Synthesis and supramolecular features of hybrid POM/onium solid-state assemblies

Article abstract of DOI:10.1080/10610278.2015.1108418

Polyoxomolybdate-based organic-inorganic hybrid architectures were synthesised and characterised by X-ray crystallography. The supramolecular assemblies present rows of metallic clusters H-bonded by ammonium cations, with a 1:2 molybdate/ammonium ratio. The organic moieties of the ammonium cations establish hydrophobic contact among them such as van der Waals, C-Hπ and ππ interactions that stabilise the supramolecular architectures. In particular, for compound 5 the n-alkyl tails pack closely together giving a lipid-like bilayer. In compound 6, the aromatic phenyl rings of the organic cation allow the stabilisation of the supramolecular architecture by C-Hπ and ππ interactions. Regarding the X-ray structure of the compound 11, the tetraanionic octa-molybdate [Mo₈O₂₆]^4- cluster is surrounded by four ethyl-triphenyl-phosphonium cations. Running along the b-axis open channels are occupied by DMF solvent molecules. Interestingly, a soaking experiment in n-pentane with the corresponding crystals of compound 11 afforded to a crystal structure very different from the native one. Van der Waals, C-Hπ and ππ interactions between large organic moieties are fundamental in the stabilization of hybrid organic-inorganic POM architectures.

Full text of DOI:10.1080/10610278.2015.1108418

Supramolecular Chemistry
ISSN: 1061-0278 (Print) 1029-0478 (Online) Journal homepage: http://www.tandfonline.com/loi/gsch20
Synthesis and supramolecular features of hybrid
POM/onium solid-state assemblies
Carmen Talotta, Luca Rubino, Carmine Gaeta, Francesco Capitelli, Michele
Saviano, Giovanna Brancatelli, Silvano Geremia, Ermanno Vasca & Placido
Neri
To cite this article: Carmen Talotta, Luca Rubino, Carmine Gaeta, Francesco Capitelli,
Michele Saviano, Giovanna Brancatelli, Silvano Geremia, Ermanno Vasca & Placido Neri
(2015): Synthesis and supramolecular features of hybrid POM/onium solid-state assemblies,
Supramolecular Chemistry, DOI: 10.1080/10610278.2015.1108418
To link to this article: http://dx.doi.org/10.1080/10610278.2015.1108418
Published online: 20 Nov 2015.
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Date: 24 November 2015, At: 02:59

Supramolecular chemiStry, 2015
ꢁꢁꢂ://dx.dꢃꢄ.ꢃꢅg/10.1080/10610278.2015.1108418
ꢀ
Synthesis and supramolecular features of hybrid POM/onium solid-state
assemblies
a
a
a
b
c
d
Carmen Talotta , Luca Rubino , Carmine Gaeta , Francesco Capitelli , Michele Saviano , Giovanna Brancatelli ,
d
a
a
Silvano Geremia , Ermanno Vasca and Placido Neri
ꢆ
b
ꢉ
Dꢄꢂꢆꢅꢁꢄꢇꢈnꢁꢃ dꢄ cꢀꢄꢇꢄꢉꢆ ꢈ Bꢄꢃꢊꢃgꢄꢆ, unꢄvꢈꢅsꢄꢁà dꢈgꢊꢄ Sꢁꢋdꢄ dꢄ Sꢆꢊꢈꢅnꢃ, Sꢆꢊꢈꢅnꢃ, iꢁꢆꢊꢌ; isꢁꢄꢁꢋꢁꢃ dꢄ cꢅꢄsꢁꢆꢊꢊꢃgꢅꢆfiꢆ – cNr, rꢃꢇꢆ, iꢁꢆꢊꢌ; isꢁꢄꢁꢋꢁꢃ dꢄ
d
cꢅꢄsꢁꢆꢊꢊꢃgꢅꢆfiꢆ – cNr, Bꢆꢅꢄ, iꢁꢆꢊꢌ; cꢈnꢁꢅꢃ dꢄ eꢉꢉꢈꢊꢊꢈnzꢆ ꢄn Bꢄꢃꢉꢅꢄsꢁꢆꢊꢊꢃgꢅꢆfiꢆ, Dꢄꢂꢆꢅꢁꢄꢇꢈnꢁꢃ dꢄ Sꢉꢄꢈnzꢈ cꢀꢄꢇꢄꢉꢀꢈ ꢈ Fꢆꢅꢇꢆꢉꢈꢋꢁꢄꢉꢀꢈ, unꢄvꢈꢅsꢄꢁà dꢄ
tꢅꢄꢈsꢁꢈ, tꢅꢄꢈsꢁꢈ, iꢁꢆꢊꢌ
ABSTRACT
ARTICLE HISTORY
rꢈꢉꢈꢄvꢈd 8 Sꢈꢂꢁꢈꢇbꢈꢅ2015
aꢉꢉꢈꢂꢁꢈd 9 oꢉꢁꢃbꢈꢅ2015
Polyoxomolybdate-based organic−inorganic hybrid architectures were synthesised and
characterised by X-ray crystallography. The supramolecular assemblies present rows of metallic
clusters H-bonded by ammonium cations, with a 1:2 molybdate/ammonium ratio. The organic
moieties of the ammonium cations establish hydrophobic contact among them such as van der
Waals, C–H⋯π and π⋯π interactions that stabilise the supramolecular architectures. In particular,
for compound 5 the n-alkyl tails pack closely together giving a lipid-like bilayer. In compound 6, the
aromatic phenyl rings of the organic cation allow the stabilisation of the supramolecular architecture
byC–H⋯π andπ⋯π interactions. RegardingtheX-raystructureofthecompound11, thetetraanionic
KEYWORDS
cꢆꢊꢄxꢆꢅꢈnꢈs; pom; ꢀꢌbꢅꢄd
ꢇꢆꢁꢈꢅꢄꢆꢊs; dꢄꢆꢊkꢌꢊꢆꢇꢇꢃnꢄꢋꢇ;
ꢂꢀꢃꢂsꢀꢂꢃnꢄꢋꢇ; sꢃꢆkꢄng
4
−
octa-molybdate [Mo O ] cluster is surrounded by four ethyl-triphenyl-phosphonium cations.
8
26
Running along the b-axis open channels are occupied by DMF solvent molecules. Interestingly, a
soaking experiment in n-pentane with the corresponding crystals of compound 11 afforded to a
crystal structure very different from the native one.
Van der Waals, C–H⋯π and π⋯π interactions between large organic moieties are fundamental in
the stabilization of hybrid organic-inorganic POM architectures.
1
. Introduction
and organic compounds were reported, which exhibited
porous three-dimensional (3D) structures and guest-sorp-
tion abilities (3). These POM-based hybrid architectures
are essentially supported by non-covalent interactions
between the organic and inorganic moieties, such as elec-
trostatic interactions, hydrogen bonding, π⋯π stacking
and C−H⋯π interactions, whose geometric properties (e.g.
bonding angles and lengths) define their structural fea-
tures. Consequently, in the context of crystal engineering
the knowledge of the secondary interactions at the base of
In the last two decades, research interest in solid-state
materials has increased dramatically thanks to their appli-
cations ranging from gas storage and catalysis to mate-
rial science (1). Among them, inorganic−organic hybrid
materials (2) have attracted considerable attention due
to their intriguing variety of architectures and remark-
able range of applications. Recently, interesting hybrid
organic–inorganic assemblies composed of inorganic
metal clusters [e.g. Keggin polyoxometalate (POM) anions]
CONTACT cꢆꢅꢇꢄnꢈ Gꢆꢈꢁꢆ
ꢉgꢆꢈꢁꢆ@ꢋnꢄsꢆ.ꢄꢁ; cꢆꢅꢇꢈn tꢆꢊꢃꢁꢁꢆ
ꢉꢁꢆꢊꢃꢁꢁꢆ@ꢋnꢄsꢆ.ꢄꢁ
©
2015 tꢆꢌꢊꢃꢅ & Fꢅꢆnꢉꢄs

