and 2.007(3) Å for Zn2 and
1.962(2) and 1.997(3) Å for Zn4. The SO42– tetrahedron shows
only minute deviations from ideal values and has typical bond
lengths and angles (bond lengths range 1.469(3)–1.484(3) Å;
angular range 107.50(17)–110.99(15)°]. The coordination
numbers of the three tellurium(IV) atoms are [3+1] for Te1
and Te2, and [3] for Te3. Again, like in the Zn2(SeO4)(TeO3)
structure described above, three oxygen atoms are bonded at
short distances around 1.88 Å in the shape of a trigonal pyra-
mid, and the remotely bonded oxygen atoms lead to a higher
saturation of the bond valence for the coordination partners. In
this regard O6, bonded to Te1 at 2.587(2) Å, and O13, bonded
at Te2 at 2.347(3) Å, increase the bond valence sum by 0.19
and 0.37 v.u., respectively, resulting in overall distorted bis-
phenoidal coordination environments. For clarity, the follow-
ing crystal structure description is solely based on trigonal-
Figure 6. The crystal structure of Zn4(SO4)(TeO3)3 in a projection
along [010]. Color codes as in Figure 4 with SO4 anions in yellow.
Displacement ellipsoids are drawn at the 97% probability level.
2–
Conclusions
Low yields and multi-phase formation during hydrothermal
synthesis prevented further examination of physical properties
for Mg2(SO4)(TeO3)(H2O), Mg3(SO4)(TeO3)(OH)2(H2O)2, and
Zn2(SeO4)(TeO3). Zn4(SO4)(TeO3)3 could be obtained as a sin-
gle phase and is stable up to 860 °C as revealed by thermogra-
vimetry. From the four compounds, only Zn2(SeO4)(TeO3)
crystallizes in a non-centrosymmetric space group. Optimiza-
tion of the hydrothermal reaction conditions for preparation of
single phase material requires adjustment of variable interde-
pendent parameters (educt materials, filling degree, pH, tem-
perature, duration etc.) and is currently in progress. This in-
cludes also studies whether other divalent first row transition
metals (Mn, Fe, Co, Ni, Cu) form new oxotellurate(IV) oxoch-
alcogenate(VI) double salts under similar conditions.
2–
pyramidal TeO3 coordination polyhedra.
Another similarity with the Zn2(SeO4)(TeO3) structure per-
tains to the connection of the principal building units, viz.
2–
2–
[ZnO6] and [ZnO4] polyhedra, TeO3 and XO4 anions (here
X = S), into a framework structure. [ZnO6] and [ZnO4] polyhe-
dra share corners, resulting in the formation of sheets ex-
Acknowledgements
The X-ray centre of the Vienna University of Technology is acknowl-
edged for providing access to the powder and single-crystal dif-
fractometers.
¯
tending parallel (201). Adjacent sheets are connected along
2–
2–
[001] through corner-sharing with the SO4 and the Te3O3
anions. The two remaining tellurium atoms bridge the zinc ox-
ide sheets in such a way that the lone electron pairs point away
from the mean plane of the sheet, and the apices of all three
Keywords: Crystal engineering; Hydrothermal synthesis;
Oxotellurates(IV); Magnesium; Zinc; Mixed oxochalcogen-
ates; Crystal structure
2–
TeO3 anions are oriented towards the empty space of the
framework. Likewise for all other structures, a condensation
2–
of the oxochalcogenate anions is not observed, and the TeO3
2–
and SO4 anions again remain isolated in the structure (Fig-
ure 6).
References
A thermogravimetric measurement (see Figure S2, Support-
ing Information) revealed this phase to be stable up to 860 °C
(onset). The decomposition is accompanied with a constant
mass loss up to 1000 °C (end of measurement). The final prod-
uct of this heat treatment was a glass.
[1] A. G. Christy, S. J. Mills, A. R. Kampf, Mineral. Mag. 2016, 80,
415–545.
[2] J. Zemann, Monatsh. Chem. 1971, 102, 1209–1216.
