Three-dimensional MOF-type architectures with tetravalent uranium hexanuclear motifs (U6O8)

Article abstract of DOI:10.1002/chem.201203914

Four metal-organic frameworks (MOF) with tetravalent uranium have been solvothermally synthesized by treating UCl₄ with rigid dicarboxylate linkers in N,N-dimethylfomamide (DMF). The use of the ditopic ligands 4,4′-biphenyldicarboxylate (1), 2,6-naphthalenedicarboxylate (2), terephthalate (3), and fumarate (4) resulted in the formation of three-dimensional networks based on the hexanuclear uranium-centered motif [U₆O₄(OH)₄(H₂O)₆]. This motif corresponds to an octahedral configuration of uranium nodes and is also known for thorium in crystalline solids. The atomic arrangement of this specific building unit with organic linkers is similar to that found in the zirconium-based porous compounds of the UiO-66/67 series. The structure of [U₆O₄(OH)₄(H₂O)₆(L) ₆]·X (L=dicarboxylate ligand; X=DMF) shows the inorganic hexamers connected in a face-centered cubic manner through the ditopic linkers to build up a three-dimensional framework that delimits octahedral (from 5.4A for 4 up to 14.0A for 1) and tetrahedral cavities. The four compounds have been characterized by using single-crystal X-ray diffraction analysis (or powder diffraction analysis for 4). The tetravalent state of uranium has been examined by using XPS and solid-state UV/Vis analyses. The measurement of the Brunauer-Emmett-Teller surface area indicated very low values (Langmuir <300 m² g^-1 for 1, <7 m² g^-1 for 2-4) and showed that the structures are quite unstable upon removal of the encapsulated DMF solvent. Copyright

Full text of DOI:10.1002/chem.201203914

DOI: 10.1002/chem.201203914
Three-Dimensional MOF-Type Architectures with Tetravalent Uranium
Hexanuclear Motifs (U O )
6
8
Clꢀment Falaise, Christophe Volkringer, Jean-FranÅois Vigier, Natacha Henry,
[
a]
Arnaud Beaurain, and Thierry Loiseau*
Abstract: Four metal–organic frame-
works (MOF) with tetravalent uranium
have been solvothermally synthesized
building unit with organic linkers is
similar to that found in the zirconium-
based porous compounds of the UiO-
66/67 series. The structure of
octahedral (from 5.4 ꢂ for 4 up to
14.0 ꢂ for 1) and tetrahedral cavities.
The four compounds have been charac-
terized by using single-crystal X-ray
diffraction analysis (or powder diffrac-
tion analysis for 4). The tetravalent
state of uranium has been examined by
using XPS and solid-state UV/Vis anal-
yses. The measurement of the Bru-
by treating UCl with rigid dicarboxACTHUNGTRENNNUG
4
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[U O (OH)4 ACHTUGNETRNUNG( H O) (L) ]·X (L=dicar-
6 4 2 6 6
(
4
boxylate ligand; X=DMF) shows the
inorganic hexamers connected in a
face-centered cubic manner through
the ditopic linkers to build up a three-
dimensional framework that delimits
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
ACHTUNGTRENNUNG
ed in the formation of three-dimen-
sional networks based on the hexa-
ACHTUNGTRENNUNG
2
ꢀ1
2
ꢀ1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
nuclear
uranium-centered
motif
<300 m g for 1, <7 m g for 2–4)
and showed that the structures are
quite unstable upon removal of the en-
capsulated DMF solvent.
Keywords: dicarboxylic acids
·
·
·
[
U O (OH) ACHTUNGTRENNUNG
(H O) ]. This motif corre-
6
4
4
2
6
A
H
U
G
R
N
U
G
frameworks
spectroscopy
sponds to an octahedral configuration
of uranium nodes and is also known
for thorium in crystalline solids. The
atomic arrangement of this specific
solvothermal synthesis · uranium ·
X-ray diffraction
Introduction
this context, the crystallization and isolation of oxalate ura-
nium(IV) phases have been examined and are known to
lead to different compositions that also incorporate hetero
The chemistry of actinide metals is very rich and exhibits di-
verse crystalline atomic arrangements of molecular species
or infinite extended networks partly driven by the wide
range of oxidation states (from 3+ up to 7+). One of the
most studied elements is uranium because of its use as a
fuel in nuclear industry. Although the hexavalent form
[2]
elements. More generally, the reactivity of carboxylates
with hexavalent uranium has been very well explored. Over
the last decade, a large number of contributions have been
reported structural descriptions of the so-called uranyl–or-
[3]
ganic frameworks (UOFs), which follow the idea devel-
oped for the generation of metal–organic frameworks
2
+
(
uranyl cation, [UO2] ) is the most stable oxidation state
[4]
under ambient conditions and is encountered in most natu-
ral minerals, nuclear reactors commonly use ceramic urani-
um dioxide, UO , which corresponds to the tetravalent
form. Considering the chemical processing for separation
and purification of uranium from spent nuclear fuel, the ox-
alate route has been intensively investigated, which gave
rise to dedicated studies of the interactions of this particular
ditopic ligand with tetravalent uranium in nitric solution. In
(MOFs). In this area, the strategy relies on the choice of
aliphatic or aromatic carboxylate ligands, which may have
multidentate O-donor (and N-donor) functions that chelate
or/and bridge the uranyl cations to form extended coordina-
tion polymers with different dimensionalities (1D, 2D, or
3D). In contrast, available structural data for tetravalent
uranium in association with carboxylate ligands (other than
oxalates) are quite rare, which is partly due to the difficulty
of stabilizing the low valent states of uranium in an ambient
air atmosphere. The synthesis of uranium(IV) carboxylates
[1]
2
[
a] C. Falaise, Dr. C. Volkringer, Dr. J.-F. Vigier, Dr. N. Henry,
Dr. A. Beaurain, Dr. T. Loiseau
Unitꢀ de Catalyse et Chimie du Solide (UCCS)
UMR CNRS 8181, Universitꢀ de Lille Nord de France
USTL-ENSCL, Bat C7, BP 90108
[5]
was first reported in the 1960s, but this research domain
has been renewed quite recently with the identification of
discrete molecular oxo/hydroxo polynuclear entities in
[6]
which the numbers of uranium centers vary from 1 to 16.
5
9652 Villeneuve dꢁAscq (France)
The role of the water content in the organic solvent medium
was found to be crucial for the hydrolysis rate of the con-
densation process, leading to the formation of molecular as-
semblies of large and well-defined polymeric species
Fax : (+33)320-43-48-95
E-mail: thierry.loiseau@ensc-lille.fr
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201203914.