2
C. TALOTTA ET AL.
the crystal-lattice stabilisation is of crucial importance for
the rational design of novel POM-based hybrid materials.
At this regard, it has been reported (4) that one-dimen-
phosphonium cations in which the hydrophobic groups
are ranging from simple alkyl groups to large and complex
calix[4]arene macrocycles (e.g. ammonium derivatives 1−4
in Chart 1).
4
−
sional chains constituted by octamolybdate [Mo O ]
8
26
+
anion sealed by a single Ag cation were linked in a
three-dimensional supramolecular network through
intermolecular hydrogen bond (N–H⋯O=Mo), halogen
bond and π-stacking interactions between a bipyridine
derivative and the octamolybdate anion. Analogously, a
solid-state supramolecular architecture has been reported
2
. Results and discussion
2.1. Synthesis of dialkyl and bis(alkylbenzyl)
ammonium-based polyoxomolybdate 5 and 6
Compound
5
{[(n-C H ) NH ] ∙[Mo O (OMe) ]}.
10 21 2 2 2 4 10 6
(
5) in which a protonated bis-imidazol derivative was com-
Acidification of didecylamine with HCl lead to the cor-
responding didecylammonium chloride 7 (Scheme 1),
which was dissolved in methanol and mixed with an
aqueous solution of (NH ) Mo O ∙4H O at pH 3.0. The solid
2
−
bined with a [Mo O ] anion through intermolecular
6
19
hydrogen bonding interactions.
Regarding calixarene-based polyoxometalate assem-
blies, interesting examples have been reported in the
literature, in which the 3D-structural and conformational
properties of the calixarene macrocycles led to peculiar
solid-state assemblies with novel physical and chemical
properties. Thus, Konishi (3) and coworkers reported an
example of porous hybrid solid-state assemblies based on
4
6
7
24
2
obtained was filtered and crystallised from methanol. It
was characterised by X-ray crystallography (vide infra).
Compound 6 {(BnNH CH CH NH Bn) ∙[Mo O ]}. The
2
2
2
2
2
8
26
synthesis of compound 6 is outlined in (Scheme 2). In par-
ticular, 1,2-diaminoethane was coupled with benzaldehyde in
CHCl as the solvent to give the imine intermediate 8, which
+
3
Keggin POM anions and Na -calix[4]arene–tetraethyl ester
was directly reduced, without any further purification, in the
complexes that display reversible guest sorption. Regarding
the catalytic activity of these POM-based hybrid materials,
very recently (6) has been reported as an example of het-
erogeneous catalyst based on a hybrid calixarene-based
POM able to catalysing the oxidative desulfurisation of the
presence of NaBH to give the diamine derivative 9.
4
Acidification of 9 with HCl lead to (BnNH CH CH NH Bn)
2
2
2
2
Cl salt 10 which was dissolved in methanol and mixed with
2
an aqueous solution of (NH ) Mo O ∙4H O at pH 3.0. The
4
6
7
24
2
solid obtained was filtered and crystallised from methanol/
DMF. It was characterised by X-ray crystallography (vide infra).
4,6-dimethyldibenzothiophene and benzothiophene. In this
example, the calix[4]arene macrocycle was functionalised at
the endo rim with imidazolium moieties to give a dicationic
macrocycle which was reacted with Na EuW O ·32H O.
2.2. Synthesis of phosphonium-based
polyoxomolybdate 11
9
10 36
2
These reports show that in the last decade, organic cations
have become of greater interest for the preparation of novel
hybrid organic–inorganic porous materials, thanks to their
coordination abilities to polyoxometalate anions.
Prompted by these observations and on the basis of
our experience with the chemistry of ammonium ions (7),
we decided to study the solid-state assembly features of
POM-based hybrid materials containing ammonium or
Compound 11 {[(Ph) PCH CH ] ∙[Mo O ]}. A solution of
4
2
3 4
8
26
phosphonium iodide 3 in methanol was added to a hot
aqueous solution of (NH ) Mo O ∙4H O at pH 3.0 (Scheme
4
6
7
24
2
3
). The solid obtained was filtered and crystallised from
diethyl ether/DMF. It was characterised by X-ray crystal-
lography (vide infra).
Cl-
H2 Cl-
N
H2
N
Cl-
N
H2
1
2
But
But
But
But
P
O
O O
O
I-
Cl-
NH NH
HN
Cl-
3
HN
Cl-
Cl-
4
Chart 1. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)

SꢀPRAMOLECꢀLAR CHEMISTRꢁ
3
Cl-
procedure with respect to that reported earlier by ꢀngaro
(8, 9). p-tert-Butylcalix[4]arene 12 was exhaustively alky-
lated with α-bromo-N,N′-diethylacetammide in the pres-
ence of NaH as the base to give derivative 13 which was
HCl
Et O, 25 °C,
N
H
N
8
8
2
8
H2
8
3
0 min
7
(
NH4+) Mo O x4H O
6
7
24
2
reacted with LiALH , to give the corresponding tetra-amine
4
H O pH = 3.0/CH OH
2
3
derivative that was directly treated with HCl to give tet-
ra-ammonium calix[4]arene derivative 4.
1
The H NMR spectrum of derivative 4 in CDCl evi-
3
{
[(n-C10H21)2NH2]2x[Mo4O10(OMe)6]}
denced the presence of two broad triplets at 4.55 and
5
3
.81 ppm relative to OCH and NCH groups, respectively,
2 2
while the resonance of the ammonium protons was pres-
ent at 11.7 ppm.
Scheme 1. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)
Compound 14. A solution of calix[4]arene derivative
in methanol was added to a hot aqueous solution of
O
H
4
NH2
+
H2N
N
N
CHCl3
5 °C
0 min
(Na) WO at pH 3.0 (Scheme 5). The solid obtained was
2
4
2
8
3
filtered and washed with H O and MeOH.
2
dry CH3OH NaBH4
1
The H NMR spectrum of derivative 14 (DMSO-d ,
1
h
6
Cl-
300 MHz) is reported in (Figure 1(b)). Interestingly, the res-
onance of the ammonium protons of 14 is shifted upfield
at 9.68 ppm with respect to the analogous protons of 4 in
H2
HCl
H
N
N
N
N
H
H2
Cl-
Et2O, 25 °C,
30 min
1
0
9
DMSO-d (11.70 ppm).
+
6
(
NH4 )6Mo7O24x4H2O
A comparison between the IR spectra of derivatives
H2O pH = 3.0/CH3OH
4
(Figure 2, red) and 14 (Figure 2, black) evidenced the
−1
appearance of a signal at 850 cm in the IR spectrum of
{
(BnNH2CH2CH2NH2Bn)2x[Mo8O26]}
4−
1
4 relative to the W−O−W stretching of the W O
anion.
6
10 32
No crystals suitable for X-ray analysis were obtained.
Compound 15. A solution of calix[4]arene deriva-
tive 4 in methanol was added to an aqueous solution of
Scheme 2. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)
(
Na) MoO ·2H O at pH 5.0 (Scheme 6). The solid obtained
2 4 2
2
.3. Synthesis of calixarene-based
was filtered and washed with H O and MeOH.
2
polyoxometalates
1
Analogously to the above-mentioned H NMR spectrum
Compound 4. The synthesis of derivative 4, outlined
in (Scheme 4), has been obtained following a modified
of 14, also in this case, the resonance of the ammonium
protons of 15 is shifted upfield at 8.51 ppm with respect to
+
(
NH4 )6Mo7O24x4H2O
H2O pH = 3.0/CH3OH
P
{[(Ph) PCH CH ] x[Mo O ]}
4
2
3 4
8
26
I-
11
3
Scheme 3. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)
But
But
But
But
But
But
But
But
But
But
But
But
O
Br
NaI,
N
4,
1) LiAlH dry THF
2
) HCl
NaH, dry THF/DMF 4/1
OH
HO HO
OH
O
O O
O
O
O O
O
O
O
O
O N
N
Cl- HN
NH NH
Cl-
N
12
N
HN
Cl-
Cl-
1
3
4
Scheme 4. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)

