Dissolution/reorganization toward the destruction/construction of porous cobalt(II) - and Nickel(II) carboxylate coordination polymers

Article abstract of DOI:10.1021/ic900037g

The alkali-metal-cation-induced structural transformation of porous coordination polymers (CPs), {A₂[M₃(btec) ₂(H₂O)₄]}_n (1, A = K,M = Co; 2, A=K, M = Ni; 3, A = Cs, M = Co; and 4, A=Cs, M

Full text of DOI:10.1021/ic900037g

Inorg. Chem. 2009, 48, 7457–7465 7457
DOI: 10.1021/ic900037g
Dissolution/Reorganization toward the Destruction/Construction of Porous
Cobalt(II)- and Nickel(II)-Carboxylate Coordination Polymers
Miao-Tzu Ding,†,‡ Jing-Yun Wu,† Yen-Hsiang Liu,§ and Kuang-Lieh Lu*,†
†Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan, ‡Department of Chemistry, National Central
University, Taoyuan 320, Taiwan, and §Department of Chemistry, Fu Jen Catholic University, Taipei 242,
Taiwan
Received January 8, 2009
The alkali-metal-cation-induced structural transformation of porous coordination polymers (CPs), {A2[M3(btec)2(H2O)4]}n
(1,A=K,M=Co;2,A=K,M=Ni;3,A=Cs,M=Co;and4, A = Cs, M = Ni; btec = benzene-1,2,4,5-tetracarboxylate), occurred
via a unique dissolution/reorganization process in the presence of an alkali chloride (LiCl, NaCl) in water. Treatment of 1 or 2
in an aqueous solution of LiCl resulted in the formation of new metal-carboxylate species [Co2(btec)(H2O)10] H2O
3
(5 H2O) and {Li2[Ni3(btec)2(H2O)10] 3.5H2O}n (6 3.5H2O), respectively. When NaCl was used in place of LiCl under similar
3
3
3
reaction conditions, similar dissolution/reorganization processes were observed. The cobalt species 1and 3 were converted
into the metal-carboxylate product [Na2Co(btec)(H2O)8]n (7), whereas the nickel-carboxylate frameworks 2 and 4 were
transformed into {[Na4Ni2(btec)2(H2O)18] 3H2O}n (8 3H2O). Single-crystal X-ray diffraction analysis revealed that 5 H2O is
a discrete molecule, which extends to a hydrogen-bonded 3D porous supramolecular network including tetrameric water
aggregates. Compound 6 3.5H2O adopts a 3D polymeric structure with a novel (2,4,4)-connected net on the basis of a
4-connecting organic node of a btec ligand, a square-planar 4-connecting metallic trans-Ni(O2C)4(H2O)2 node, and a
2-connecting octahedral metallic trans-Ni(O2C)2(H2O)4 hinge. Compound 7 possesses a 3D polymeric structure comprised
of two types of intercrossed (4,4)-layers, a [CoII(btec)]-based layer and a [NaI(btec)]-based layer, in a nearly perpendicular
3
3
3
3
orientation (ca. 87°). Compound 8 3H2O adopted a 2D sheet network by utilizing heterometallic trinuclear clusters of Na2Ni
3
(O2C)5(H2O)9 as secondary building units. Each sheet is hydrogen-bonded to neighboring units, giving a 3D supramolecular
network. It is noteworthy that the dissolution/reorganization process demonstrates the cleavage and reformation of metal-
carboxylate bonds, leading to a destruction/construction structural transformation of CPs.
Introduction
and conformation-change (crystal-to-amorphous and crystal-
to-crystal) transformations,3a,3b,12-16 are of particular interest
Inorganic-organic hybrid materials with dynamic structural
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expansion or shrinking/extending) transformations3c,3d,4-11
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*To whom correspondence should be addressed. Tel.: þ886-2-27898518.
Fax: þ886-2-27831237. E-mail: lu@chem.sinica.edu.tw.
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r
2009 American Chemical Society
Published on Web 07/02/2009
pubs.acs.org/IC

