Self-assembly of an alkali metal cluster stabilized by a new flexidentate metalloligand: formation and structure of heterobimetallic Na-Mo and Cs-Mo 2D networks

Article abstract of DOI:10.1002/ejic.200500601

A new tridentate ligand, {(3,5-di-tert-butyl-2-hydroxybenzyl) amino}acetic acid, has been synthesized. This ligand forms [{Na₄(H ₂O)₄(μ-H₂O)₂}?(Mo ₂O₅L₂)₂]

Full text of DOI:10.1002/ejic.200500601

FULL PAPER
DOI: 10.1002/ejic.200500601
Self-Assembly of an Alkali Metal Cluster Stabilized by a New Flexidentate
Metalloligand: Formation and Structure of Heterobimetallic Na–Mo and
Cs–Mo 2D Networks
Snehadrinarayan Khatua,[a] Sohaham Dasgupta,[a] Kumar Biradha,*[a] and
Manish Bhattacharjee*[a]
Keywords: Alkali metals / Heterometallic complexes / Metalloligands / Molybdenum / Self-assembly
A new tridentate ligand, {(3,5-di-tert-butyl-2-hydroxybenzyl)
amino}acetic acid, has been synthesized. This ligand forms
with CsCl in aqueous methanol. Similarly, 2 reacts with an
excess of NaCl to produce 1. Complex 2 crystallizes in the
monoclinic space group C2/c. The crystal structure of this
compound reveals that the geometry of the [LMoO2(µ-O)-
MoO2L]2– unit stays almost intact but that it stabilizes a poly-
meric chain of Cs+ cations, unlike in 1.
[{Na4(H2O)4(µ-H2O)2}ʚ(Mo2O5L2)2] (1), which contains an
4+
Na4 cluster cation stabilized by [LMoO2(µ-O)MoO2L]2–
,
upon reaction with Na2MoO4 in aqueous methanol. This
compound has been characterized by various spectroscopic
¯
techniques and crystallizes in the triclinic space group P1.
Furthermore, compound 1 undergoes smooth exchange of
Na+ for Cs+ to give [Cs2(Mo2O5L2)·H2O]n (2) upon treatment
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
4+
(µ-H2O)2}ʚ(Mo2O5L2)2] (1), which bears an Na4 cluster
Introduction
cation stabilized by the metalloligand [LMoO2(µ-O)-
MoO2L]2– (LMo), and the corresponding cesium compound,
a helical 1D infinite chain of [Cs2(Mo2O5L2)·H2O]n (2), ob-
tained by transmetalation of the Na+ ions in 1. The trans-
metalation behavior of the compounds has also been inves-
tigated.
The role of judiciously designed ligands in the synthesis
of supramolecular assemblies containing two types of metal
ions has been demonstrated.[1,2] In recent years, a large
number of metalloligands have been synthesized for the as-
sembly of bimetallic complexes.[3] The main thrust has been
on the aggregation of transition metal ions using main
group metals as templates.[2] However, alkali metal cluster
cations have received scant attention. Molybdates and tung-
states have been widely used as ligands for metal ions due
to their diverse structural flexibility and their applications
in fields such as catalysis, analytical and clinical chemistry,
biochemistry, and medicine.[4] Although a lot of attention
has been paid to the synthesis of transition metal and rare-
earth metal derivatives of polyoxometalates, alkali metal
complexes of polyoxometalates have received much less at-
tention.[5–7] We were interested in the synthesis of a flexible
metalloligand that can coordinate alkali metal cations, and
the effect of their size on the architecture of the structure.
Also, we intended to explore the transmetalation of the al-
kali metal cations.
Results and Discussion
Synthesis and Characterization of {(3,5-Di-tert-butyl-2-
hydroxybenzyl)amino}acetic Acid
Our synthetic strategy was to design a tridentate, dibasic
ligand (L) containing one carboxylate donor site that is ex-
pected to form the metalloligand [LMoO2(µ-O)MoO2L]2–
(LMo). This ligand has the potential to coordinate alkali-
metal cations through bridging carboxylate and self-as-
semble into various architectures (Scheme 1).