4
C. TALOTTA ET AL.
But
But
But
But
But
But
But
But
(
Na)2WO4
H2O pH = 3.0/CH3OH
O
O O
O
O
O O
O
4-
W O
32
1
0
Cl-
NH NH
HN
Cl-
HN
NH NH
HN
HN
Cl-
Cl-
4
14
Scheme 5. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)
analogous protons of 4 in DMSO-d (11.70 ppm). In addi-
2.4. X-ray diffraction study of dialkyl- and
bis(alkylbenzylammonium)-based POM derivatives
5 and 6
6
tion, the band relative to the Mo−O−Mo stretching of the
2−
19
−1
Mo O
anion was present at 850 cm in the IR spectrum
6
of 15. No crystals suitable for X-ray analysis were obtained.
Compound 16. A solution of calix[4]arene deriva-
tive 4 in methanol was added to an aqueous solution of
A single crystal of 5 or 6 (0.10 × 0.20 × 0.20 mm) was sealed
with its mother liquid in a Lindemann capillary to avoid
efflorescence. Diffraction data were collected at room tem-
perature on a Nonius Kappa CCD area diffractometer with
graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å).
The structures were solved (Table 1) through the
direct methods procedure of SIR2008 (10), within the tri-
clinic space group P − 1, with the following unit cell con-
stants: a = 10.0520(6), b = 11.0540(7), c = 15.2870(14) Å,
α = 88.632(8)°, β = 78.980(6)°, γ = 67.102(5), V = 1533.51(19)
(
Na) MoO ·2H O acidified with HCl 12.0 M (Scheme 7).
2 4 2
The solid obtained was filtered and washed with H O and
2
MeOH.
1
The H NMR spectrum of 16 (DMSO-d , 300 MHz)
6
showed the ammonium resonance at 9.41 ppm. In addi-
tion, the band relative to the Mo−O−Mo stretching of the
2−
19
−1
Mo O
anion was present at 850 cm in the IR spectrum
6
of 16. No crystals suitable for X-ray analysis were obtained.
3
Å for compound 5; a = 9.4415(2), b = 13.1788(2),
1
Figure 1. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) h Nmr sꢂꢈꢉꢁꢅꢆ (298 K) ꢃf: (ꢆ) 4 (cDcꢊ , 400 mhz); (b) 14 (DmSo-d , 300 mhz); (ꢉ) 15 (DmSo-d , 400 mhz); (d)
3
6
6
1
6 (DmSo-d , 300 mhz).
6

SꢀPRAMOLECꢀLAR CHEMISTRꢁ
5
Figure 2. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) Sꢋꢂꢈꢅꢄꢇꢂꢃsꢄꢁꢄꢃn ꢃf ꢁꢀꢈ ir sꢂꢈꢉꢁꢅꢆ ꢃf: (ꢅꢈd) 4; (bꢊꢆꢉk) 14.
c = 14.1482(3) Å, α = 75.9666(8)°, β = 79.5063(8)°,
γ = 85.7820(9)°, V = 1678.53(6) Å for compound 6 and
atom shows an average distance of 1.912 Å. (Table 2). The
bridging oxygen atoms (Ob: O3 in Figure 3(a)) show a Mo−
Ob average distance of 1.913 Å (Figure 3(a), Table 2), which
is significantly shorter than the average distance (2.133 Å)
between the bridging O5 methanolic-oxygen atom and
Mo1 and Mo2. In addition, the Mo1–O3–Mo2 bridge shows
an angle of 119.3° while a value of 113.4° was measured for
the bridge Mo1–O5′–Mo2′ in which the bridging oxygen
atom belong to a methanol molecule. Finally, the central
oxygen atoms (Oc: O1) belonging to methanol molecules
showed an average distance of 2.285 Å with respect to
three Mo atoms Mo1, Mo1′ and Mo2′.
3
refined by a full-matrix least-squares technique based on
2
F , SHELXL-97 (11).
Non-hydrogen atoms were refined with anisotropic
displacement parameter, hydrogen atoms were found in
successive Fourier map applications (5), or placed in ideal-
ised positions riding on their attached atoms (C–H 0.93 Å,
Ar
C–HMethyl 0.96 Å, C–HMethine = 0.93 Å, ꢀ (H) = 1.2ꢀ (C)) (6).
iso
iso
The final cycle of least-squares refinement included,
respectively, 351 and 419 parameters, with SHELXL-97
2
2
2
weighting scheme applied: w = 1/[s (F ) + (0.0549P) +
o
2
2
2
2
2
0
P [P = (Fo + 2F )/3] (5) and w = 1/[s (F ) + (0.0652P)
1.5308P [P = (Fo + 2F )/3] (6); final R indices for
Regarding the didecylammonium cation, in the solid
state, two alkyl chains adopt a bended conformation char-
acterised by two unfavourable gauche geometries around
the C(6)–C(7)–C(8)–C(9) and C(11)–C(12)–C(13)–C(14)
bonds with torsion angles of 63° and 68°, respectively
c
o
2
2
+
c
I > 2σ(I) were R = 0.0410 and wR2 = 0.0961 (5) and
R = 0.0441/wR2 = 0.1132 (6).
Complete crystallographic data are available upon
request from the Cambridge Crystallographic Data Centre
+
2
(Figure 3(a)). Along the b-axis (n-C H ) NH cations form
10
21 2
(
12 ꢀnion Road, Cambridge, CB2 1EZ, ꢀK; email: deposit@
hydrogen bond linkages with terminal O–Mo atoms of the
2
−
ccdc.cam.ac.uk), by quoting the depository numbers
CCDC-1013326 (5) and 1013327 (6).
[Mo O (OMe) ] anions generating a chain as shown in
4 10 6
2−
(Table 3). In particular, along this [Mo O (OMe) ] chain,
4
10
6
Compound 5 {[(n-C H ) NH ] ∙[Mo O (OMe) ]}.
two organic cations bridge two consecutive molybdenum
clusters through H-bonds. The ammonium group 1 (see
Figure in Table 3) is H-bonded with the terminal oxygen
atom of the molybdenum cluster O1 with a N1-O1 distance
of 2.75 Å and an N1–H1-O1 angle of 175.0°. Interestingly,
the same ammonium group N1 form a bifurcated H-bond
N1–H2⋯O2 and N1–H2⋯O3 with distances, respec-
tively, of 2.79 and 3.05 Å, and angles of 132.0° and 139.7°,
respectively.
10
21 2
2 2
4
10
6
Compound 5 was isolated as an oxo-methoxy cluster of
2
−
molybdenum (VI) whose structure [Mo O (OMe) ] con-
4
10
6
sists of four pseudooctahedral [MoO ,] with distinct types
6
of Mo−O bond lengths (Figure 3(a)) (12). In particular,
according to their different coordination environments
in the polyanion, the oxygen atoms can be divided into
different groups.
Thus, the terminal oxygen atoms, Ot: O2, O4, O7 and O8
in (Figure 3(a)), show an Mo−Ot average distance of 1.705 Å
The presence of molybdenum (VI) clusters and didec-
ylammonium cations linked by an intermolecular H-bond
network defines a row (Figure 3(b)) from which the aliphatic
(
Table 2), while the terminal oxygen atom O6 (Figure 3(a))
belonging to a methanol molecule linked to molybdenum

6
C. TALOTTA ET AL.
Figure 3. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) (ꢆ) mꢃꢊꢌbdꢆꢁꢈ ꢇꢃꢊꢈꢉꢋꢊꢆꢅ sꢁꢅꢋꢉꢁꢋꢅꢈ ꢃf ꢉꢃꢇꢂꢃꢋnd 5 {[(n-c h ) Nh ] ∙[mꢃ o (omꢈ) ]} wꢄꢁꢀ ꢆꢁꢃꢇs nꢋꢇbꢈꢅꢄng
1
0
21 2
2 2
4
10
6
sꢉꢀꢈꢇꢈ [Sꢌꢇꢇꢈꢁꢅꢌ: i) −x, −1 − y, −z]. (b) Vꢄꢈw ꢃf ꢁꢀꢈ ꢃnꢈ-dꢄꢇꢈnsꢄꢃnꢆꢊ {[(n-c h ) Nh ] ∙[mꢃ o (omꢈ) ]} ꢉꢀꢆꢄn ꢆꢊꢃng ꢁꢀꢈ a-ꢆxꢄs. (ꢉ ꢆnd
1
0
21 2
2 2
4
10
6
d) Vꢄꢈw ꢃf ꢁꢀꢈ ꢊꢄꢂꢄd-ꢊꢄkꢈ bꢄꢊꢆꢌꢈꢅ ꢆssꢈꢇbꢊꢌ ꢆꢊꢃng ꢁꢀꢈ b-ꢆxꢄs.
chains of the ammonium ions are branching in a herring-
bone like way (Figure 3(c) and (d)). In this way, parallel rows
stack along the a direction embedding the alkyl chains via
van der Waals interactions (Figure 3(c) and (d)) and giving
rise to a lipid-like bilayer assembly.
1.699 Å (Table 2). The bridging oxygen atoms (Ob) Mo(1)-
O(7)-Mo(4) and Mo(4’)-O(13’)-Mo(2) show a Mo−Ob aver
-
age distance of1.920 and 1.904 Å (Table 2), respectively,
and an angle of 118.1° and 118.3°. The central oxygen
atoms O(3) and O(4) bridged to Mo(1), Mo(2) and Mo(3)
show an average distance of 2.098 and 2.090 Å (Table 2),
respectively.
Compound 6 {(BnNH CH CH NH Bn) ∙[Mo O ]}.
2
2
2
2
2
8
26
The X-ray crystal structure revealed the presence of
4
−
β-[Mo O ]
octamolybdate tetraanionic clusters
Finally, the central oxygen atom O(8) (Figure 4(a)) linked
to five metallic centres shows an average distance of 2.335 Å.
8
26
(
Figure 4(a)). Interestingly, the octamolybdate species
2
−
presents nine structural isomers (13) including the β form,
which is characterised by eight distorted edge-shared
octahedral [MoO6].
Analogouslytotheaboveassemblyof[Mo O (OMe) ] ,
4 10 6
also in this case we observed a chain constituted by
4
−
β-[Mo O ] clusters alternating to bis(alkylbenzylam-
8
26
2
−
Analogously to the [Mo O (OMe) ] above described,
monium) cations running along the c-axis (Figure 4(b)),
which are linked through H-bonds between organic and
inorganic building blocks (Figure in Table 4). In particu-
lar, a H-bond network was established between two
4
10
6
4−
the β-[Mo O ] octamolybdate tetraanionic cluster shows
8
26
different oxygen atoms. Thus, the terminal oxygen atoms
Ot in (Figure 4(a)), present an Mo−Ot average distance of

