Synthesis and X-ray crystallographic characterization of two different inorganic-organic hybrid isopolyoxomolybdates with α-dipropylammonium N,N-diisobutylacetamide by varying reaction conditions

Article abstract of DOI:10.1016/j.poly.2015.08.029

Two new polyoxomolybdate based inorganic-organic hybrid compounds have been obtained from same ammonium ion ligand 1 and molybdate source just by altering reaction conditions. The new hybrid polyoxomolybdate complexes (LH)₂[Mo₆O₁₉] 3 and (LH)₄[Mo₈O₂₆] (MeCN)₂ 4 have distinct structural features revealed by X-ray crystallographic studies. The complex 3 contains two ammonium ligands to balance the charge on hexamolybdate dianion. The most striking feature of (LH)₂[Mo₆O₁₉] is the presence of inter-ligand hydrogen bonding (N-HaO=C) between two ligands arranged in an antiparallel fashion that favors the formation of a net like structure which embeds the Mo₆O₁₉ dianion. The complex 4 contains four ammonium ligands to balance the charge on β-octamolybdate tetraanion. Interestingly, complex 4 exhibits strong hydrogen-bonding interactions between ammonium ligand and octamolybdate anion (N-HaO-Mo) and no inter-ligand H-bonding interaction. The different structural features of hybrid compounds 3 and 4 suggest that different polyoxomolybdate clusters play a key role in the process of assembling of ligands.

Full text of DOI:10.1016/j.poly.2015.08.029

Polyhedron 100 (2015) 290–295
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis and X-ray crystallographic characterization of two
different inorganic–organic hybrid isopolyoxomolybdates
with
a-dipropylammonium N,N-diisobutylacetamide by
varying reaction conditions
b,
c
Shikha Sharma a, Sunil K. Ghosh a, , Mukesh Kumar , Joti N. Sharma
⇑
⇑
a Bio-Organic Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
b Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
c Process Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Two new polyoxomolybdate based inorganic–organic hybrid compounds have been obtained from same
ammonium ion ligand 1 and molybdate source just by altering reaction conditions. The new hybrid
polyoxomolybdate complexes (LH)2[Mo6O19] 3 and (LH)4[Mo8O26] (MeCN)2 4 have distinct structural
features revealed by X-ray crystallographic studies. The complex 3 contains two ammonium ligands to
balance the charge on hexamolybdate dianion. The most striking feature of (LH)2[Mo6O19] is the presence
of inter-ligand hydrogen bonding (NAHÁ Á ÁO@C) between two ligands arranged in an antiparallel fashion
that favors the formation of a net like structure which embeds the Mo6O19 dianion. The complex 4
contains four ammonium ligands to balance the charge on b-octamolybdate tetraanion. Interestingly,
complex 4 exhibits strong hydrogen-bonding interactions between ammonium ligand and octamolyb-
date anion (NAHÁ Á ÁOAMo) and no inter-ligand H-bonding interaction. The different structural features
of hybrid compounds 3 and 4 suggest that different polyoxomolybdate clusters play a key role in the
process of assembling of ligands.
Received 16 June 2015
Accepted 24 August 2015
Available online 29 August 2015
Keywords:
Inorganic–organic hybrid
Polyoxomolybdates
Crystal structure
Self assembly
H-bonding
Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction
gives rise to the formation of inorganic–organic hybrid materials
where POMs work as building blocks. As the POM anions contain
Molybdenum compounds are popular target for studies because
of their importance in biological systems [1–3], interesting struc-
tural features [3,4] and extensive applications in various fields of
sciences [5]. Besides normal compounds and complexes, Mo forms
extensive range of oxometalate clusters consists of isopolyacids or
many oxygen atoms which act as good hydrogen bond acceptors,
fictionalization of these POMs with organic molecules having many
hydrogen atoms give rise to interesting supramolecular
chemistry [11–13]. The supramolecular interactions are mediated
by various type of hydrogen bonds like OAHÁ Á ÁO, NAHÁ Á ÁO,
CAHÁ Á ÁO, OAHÁ Á ÁN, etc. [11,12].