Accordingly, the ligand was synthesized by a one-pot
Mannich reaction of glycine, 2,4-di-tert-butylphenol, and
formaldehyde in aqueous ethanol. Glycine and formalde-
hyde (40%) were dissolved in water in a 1:10 ratio and an
ethanolic solution of the phenol was added. The reaction
solution afforded the ligand on standing for about 10 h.
The ligand was characterized by elemental analysis, mass
Herein we report the synthesis of the ligand {(3,5-di-tert-
butyl-2-hydroxybenzyl)amino}acetic acid, and the synthesis
and structure of an unusual polyoxomolybdate, [{Na4(H2O)4-
1
spectrometry, and IR, UV/Vis, and H and 13C NMR spec-
[a] Department of Chemistry, Indian Institute of Technology
Kharagpur,
troscopy. The elemental analysis and mass spectral mea-
surements agreed well with the proposed composition. The
1H and 13C NMR data were also in agreement with the
proposed structure (see Experimental Section).
Kharagpur 721 302, India
Fax: +91-3222-282252
E-mail: mxb@iitkgp.ac.in
kbiradha@chem.iitkgp.ernet.in
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136.7, 136.8, 137.9, 138.3, 159.8, and 159.9 ppm. The car-
boxylate carbon signals appear at δ = 175.2 and 175.3 ppm.
The appearance of two signals for each carbon indicates
that the ligands are bonded in a slightly different fashion.
1
Thus, the H and 13C NMR and IR spectral studies clearly
indicate the presence of an [LMoO2(µ-O)MoO2L] moiety
in solution and the solid state. The 23Na NMR spectrum of
1 shows a single broad signal at δ = 2.0 ppm (relative to
NaCl as an external reference). This clearly shows that the
coordinated nature of the sodium is maintained even in
solution and that all the sodium ions are in a similar chemi-
cal environment. The observed low-field position of the
23Na NMR signal, with respect to the NaCl reference, indi-
cates the existence of an interaction between the sodium
ions and between sodium and molybdenum, even in solu-
tion. The 95Mo NMR spectra of the compounds show a
sharp signal at δ = 0.3 ppm, which indicates that the molyb-
denum atoms are in a predominantly oxo environment.
Similar spectral features were observed in the case of 2. The
Scheme 1.
observed molar conductance of
1
in methanol
Synthesis, Characterization, and Solution Properties of the
Molybdenum Complexes 1 and 2
(95 Ω–1 cm2 mol–1) clearly indicates that the aggregate
[{Na4(H2O)4(µ-H2O)2}ʚ(Mo2O5L2)2] partially disinte-
Compound 1 was synthesized by the reaction of LH2 grates in solution. The high-resolution ESI mass spectrum
with Na2MoO4·2H2O in aqueous methanol and 2 was ob- (methanol solution) of 1 shows a peak at m/z = 936.3138,
tained by the reaction of CsCl with 1 in aqueous methanol. which corresponds to C34H54Mo2N2Na2O13 {or [Na2-
Compound 2 can also be prepared from an in situ reaction (Mo2O5L2)(H2O)2]}. Similarly, the mass spectrum of com-
between an excess of CsCl and Na2MoO4 and the ligand. pound 2 shows a peak at m/z = 1138.2913 corresponding
It should be noted that Cs+ ions can be exchanged by Na+ to C34H52Cs2Mo2N2O12, which can be formulated as
ions by treating 2 with an excess of NaCl. Thus, it is clear [Cs2(Mo2O5L2)(H2O)]. The mass spectral studies clearly
that both compounds show the ability to exchange cations show that the coordinated nature of the alkali metals is
and are interconvertable, which is rare in such molecules.
maintained even in solution and that the clusters undergo
The elemental analyses agree well with the compositions. partial disintegration in solution.