5324
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 5324 – 5331

FULL PAPER
[
6c,d,7]
[6e]
[7]
[6e]
U6,
U , U , or U16. In these different examples,
10 12
the polyoxo clusters are stabilized by peripheral monoden-
tate ligands, such as formate, triflate, or benzoate groups. To
design frameworks based on interconnected uranium-based
motifs, we initiated investigations using polydentate carbox-
ylate linkers, such as the trimesate group. With this particu-
lar molecule, we recently reported the first three-dimension-
al framework based on uranium(IV) cations, which interact
with these tritopic molecules to generate a channel-like
[8]
open structure.
Herein, we systematically explore the solvothermal reac-
tivity of linear ditopic molecules, such as terephthalate, 2,6-
naphthalendicarboxylate, 4,4’-biphenyldicarboxylate, and fu-
marate, with low valent uranium(IV) cations in N,N-di
ylformamide solvent. Four compounds with uranium(IV)
that are closely related to the zirconium-based porous coor-
ACHTUNGTNERNUNGm eth-
ACHTUNGTRENNUNG
[9]
dination polymers of UiO-66 have thus been prepared and
structurally characterized. Spectroscopic analyses (XPS, UV/
Vis) and estimations of surface area have been carried out.
Results and Discussion
Figure 1. Top: Coordination environment around the tetravalent uranium
cation (central atom), defining a monocapped square anti-prism polyhe-
Four MOF-type compounds 1–4 of tetravalent uranium with
aromatic dicarboxylate linkers 4,4’-biphenyldicarboxylate
6
4A
of the hexanuclear uranium-centered core. One illustration of the atomic
labels is given for the ninefold coordinated uranium in [U (OH)
(H O) (L) ] (L=4,4’-bpdc, 1). Each uranium center is located at the
corner of an octahedral polyhedron. O1 is the m -oxo or m -hydroxo
group. O3 is a carboxyl oxygen. O2 is a terminal water molecule.
3 3 2 2 6
dron [U O CHTUGNTRENNNG(U m -O)2 ACHTUNGTERNNUG( m -OH) ACTHNUGRTNENU(G H O) ]. Bottom: Polyhedral representation
(
4,4’-bpdc; 1), 2,6-naphthalenedicarboxylate (2,6-ndc; 2),
,4-benzenedicarboxylate (1,4-bdc; 3), or fumarate (fum; 4)
have been isolated. They have been obtained by solvother-
mal treatment of uranium chloride (UCl ) with ditopic acids
6
O
4
4
-
1
A
H
U
G
R
N
N
2
6
6
3
3
4
(
HO C-R-CO H, R=benzene, biphenyl, naphthalene, or
2 2
HC=CH groups) in N,N-dimethylformamide together with a
controlled amount of water (30 mL; 1.67 mmol). These
phases exhibit a three-dimensional atomic arrangement that
consists of the same hexanuclear uranium-centered building
blocks connected to each other by the ditopic organic car-
boxylates and corresponding to a chemical composition
one square plane and are linked to three uranium atoms,
which gives rise to an edge-sharing connection mode be-
tween the UO polyhedra. Regarding the electroneutrality
9
of the structure, half of the oxygen atoms are m -oxo groups
3
and half are m -hydroxo groups. Four other oxygen atoms
3
[
U O (OH)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(H O) (L) ]·X (L=4,4’-bpdc, 1,4-bdc, 2,6-ndc,
are located at each corner of the second square plane of the
anti prism and belong to the carboxylate arms of the organic
molecules (UꢀO3 2.318(11) ꢂ for 1; UꢀO11,12 2.382(7)–
86(8) ꢂ for 2; UꢀO11 2.367(6) ꢂ for 3). The remaining
6
4
4
2
6
6
or fum; X=solvent). The resulting frameworks are similar
to those found for tetravalent zirconium UiO-66 (with 1,4-
bdc), UiO-67 (with 4,4’-bpdc), or with fumarate.
structures of compounds 1–3 have been determined from
single-crystal XRD analysis, whereas the cell parameters
and structural model of 4 were obtained from the powder
XRD pattern data due to the small size of the crystallites.
All the compounds crystallize in a cubic cell with a=
[9]
[10]
The
oxygen atom is in a terminal position and is assigned to a
water molecule that caps one square plane of the anti-prism
(UꢀOw 2.70(4) ꢂ for 1; UꢀOw 2.6705(11) ꢂ for 2; UꢀOw
2.657(17) ꢂ for 3). This super-octahedral building block has
been reported for tetravalent uranium several times in the
[11]
[12]
2
7.4526(9) ꢂ for 1, a=24.5681(1) ꢂ for 2, a=21.5151(11) ꢂ
literature. First described with sulfates or phosphonates,
for 3, and a=18.75518(8) ꢂ for 4, but different space groups
were observed for each because the locations of the dicar-
boxylate linker induce some lower symmetries, as previously
reported in the literature. The crystal structures are built
from six uranium cations lying in one crystallographically in-
dependent site in 1–3 and two sites in 4. These cations are
coordinated to nine oxo, hydroxo, or aquo groups, which
it was then encountered in different coordination complexes
as discrete entities involving organic ligands, such as trif-
[7,13]
[6c]
[6d]
A
H
U
G
R
N
U
late,
formate,
or benzoate
molecules. Due to the
[10]
¯
high symmetry of the cubic framework (Fm3m for 1 and 3
or derived space groups F23 for 2 and P23 for 4), distin-
guishing the m -O or m -OH ligands from the UꢀO bonds is
3
3
rather difficult (by XRD analysis) because only average Uꢀ
O or UꢀOH lengths are observed. In 1 and 3 (from single-
define
Figure 1). The uranium centers are located in such a way
that they occupy each corner of an ideal octahedral core
O point symmetry). Four of the oxygen atoms belong to
a monocapped square anti-prismatic geometry
(
crystal structure determination), the Uꢀ
ACHTUNGTNERNGNU( m -O) bonds are
3
2.332(12) ꢂ for 1 and 2.314(9) ꢂ for 3, which correspond to
an average value between the UꢀOH bond (2.40–
(
h
Chem. Eur. J. 2013, 19, 5324 – 5331
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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5325

T. Loiseau et al.
[
6c,d]
[6c,d,7,13]
[14]
2
.50 ꢂ)
and the UꢀO bond (2.20–2.27 ꢂ)
previ-
in the literature. Solid-state UV/Vis spectra (Figure 2, Fig-
ure S9 in the Supporting Information) of the different sam-
ples show a broad signal in the range of l=600 to 700 nm,
ously observed for hexanuclear blocks that have been de-
scribed in lower symmetry. Indeed, in the highly symmetri-
cal uranium sulfate, the average value for the UꢀO,OH
bond is 2.367 ꢂ. In compounds 1 and 3, the O or OH spe-
cies are delocalized on the m nodes because they are struc-
[
11]
3
3
3
1
3
1
which was assigned to the H ! P , H ! G , and H ! D
4
0
4
4
4
2
transitions and also characterizes the tetravalent state of
[15]
uranium.