heteropolyacids [3–6]. The Lindqvist anionic hexamolybdate
2À
[Mo6O19
]
has been structurally characterized as isolated salt in
Quaternary ammonium salt such as Aliquat and tertiary amine
like Alamines are generally used for extraction of Mo from weakly
solid state [7]. The interesting aspects of structure chemistry of
4À
the octamolybdate anion, [Mo8O26
]
is seen in varied structural
of
4À are known [8–10]. The structures dif-
acidic aqueous medium [14–16]. Crystal structure of POM anion
2À
patterns in the solid state [8]. Seven isomeric forms viz.
octamolybdates, [Mo8O26
a–g
with Bu4N+ as a mixed [Mo6O19
]
and [Mo8O26]
4À, i.e., [n-Bu4N]8
]
[Mo6O19]2[
of [Mo6O19
a
]
-(Mo8O26)] [17] has been reported recently. Crystals
fer in the types of polyhedron that fuse to form the cluster and in
the linkage between polyhedra.
Several research attempts have been made to functionalize the
polyoxomolybdates (POMs) with an organic component which
2À and [Mo8O26 4À have also been made using different
]
organic ligands [12,18–20]. Complexes of POM with organic amino
type ligands associated with transition metals such as Cu or Co
have been prepared and characterized by X-ray crystallography
2À
4À
[21–24]. But, individual complexes of [Mo6O19
with the same ligand are not known. Recently, we have developed
a-dipropylamino N,N-diisobutylacetamide (L) 1 (Scheme 1) as an
]
and [Mo8O26]
⇑
Corresponding authors. Tel.: +91 22 25595012; fax: +91 22 25505151.
E-mail address: ghsunil@barc.gov.in (S.K. Ghosh).
http://dx.doi.org/10.1016/j.poly.2015.08.029
0277-5387/Ó 2015 Elsevier Ltd. All rights reserved.

S. Sharma et al. / Polyhedron 100 (2015) 290–295
291
Table 1
Crystallographic data and details of structure refinement for complexes 3 and 4.
3
4
Empirical formula
Mo6O19, 2(C16H35N2O) Mo8O26, 4(C16H35N2O), 2
(C2H3N)
Formula weight
T (K)
k (Å)
Crystal system
Space group
a (Å)
1422.56
293(2)
1.5418
monoclinic
I2/a
24.8703(11)
11.1774(3)
20.4442(9)
90
119.195(6)
90
4961.2(4)
4
2351.46
293(2)
1.5418
triclinic
ꢀ
P1
11.8091(11)
12.1612(11)
18.2009(13)
77.755(7)
81.247(7)
87.642(7)
2524.6(4)
1
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Scheme 1. Synthesis of a-dipropylamino N,N-diisobutylacetamide 1.
Z
Dcalc (g/cm3)
1.905
12.706
2840.0
1.547
8.471
1200.0
l
(mmÀ1
)
F(000)
Crystal size (mm3)
0.4585 Â 0.288 Â 0.1217 0.5939 Â 0.3818 Â 0.1877
h max (°)
69.865
70.096
Reflections collected/unique 8318/4616
Rint 0.0621
Data/restraints/parameters 4616/48/332
16607/9390
0.0809
9390/24/535
1.133
0.1100/0.2873
0.1319/0.3204
3.48, À2.54
Goodness-of-fit on F2
R1/wR2 [I P 2 (I)]
R1/wR2 (all data)
Residuals (e ÅÀ3
1.010
r
0.0943/0.2491
0.1161/0.2800
1.92, À3.29
)
(NH4)6Mo7O24Á4H2O and a methanolic solution of ligand 1 were
mixed and stirred at room temperature. Interestingly, when
(NH4)6Mo7O24Á4H2O was dissolved in water, mixed with
a
methanolic solution of ligand 1 and heated at 100 °C, a colorless
complex (LH)4[Mo8O26] 4 was formed.