The compounds were further characterized by IR, UV/Vis,
1
and H, 13C, 95Mo, and 23Na (compound 1) NMR spectra
and solution conductivity measurements. The IR spectrum
Crystal Structures of [{Na4(H2O)4(µ-H2O)2}ʚ(Mo2O5L2)2]
(1) and [Cs2(Mo2O5L2)·H2O]n (2)
of the compounds show two sharp bands at about 920 and
880 cm–1 due to symmetric and antisymmetric cis-Mo=(O)2
stretches, respectively, and a band at around 780 cm–1 due
X-ray diffraction analysis revealed that the asymmetric
to the Mo–O–Mo stretch; these clearly show the presence unit of 1 contains only half of the cluster as it sits on an
of the [MoO2(µ-O)MoO2] moiety. The UV/vis spectra of inversion center, with one LMo unit, two Na atoms, and
the compounds show strong bands due to a ligand-to-metal three water molecules being present (Figure 1). The coordi-
charge-transfer transition at about 350 nm along with in- nation environments of the two Mo atoms are almost sim-
ternal ligand transitions.
ilar: both have an octahedral geometry and are bonded to
The 1H NMR spectra of 1 in [D6]DMSO show signals at five oxygens and one nitrogen. The ligand LMo binds the
δ = 1.20 (br. s, 9 H) and 1.30 ppm (br. s, 9 H) due to the two sodium atoms in two different ways and one of the
methyl protons of the tert-butyl groups. The CH2 proton Mo centers has an interaction with sodium [Mo1···Na2 =
signals appear at δ = 3.36 (br. m, 2 H) and 4.25 ppm (br. 3.553(5) Å]. The distinctive feature of the structure is the
m, 2 H). The signal at δ = 4.80 ppm (br. s, 1 H) can be formation of a rectangular (Na4)4+ cluster cation (Figure 2,
assigned to the NH proton. We could not observe the sig- a). The distinctly shorter Na···Na distances of 3.539(5) Å
nals due to the protons of coordinated water. This may be (Na1–Na2) and 3.728(6) Å (Na1–Na1Ј) compared to that
due to excessive broadening of the signals. The signals for in elemental sodium (3.82 Å) show attractive Na–Na inter-
the aromatic protons appear at δ = 6.85 (br. m, 1 H) and actions in the cluster. The Na1–Na2Ј distance [3.898(5) Å]
7.10 ppm (br. m, 1 H). The 13C NMR spectrum of 1 in [D6]- is longer than that in elemental sodium. Recently, a tetraso-
DMSO shows signals at δ = 29.6, 29.9, 30.1, 31.5, 31.7, dium dication, Na42+, stabilized by two silyl(fluorosilyl)
33.7, 34.4, and 34.5 ppm due to the CH3 and tertiary car- phosphonides, with a similar structure but with shorter Na–
bons of the tert-butyl group. The CH2 signals appear at δ Na distances has been reported.[8] The (Na4)4+ unit binds
= 51.3, 51.6, 52.7, and 53.1 ppm, with the aromatic carbon six O atoms to form a Na4O6 cluster that can be described
signals at δ = 121.5, 121.9, 122.5, 122.7, 123.0, 124.1, 124.3, as a dicubane unit of the type M6O6 in which the two ex-
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Eur. J. Inorg. Chem. 2005, 5005–5010

Heterobimetallic Na–Mo and Cs–Mo 2D Networks
FULL PAPER
Figure 1. ORTEP drawing of the asymmetric unit of 1 (thermal ellipsoids at 50% probability).
treme and opposite corners have been removed (Figure 2,
b). Two of the Na+ ions (Na1) in the Na4O6 cluster are
coordinated to five oxygens, and two (Na2) are hexacoordi-
nate. Each of the four Na+ ions is coordinated to one ter-
minal water molecule [Na1–O3W = 2.277(9) and Na2–
O1W = 2.301(11) Å] and are bridged by one water molecule
[Na2–O2W = 2.366 (8) and Na1–O2W = 2.512 (7) Å; Na1–
O2W–Na2 = 93.0(2)°]. In addition, Na1 and Na2 are also
bridged by a Mo–O µ3 oxygen (O102) [Na2–O102 = 2.727
(7) Å] and one carboxylate oxygen (O22) bridges three sodi-
ums in a µ3-fashion [Na1–O22 = 2.567(6), Na2–O22 =
2.318 (6) Å; Figure 2, b]. The compound forms a one-di-
mensional chain through Mo–O···H–N hydrogen bonding,
and the 1D chains are joined by –COO···O and Mo–O···O
hydrogen bonds to form a 2D network (Figure 3).