These hexanuclear [U O (OH) ACHTGNUTRNEUNG( H O) ] cores are connect-
4 2 6
3
turally equivalent. However, the structure of 2 is described
with a distinct space group (F23) and two sets of contrasted
UꢀO bond lengths are observed with values of 2.225(6) or
6
4
ed to each other through twelve ditopic ligands, which act as
syn–syn bidentate bridging linkers with four uranium cen-
ters. The aromatic ring of the dicarboxylate linkers is found
to be statistically disordered over two equivalent positions
for compounds 1 and 2 (see Figure S4 in the Supporting In-
formation). This situation did not change when the XRD in-
tensity was measured at low temperature (100 K for 1). This
bidentate connection results in a face-centered cubic lattice
of hexamers and generates a three-dimensional system of
2
.390(6) ꢂ, which would indicate the occurrence of m -oxo
3
and m -hydroxo groups, respectively. Such a discussion com-
3
paring the UꢀO bonds in compound 4 is quite delicate be-
cause the powder XRD data (from a conventional source)
are not accurate enough for a proper interpretation. The ox-
idation state of uranium, which may be questionable in this
[6e,7]
type of coordination compound,
has been analyzed by
X-ray photoelectron spectroscopy (XPS) analysis (Figure 2,
cavities delimited by [U O (OH) ACHNUTGTRNNEG(U H O) ] nodes with octahe-
6 4 4 2 6
dral and tetrahedral symmetries (Figure 3). Within the cubic
cell, the arrangement of these two geometrical types of
voids is identical to that observed in the dense archetypal
phases of NaCl (rock salt) or ZnS (blende) with fcc packing.
This type of connection was illustrated by zirconium in a
series of isoreticular porous coordination polymers built on
the closely related Zr O (OH) clusters linked through dif-
6
4
4
Figure 2. Top: XPS spectrum and bottom: UV/Vis spectrum of
[
6 4 4 2 6 6
U O (OH) ACHTUNGTRENNUNG( H O) (4,4’-bpdc) ]·14DMF (1).
Figure S8 in the Supporting Information). The U4f XPS
spectra shows two sets of binding energies in the range of
Figure 3. Representation of the connection of the hexameric [U
6 4 3
O ACHTUNGTRENNUNG( m -
O)2(m -OH) (H O) ] building units that generate a cubic arrangement
A
H
U
G
R
N
U
G
3
2
ACHTUNGTRENNUNG
2
6
3
80.2 to 380.7 and 391.1 to 391.6 eV, which correspond to
(face-centered cubic or fcc) delimiting octahedral cavities (light gray
sphere) and tetrahedral cavities (dark gray sphere). This type of topology
was previously referred to as UiO-67 (with 4,4’-bpdc) or UiO-66 (with
the U4f7/2 and U4f5/2 components, respectively. These bind-
ing energy values and their satellite shifts (+6.4—6.8 eV)
are similar to those observed in uranium(IV) trimesate or
other tetravalent uranium compounds previously reported
1
,4-bdc) with zirconium. The structure of compound 1 (with 4,4’-bpdc) is
[8]
presented here and disordering of the benzene ring of the organic ligand
is not shown for clarity.
5326
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ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 5324 – 5331

Tetravalent Uranium Hexanuclear Motifs
FULL PAPER
Figure 4. Top: SEM images of compounds [U
Bottom: Evolution of the size of the octahedral cavity in the series [U
bdc (3), and fum (4).
6
O
4
(OH)
4
A
T
N
T
E
U
(H
2
O)
6
(L)
6
]·xDMF; scale bars: 2 mm, 10 mm, 40 mm, 50 mm for 1, 2, 3, and 4, respectively.
O (OH) ACHTUTGNERNNNUG( H O) (L) ]·xDMF; from left to right: L=4,4’-bpdc (1), 2,6-ndc (2), 1,4-
6 4 4 2 6 6
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
ferent linear ditopic ligands, such as terephthalate (UiO-
nation polymers that form extended networks through the
use of ditopic ligands is quite new because only discrete mo-
[
9,16]
[9,17]
6
6),
4,4’-biphenyldicarboxylate (UiO-67),
terphenyl-
[9]
[18]
dicarboxylate (UiO-68), and their NH -derived ligands
azobenzenedicarboxylate,
rate. For these different compounds, the size of the octa-
hedral and tetrahedral voids is directly correlated to the
length of the linear dicarboxylate molecules and can reach,
for example, a value of 25.6 ꢂ (octahedral pore) in UiO-
lecular species have been previously reported in the liter
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
a-
2
[19]
[17]
[6c,d,7,13]
trans-muconate,
or fuma-
ACHTUNGTNERNUNGt ure.
In fact, this situation exists in the first example
[10]
of [U O (OH) ] units linked to each other through [SO ]
6
4
11]
4
4
[
groups.
It represents a dense, purely inorganic uranium
sulfate, which was obtained by crystallization from aqueous
solvent. Considering this specific coordination chemistry
with tetravalent heavy metals, similar isolated molecular
hexanuclear clusters have been previously reported for crys-
[
18]
68.
The hexanuclear unit [Zr O (OH) ] was recently in-
6 4 4
volved in the construction of different topologies that offer
[20]
[21]
[22]
large cavity diameters. In our uranium-based compounds,
the estimated pore sizes of the octahedral voids (based on
an ionic radius of 1.35 ꢂ for oxygen) are 14.0, 11.1, 8.1, and
tal structures with zirconium, cerium, and also with tho-
rium. Thorium can be stabilized by monotopic carboxylate
linkers
by
forming
similar
discrete
hexanuclear
[
6c,23]
5.4 ꢂ for 1, 2, 3, and 4, respectively (Figure 4). The XRD
[Th O (OH) ] blocks.