SꢀPRAMOLECꢀLAR CHEMISTRꢁ
7
4
−
Figure 4. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) (ꢆ) mꢃꢊꢌbdꢆꢁꢈ ꢇꢃꢊꢈꢉꢋꢊꢆꢅ sꢁꢅꢋꢉꢁꢋꢅꢈ ꢃf [mꢃ o ] ꢄn ꢉꢃꢇꢂꢃꢋnd 6, wꢄꢁꢀ ꢆꢁꢃꢇs nꢋꢇbꢈꢅꢄng sꢉꢀꢈꢇꢈ [Sꢌꢇꢇꢈꢁꢅꢌ: i)
8
26
1
− x; −y, 1 − z.]. (b) Vꢄꢈw ꢃf ꢁꢀꢈ ꢃnꢈ-dꢄꢇꢈnsꢄꢃnꢆꢊ {(BnNh ch ch Nh Bn) ∙[mꢃ o ]} ꢉꢀꢆꢄn ꢆꢊꢃng ꢁꢀꢈ a-ꢆxꢄs. (ꢉ) Vꢄꢈw ꢃf ꢁꢀꢈ 3D ꢆꢅꢉꢀꢄꢁꢈꢉꢁꢋꢅꢈ
2 2 2 2 2 8 26
ꢆꢊꢃng ꢁꢀꢈ a-ꢆxꢄs. (d) pꢆꢅꢁꢄꢉꢋꢊꢆꢅ ꢃf ꢁꢀꢈ c–h⋯π ꢄnꢁꢈꢅꢆꢉꢁꢄꢃn bꢈꢁwꢈꢈn bꢈnzꢌꢊꢄꢉ gꢅꢃꢋꢂs ꢃf ꢁwꢃ ꢆdjꢆꢉꢈnꢁ ꢆꢇꢇꢃnꢄꢋꢇ ꢉꢆꢁꢄꢃns. (ꢈ) pꢆꢅꢁꢄꢉꢋꢊꢆꢅ ꢃf
ꢁꢀꢈ π⋯π ꢄnꢁꢈꢅꢆꢉꢁꢄꢃn bꢈꢁwꢈꢈn ꢂꢀꢈnꢌꢊ gꢅꢃꢋꢂs ꢃf ꢁwꢃ ꢆdjꢆꢉꢈnꢁ ꢆꢇꢇꢃnꢄꢋꢇ ꢉꢆꢁꢄꢃns.
bis(alkylbenzylammonium) cations sandwiched between
2.97 Å and with an N2–H4–O6 angle of 173°. The packing
along the a,b plane presents a peculiar interactional motif
between the hydrophobic groups of the bis(alkylben-
zylammonium) cations. In particular, along the a,b plane a
benzylic hydrogen atom interacts via C–H⋯π interactions
with a phenyl ring of the contiguous bis(alkylbenzylam-
monium) (Figure 4(c) and (d)) cation.
4
−
two β-[Mo O ] clusters and DMF and H O solvent
8
26
2
molecules. Thus, the terminal oxygen atom O1 of one
tetranionic cluster is H-bonded to the ammonium group
N1 (see Figure in Table 4) with a distance of 2.90 Å and
an angle O1–H1–N1 of 168°. In addition, N1 presents a
bifurcated H-bond with the DMF molecule (in blue), with
a N1–O2 distance of 2.90 Å and an angle N1–H2–O2 of
This interaction presents a C⋯Ar-centroid distance of
3.39 Å and a C–H⋯Ar-centroid distance of 2.63 Å.
1
19°, and with the H O molecule (in yellow, Table 4) with
2
a N1–O3 distance of 2.82 Å and an N1–H2–O3 angle of
37°. The H O molecule in turn acts as H- bond donor
Interestingly, the free phenyl rings interact along the
a,c plane by a face-to-face stacked geometry (Figure 4(e))
with phenyl rings of contiguous bis(alkylbenzylammo-
nium) ions. In this case, a distance of 3.50 Å was meas-
ured between two stacked Ar rings with an offset of 1.39
Å between the centroid–centroid axes (Figure 4(e)) (14).
Last, weak but non-negligible inter-molecular C–H⋯O
hydrogen bonds are observed in both structures (15),
with donor⋯acceptor distances ranging from 3.00 up
to 3.40 Å and CHO angles over 120°, acting as support
1
2
group towards the terminal oxygen atom of the second
molybdenum cluster, with an O3–O5 distance of 2.91 Å,
and towards the second DMF molecule (in green), with an
O3–O4 distance of 2.68 Å (Table 4). Finally, the ammonium
group N2 is H-bonded to the carbonyl group of the DMF
(
in blue), with a N2–O2 distance of 2.83 Å and a N2–H3–
O2 angle of 149°, and with the O6 oxygen atom of the
second molybdenum cluster, with a N2–O6 distance of

8
C. TALOTTA ET AL.
4
−
Figure 5. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) (ꢆ) cꢅꢌsꢁꢆꢊꢊꢃgꢅꢆꢂꢀꢄꢉ sꢁꢅꢋꢉꢁꢋꢅꢈ ꢃf ꢉꢃꢇꢂꢃꢋnd 11: ꢁꢀꢈ ꢁꢈꢁꢅꢆꢆnꢄꢃnꢄꢉ ꢃꢉꢁꢆ-ꢇꢃꢊꢌbdꢆꢁꢈ [mꢃ o ] ꢉꢊꢋsꢁꢈꢅ ꢄs sꢋꢅꢅꢃꢋndꢈd
8
26
bꢌ fꢃꢋꢅ ꢈꢁꢀꢌꢊ-ꢁꢅꢄꢂꢀꢈnꢌꢊ-ꢂꢀꢃsꢂꢀꢃnꢄꢋꢇ ꢉꢆꢁꢄꢃns. (b) tꢀꢈ ꢃꢉꢁꢆꢆnꢄꢃnꢄꢉ poms ꢆꢅꢈ ꢄnꢁꢈꢅꢉꢆꢊꢆꢁꢈd bꢈꢁwꢈꢈn ꢉꢆꢁꢄꢃnꢄꢉ ꢊꢆꢌꢈꢅs ꢃf ꢁꢀꢈ ꢂꢀꢃsꢂꢀꢃnꢄꢋꢇ
ꢄꢃns ꢁꢀꢆꢁ ꢊꢈꢆvꢈ ꢃꢂꢈn ꢉꢀꢆnnꢈꢊs ꢃꢉꢉꢋꢂꢄꢈd bꢌ DmF sꢃꢊvꢈnꢁ ꢇꢃꢊꢈꢉꢋꢊꢈs (ꢉ).
for the previously described investigations and thus
contributing to further stabilise the three-dimensional
frameworks.
solved through the direct methods procedure of SIR2011
(10), and refined by the full-matrix least-squares method
2
based on F , using SHELXL-13 (17). Empirical absorption
corrections were applied for the intensities from both crys-
tals, by using the XABS2 software (18).
2
.5. X-ray diffraction study for phosphonium-based
4
−
Besides the presence of half [Mo O ] and two phos-
8
26
POM derivative 11
phonium ions in the asymmetric unit of 11, a DMF mole-
cule was found disordered over two positions around an
inversion centre. The two orientations of the DMF mole-
cule were refined at equal partial occupancy.
Non-hydrogen atoms with occupancy higher than 50%
were refined anisotropically.
Complete crystallographic data are available upon
request from the Cambridge Crystallographic Data Centre
(12 ꢀnion Road, Cambridge, CB2 1EZ, ꢀK; email: deposit@
Crystals of compound 11 and the corresponding ones
soaked in n-pentane were analysed at the XRD1 beamline
of the Elettra synchrotron (Trieste, Italy), by employing the
rotating-crystal method with the cryo-cooling technique.
Routinely, the crystal dipped in Paratone, as cryo-pro-
tectant, was mounted in a loop and flash frozen to 100 K
with liquid nitrogen. Diffraction data were integrated and
scaled by using the XDS package (16). The structures were