Figure 3. View of the 2D hydrogen-bonding network along the c
axis (H bonds are shown as dotted lines; tert-butyl groups have
been omitted for clarity).
groups of LMo, and are coordinated to six oxygens (Fig-
ure 5, a). This polymeric chain is generated by two Cs–Cs
distances of 4.093(11) and 4.717(12) Å. The shorter Cs–Cs
bond is bridged by two O atoms of two –COO– groups [Cs–
O11 = 3.099(6) and 3.263(7) Å], whereas the longer one is
not bridged by O atoms (Figure 5, b). The observed Cs···Cs
Figure 2. (a) Illustration of the tetramolybdate cluster 1. The
double dashed lines are long-distance interactions; H atoms have
been omitted for the sake of clarity. (b) Illustration of the Na4O6
cluster with its terminal O atoms on Na; some atoms have been
omitted for the sake of clarity.
The crystal structure of 2 reveals that the geometry of distance clearly shows that there is substantial interaction
LMo (Figure 4) is almost the same as that of compound 1. between the Cs+ ions. Similar to the structure 1, the Mo
However, unlike in structure 1, the asymmetric unit in 2 atom interacts with Cs+ with a distance of 4.172 Å. Inter-
contains half of LMo, one Cs+ ion, and one H2O. The Cs+ estingly, unlike 1, the water molecules do not bind to the
ions are found to form an infinite 1D-helical chain, which alkali metal ion (Cs+) but join the one-dimensional poly-
is stabilized by coordination of the –COO– and Mo–O meric chains of [{(Cs)2LO2Mo-O-MoO2L}] via hydrogen
Eur. J. Inorg. Chem. 2005, 5005–5010
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S. Khatua, S. Dasgupta, K. Biradha, M. Bhattacharjee
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Figure 4. ORTEP drawing of the [Cs2(LO2Mo-O-MoO2L)] unit in the crystal structure of 2 (thermal ellipsoids at 50% probability). The
double dashed lines represent long-distance interactions.
bonds [N–H···O = 3.006(8) Å (178°); O···O = 2.764(8); Fig- bonded by the –COO– oxygen to form a 1D chain. Thus,
ure 5, c]. In 1, water is able to bridge two Na+ ions, whereas, both 1 and 2 form 2D networks but in 1 the network is
due to the larger size of the cation, water cannot bind the built by hydrogen bonding only, whereas in 2 a 1D network
Cs+ ions in a similar fashion in 2. Similarly, in 1, one of the is generated by Cs–Cs polymeric cluster chains that are
O atoms of –COO– binds three Na+ ions, whereas in 2, due joined by hydrogen bonding to form a 2D network.
to the larger size of the Cs+ ion, only two cations are
Conclusions
A tridentate dibasic ligand has been designed which
forms a new metalloligand, [LMoO2(µ-O)MoO2L]2– (LMo
)
upon reaction with MoO42–. This metalloligand binds Na+
ions to form a heterobimetallic octanuclear compound. It
has been shown that the alkali metal cations in 1 and 2 can
easily undergo exchange with each other and the resulting
compounds are structurally different. It should be noted
that such interconvertibility in this type of molecules is rare.
The structural differences between 1 and 2 can be attributed
to the difference in size of the cations. Thus, LMo may be
treated as a new polydentate flexible metalloligand for as-
sembly of heterobimetallic complexes. These complexes are
expected to afford mixed oxides of molybdenum on heating
to high temperature, and work in this direction is already
in progress. It should be mentioned that such mixed oxides
have been shown to be effective catalysts for various coup-
ling and oxidation reactions.[9] It would be interesting to
explore the reactions of LMo with various transition metal
ions and study their structural, magnetic, and catalytic
properties.