Note that other polyoxo U cores
6
4
4
6
analysis did not reveal any clear evidence of the nature of
the encapsulated molecules within these cavities, but one
may assume the presence of trapped DMF molecules. From
the elemental chemical analyses, we found that the amount
of DMF species decreases with the size of cavities. Infrared
spectroscopy (see Figure S7 in the Supporting Information)
also confirms the presence of DMF, with a doublet at
have been identified with m -oxo connection configurations,
2
[24]
[25]
such as Lindqvist or ring-based clusters. Another illus-
tration of an actinide-based hexanuclear core has been re-
cently observed in solution for neptunium(IV) stabilized by
[26]
formate groups.
The different compounds were analyzed by thermogravi-
metric analysis (see Figure S5 in the Supporting Informa-
tion), which showed quite similar thermal behavior for 1–3.
Under an air atmosphere, a continuous weight loss was ob-
served from room temperature up to 4008C, followed by a
second event up to 4108C for 1 and 2 and up to 4308C for 3.
These two events could be successively assigned to the evac-
uation of the trapped DMF molecules and the degradation
of the organic linkers. Based on the final composition, U O ,
ꢀ1
around 2900 cm
(nO= ꢀH) and the vibration band at
C
ꢀ
1
1
656 cm (nC ). The broad band centered in the range of
O
=
ꢀ
1
3500 to 3300 cm is characteristic of hydrogen bonds be-
tween species such as bonded hydroxyl groups, water, or
trapped DMF.
Moreover, the parent UiO-66-type structure containing
the 2,6-naphthalenedicarboxylate group (phase 2 in our
work) has not been isolated with zirconium up to now and
constitutes a new member of this topological series. For ura-
nium, the incorporation of such hexanuclear cores in coordi-
3
8
the observed remaining weight values are 44.7% (calcd:
40.8%) for phase 1, 43.1% (calcd: 43.2%) for phase 2, and
51.6% (calcd: 49.8%) for phase 3. The thermogravimetric
Chem. Eur. J. 2013, 19, 5324 – 5331
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5327

T. Loiseau et al.
curve of compound 4 is slightly different because a first
weight loss (5.6%) was observed up to 808C, followed by a
plateau up to 2008C. This could correspond to the departure
of approximately two encapsulated DMF molecules per
U O unit (calcd: 5.4%). Between 200 and 5008C, a quite
Indeed, this point was correlated to the tentative meas-
urements of porosity, which was estimated by performing a
gas sorption isotherm experiment in liquid nitrogen by using
a Micromeritics ASAP2010 apparatus. The removal of the
trapped species from the as-synthesized phases was found to
be quite delicate because washing with solvent (e.g., with
chloroform) was not a successful way to get materials with
empty pores. Thus, the nitrogen sorption experiment was
carried out on samples 1–4 (initially stored in a glovebox
under Ar) that were degassed at 808C overnight under pri-
mary vacuum. Only compound 1 revealed a type IV iso-
therm with a hysteresis upon desorption, which is character-
istic of a porous solid (Figure 5). The measured Brunauer–
6
8
slow and continuous weight loss was observed. The final re-
maining weight is 60.8% and agrees well with the theoreti-
cal value for U O (calcd: 62.5%).
3
8
The X-ray thermodiffraction experiment (Figure 5, Fig-
ure S6 in the Supporting Information) showed that the
Bragg peaks of the different phases are clearly visible up to
1208C for 1 and 2 and 1408C for 3 and 4. The thermal evo-
2
ꢀ1
Emmett–Teller (BET) surface area was 254(2) m g and,
assuming a monolayer coverage by nitrogen, the Langmuir
2
ꢀ1
surface area was 342(2) m g . For the other samples, the
BET surface area values were measured to be lower than
2
ꢀ1
7
m g and indicated the collapse of the three-dimensional
framework upon removal of the trapped species. These re-
sults are quite disappointing when considering the thermal
behavior and high BET surface values reported for the
parent zirconium UiO-66-type series. For instance, the Lang-
muir surface areas of Zr-UiO-66 (L=1,4-bdc) or Zr-UiO-67
[9,18]
2
ꢀ1 [9,18]
(
L=4,4’-bpdc) were 1187 to 1400
or 3000 m g ,
AHCTUNGTREGUNrNN espectively.
Conclusion
This contribution dealt with the second illustration of ex-
tended infinite networks that contain tetravalent uranium
cations linked to each other through carboxylate linkers.
The first example of such MOF-type connection was ob-
served with the isolation of one-dimensional channel frame-
works with trinuclear uranium-centered units linked by tri-
[8]
mesate ligand. Here, the use of rigid ditopic carboxylate
ligands that contained an aromatic ring (terephthalate, 2,6-
AHCTUNGTRENNUNG
naphathalenedicarboxylate, 4,4’-biphenyldicarboxylate) or
alkene group (fumarate) led to the formation of three-di-
mensional structures based on a hexanuclear [U O (OH) -
6
4
4
Figure 5. Top: X-ray thermodiffraction patterns (CuKa radiation, air at-
mosphere) and bottom: BET curve of [U (OH) (H O) (4,4’-
bpdc) ]·14DMF (1).
AHCTUNGTNERNU(G H O) ] motif with an octahedral configuration of uranium
2 6
6
O
4
4
A
H
U
G
R
N
U
G
2
6
centers. The arrangement of this specific building unit gener-
ates an open framework that delimits octahedral and tetra-
hedral cavities similar to those previously described for zir-
6
[9]
lution of the powder XRD patterns indicated a structural
transformation into amorphous phases for 2, 3, and 4,
whereas the broad Bragg peaks of the initial phase persisted
for phase 1. At higher temperature, crystallization of the
uranium oxide a-U O (pdf file: 47-1493) was observed, and
conium cations in the UiO-66 series of compounds. As ex-
pected, the size of the pores is correlated to the length of
the ligand, which may be as long as 14 ꢂ when using the
4,4’-biphenyldicarbylate molecule and as short as 5.4 ꢂ for
the fumarate molecule. However, the measured accessible
BET surface area values were very low compared with
those observed for the zirconium series and indicated the
difficulty of maintaining the integrity of the three-dimen-
sional framework upon removal of the trapped species in
the case of tetravalent uranium. Nevertheless, this work
opens the way to the formation of other compounds of
UiO-66 type that incorporate other tetravalent heavy atoms,
3
8
appeared at 360, 380, 400, and 4208C for compounds 1, 2, 3,
and 4, respectively. It was interesting to note that the tem-
perature value of U O crystallization increases when the
3
8
number of carbons from the linker decreases. From these
observations, it was surprising to note that compound 1
(
with the longest and also the most flexible ligand) is more
thermally stable than the other analogues of the UiO-66
parent series.