SꢀPRAMOLECꢀLAR CHEMISTRꢁ
9
Figure 6. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) (tꢃꢂ) asꢌꢇꢇꢈꢁꢅꢄꢉ ꢋnꢄꢁ ꢉꢃnꢁꢈnꢁ ꢃf ꢁꢀꢈ ꢉꢅꢌsꢁꢆꢊs sꢃꢆkꢈd ꢄn n-ꢂꢈnꢁꢆnꢈ, wꢄꢁꢀ ꢆꢁꢃꢇ nꢋꢇbꢈꢅꢄng sꢉꢀꢈꢇꢈ. onꢈ ꢃf ꢁꢀꢈ
4
−
ꢁ
wꢃ ꢀꢆꢊvꢈs ꢃf ꢁꢀꢈ β-[mꢃ o ] ꢃꢉꢁꢆꢇꢃꢊꢄbdꢆꢁꢈ ꢆnꢄꢃns wꢆs ꢃꢇꢄꢁꢁꢈd fꢃꢅ ꢉꢊꢆꢅꢄꢁꢌ. (Bꢃꢁꢁꢃꢇ) Vꢄꢈw ꢃf ꢁꢀꢈ ꢁwꢃ dꢄꢇꢈꢁꢀꢌꢊꢆꢇꢇꢃnꢄꢋꢇ ꢉꢆꢁꢄꢃns
8 26
4
−
bꢅꢄdgꢄng ꢁwꢃ β-[mꢃ o ] ꢃꢉꢁꢆꢇꢃꢊꢄbdꢆꢁꢈ ꢆnꢄꢃns ꢁꢀꢅꢃꢋgꢀ bꢄfꢋꢅꢉꢆꢁꢈd ꢆnd ꢁꢅꢄfꢋꢅꢉꢆꢁꢈd h-bꢃnds.
8
26
4
−
ccdc.cam.ac.uk), by quoting the depository numbers
CCDC-1415172, 1416395.
unit the presence of half β-[Mo O ] octamolybdate tetraan-
8 26
ionic cluster and two ethyl-triphenyl-phosphonium species
as counterions (Figure 5(a)).The octamolybdate anion found
in the crystallographic structure of the compound 11, shows
Compound 11 {[(Ph) PCH CH ] x[Mo O ]}. Also in this
3
2
3 4
8
26
case, the X-ray crystal structure revealed in the asymmetric

10
C. TALOTTA ET AL.
Figure 7. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) (ꢆ) hꢃnꢈꢌꢉꢃꢇb ꢆꢅꢅꢆngꢈꢇꢈnꢁ ꢃf ꢁꢀꢈ dꢄꢇꢈꢁꢀꢌꢊꢆꢇꢇꢃnꢄꢋꢇ ꢉꢆꢁꢄꢃns ꢆꢊꢃng ꢁꢀꢈ ꢆꢉ ꢂꢊꢆnꢈ. (b) tꢀꢈ ꢀꢈxꢆgꢃnꢆꢊ ꢀꢃꢊꢈs
ꢃsꢁ ꢃꢉꢁꢆ-ꢆnꢄꢃnꢄꢉ pom ꢉꢊꢋsꢁꢈꢅs. (ꢉ) tꢀꢈ ꢃvꢈꢅꢆꢊꢊ ꢆnꢄꢃnꢄꢉ ꢊꢆꢌꢈꢅs ꢆꢅꢈ ꢀꢈꢊd ꢁꢃgꢈꢁꢀꢈꢅ bꢌ ꢄnꢁꢈꢅꢉꢆꢊꢆꢁꢈd ꢂꢃsꢄꢁꢄvꢈ ꢊꢆꢌꢈꢅs, ꢉꢃnsꢄsꢁꢄng ꢃf ꢈꢁꢀꢌꢊ-
ꢅꢄꢂꢀꢈnꢌꢊ-ꢂꢀꢃsꢂꢀꢃnꢄꢋꢇ ꢉꢆꢁꢄꢃns.
ꢀ
ꢁ
But
But
But
But
But
But
But
But
(
Na)2MoO4x2H2O
H2O pH = 5.0/CH3OH
O
O O
O
O
O O
O
2-
2
Mo O
6 19
Cl-
NH NH
HN
Cl-
HN
NH NH
HN
HN
Cl-
Cl-
4
15
Scheme 6. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)
similar Mo−O bond lengths and similar Mo−O−Mo bond
angles with respect to those reported in (Table 2) for the
(7Å × 7 Å) occupied by DMF solvent molecules, running
along the b-axis (Figure 5(b) and (c)).
The corresponding crystals of compound 11 soaked in
n-pentane for one week afforded a crystal structure very
different from the native one. From the single-crystal
X-ray diffraction analysis it resulted that the cell changed
4−
β-[Mo O ] tetraanionic cluster of 6.
8
26
4
−
Interestingly, a chain constituted by β-[Mo O ] clus-
8
26
ters runs along the a-axis, where the single POMs anions
are intercalated between the cationic layers of phos-
phonium ions, that leave open hydrophobic channels
space group from P 2 /n (monoclinic) to P − 1 (triclinic).
1