Experimental Section
Figure 5. (a) Binding of Cs+ ions by [LO2Mo-O-MoO2L] units in
the crystal structure of 2. The tert-butyl groups have been omitted
for the sake of clarity. The 1D chain is parallel to the crystallo-
graphic c axis. (b) Illustration of the Cs4O6 unit with its terminal
O atoms on Cs; some atoms have been omitted for the sake of
clarity. (c) 2D arrays of infinite 1D chains of 2 formed by hydrogen
bonds.
General Remarks: 2,4-Di-tert-butylphenol was purchased from
Fluka. Glycine, formaldehyde, Na2MoO4·2H2O, and all solvents
used were reagent-grade products. Elemental analyses were per-
formed with a Perkin–Elmer C,H,N analyzer model 2400. Sodium
was estimated by a flame photometric method. Molybdenum was
estimated by gravimetric analysis [dioxobis(oxinate)molybdenum;
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Heterobimetallic Na–Mo and Cs–Mo 2D Networks
FULL PAPER
MoO2(C9H9ON)2]. 1H, 13C, 23Na, and 95Mo NMR spectra were
recorded in CDCl3, CD3OD, or [D6]DMSO on a Bruker AC-200
instrument. The IR spectra were recorded on a Perkin–Elmer
model 883 spectrometer. UV/vis spectra were recorded in solution
with a Shimadzu model UV-1601 spectrophotometer. For the mass
spectral measurements a methanolic solution of the compounds
was prepared and the spectra recorded on a Waters LCT mass spec-
trometer using the electrospray ionization (ES+ mode) technique.
s, 1 H), 6.85 (br. m, 1 H), 7.10 (br. m, 1 H) ppm. 13C NMR ([D6]
DMSO): δ = 29.6, 29.9, 30.1, 31.5, 31.7, 33.7, 34.4, 34.5, 51.3, 51.6,
52.7, 53.1, 121.5, 121.9, 122.5, 122.7, 123.0, 124.1, 124.3, 136.7,
136.8, 137.9, 138.3, 159.8, 159.9, 175.2, 175.3 ppm. ESI HRMS:
m/z = 936.3138 [Na2(Mo2O5L2)(H2O)2].
Reaction of 1 with CsCl. Synthesis of [Cs2(Mo2O5L2)·H2O]n (2):
Compound 1 (0.048 g, 0.025 mmol) was dissolved in methanol
(20 mL), an aqueous solution (5 mL) of CsCl (0.037 g, 0.2 mmol)
was added, and the reaction solution was stirred for 5 h. On stand-
ing for about 20 days orange crystals of 2 were obtained in 50%
yield. C34H52Cs2Mo2N2O12 (1138.5): calcd. C 35.87, H 4.60, Mo
16.85, N 2.46; found C 36.05, H 4.34, Mo 17.15, N 2.54. IR (KBr
Synthesis of {(3,5-Di-tert-butyl-2-hydroxybenzyl)amino}acetic Acid
(L): Glycine (3.00 g, 40 mmol) was dissolved in water (20 mL), a
40% aqueous formaldehyde (30 mL, 400 mmol) solution was
added, and the mixture was stirred for 20 min. An ethanolic solu-
tion (30 mL) of 2,4-di-tert-butylphenol (2.06 g, 10 mmol) was then
added dropwise and the reaction mixture was stirred for 30 min
and allowed to stand overnight. The precipitated ligand was fil-
tered, washed with water, dried, and finally recrystallized from a
mixture of methanol and dichloromethane. Yield: 2.53 g (86.5%).
C17H27NO3 (293.4): calcd. C 69.59, H 9.28, N 4.77; found C 69.25,
pellet): ν = 2960 cm–1, 1580, 1475, 1260, 906, 870, 790. UV/Vis:
˜
λmax (ε) = 356 nm (6460), 213 (27590). ESI HRMS: m/z =
1138.2913 [Cs2(Mo2O5L2)(H2O)]. 1H NMR ([D6]DMSO): δ = 1.27
(br. s, 9 H), 1.39 (br. s, 9 H), 3.28 (br. m, 2 H), 4.64 (br. s, 1 H),
6.95 (br. m, 1 H), 7.20 (br. m, 1 H) ppm.