[6c,23]
[22]
such as thorium(IV)
or cerium(IV), for which identi-
5328
www.chemeurj.org
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 5324 – 5331

Tetravalent Uranium Hexanuclear Motifs
FULL PAPER
cal hexameric units with monocarboxylate ligands have al-
ready been encountered in crystalline molecular assemblies.
size of 10–50 mm (Figure S1 in the Supporting Information). Elemental
analysis calcd (%) for C78
7.9, N 3.7, H 3.0.
Compound 4: [U
solvothermal reaction in which a mixture of UCl
fum (0.030 g, 0.26 mmol), and H O (30 mL, 1.67 mmol) in DMF (4 mL,
1 mmol), heated at 1308C for 36 h. The resulting green powder was then
110 48 10 6
H O N U : C 27.7, N 4.1, H 3.2; found: C
2
6
O
4
(OH)
4
A
H
N
T
E
N
N
(H
2
O)
6
A
H
U
G
R
N
N
6
]·5DMF (4) was obtained by a
(0.1 g, 0.26 mmol),
4
Experimental Section
H
2
2
5
filtered off, washed with DMF, and dried at RT in an air atmosphere.
The product was stable in air for 4–5 d. Compound 4 was analyzed by
using a scanning electron microscope (Hitachi S-3400N) and shows typi-
cal octahedrally shaped crystals with a size of 5–30 mm (Figure S1 in the
Supporting Information). Elemental analysis calcd (%) for
4
Synthesis: Caution! Uranium chloride (UCl ) is a radioactive and chemi-
cally toxic reactant; suitable precautions, care, and protection for the
handling of such substances should be followed.
The starting chemical reactants were uranium tetrachloride (UCl
benzenedicarboxylate (C , 1,4-H bdc, Aldrich, 98%), 4,4’-biphenyl-
dicarboxylate (C14 , 4,4’-H bpdc, Aldrich, 97%), 2,6-naphthalendi-
carboxylic acid (C12 2,6-H ndc, Aldrich, 99%), fumaric acid
, H fum, Aldrich, 99%), and anhydrous N,N’-dimethylforma-
NO, DMF, Aldrich, 99.8%). The starting chemical reactants
except UCl ) are commercially available and were used without any fur-
ther purification. UCl was obtained by using the procedure described in
the literature (see the Supporting Information), by using uranium oxide
UO , Prolabo Rectapur) and hexachloropropene (Aldrich, 96%). All
4
), 1,4-
8
H
6
O
4
2
39 47 43 5 6
C H O N U : C 17.4, N 2.6, H 1.7; found: C 16.2, N 2.2, H 1.9.
H
10
O
4
2
Characterization: Crystals were selected and isolated from powdered
compounds 1–3 by using a polarizing optical microscope and glued on a
glass fiber for a single-crystal X-ray diffraction experiment. X-ray intensi-
ty data were collected at 100 K (for 1) or 293 K (for 2) by using a Bruker
X8-APEX2 CCD area-detector diffractometer with MoKa radiation (l=
0.71073 ꢂ) equipped with an optical fiber as collimator. Several sets of
narrow data frames (20 s per frame) were collected at different values of
q for two initial values of f and w, respectively, using 0.38 increments of
H
8
O
4
,
2
(
C
4
H
4
O
4
2
3 7
mide (C H
(
4
4
[
8]
(
3
the reactants were manipulated, weighed, and mixed in a 23 mL Teflon
cell under an Ar atmosphere in a glovebox. They were then placed in a
closed stainless steel PARR autoclave (type 4746), which was removed
from the glovebox and then heated in a conventional electrical oven.
[
27]
f or w. Data reduction was accomplished by using SAINT V7.53a. The
substantial redundancy in data allowed a semi-empirical absorption cor-
rection (SADABS V2.10) to be applied on the basis of multiple measure-
ments of equivalent reflections. The structure was solved by direct meth-
ods, developed by successive difference Fourier syntheses, and refined by
full-matrix least-squares on all F data by using the JANA2006 pro-
Compound 1: [U
by a solvothermal reaction in which a mixture of UCl
,4’-H bpdc (0.063 g, 0.26 mmol), and H O (30 mL, 1.67 mmol) in DMF
4 mL, 51 mmol) was heated at 1308C for 36 h. The resulting green
6
O
4
(OH)
4
A
H
U
G
E
N
N
(H
2
O)
6
(4,4’-bpdc)
6
]·14DMF (1) was obtained
4
(0.1 g, 0.26 mmol),
4
2
2
[
29]
gram. The carbon atoms of the benzene rings were refined in two posi-
tions due to statistical disorder. The crystal data are given in Table 1.
(
powder was then filtered off, washed with DMF, and dried at RT in an
air atmosphere. The product was stable in air for 1 d. Compound 1 was
analyzed by using a scanning electron microscope (Hitachi S-3400N) and
shows typical octahedrally shaped crystals with a size of 5–10 mm (see
Figure S1 in the Supporting Information). Elemental analysis calcd (%)
The pattern of compound 4 (fumarate analog of UiO-66) was scanned at
RT by using a Bruker D8 Advance A25 diffractometer with a Debye–
Scherrer geometry in the range 2q=5–1108 with a step length of 0.028
ꢀ
1
(2q) and a counting time of 3 sstep . The D8 system was equipped with
a LynxEye detector with CuKa1/a2 radiation. After data collection, the sta-
for C126
H
162
O
52
N
14
U
6
: C 36.6, N 4.7, H 3.9; found: C 36.8, N 4.4, H 4.2.
(OH) (H O) (2,6-
]·13DMF (2) was obtained by a
solvothermal reaction in which a mix-
ture of UCl (0.1 g, 0.26 mmol), 2,6-
ndc (0.057 g, 0.26 mmol), and H
30 mL, 1.67 mmol) in DMF (4 mL,
Compound 2: [U
ndc)
6
O
4
4
A
H
U
T
E
N
N
2
6
ACHTUNGTRENNUNG
Table 1. Crystal data and structure refinement for tetravalent uranium dicarboxylates.