2.1. Synthesis of complex (LH)2[Mo6O19] 3 (route A)
A solution of acetamide 1 (271 mg, 1 mmol) in chloroform (5 mL)
wasrepeatedlycontactedwithfresh solutionof (NH4)6Mo7O24Á4H2O
(46 mg, 0.037 mmol) in 0.1 M aqueous HNO3 (5 mL). The chloro-
form extract was concentrated under reduced pressure to give a
yellow precipitate of metal ligand complex. The precipitate was
triturated with 10% ethyl acetate–hexane solution to remove
excess ligand 1. The solid residue was then crystallized from
acetonitrile to obtain the yellow crystalline complex 3 (603 mg,
ꢀ
Scheme 2. Synthesis of metal–ligand complexes 3 and 4.
amine based extractant for Mo with an aim for its recovery from
spent nuclear fuel dissolved in nitric acid where other amine based
extractants did not work [25]. Considering the great importance of
inorganic–organic hybrid materials of polyoxomolybdates, we
herein report the condition dependent crystal engineered synthe-
85%). IR (KBr):
m 3450, 3109, 2960, 2877, 1643 (C@O), 1464,
1387, 1257, 1157, 953 (Mo@O), 800, 592 (MoAOAMo), 436 cmÀ1
.
ses of (LH+)2[Mo6O19 2À and (LH+)4[Mo8O26 4À complexes and their
] ]
2.2. Synthesis of Mo crystal (LH)2[Mo6O19] 3 (route B)
X-ray crystallographic characterization.
A solution of (NH4)6Mo7O24Á4H2O (84 mg, 0.068 mmol) in 0.5 M
HNO3 (3 mL) was added to a solution of acetamide 1 (55 mg,
0.204 mmol) in MeOH (2 mL) and the reaction mixture was stirred
at room temperature for 5 h. The reaction mixture was filtered and
the light yellow precipitate was washed with 10% ethyl acetate–
hexane solution to remove the excess ligand 1. The yellow powder
was crystallized from acetonitrile to give yellow crystals of
complex 3 (79 mg, 81%).
2. Results and discussion
a-Dipropylamino N,N-diisobutylacetamide 1 was synthesized
following our reported procedure [25] from the commercially
available starting materials as described in Scheme 1. For this,
chloroacetyl chloride was reacted with diisobutylamine in the
presence of triethylamine to give the amide
subsequently reacted with diisopropylamine to give the desired
-dipropylamino N,N-diisobutylacetamide 1 in very good overall
yield.
When the chloroform solution of ligand 1 was repeatedly con-
2 which was
a
2.3. Synthesis of Mo crystal (LH)4[Mo8O26] (MeCN)2 4
A
solution of (NH4)6Mo7O24Á4H2O (42 mg, 0.034 mmol) in
tacted with fresh solution of (NH4)6Mo7O24Á4H2O in 0.1 M aqueous
HNO3 and the resultant organic phase was concentrated, a yellow
precipitate was obtained which on crystallization from acetonitrile
provided a yellow complex (LH)2[Mo6O19] 3 (Scheme 2). The same
complex 3 was achieved when a 0.5 M nitric acid solution of
water (2 mL) was added to a solution of acetamide 1 (64 mg,
0.238 mmol) in MeOH (1 mL). The reaction mixture was stirred
at 100 °C for 3 h, brought to room temperature and concentrated
under reduced pressure. The solid residue was washed with 10%
ethyl acetate–hexane solution to remove the excess ligand 1. The

292
S. Sharma et al. / Polyhedron 100 (2015) 290–295
Fig. 1. Cluster packing of complex 3, (LH)2[Mo6O19], in the crystal. The dark blue balls are Mo; red balls: O; light blue balls: N; gray balls: C; white balls: H. (Color online.)
Fig. 2. Space filled cluster packing of complex 3, (LH)2[Mo6O19], in the crystal. The
dark blue balls are Mo; red balls: O; light blue balls: N; gray balls: C; white balls: H.
(Color online.)
white powder was crystallized from acetonitrile to give colorless
Fig. 3. The hexamolybdate anion with a pair of anti-parallel cationic ligand in
ꢀ
m
crystals of complex 4 (59 mg, 74%). IR (KBr):
3467, 2964, 2939,
complex 3, (LH)2[Mo6O19]. The inter ligand hydrogen bonds (NAHÁ Á ÁO@C) are
shown as red dotted lines. The dark blue balls are Mo; red balls: O; light blue balls:
N; gray balls: C; white balls: H. (Color online.)
2875, 1647 (C@O), 1471, 1431, 1369, 944, 913 (Mo@O), 848, 714,
664 (MoAOAMo), 557, 525 cmÀ1
.
interface [28]. All the nonhydrogen atoms were refined anisotrop-
ically and hydrogens were generated at their idealized positions
and refined isotropically according to riding model.