H 9.10, N 4.46. IR (KBr pellet): ν = 2960 cm–1, 1710, 1630, 1230,
Independent Synthesis of [Cs2(Mo2O5L2)•H2O]n (2): An aqueous
solution (5 mL) of Na2MoO4·2H2O (0.061 g, 0.25 mmol) was
added to a methanolic solution (25 mL) of the ligand (0.073 g,
0.25 mmol). The solution immediately turned orange. The reaction
solution was stirred for 6 h and then CsCl (0.2524 g; 1.5 mmol) was
added and solution was stirred for a further hour. On standing for
10 days crystals of compound 2 were obtained in 60% yield.
˜
1122. UV/Vis: λmax (ε) = 280 nm (2290), 220 (7470). 1H NMR
(CDCl3): δ = 1.28 (s, 9 H), 1.37 (s, 9 H), 3.62 (s, 2 H), 4.10 (s, 2
H), 4.86 (s, 1 H), 6.79 (d, J = 2.3 Hz, 1 H), 7.19 (d, J = 2.4 Hz, 1
H) ppm. 13C NMR (CDCl3): δ = 29.6, 31.4, 34.2, 34.8, 52.0, 53.3,
116.8, 121.9, 122.8, 137.3, 143.5, 149.4, 172.6 ppm. MS: m/z = 293
[M+] (C17H27NO3).
Synthesis of [{Na4(H2O)4(µ-H2O)2}ʚ(Mo2O5L2)2] (1): An aqueous
solution (5 mL) of Na2MoO4·2H2O (0.121 g, 0.5 mmol) was added
to a methanolic solution (25 mL) of the ligand (0.147 g, 0.5 mmol).
The solution immediately turned orange. The solution was stirred
for 3 h and was then allowed to stand overnight. The precipitated
crystalline compound was filtered, washed 3–4 times with water,
dried in vacuo, and finally recrystallized from a mixture of meth-
anol and acetonitrile. Yield: 0.13 g (54%). C68H112Mo4N4Na4O28
(1909.3): calcd. C 42.78, H 5.91, Mo 20.10, N 2.93, Na 4.82; found
X-ray Crystallographic Study: Suitable crystals of 1 and 2 were
grown from dilute acetonitrile/MeOH and MeOH/water solutions,
respectively, at room temperature over a period of 5 to 20 days.
The single crystal data were collected on Bruker–Nonius Mach3
CAD4 X-ray diffractometer that uses graphite monochromated
Mo-Kα radiation (λ = 0.71073 Å) by the ω-scan method. No ab-
sorption correction was used. The structure was solved by direct
methods and refined by least-squares methods on F2 using
SHELX-97.[10] Non-hydrogen atoms were refined anisotropically
C 43.25, H 6.10, Mo 19.45, N 2.40, Na 4.20 (by flame photometry). and hydrogen atoms on C atoms were fixed at calculated positions
IR (KBr pellet): ν = 3433 cm–1, 2960, 1600, 1470, 1250, 1170, 920,
and refined using a riding model. The H atoms of the water mole-
cules in 1 and 2 and N atoms in 1 and 2 could not be located. The
details of crystal data are given in Table 1; selected bond lengths
are summarized in Table 2.
˜
880, 780. UV/Vis: λmax (ε) = 355 nm (11830), 270 (22950), 230
(24440). 95Mo NMR ([D6]DMSO) [reference Na2MoO4 (δ =
0 ppm)]: δ = 0.3 ppm. 23Na NMR ([D6]DMSO) [reference NaCl (δ
1
= 0 ppm)]: δ = 2.0 ppm. H NMR ([D6]DMSO): δ = 1.20 (br. s, 9
CCDC-269980 (for 1) and -269981 (for 2) contain the supplemen-
H), 1.34 (br. s, 9 H), 3.36 (br. m, 2 H), 4.25 (br. m, 2 H), 4.78 (br. tary crystallographic data for this paper. These data can be ob-
Table 1. Crystal data for [{Na4(H2O)4(µ-H2O)2}ʚ(Mo2O5L2)2] (1) and [Cs2(Mo2O5L2)·H2O]n (2).