6
1
2
3
4
4
formula
C
6090.1
100
168
O
76
U
12
C
106
O
38
U
6
C
68
H
24
O
38
U
6
C
54 38 6
O U
H
(
2
2
O
M
r
3309.3
293
2877.1
293
2684.8
293
T [K]
color
5
4
1 mmol) was heated at 1308C for
8 h. The resulting green powder was
green
green
0.10ꢄ0.08ꢄ0.07
cubic
green
green
–
cubic
P23
size [mm]
crystal system
space group
a [ꢂ]
0.18ꢄ0.16ꢄ0.09
cubic
0.10ꢄ0.09ꢄ0.06
cubic
then filtered off, washed with DMF,
and dried at RT in an air atmosphere.
The product was stable in air for 1 d.
Compound 2 was analyzed by using a
scanning electron microscope (Hitachi
S-3400N) and shows typical octahe-
drally shaped crystals with a size of
¯
¯
Fm3m
F23
Fm3m
27.4526(9)
20689.5(1)
2
24.5681(1)
14829.1(1)
4
21.5151(11)
9959.3(9)
4
18.7563(3)
6598.41(19)
4
3
V [ꢂ ]
Z
ꢀ
3
1
calcd [gcm
]
0.9773
4.717
1.4818
1.9182
2.7024
ꢀ
1
m [mm
]
6.589
9.793
–
1
0–50 mm (Figure S1 in the Supporting
Information). Elemental analysis calcd
%) for C111 : C 34.1, N
.7, H 3.7; found: C 35.1, N 4.9, H 3.6.
Compound 3: [U (OH) (H O) (1,4-
bdc) ]·10DMF (3) was obtained by a
solvothermal reaction in which a mix-
ture of UCl (0.1 g, 0.26 mmol), 1,4-
bdc (0.043 g, 0.26 mmol), and H
30 mL, 1.67 mmol) in DMF (4 mL,
f range [8]
limiting indices
1.48–23.49
ꢀ29ꢁhꢁ29
1.66–31.74
ꢀ36ꢁhꢁ36
ꢀ36ꢁkꢁ30
ꢀ28ꢁlꢁ36
50459
1.64–30.5
ꢀ30ꢁhꢁ30
ꢀ14ꢁkꢁ30
ꢀ30ꢁlꢁ18
24013
5.123–109.996
–
(
4
143 51 13 6
H O N U
ꢀ
ꢀ
29ꢁkꢁ29
29ꢁlꢁ29
6
O
4
4
A
H
U
T
E
N
N
2
6
ACHTUNGTRENNUNG
collected reflns
unique reflns
parameters
34981
–
6
750 [Rint =0.0639]
4236 [Rint =0.0417]
71
3.51
826 [Rint =0.0799]
37
2.24
3312
179
–
22
4.34
R
4
2
GOF on F
H
(
2
2
O
Final R indices [I>2s(I)]
R indices (all data)
Largest diff. peak
1
=0.0582
wR =0.0724
=0.0805
wR =0.0734
R
1
=0.0592
wR =0.0739
=0.0896
wR =0.0752
R
1
=0.0318
wR =0.0412
=0.0413
wR =0.0417
–
2
2
2
5
4
1 mmol) was heated at 1208C for
8 h. The resulting green powder was
R
1
R
1
R
1
–
–
2
2
2
then filtered off, washed with DMF,
and dried at RT in an air atmosphere.
The product was stable in air for 2–
2.46, ꢀ1.71
4.09, ꢀ2.85
2.04, ꢀ1.23
ꢀ
3
and hole [eꢂ
]
R
WP
–
–
–
–
–
–
–
–
–
–
–
–
0.119
0.112
0.0617
0.0309
3
d. Compound
using a scanning electron microscope
Hitachi S-3400N) and shows typical
3 was analyzed by
R
R
R
P
Bragg
F
(
octahedrally shaped crystals with
a
Chem. Eur. J. 2013, 19, 5324 – 5331
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
5329

T. Loiseau et al.
bility of the X-ray source and sample was checked by recording the dif-
Acknowledgements
[
30]
fraction lines again at low angles. By using DICVOL06 software,
a
cubic cell with satisfactory figures of merit was found with cell parame-
ters of a=18.7543 ꢂ (obtained with the figures of merit M20 =92.0 and
The authors would like to thank the GNR MATINEX of PACEN inter-
disciplinary program and the French ANR project no. ANR-08-BLAN-
F
20 =167.5 (0.0025, 48)). From the analysis of the available powder data,
0
216-01 for financial support. The authors also thank Prof. Marc Vis-
systematic absences were found to be consistent with the space group
P23 (no. 195). Structure determination of 4 was carried out by using the
parallel tempering algorithm available in the global optimization pro-
seaux for help with the synthesis of UCl and Prof. Francis Abraham for
4
helpful discussions, Mrs. Nora Djelal and Laurence Burylo for their tech-
nical assistance with the SEM images, TG measurements, and powder
XRD (UCCS). The Fonds Europꢀen de Dꢀveloppement Rꢀgional
[
31]
gram FOX. A partial structure was found starting from a unit-cell con-
taining U SBU and six fumarate groups described as a rigid body. The
6
O
8
(
FEDER), the CNRS, the Rꢀgion Nord Pas-de-Calais, and the Ministꢅre
de l’Education Nationale de l’Enseignement Supꢀrieur et de la Re-
AHCTUNGERTGcNNUN herche are acknowledged for funding of the X-ray diffractometers. C.F.
model was completed by Fourier difference analyses. The residue in the
cavity was attributed to oxygen atoms. Rietveld refinements were ach-
[
32]
ieved by using FULLPROF. The distances within the fumarate group
were restrained to 1.30(2) ꢂ for C2(X)ꢀC2(X), 1.49(2) ꢂ for C1(X)ꢀ
C2(X), and 1.26(2) ꢂ for CꢀO within the carboxylate functions. Addi-
tionally, soft restrains of 2.67(2) ꢂ were also applied to UꢀOw. Final re-
acknowledges Universitꢀ Lille 1 and Rꢀgion Nord Pas-de-Calais for PhD
grant support.
finements involved the following parameters: atomic coordinates, iso-
tropic atomic displacement parameters, scale factor, zero-point, unit cell
parameters, three coefficients for the peak widths, and two line asymme-
try parameters. Crystallographic data and details of the Rietveld refine-
ments are given in Table 1. The final Rietveld plot (Figure S3 in the Sup-
porting Information) corresponds to satisfactory model indicators and
profile factors (see Table 1).
[
[
1] P. C. Burns, Can. Mineral. 2005, 43, 1839.
2] a) M. C. Favas, D. L. Kepert, J. M. Patrick, A. H. White, J. Chem.