SꢀPRAMOLECꢀLAR CHEMISTRꢁ
11
But
But
But
But
But
But
But
But
(
Na)2MoO4x2H2O
H2O/HCl 12 M/CH3OH
O
O O
O
O
O O
O
4-
Mo O
8
26
Cl-
NH NH
HN
Cl-
HN
NH NH
HN
HN
Cl-
Cl-
4
16
Scheme 7. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ)
Table 1. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) Dꢆꢁꢆ ꢉꢃꢊꢊꢈꢉꢁꢄꢃn ꢂꢆꢅꢆꢇꢈꢁꢈꢅs fꢃꢅ ꢉꢅꢌsꢁꢆꢊs 5
ꢆnd 6.
Table 2. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) Bꢃnd ꢊꢈngꢁꢀs (Å) fꢃꢅ ꢇꢃꢊꢌbdꢆꢁꢈ ꢉꢊꢋsꢁꢈꢅs
2
−
4−
[mꢃ o (omꢈ) ] ꢆnd β-[mꢃ o ] .
4
10
6
8 26
2
−
4−
Compound 5
Compound 6
[Mo O (OMe) ]
β-[Mo O ]
8 26
4
10
6
cꢆꢇbꢅꢄdgꢈ dꢆꢁꢆbꢆsꢈ nꢅ.
eꢇꢂꢄꢅꢄꢉꢆꢊ fꢃꢅꢇꢋꢊꢆ
Fꢃꢅꢇꢋꢊꢆ wꢈꢄgꢀꢁ
tꢈꢇꢂꢈꢅꢆꢁꢋꢅꢈ (K)
Wꢆvꢈꢊꢈngꢁꢀ (Å)
cꢈꢊꢊ ꢅꢈflꢈꢉꢁꢄꢃns, θ ꢅꢆngꢈ
cꢅꢌsꢁꢆꢊ sꢌsꢁꢈꢇ
Sꢂꢆꢉꢈ gꢅꢃꢋꢂ
a (Å)
ccDc 1013326
c23h53mꢃ No
663.54
293(2)
0.71073
319 (3.44°−18.55°)
tꢅꢄꢉꢊꢄnꢄꢉ
ccDc 1013327
c22h36mꢃ N o
996.31
293(2)
0.71073
155 (3.45°−18.45°)
tꢅꢄꢉꢊꢄnꢄꢉ
mꢃ1–o2
mꢃ1–o4
mꢃ1–o3
mꢃ1–o5i
mꢃ1–o1i
mꢃ1–o1
mꢃ2–o7
mꢃ2–o8
mꢃ2–o6
mꢃ2–o3
mꢃ2–o5
mꢃ2–o1
N1–c11
N1–c10
c1–c2
c2–c3
c3–c4
c4–c5
c5–c6
c6–c7
c7–c8
c8–c9
c9–c10
c11–c12
c12–c13
c13–c14
c14–c15
c15–c16
c16–c17
c17–c18
c18–c19
c19–c20
o1–c21
o5–c22
o6–c23
1.694(2)
1.714(3)
1.847(3)
2.042(3)
2.195(2)
2.396(2)
1.689(3)
1.725(3)
1.912(2)
1.980(2)
2.224(2)
2.265(3)
1.479(5)
1.485(5)
1.472(13)
1.435(11)
1.494(9)
1.419(9)
1.520(8)
1.441(8)
1.504(8)
1.517(7)
1.479(6)
1.512(6)
1.517(6)
1.524(6)
1.500(7)
1.514(7)
1.472(7)
1.509(7)
1.440(8)
1.490(8)
1.439(5)
1.412(6)
1.409(5)
mꢃ1–o1
mꢃ1–o2
mꢃ1–o7
mꢃ1–o4
mꢃ1–o8
mꢃ1–o3
mꢃ2–o5
mꢃ2–o6
mꢃ2–o13i
mꢃ2–o3
mꢃ2–o4
mꢃ2–o8i
mꢃ3–o9
mꢃ3–o10
mꢃ3–o3
mꢃ3–o4i
mꢃ3–o8i
mꢃ3–o8
mꢃ4–o12
mꢃ4–o11
mꢃ4–o13
mꢃ4–o7
mꢃ4–o10
mꢃ4–o8
c1–c6
1.693(3)
1.716(3)
1.908(3)
2.000(3)
2.274(3)
2.349(3)
1.693(3)
1.699(3)
1.895(3)
2.002(3)
2.320(3)
2.351(3)
1.683(3)
1.748(3)
1.945(3)
1.951(3)
2.142(3)
2.391(3)
1.692(3)
1.719(3)
1.913(3)
1.932(3)
2.263(3)
2.519(3)
1.376(7)
1.394(7)
1.504(6)
1.376(8)
1.356(9)
1.363(10)
1.389(9)
1.487(6)
1.496(5)
1.500(6)
1.497(5)
1.502(5)
1.503(6)
1.374(7)
1.381(7)
1.387(8)
1.372(9)
1.355(9)
1.397(8)
1.321(7)
1.426(9)
1.454(8)
1.241(7)
1.278(8)
1.425(10)
1.459(9)
2
8
4
4
16
P − 1
P − 1
10.0520(6)
11.0540(7)
15.2870(14)
88.632(8)
9.4415(2)
13.1788(2)
14.1482(3)
75.9666(8)
79.5063(8)
85.7820(9)
1678.53(6)
2, 1.971
b (Å)
c (Å)
α (°)
β (°)
78.980(6)
67.102(5)
1533.51(19)
2, 1.437
0.858
γ (°)
3
V (Å )
Z, ρ (mgꢇ−3)
ꢉꢆꢊꢉ.
−1
μ (ꢇꢇ
)
1.534
984
F(000)
692
cꢅꢌsꢁꢆꢊ sꢄzꢈ (ꢇꢇ)
Sꢀꢆꢂꢈ, ꢉꢃꢊꢃꢋꢅ
0.10 × 0.20 × 0.40
iꢅꢅꢈgꢋꢊꢆꢅ, ꢉꢃꢊꢃꢋꢅꢊꢈss
0.10 × 0.20 × 0.60
iꢅꢅꢈgꢋꢊꢆꢅ, ꢉꢃꢊꢃꢋꢅ-
ꢊꢈss
3.06°−30.00°
47704/9760
0.0796
Dꢆꢁꢆ ꢉꢃꢊꢊꢈꢉꢁꢄꢃn θ ꢅꢆngꢈ
rꢈfl. ꢉꢃꢊꢊꢈꢉꢁꢈd/ꢋnꢄqꢋꢈ
Rꢄnꢁ
5.03°−27.50°
18085/6964
0.0489
cꢃꢇꢂꢊꢈꢁꢈnꢈss
98.9%
98.8%
mꢆx. ꢆnd ꢇꢄn. ꢁꢅꢆnsꢇꢄssꢄꢃn
rꢈfinꢈꢇꢈnꢁ ꢇꢈꢁꢀꢃd
Dꢆꢁꢆ/ꢅꢈsꢁꢅꢆꢄnꢁs/ꢂꢆꢅꢆꢇꢈꢁꢈꢅs
GoF
R1 ꢄndꢄꢉꢈs [I > 2σ(I)]
wR2 ꢄndꢄꢉꢈs [I > 2σ(I)]
R1 ꢄndꢄꢉꢈs (ꢆꢊꢊ dꢆꢁꢆ)
wR2 ꢄndꢄꢉꢈs (ꢆꢊꢊ dꢆꢁꢆ)
lS sꢀꢄfꢁ sꢋ ꢇꢆx/ꢇꢈꢆn
lꢆꢅg. dꢄff. ꢂꢈꢆk/ꢀꢃꢊꢈ (ꢈ·Å−3)
0.983 ꢆnd 0.967
0.985 ꢆnd 0.914
c1–c2
c1–c7
c2–c3
c3–c4
c4–c5
c5–c6
c7–N1
N1–c8
2
2
FmlS ꢃn F
FmlS ꢃn F
6694/0/351
1.042
0.0410
0.0961
0.0683
0.1098
0.000/0.000
0.435/−1.450
9760/2/419
1.019
0.0441
0.1132
0.0749
0.1246
0.000/0.001
0.154/−1.059
c8–c9
c9–N2
N2–c10
c10–c11
c11–c12
c11–c16
c12–c13
c13–c14
c14–c15
c15–c16
N1a–c3a
N1a–c1a
N1a–c2a
c3a–o1a
N1B–c3B
N1B–c2B
N1B–c1B
The asymmetric unit of the soaked crystals contained
two halves of the β-[Mo O ] octamolibdate anion and
4
−
8
26
two ethyl-triphenyl-phosphonium ions. Surprisingly,
two dimethylammonium cations were located hydrogen
bonded to the octamolybdate clusters with distances
ranging from 2.788(5) to 3.139(5) Å (see Figure 6).
Likely, the dimethylammonium cations have been
formed in acidic medium by hydrolysis of the DMF cat-
alysed by MoO , as suggested by Gili and coworkers (19).
3
In this crystal structure, the small dimethylammonium
cations play the adhesive role between metal clusters. As
Nꢃꢁꢈ: hꢌdꢅꢃgꢈn ꢆꢁꢃꢇs ꢃf nꢃn-ꢉꢃꢃꢅdꢄnꢆꢁꢈd o100 wꢆꢁꢈꢅ ꢇꢃꢊꢈꢉꢋꢊꢈ wꢈꢅꢈ nꢃꢁ
fꢃꢋnd bꢌ Fꢃꢋꢅꢄꢈꢅ ꢇꢆꢂ ꢆꢂꢂꢊꢄꢉꢆꢁꢄꢃn ꢄn (5).