1
2
Empirical formula
Formula mass
C68H112Mo4N4Na4O28
1909.34
C34H52Cs2Mo2N2O12
1138.47
Temperature [K]
Wavelength [Å]
293(2)
0.71073
293(2)
0.71073
Crystal system
Space group
triclinic
P1
monoclinic
C2/c
¯
a [Å]
b [Å]
c [Å]
10.746(2)
11.517(2)
18.427(4)
38.280(8)
10.961(2)
10.391(2)
α [°]
β
104.26(3)
94.19(3)
103.41(3)
γ
90.62(3)
2203.4(8)
Volume [Å3]
4241.1(15)
4
1.783
2.340
Z
1
Dcalcd. [Mg/m3]
1.439
0.649
984
Absorption coefficient [mm–1]
F(000)
2240
Final R indices [I Ͼ 2σ(I)]
R1 = 0.0751, wR2 = 0.1834
R1 = 0.0550; wR2 = 0.1343
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S. Khatua, S. Dasgupta, K. Biradha, M. Bhattacharjee
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Table 2. The bond lengths [Å] around the Mo and alkali metal
atoms in compounds 1 and 2.[a]
[1] a) X. Sun, D. W. Johson, D. L. Caulder, R. E. Powers, K. N.
Raymond, E. H. Wong, Angew. Chem. Int. Ed. 1999, 38, 1303–
1307; b) X. Sun, D. W. Johnson, D. L. Caulder, K. N. Ray-
mond, E. H. Wong, J. Am. Chem. Soc. 2001, 123, 2752–2763;
c) X. Sun, D. W. Johnson, K. N. Raymond, E. H. Wong, Inorg.
Chem. 2001, 40, 4504–4506.
1
2
Mo(1)–O(1B)
Mo(1)–O(10)
Mo(1)–O(12)
Mo(1)–O(101)
Mo(1)–O(102)
Mo(1)–N(11)
Mo(2)–O(1B)
Mo(2)–O(20)
Mo(2)–O(21)
Mo(2)–O(201)
Mo(2)–O(202)
Mo(2)–N(21)
Na(1)–O(2W)
Na(1)–O(3W)
Na(1)–O(21)
Na(1)–O(22)
Na(1)–O(22)e
Na(1)–O(102)e
Na(2)–O(1W)
Na(2)–O(2W)
Na(2)–O(12)
Na(2)–O(102)
Na(2)–O(22)e
1.887(5)
1.947(5)
2.235(5)
1.707(6)
1.750(7)
2.360(7)
1.904(5)
1.931(5)
2.211(5)
1.725(6)
1.706(7)
2.343(6)
2.511(7)
2.277(13)
2.511(7)
2.567(7)
2.476(6)
3.409(7)
2.300(12)
2.367(8)
2.395(7)
2.726(8)
2.319(7)
Mo(1)–O(101)
Mo(1)–O(100)
Mo(1)–O(102)
Mo(1)–O(10)
Mo(1)–O(12)
Mo(1)–N(11)
Cs(1)–O(12)a
Cs(1)–O(100)
Cs(1)–O(11)b
Cs(1)–O(100)c
Cs(1)–O(101)c
Cs(1)–O(11)d
1.702(5)
1.729(5)
1.887(2)
1.944(5)
2.248(5)
2.355(6)
3.048(6)
3.066(5)
3.263(7)
2.986(5)
3.287(5)
3.099(6)
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structures, University of Göttingen, Germany, 1997.
Received: July 6, 2005
This work was funded by DST, Government of India, New Delhi.
The single crystal XRD facility was provided by DST under the
FIST Program.
Published Online: November 2, 2005
5010
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Eur. J. Inorg. Chem. 2005, 5005–5010