Soc. Dalton Trans. 1983, 571; b) M. R. Spirlet, J. Rebizant, B. Kanel-
lakopulos, E. Dornberger, J. Less-Common Met. 1986, 122, 205;
c) K. P. Mçrtl, J.-P. Sutter, S. Golhen, L. Ouahab, O. Kahn, Inorg.
Chem. 2000, 39, 1626; d) I. Imaz, G. Bravic, J.-P. Sutter, Dalton
Trans. 2005, 2681; e) B. Chapelet-Arab, G. Nowogrocki, F. Abraham,
S. Grandjean, J. Solid State Chem. 2005, 178, 3046; f) B. Chapelet-
Arab, G. Nowogrocki, F. Abraham, S. Grandjean, J. Solid State
Chem. 2005, 178, 3055; g) B. Chapelet-Arab, L. Duvieubourg, G.
Nowogrocki, F. Abraham, S. Grandjean, J. Solid State Chem. 2006,
The thermogravimetric experiments were carried out by using a thermo-
ACHTUNGTRENNUNGa nalyzer TGA 92 SETARAM under air atmosphere with a heating rate
ꢀ
1
of 58Cmin from RT up to 8008C. X-ray thermodiffractometry was per-
ꢀ1
formed under an air flow of 5 Lh by using an Anton Paar HTK1200N
of a D8 Advance Bruker diffractometer (q–q mode, CuKa radiation)
equipped with a Vantec1 linear position sensitive detector (PSD). Each
powder pattern was recorded in the range of 5–608 (2q; at intervals of
1
79, 4029; h) B. Arab-Chapelet, S. Grandjean, G. Nowogrocki, F.
Abraham, J. Alloys Compd. 2007, 444–445, 387; i) B. Arab-Chapel-
et, S. Grandjean, G. Nowogrocki, F. Abraham, J. Nucl. Mater. 2008,
ꢀ
1
2
08C up to 8008C) with a 0.5 sstep scan, which corresponded to an ap-
proximate duration of 30 min. The temperature ramps between two pat-
3
73, 259; j) L. Duvieubourg-Garela, N. Vigier, F. Abraham, S.
ꢀ
1
terns were 0.088Cs up to 6008C.
Grandjean, J. Solid State Chem. 2008, 181, 2008; k) C.-M. Wang, C.-
H. Liao, P.-L. Chen, K.-H. Lii, Inorg. Chem. 2006, 45, 1436; l) C.-M.
Wang, Y.-Y. Wu, P.-L. Chen, K.-H. Lii, Dalton Trans. 2007, 1034;
m) N. Clavier, N. Hingant, M. Rivenet, S. Obbade, N. Dacheux, N.
Barrꢀ, F. Abraham, Inorg. Chem. 2010, 49, 1921; n) G. Andreev, N.
Budantseva, A. Fedoseev, P. Moisy, Inorg. Chem. 2011, 50, 11481.
The XPS spectrum was collected by using an Axis Ultra DLD (Kratos
Analytical) instrument equipped with
a monochromatic Al source
(
1486.69 eV) working at 10 mA and 15 kV with charge compensation.
Infrared analysis was carried out by using a Perkin–Elmer Spectrum 2 in-
strument equipped with a single reflection diamond module (ATR). IR
ꢀ
1
ꢀ1
spectra were recorded in the 400–4000 cm range with 4 cm resolution.
[3] a) J. Leciejewicz, N. W. Alcock, T. J. Kemp, Struct. Bonding (Berlin)
1
2
5
995, 82, 43; b) C. L. Cahill, D. T. de Lill, M. Frisch, CrystEngComm
007, 9, 15; c) K.-X. Wang, J.-S. Chen, Acc. Chem. Res. 2011, 44,
31; d) P. Thuꢀry, B. Masci, CrystEngComm 2012, 14, 131; e) I. Mi-
UV/Vis spectra were collected by using a Perkin–Elmer Lambda 650
spectrophotometer equipped with a powder sample holder set.
Crystallographic data
halcea, N. Henry, C. Volkringer, T. Loiseau, Cryst. Growth Des.
012, 12, 526.
¯
Data for 1:
C
84
O
38
U
6
;
M
r
=3045.1; space group Fm3m, cubic; a=
2
3
2
7.4526(9) ꢂ; V=20689.5(1) ꢂ ; T=100 K, Z=4;
m
A
H
U
G
R
N
N
(MoKa)=4.717;
[
4] Special issue on MOFs: Guest Editors: H.-C. Zhou, J. R. Long,
O. M. Yaghi, Chem. Rev. 2012, 112, 673.
5] a) R. C. Paul, J. S. Ghotra, M. S. Bains, J. Inorg. Nucl. Chem. 1965,
27, 265; b) I. Jelenic, D. Grdenic, A. Bezjak, Acta Crystallogr. 1964,
17, 758.
[6] a) Y.-J. Zhang, D. Collison, F. R. Livens, A. K. Powell, S. Wocadlo,
H. Eccles, Polyhedron 2000, 19, 1757; b) G. J. Vazquez, C. J. Dodge,
A. J. Francis, Inorg. Chem. 2009, 48, 9485; c) S. Takao, K. Takao, W.
Kraus, F. Emmerling, A. C. Scheinost, G. Bernhard, C. Hennig, Eur.
J. Inorg. Chem. 2009, 4771; d) V. Mougel, B. Biswas, J. Pꢀcaut, M.
Mazzanti, Chem. Commun. 2010, 46, 8648; e) B. Biswas, V. Mougel,
J. Pꢀcaut, M. Mazzanti, Angew. Chem. 2011, 123, 5863; Angew.
Chem. Int. Ed. 2011, 50, 5745; f) K. E. Knope, L. Soderholm, Chem.
Rev. 2013, 113, dx.doi.org/10.1021/cr300212f.
7] G. Nocton, F. Burdet, J. Pꢀcaut, M. Mazzanti, Angew. Chem. 2007,
1
8] C. Volkringer, I. Mihalcea, J.-F. Vigier, A. Beaurain, M. Visseaux, T.
Loiseau, Inorg. Chem. 2011, 50, 11865.
9] J. Hafizovic Cavka, S. Jakobsen, U. Olsbye, N. Guilou, C. Lamberti,
S. Bordiga, K. P. Lillerud, J. Am. Chem. Soc. 2008, 130, 13850.
3
R
4981 reflections measured, 750 independent reflections (Rint =0.0639);
=(I>2s(I))=0.0582, wR =0.0724; GOF=4.34.