12
C. TALOTTA ET AL.
Table 3. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) cꢃꢇꢂꢃꢋnd 5: h-bꢃndꢄng ꢄnꢁꢈꢅꢆꢉꢁꢄꢃns
bꢅꢄdgꢄng ꢉꢃnsꢈꢉꢋꢁꢄvꢈ pom ꢉꢊꢋsꢁꢈꢅs ꢄn ꢆ ꢉꢀꢆꢄn.
Table 5. cꢅꢌsꢁꢆꢊ dꢆꢁꢆ ꢆnd ꢅꢈfinꢈꢇꢈnꢁ dꢈꢁꢆꢄꢊs fꢃꢅ nꢆꢁꢄvꢈ ꢉꢅꢌsꢁꢆꢊs ꢃf
ꢉꢃꢇꢂꢃꢋnd 11 ꢆnd ꢁꢀꢃsꢈ sꢃꢆkꢈd ꢄn n-ꢂꢈnꢁꢆnꢈ.
Crystal soaked in
1
1
n-pentane
eꢇꢂꢄꢅꢄꢉꢆꢊ fꢃꢅꢇꢋꢊꢆ
mꢃ o26, 4(c20 h20 p),
mꢃ o26, 4(c20 h20 p),
8
8
3
(c h N)
4(c h N)
3
7
2
8
Fꢃꢅꢇꢋꢊꢆ wꢈꢄgꢀꢁ
T (K)
4959.98
100(2)
0.800
3716.72
100(2)
0.700 Å
tꢅꢄꢉꢊꢄnꢄꢉ
P −1
λ (Å)
cꢅꢌsꢁꢆꢊ sꢌsꢁꢈꢇ
Sꢂꢆꢉꢈ gꢅꢃꢋꢂ
unꢄꢁ ꢉꢈꢊꢊ dꢄꢇꢈnsꢄꢃns
mꢃnꢃꢉꢊꢄnꢄꢉ
P 2 /n
1
a = 17.675(2), α = 90
a = 12.52(1), α =
(Å, °)
71.525(3)
b = 12.928(1), β =
b = 12.90(1), β =
85.404(2)
9
2.81(2)
c = 19.838(2), γ = 90
c = 18.47(1), γ =
8
6.809(2)
V (Å3)
4527.6(8)
4
1.819
1.663
2470
2821(3)
2
2.188
1.771
1816
Z
N1–o1 2.75 Å
N1–o2 2.79 Å
N1–o3 3.05 Å
N1–h1–o1 175.0°
N1–h2–o3 139.7°
N1–h2–o2 132.0°
3
ρ
(g/ꢇꢇ )
μ (ꢇꢇ
ꢉꢆꢊꢉ
−1
)
F(000)
rꢈflꢈꢉꢁꢄꢃns ꢉꢃꢊꢊꢈꢉꢁꢈd
Dꢆꢁꢆ/ꢅꢈsꢁꢅꢆꢄnꢁs/ꢂꢆꢅꢆꢇ-
ꢈꢁꢈꢅs
10007
10,007/0/571
9280
9280/0/745
Table 4. (cꢃꢊꢃꢋꢅ ꢃnꢊꢄnꢈ) Fꢋndꢆꢇꢈnꢁꢆꢊ h-bꢃndꢄng ꢄnꢁꢈꢅꢆꢉꢁꢄꢃns ꢄn
ꢉꢃꢇꢂꢃꢋnd 6.
GꢃꢃF
R1, wR2
1.177
0.0448, 0.1180
0.0451, 0.1184
1.109
0.0371, 0.0975
0.0377, 0.0979
R , wR (ꢆꢊꢊ dꢆꢁꢆ)
1
2
Table 6. hꢌdꢅꢃgꢈn bꢃnd dꢄsꢁꢆnꢉꢈs ꢆnd ꢆngꢊꢈs bꢈꢁwꢈꢈn ꢁꢀꢈ dꢄ-
4
−
ꢇꢈꢁꢀꢌꢊꢆꢇꢇꢃnꢄꢋꢇ ꢉꢆꢁꢄꢃns ꢆnd ꢁꢀꢈ β-[Mo o ] ꢃꢉꢁꢆꢇꢃꢊꢄbdꢆꢁꢈ
8
26
ꢆnꢄꢃns (Å, °).
d(N⋯O)
N(1d)–h(1d4)⋯o(11)
N(1d)–h(1d4)⋯o(26)
N(1d)–h(1d5)⋯o(9)
N(1d)–h(1d5)⋯o(15)
N(1d)–h(1d5)⋯o(16)
N(1ꢈ)–h(1ꢈ1)⋯o(10)
N(1ꢈ)–h(1ꢈ1)⋯o(24)
N(1ꢈ)–h(1ꢈ2)⋯o(1)
2.876(5)
2.825(5)
3.137(5)
2.878(5)
3.139(5)
2.917(5)
2.788(5)
3.084(5)
2.912(5)
3.255(5)
2.917(5)
118.7
158.2
134.7
129.6
138.9
120.2
155.9
128.5
129.7
149.4
120.2
ꢄ
N(1ꢈ)–h(1ꢈ2)⋯o(3)
N(1ꢈ)–h(1ꢈ2)⋯o(25)
N(1ꢈ)–h(1ꢈ1)⋯o(10)
N1–o1 2.90 Å
N1–o2 2.90 Å
N1–o3 2.82 Å
o3–o5 2.91 Å
o3–o4 2.68 Å
N2–o2 2.83 Å
N2–o6 2.97 Å
ꢄ−x + 1, −y + 1, −z + 2.
means of hydrogen bonds with ammonium cations. In par-
ticular, a 2+2 motif is observed in which two consecutive
clusters are H-bonded by means of two dialkylammonium
cations. Interestingly, the large hydrophobic moieties of
the organic cations establish peculiar interactions (van
der Waals, C–H⋯π and π⋯π) which are fundamental to
stabilise the assembled architectures. The knowledge of
the interactions able to stabilise this solid-state supramo-
lecular architectures could allow the design of novel POM-
based hybrid organic/inorganic materials with important
functions or applications.
shown in Figure 7(a) and (b), the dimethylammonium cat-
ions are arranged in honeycomb layers, where six cations
surround an octaanionic POM. The latter overall negatively
charged layers are intercalated by the positively charged
ones consisting of the larger ethyl-triphenyl-phosphonium
cations (Figure 7(c)), resembling the clay structure.
3
. Conclusions
In conclusion, we have reported the synthesis and the
X-ray crystal structure of some POM-based hybrid organic/
inorganic compounds. In the solid-state architectutres,
polyoxomolybdate clusters were assembled with dialky-
lammonium and bis(dialkylammonium) cations. Both
4. Experimental section
4
.1. General comments
2
−
4−
[
Mo O (OMe) ] and β-[Mo O ] polyanionic clusters
All chemicals were of reagent grade and were used with-
out further purification. Anhydrous DMF and THF were
4
10
6
8
26
form chains in which the metallic clusters are linked by

SꢀPRAMOLECꢀLAR CHEMISTRꢁ
13
purchased and used without further purification. Reaction
temperatures were measured externally; reactions were
monitored by TLC on silica gel plates (0.25 mm) and visual-
ised by ꢀV light and spraying with H SO –Ce(SO ) . All 1D
0.14 mmol, 82%), which was dissolved in warm methanol.
Slow evaporation of the methanol solution gave crystals
suitable for X-ray analysis.
2
1
4
4 2
13
NMR spectra were recorded at 400 ( H) and 100 ( C) MHz
4.2.4. Synthesis of compound 6
1
on Bruker Avance-400 spectrometer, or at 300 ( H) and
An aqueous solution of (NH ) Mo O ·4H O (0.10 g,
4
6
7
24
2
1
3
7
5.5 MHz ( C) on a Bruker Avance-300 spectrometer, or
0.081 mmol in 10 mL) was acidified with 2.0 mL of 0.01 M
HCl. Methanol solution (5 mL) of (BnNH CH CH NH Bn)
1
13
at 250 ( H) and 62.8 MHz ( C) on a Bruker Avance-250
spectrometer; chemical shifts are reported relative to the
residual solvent peak.
2
2
2
2
Cl (0.30, 0.243 mmol) was added and a precipitate was
2
formed. The solution was filtered and the precipitate was
washed with water and methanol to give a white solid
(
1
0.10 g, 0.073 mmol, 90%), which was dissolved in a warm
:1 mixture of methanol/DMF. Slow evaporation of this
4
1
.2. Synthesis of derivatives 1, 4, 5, 6, 10, 11, 13, 14,
5 and 16
solution gave crystals suitable for X-ray analysis (seeTables
5 and 6).
4
.2.1. Synthesis of derivative 1
Didecylamine (1.0 g, 3.4 mmol) was dissolved in Et O
2
(
30 mL) at room temperature and an aqueous solution of
4.2.5. Synthesis of derivative 10
HCl (37% w/w, 0.5 mL) was added dropwise. The mixture
was kept under stirring for 15 min, until a white precipitate
was formed. The solid was collected by filtration, washed
To a solution of benzaldehyde (3.5 g, 3.4 mL, 33.3 mmol)
in CHCl (5 mL) was added 1,2-diaminoethane (1.0 g,
3
16.7 mmol). The reaction mixture was stirred at room
temperature for 30 min. The solvent was evaporated
to give the imine intermediate 8 as a yellow solid in a
quantitative yield. The solid was used for the next step
without further purification. The imine 8 was dissolved
in dry MeOH (100 mL) under a nitrogen atmosphere and
with MeOH (10 mL) and CH CN (10 mL) and dried under
3
vacuum, to give derivative [(n-C H ) NH ]Cl 1 as a white
1
0
21 2
2
1
solid (0.96 g, 2.9 mmol, 84%). H NMR (250 MHz, CD OD,
3
2
2
98 K): δ 0.90 (t, J = 6.0 Hz, 6H), 1.31–1.38 (overlapped,
8H), 1.69 (broad, 4H), 2.97 (t, J = 8.0 Hz, 4H). C NMR
1
3
(
63 MHz, CD OD, 298 K): δ 13.2, 22.4, 26.1, 26.3, 29.0, 29.2,
NaBH (1.10 g, 28.2 mmol) was added at 0 °C and then the
3
4
2
1
9.3, 29.4, 31.8, 47.7. Anal. Calcd for C H ClN: C, 71.92; H,
3.28. Found: C, 71.83; H, 13.37.
mixture was allowed to warm at room temperature. The
solution was kept under stirring for 1 h. The solvent was
removed under reduced pressure and the residue parti-
2
0
44
4
.2.2. Synthesis of compound 4
To a mixture of 13 (2.3 g, 2.1 mmol)
°C was added LiAlH (3.2 g, 84 mmol) and successively
tioned between Et O (150 mL) and an aqueous saturated
2