2.4. Crystallographic characterization of complexes 3 and 4
Single crystal X-ray diffraction data were collected on Agilent
The complex 3 crystallizes in the monoclinic space group I2/a
while complex 4 crystallizes in the triclinic space group P1. The
Supernova system equipped with
a microfocus Cu-source
ꢀ
(k = 1.5418 Å) and a Titan CCD detector. The crystals were sepa-
rated, coated with paraffin oil and mounted on a loop for X-ray
diffraction data collection at room temperature (293 K). The data
reduction and analysis were carried out with CrysAlisPro software
suit. Analytical absorption correction using a multifaceted crystal
model based on expressions derived by Clark and Reid [26] and
as implemented in the CrysAlisPro software suit was carried out
for both the crystals. The structures were solved by direct method
using SHELXS and refined using SHELXL softwares [27] using Olex2
crystal data and the refinement statistics is shown in Table 1.
The crystal structure of complex 3 shows that the protonated
ligand (LH+) 1 forms a cage-like structure in which the Mo6O19 fits
in the cavity (Figs. 1 and 2). The counterions (LH+)-1 regularly
distribute in the interspaces formed by the polyanions. A pair of
(LH+)-1 ligand molecules orient in anti-parallel fashion with
formation of two inter-ligand hydrogen bonds between amide
oxygen atom of one ligand molecule and the quaternary nitrogen

S. Sharma et al. / Polyhedron 100 (2015) 290–295
293
Fig. 6. Space filled cluster packing of complex 4, (LH)4[Mo8O26] (MeCN)2. The dark
blue balls are Mo; red balls: O; light blue balls: N; gray balls: C; white balls: H.
(Color online.)
Fig. 4. The hexamolybdate anion surrounded by four anti-parallel dimeric units of
ligand in the complex 3, (LH)2[Mo6O19]. The dark blue balls are Mo; red balls: O;
light blue balls: N; gray balls: C; white balls: H. (Color online.)
Fig. 7. The octamolybdate anion surrounded by eight ligands in complex 4, (LH)4
[Mo8O26] (MeCN)2. The dark blue balls are Mo; red balls: O; light blue balls: N; gray
balls: C; white balls: H. (Color online.)
and several hydrogen bonds between oxygen atoms of the polyan-
ions and the hydrogens attached to carbon atoms of (LH+)-1 have
been observed between (LH+)-1 cations and polyanion layers. The
shortest CAH/O distance observed was 3.41 Å [between C(16)
and O(10)]. The structure of [Mo6O19]
2À anion in complex 3 shows
slightly distorted cage of six molybdenum atoms located octahe-
drally around a central oxygen atom, with 12 oxygen atoms dis-
posed in MoAOAMo units and one terminal oxygen attached to
each molybdenum. Three distinct types of MoAO bond lengths
are observed. The terminal MoAO bond lengths are shorter with
an average bond length of 1.66 Å and the bridging MoAO bonds
have an average bond length of 1.91 Å. The central MoAO bond
lengths are the longest with an average value of 2.32 Å. The exact
values are presented in Table 2.
Fig. 5. Cluster packing of complex 4, (LH)4[Mo8O26] (MeCN)2. The dark blue balls
are Mo; red balls: O; light blue balls: N; gray balls: C; white balls: H. (Color online.)
atom of other ligand molecule (Fig. 3). The inter ligand NAHÁ Á ÁO@C
H-bond distance is 2.92 Å. Each [Mo6O19]
2À anion is surrounded by
six (LH+)-1 cations but its surrounding is not uniform. Each cluster
anion is surrounded by two H-bonded dimeric (LH+)-1 cations and
two (LH+)-1 cations not H-bonded to each other but to other pro-
tonated ligand molecules. The cage-like structure is then formed
by hydrophobic interactions among intermolecular hydrogen
bonded ligand dimers surrounding the central metal cluster
(Fig. 4). The distances of quaternary N in (LH+)-1 cations and the
nearest Mo in adjacent polyanions range from 4.77 to 5.31 Å. Three
The crystal structure for complex 4 shows that octamolybdate
anion is present in b-form and the protonated ligand (LH+) 1 forms
a different cage structure (Figs. 5 and 6) to accommodate the
4À
polyanion in the cavity. Each b-[Mo8O26
]
anion is surrounded
by eight (LH+)-1 cationic ligands (Fig. 7). Two MeCN molecules
per cluster anion are incorporated into the interstitial positions
held by hydrophobic interaction with the ligands and a weak
CAHÁ Á ÁO hydrogen bonding interaction (CÁ Á ÁO distance 3.1 Å) with
4À
kinds of interactions viz. the Van der Waals forces, electrostatic
b-[Mo8O26
]
anion (Fig. 8). The size of the cavity in this
2À
attractions between (LH+)-1 cations and polyanions [Mo6O19
]
cage-structure is bigger than that in complex 3. The clustering of

294
S. Sharma et al. / Polyhedron 100 (2015) 290–295
Fig. 8. The hydrogen bonding interactions in complex 4, (LH)4[Mo8O26] (MeCN)2. The ligand NAHÁ Á ÁOAMo bondings are shown as dotted lines. The dark blue balls are Mo;
red balls: O; light blue balls: N; gray balls: C; white balls: H. (Color online.)