Data for 2: =3309.3; space group F23, cubic; a=
1
2
[
106 38 6 r
C O U ; M
3
2
5
R
4.5681(1) ꢂ; V=14829.1(1) ꢂ ; T=293 K, Z=4;
0459 reflections measured, 4236 independent reflections (Rint =0.0417);
=(I>2s(I))=0.0592, wR =0.0739; GOF=3.51.
Data for 3: C68 ; M =2877.1; space group Fm3m, cubic; a=
1.5151(11) ꢂ; V=9959.3(9) ꢂ ; T=293 K, Z=4;
4013 reflections measured, 826 independent reflections (Rint =0.0799);
=(I>2s(I))=0.0318, wR =0.0412; GOF=2.24.
Data for 4: =2684.8; space group P23, cubic; a=
8.7563(3) ꢂ; V=6598.41(19) ꢂ ; T=293 K, Z=4; 3312 reflections
measured, RWP =0.119, R =0.112; RBragg =0.0617, R =0.0309.
m AHCTUNGTERNNNU(G MoKa)=6.589;
1
2
¯
H
24
O
24
U
6
r
3
2
2
R
m AHCTUNGTERNNNU(G MoKa)=9.793;
1
2
54 38 6 r
C O U ; M
3
1
P
F
[
[
[
CCDC-906871 (1), CCDC-906872 (2) and CCDC-906873 (3) contain the
supplementary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
19, 7718; Angew. Chem. Int. Ed. 2007, 46, 7574.
[
10] G. Wissmann, A. Schaate, S. Lilienthal, I. Bremer, A. M. Schneider,
P. Behrens, Mic. Mes. Mater. 2012, 152, 64.
[
[
11] G. Lundgren, Arkiv Kemi 1953, 5, 349.
12] L. M. Mokry, N. S. Dean, C. J. Carrano, Angew. Chem. 1996, 108,
1
676; Angew. Chem. Int. Ed. Engl. 1996, 35, 1497.
5330
www.chemeurj.org
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 5324 – 5331

Tetravalent Uranium Hexanuclear Motifs
FULL PAPER
[
13] J.-C. Berthet, P. Thuꢀry, M. Ephritikhine, Chem. Commun. 2005,
415.
14] a) J.-H. Liu, S. Van den Berghe, M. J. Konstantinovic, J. Solid State
Chem. 2009, 182, 1105; b) H.-K. Liu, K.-H. Lii, Inorg. Chem. 2011,
[22] a) P. Toledano, F. Ribot, C. Sanchez, C. R. Acad. Sci. Ser. II 1990,
311, 1315; b) V. Mereacre, M. N. Akhtar, A. Lindemann, C. E.
Anson, A. K. Powell, Helv. Chim. Acta 2009, 92, 2507.
[23] a) K. E. Knope, R. E. Wilson, M. Viasiliu, D. A. Dixon, L. Soder-
holm, Inorg. Chem. 2011, 50, 9696; b) C. Hennig, S. Takao, K.
Takao, S. Weiss, W. Kraus, F. Emmerling, A. C. Scheinost, Dalton
Trans. 2012, 41, 12818.
3
[
5
2
0, 5870; c) C.-S. Lee, S.-L. Wang, K.-H. Lii, J. Am. Chem. Soc.
009, 131, 15116.
[
15] a) J. G. Conway, J. Chem. Phys. 1959, 31, 1002; b) D. Cohen, W. T.
Carnall, J. Phys. Chem. 1960, 64, 1933; c) S. Hubert, C. L. Song, M.
Genet, F. Auzel, J. Solid State Chem. 1986, 61, 252; d) N. Dacheux,
V. Brandel, M. Genet, New J. Chem. 1995, 19, 15.
[
24] P. B. Duval, C. J. Burns, D. L. Clark, D. E. Morris, B. L. Scott, J. D.
Thompson, E. L. Werkema, L. Jia, R. A. Andersen, Angew. Chem.
2
001, 113, 3461; Angew. Chem. Int. Ed. 2001, 40, 3357.
25] J. Diwu, S. Wang, T. E. Albrecht-Schmitt, Inorg. Chem. 2012, 51,
088.
26] K. Takao, S. Takao, A. C. Scheinost, G. Bernhard, C. Hennig, Inorg.
Chem. 2012, 51, 1336.
27] SAINT Plus, Version 7.53a, Bruker Analytical X-ray Systems, Madi-
son, WI, 2008.
28] G. M. Sheldrick, SADABS, Version 2008/1, Bruker-Siemens Area
Detector Absorption and Other Correction, 2008.
29] V. Petricek, M. Dusek, L. Palatinus, JANA2006, Institute of Physics,
Praha, 2006.
[
[
[
[
[
[
[
[
[
[
16] M. L. Foo, S. Horike, T. Fukushima, Y. Hijikata, Y. Kubota, M.
Takata, S. Kitagawa, Dalton Trans. 2012, 41, 13791.
17] V. Guillerm, S. Gross, C. Serre, T. Devic, M. Bauer, G. Fꢀrey, Chem.
Commun. 2010, 46, 767.
18] A. Schaate, P. Roy, A. Godt, J. Lippke, F. Waltz, M. Wiebke, P. Beh-
rens, Chem. Eur. J. 2011, 17, 6643.
19] A. Schaate, S. Dꢆhnen, G. Platz, S. Lilienthal, A. M. Schneider, P.
Behrens, Eur. J. Inorg. Chem. 2012, 790.
4
20] a) W. Morris, B. Volosskiy, S. Demir, F. Gandara, P. L. McGrier, H.
Furukawa, D. Cascio, J. F. Stoddart, O. M. Yaghi, Inorg. Chem. 2012,
[30] D. Louꢇr, A. Buoltif, Z. Kristallogr. 2007, 26, 191.
[31] V. Favre-Nicolin, R. Cerny, J. Appl. Crystallogr. 2002, 35, 734.
[32] J. Rodriguez-Carvajal, Physica B 1993, 192, 55.
5
1, 6443; b) V. Bon, V. Senkovskyy, I. Senkovska, S. Kaskel, Chem.
Commun. 2012, 48, 8407.
[
21] a) G. Kickelbick, U. Schubert, Chem. Ber. 1997, 130, 473; b) G.
Kickelbick, P. Wiede, U. Schubert, Inorg. Chim. Acta 1999, 284, 1.
Received: November 1, 2012
Published online: January 16, 2013
Chem. Eur. J. 2013, 19, 5324 – 5331
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
5331