[3] J. Galy, J. Meunier, S. Andersson, A. Åström, J. Solid State
Chem. 1975, 13, 142–159.
Z. Anorg. Allg. Chem. 0000, 0–0
www.zaac.wiley-vch.de
7
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Journal of Inorganic and General Chemistry
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
[4] S. D. Nguyen, S.-H. Kim, P. S. Halasyamani, Inorg. Chem. 2011,
[18] L. Falck, O. Lindqvist, Acta Crystallogr., Sect. B 1978, 34, 3145–
3146.
50, 5215–5222.
[19] G. Giester, M. Wildner, Neues Jahrb. Mineral. Monatsh. 1992,
[5] M. Weil, M. Shirkhanlou, Z. Anorg. Allg. Chem. 2015, 641, 1459–
1466.
135–144.
[20] M. Weil, Acta Crystallogr., Sect. E 2005, 61, i237-i239.
[21] K. D. Keefer, M. F. Hochella Jr., B. H. W. S. de Jong, Acta
Crystallogr., Sect. B 1981, 37, 1003–1006.
[22] F. Kubel, M. Cabaret-Lampin, Z. Anorg. Allg. Chem. 2013, 639,
1782–1786.
[23] C. R. Feger, G. L. Schimek, J. W. Kolis, J. Solid State Chem.
1999, 143, 246–253.
[24] O. Lindqvist, Acta Chem. Scand. 1968, 22, 977–982.
[25] L. Weber, Z. Kristallogr. 1923, 58, 398–403.
[26] Y.-Y. Tang, Z.-Z. He, W.-B. Guo, S.-Y. Zhang, M. Yang, Inorg.
Chem. 2014, 53, 5862–5868.
[6] M. Weil, M. Shirkhanlou, Z. Anorg. Allg. Chem. 2017, 643, 330–
339.
[7] M. Weil, M. Shirkhanlou, Z. Anorg. Allg. Chem. 2017, 643, pub-
lished online, DOI:10.1002/zaac.201700016.
[8] APEX2, SMART, SAINT and SADABS, Bruker and AXS Inc.,
Madison, WI, USA, 2007.
[9] G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
[10] N. E. Brese, M. O’Keeffe, Acta Crystallogr., Sect. B 1991, 47,
192.
[11] I. D. Brown, The Chemical Bond in Inorganic Chemistry: The
Bond Valence Model, Oxford University Press, Oxford, 2002.
[12] E. Dowty, ATOMS for Windows, Shape Software, Kingsport, TN,
USA, 2006.
[13] R. Miletich, Monatsh. Chem. 1995, 126, 417–430.
[14] Topas, Version 4.2, Bruker AXS GmbH, Karlsruhe, Germany,
2009.
[15] W.-F. Lin, Q.-J. Xing, J. Ma, J.-P. Zou, S.-L. Lei, X.-B. Luo, G.-
C. Guo, Z. Anorg. Allg. Chem. 2013, 639, 31–34.
[16] H. Mayer, G. Pupp, Monatsh. Chem. 1976, 107, 721–730.
[17] M. Wildner, G. Giester, Neues Jahrb. Mineral. Monatsh. 1991,
296–306.
[27] O. C. Gagné, F. C. Hawthorne, Acta Crystallogr., Sect. B 2016,
72, 602–625.
[28] F. C. Hawthorne, S. V. Krivovichev, P. C. Burns, Rev. Mineral.
Geochem. 2000, 40, 1–112.
[29] M. S. Wickleder, C. Logemann, Compounds Containing the
Chalcogen Oxygen E–O Bond (E = S, Se, Te), in: Handbook on
Chalcogen Chemistry, 2nd ed. (Ed.: F. Devillanova), Royal
Society of Chemistry, London, 2013.
Received: January 18, 2017
Published Online: ᭿
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M. Weil,* M. Shirkhanlou ................................................. 1–9
Incorporation of Sulfate or Selenate Groups into Oxotel-
lurates(IV): III. Compounds with Magnesium or Zinc
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