Table 2
Table 3
Bond lengths (Å) for complex 3 (LH)2[Mo6O19].
Bond lengths (Å) for complex 4, (LH)4[Mo8O26] (MeCN)2.
Mo3AO10
Mo3AO8
Mo3AO7
Mo3AO9
Mo3AO11
Mo3AO1
Mo2AO4
Mo2AO7
Mo2AO5
Mo2AO6
1.919(5)
1.898(8)
1.910(7)
1.654(7)
1.945(9)
2.329(7)
1.664(7)
1.920(7)
1.914(5)
1.898(8)
2.308(7)
1.934(8)
1.919(5)
1.937(7)
1.665(7)
1.937(7)
1.882(9)
1.951(8)
2.3183(8)
1.893(8)
1.914(5)
1.951(8)
2.329(7)
2.308(7)
2.3182(8)
O12AC9
C10AN2
C10AC9
N2AC11
N2AC14
N2AC11A
N2AC14A
C9AN6
C2AC1
C2AC3
C2AC4
C11AC12
C6AC5
C6AC7
C6AC8
C5AN6
C4AN6
C15AC16
C15AC14
C12AC13
C13AC12A
C16AC15A
C15AAC14A
C12AAC11A
1.224(12)
1.476(12)
1.555(14)
1.64(3)
1.38(3)
1.29(4)
C1AC2
C2AC3
C3AN2
C4AC5
C4AN2
C5AC6
C7AC8
C7AN2
1.529(16)
1.510(16)
1.495(14)
1.460(17)
1.481(14)
1.54(2)
1.518(16)
1.512(13)
1.346(14)
1.244(13)
1.59(3)
1.484(14)
1.57(3)
1.32(3)
1.540(19)
1.462(15)
1.47(2)
C30AC31
C30AC32
Mo1AO1
Mo1AO2
Mo1AO3
1.500(17)
1.58(2)
2.351(7)
1.729(6)
1.721(7)
1.884(6)
2.316(7)
1.989(7)
2.482(7)
1.917(7)
1.711(6)
1.719(7)
1.917(8)
2.271(7)
2.308(7)
1.884(7)
1.695(7)
1.706(7)
1.998(6)
2.357(7)
2.134(6)
2.388(7)
1.962(7)
1.753(6)
1.715(7)
1.932(6)
2.387(7)
2.316(7)
2.271(7)
2.357(7)
1.19(3)
Mo1AO4
1.66(4)
Mo1AO10#1
Mo1AO13
Mo2AO1
1.317(12)
1.517(17)
1.490(18)
1.501(15)
1.52(3)
1.487(17)
1.502(17)
1.52(2)
1.484(13)
1.462(13)
1.67(2)
1.58(4)
1.54(2)
C8AN1
C8AO14
C9AC10
C9AN1
Mo2AO4
Mo2AO5
Mo2AO6
Mo2AO1
Mo2AO3
O10AMo3#1
O8AMo1#1
O2AMo1
C10AC11
C10AC12
C13AC14
C13AN1
C14AC15
C14AC16
C17AC18
C19AN4
C19AC18
C20AC21
C21AC22
C22AN4
C23AC24
C23AN4
C24AN3
C24AO15
C25AC26
C25AN3
C26AC27
C26AC28
C29AC30
C29AN3
Mo2AO7
Mo2AO11#1
Mo3AO1
Mo1AO8#1
Mo1AO11
Mo1AO6#1
Mo1AO1
Mo3AO7
Mo3AO8
Mo3AO9
Mo3AO10
Mo3AO13#1
Mo4AO1
1.50(2)
1.29(4)
Mo1AO3
1.510(15)
1.493(19)
1.519(19)
1.514(17)
1.510(13)
1.520(14)
1.487(11)
1.351(13)
1.212(12)
1.52(2)
1.464(14)
1.45(3)
1.56(2)
1.486(17)
1.476(12)
O5AMo2#1
O6AMo1#1
O1AMo3#1
O1AMo2#1
O1AMo1#1
1.81(4)
1.53(3)
1.52(4)
1.50(6)
Mo4AO1#1
Mo4AO10
Mo4AO11
Mo4AO12
Mo4AO13
O1AMo4#1
O10AMo1#1
O11AMo2#1
O13AMo3#1
C34AN5
#1
Atoms generated by symmetry operation (À1/2 À X, +Y, ÀZ).