in dry THF (65 mL)

at
solution of NaHCO (150 mL). The organic layer was dried
3
0
over MgSO and the solvent was removed under reduced
4
4
refluxed under N for 8 h. Then 150 mL of a 1 N HCl solu-
pressure, to give derivative 9 as a white solid. The solid
2
tion was added (caution) and the product was extracted
with ethyl acetate (2 × 50 mL). The organic phase was
dried on Na SO filtered and the solvent was removed in
was used for the next step without further purification.
Derivative 9 was dissolved in Et O (50 mL) at room temper-
2
ature and an aqueous solution of HCl (37% w/w, 2.0 mL)
was added dropwise. The mixture was kept under stirring
for 30 min, until a white precipitate was formed. The solid
was collected by filtration, washed with MeOH (50 mL) and
2
4
1
vacuo to give 4 as a white solid (1.4 g, yield 56%). H NMR
400 MHz, CDCl , 298 K): δ 11.70 (br s, NH, 4H), 6.79 (s, ArH,
(
3
8
3
+
H), 4.55 (br t, OCH , 8H), 4.31 (d, ArCH Ar, J = 12.9 Hz, 4H),
2
2
.81 (broad, CH NH, 8H), 3.20–3.50 (overlapped, ArCH Ar
CH CN (50 mL) and dried under vacuum, to give deriva-
2
2
3
1
CH NH, 20H), 1.42 (t, CH , J = 8.1 Hz, 24H), 1.09 (s,
tive 10 as a white solid (4.3 g, 13.8 mmol, 83%). H NMR
2
3
1
3
–
1
C(CH ) , 36H); C NMR (100 MHz, CDCl , 298 K): δ 151.4,
46.0, 133.1, 125.5, 68.8, 50.7, 47.1, 33.8, 31.3, 31.1, 8.7.
(250 MHz, DMSO-d , 298 K): δ 3.39 (broad, 4H, H ), 4.21
3
3
3
6
a
13
(broad, 4H, H ),7.44–7.64 (overlapped, 10H, H ). C NMR
b c-e
Anal. Calcd for C H Cl N O : C, 68.55; H, 9.47. Found: C,
(63 MHz, DMSO-d , 298 K): δ 43.3, 50.8, 129.3, 129.6, 130.6,
6
8
112
4
4
4
6
6
8.64; H, 9.39.
132.3. Anal. Calcd for C H Cl N : C, 61.34; H, 7.08. Found:
1
6
22
2
2
C, 61.25; H, 7.17.
4
.2.3. Synthesis of compound 5
An aqueous solution of (NH ) Mo O ·4H O (0.21 g,
4.2.6. Synthesis of compound 11
4
6
7
24
2
0
.17 mmol in 10 mL) was acidified with 2.00 mL of 0.01 M
A solution of phosphonium iodide 3 (6.10 g, 14.6 mmol)
in methanol (15 mL) was added to a hot aqueous solution
of (NH ) Mo O ∙4H O (3.0 g, 2.43 mmol) at pH 3.0. The
HCl. Methanol solution (5 mL) of [(n-C H ) NH ]Cl (0.30 g,
10
21 2
2
1.01 mmol) was added and a precipitate was formed. The
4
6
7
24
2
solution was filtered and the precipitate was washed
with water and methanol to give a white solid (0.20 g,
solid obtained was filtered and crystallised from diethyl
ether/DMF.

14
C. TALOTTA ET AL.
4
.2.7. Synthesis of compound 13
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.2.8. Synthesis of compound 14
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4
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2
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1
6
ArH, 8H), 4.27 (br t, OCH , 8H), 4.14 (d, ArCH Ar, J =7.5 Hz,
2
2
12H), 3.60 (broad, NCH , 8H), 1.17 (t, CH , J = 6.8 Hz, 12H),
2 3
0.99 [s, C(CH ) , 36H].
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.2.9. Synthesis of compound 15
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4
2
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4
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2
1
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6
(
s, NH, 4H), 6.29 (s, ArH, 8H), 4.82−3.79 (overlapped, OCH2
+
ArCH Ar, 12H), 3.22 (d, ArCH Ar, J = 7.5 Hz, 4H), 1.17 (t,
2
2
CH , J = 6.8 Hz, 12H), 0.99 [s, C(CH ) , 36H].
3
3 3
4
.3.0. Synthesis of compound 16
To an aqueous solution of (Na) MoO ·2H O (0.16 g,
2
4
2
0
(
0
.67 mmol in 0.4 mL) was added a solution 12.0 M of HCl
0.17 mL). Then a methanol solution (0.24 mL) of 4 (0.10 g,
.084 mmol) was added and the precipitate was filtered
(
(
4) Han, Z.; Gao,ꢁ.; Hu, C. Cryst. Growth Des. 2008, 8, 1261–1264.
5) Li, S.; Ma, H.; Pang, H.; Zhang, L. Cryst. Growth Des. 2014,
4, 4450–4460.
(6) Zhou, X.-M.; Chen, W.; Song, ꢁ.-F. Eur. J. Inorg. Chem. 2014,
, 812–817.
and washed with water and methanol to give a white solid
1
1
(
0.14 g). H NMR (300 MHz, DMSO-d , 298 K): δ 9.59 (s, NH,
6
5
4H), 6.87 (s, ArH, 8H), 4.26 (br t, OCH , 8H), 4.15 (d, ArCH Ar,
2
2
(
7) Gaeta, C.; Troisi, F.; Neri, P. Org. Lett 2010, 12, 2092–2095;
Pierro, T.; Gaeta, C.; Talotta, C.; Casapullo, A.; Neri, P. Org.
Lett. 2011, 13, 2650–2653; Talotta, C.; Gaeta, C.; Pierro, T.;
Neri, P. Org. Lett. 2011, 13, 2098–2101; Talotta, C.; Gaeta,
C.; Neri, P. Org. Lett. 2012, 14, 3104–3107; Gaeta, C.;
Talotta, C.; Farina, F.; Teixeira, F.A.; Marcos, P.A.; Ascenso,
J.R.; Neri, P. J. Org. Chem. 2012, 77, 10285–10293; Gaeta, C.;
Talotta, C.; Farina, F.; Camalli, M.; Campi, G.; Neri, P. Chem.
Eur. J. 2012, 18, 1219–1230; Gaeta, C.; Talotta, C.; Mirra, S.;
J = 9.5 Hz, 4H), 3.25 (broad, NCH , 8H), 3.00 (broad, NCH ,
2
2
1
3
8H), 1.25 (br t, CH , 12H), 1.06 [s, C(CH ) , 36H]. C NMR
3 3 3
(
100 MHz, DMSO-d , 298 K): δ 152.4, 146.6, 133.4, 125.9,
6
68.1, 50.2, 47.4, 34.2, 31.6, 9.3.
Disclosure statement
No potential conflict of interest was reported by the authors.

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