ligand here is different and there is no inter-ligand hydrogen bond
present as in complex 3. The quaternary ammonium N atom in
each ligand molecule, however, makes hydrogen bond with one
C34AC33
C17AAC18
1.36(3)
1.43(3)
of the oxygen atoms of metal cluster as shown in Figs. 7 and 8. Each
4À
anionic cluster b-[Mo8O26
]
is strongly H-bonded to two (LH+)-1
#1
Atoms generated by symmetry operation (ÀX, 1 À Y, 2 À Z).
and weakly H-bonded to another two (LH+)-1 (NAHÁ Á ÁOAMo) with
an average bond length of 2.82 and 2.9 Å, respectively. Remaining
four (LH+)-1 ligands are not H-bonded to the cluster but H-bonded
to adjacent cluster anions. Besides H-bonding interactions, there
exist three weak kinds of interactions between (LH+)-1 cations
from 4.48 to 4.54 Å. The b-isomeric octamolybdate cluster anion
b-[Mo8O26
by two MoO6 octahedra with overall eight edge-sharing MoO6
octahedra. There are two classes of MoAO bonds, the terminal
MoAO with a bond length between 1.70 and 1.72 Å and three types
4À
]
is made up of Mo6O24 ring capped on opposite faces
and inorganic cluster anions: the Van der Waals force, electrostatic
attractions between cations (LH+)-1 and polyanions b-[Mo8O26
]
4À
and several H-bond between oxygen atoms of the polyanions and
the CAH of (LH+)-1 ligands. The shortest CAH/O distance observed
was 3.08 Å [between C(7) and O(6)]. The distances of quaternary N
in (LH+)-1 cations and the nearest Mo in adjacent polyanions range
of bridging MoAO bonds. The doubly bridged MoAO(
l2), triply
bridged MoAO( 3) and quintly bridged MoAO( 5) having bond
l
l
length in the range of 1.884(6)–1.917(7) Å, 1.932(6)–2.357(7) Å
and 2.134(6)–2.482(7) Å, respectively. In each type of bonds, the

S. Sharma et al. / Polyhedron 100 (2015) 290–295
295
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2À
In conclusion, individual complexes of [Mo6O19
[Mo8O26
]
and
]
4À with the same ligand are not known and we have pro-
vided two new homopolyoxomolybdate complexes of the same
ligand from ammonium molybdate and acetamide 1 just by chang-
ing the reaction conditions. Based on the single-crystal analysis of
these inorganic–organic hybrid compounds, the functionalized
ammonium cation of ligand 1 has been incorporated for charge
balance. In complex 3, only weak (CAHÁ Á ÁOAMo) H-bonding inter-
action between ligand 1 and hexamolybdate anion has been
observed. The hexamolybdate anion is embedded in the cage
formed by inter ligand H-bondings with antiparallel arrangement
of two ligand molecules. Interestingly, complex 4 exhibits strong
hydrogen-bonding between ligand 1 and b-octamolybdate anion
(NAHÁ Á ÁOAMo). Different reaction conditions may be developed
using the ligand for the synthesis of other inorganic–organic
hybrid polyoxomolybdates with interesting structural features
and molecular properties.
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ˇ ˇ
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CCDC 1401083 and 1401084 contains the supplementary crys-
tallographic data for 3 and 4. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
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