7458 Inorganic Chemistry, Vol. 48, No. 15, 2009
Ding et al.
in areas of coordination polymers and supramolecules, since
they may exist in several distinct extended architectures (or
lattices) in response to external stimuli. Such characteri-
stic crystal transformations are frequently triggered by
either guest elimination/inclusion1f,3d,5-12,13a,14c,16 or guest ex-
change.3a,3b,13b,14a,14b,15 In addition, a few examples have shown
that structural transformation behaviors are driven by physical
stimuli, such as light,17-19 temperature,1e,3c,12,20-22 acidobasi-
city,23 and so forth. It is noteworthy that the transformation of
the entire structure of some coordination polymers frequently
occurs from one crystalline state to another without destruction
of the molecular skeleton or without dissolution and recrystal-
lization of the materials. There are limited examples exhibiting
structural transformation through a dissolution/recrystalliza-
tion process.24 Rao and co-workers published a series of
interesting results where low-dimensional zinc phosphates
transformed to complex open-framework structures on heating
in water with or without added amines.25 We recently reported
on several charged 3D porous coordination polymers (CPs)
with the general formula {A2[M3(btec)2(H2O)4]}n (A=K, Cs;
M = Co, Ni; btec = benzene-1,2,4,5-tetracarboxylate) that
are soluble in an aqueous solution of cesium chloride (CsCl)
or potassium chloride (KCl).26 After dissolution, these com-
pounds reorganize to form new metal-carboxylate species
Cs2[M(btec)(H2O)4] (M = Co, Ni) and the stable metal-
carboxylate frameworks of K2[M3(btec)2(H2O)4] (M = Co,
Ni). Note that several products could not be obtained directly
using a simple self-assembly synthetic process. Incorporation of
alkali metal ions inside the transition metal/carboxylate frame-
work is itself interesting since the alkali ions are relevant as
potential adsorption sites in the context of adsorbents for
hydrogen.27 Herein, we report on our ongoing investigations
of dissolution/reorganization toward the structural rearrange-
ment of CPs {A2[M3(btec)2(H2O)4]}n in aqueous lithium chlor-
ide or sodium chloride solutions. Interesting modes of cleavage
and reformation of metal-carboxylate donating bonds in
coordination frameworks during dissolution/reorganization in
aqueous solution were observed, giving rise to extremely rich
and diverse structural rearrangements.
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Results and Discussion
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Dissolution/Reorganization of Cobalt(II)- and Nickel-
(II)-Carboxylate Frameworks. Porous CPs {A2[M3(btec)2-
(H2O)4] xH2O}n (1 6H2O, A = K, M = Co, x = 6; 2
3
3
3
4H2O, A=K, M=Ni, x=4; 3 3H2O, A=Cs, M=Co,
3
x=3; and 4 3H2O, A=Cs, M=Ni, x=3) were prepared
3
following procedures reported in the literature.26 Treatment
of 1 or 2 in an aqueous solution of lithium chloride (LiCl)
resulted in a dissolution/reorganization process, affording
the new metal-carboxylate products [Co2(btec)-
(H2O)10] H2O (5 H2O) and {Li2[Ni3(btec)2(H2O)10] 3.5-
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3
3
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H2O}n (6 3.5H2O), respectively. When the lithium chloride
~
3
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the
Co(btec)(H2O)8]n (7), whereas the nickel-carboxylate fra-
mework was transformed into {[Na4Ni2(btec)2-
(H2O)18] 3H2O}n (8 3H2O). These results are summarized
metal-carboxylate
product
[Na2-
2
3
3
in Scheme 1.
Structural Descriptions of Products Obtained from the
Dissolution/Reorganization Process. [Co2(btec)(H2O)10]
H2O (5 H2O). A structural analysis showed that
3
3
5 H2O is comprised of two crystallographically distinct
3
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Article
Inorganic Chemistry, Vol. 48, No. 15, 2009 7459
Figure 1. The two crystallographically distinct dinuclear molecules of [Co2(btec)(H2O)10] in 5 H2O.
3
Scheme 1
centrosymmetric dinuclear [Co2(btec)(H2O)10] mole-
cules, and free water molecules are present in the crystal
(Figure 1), which is isostructural and isomorphous with
leading to a distorted trans-Ni(OCO)2(OH2)4 octahedral
geometry. Each btec ligand is bridged to four NiII ions via
1,2,4,5-coordination. The packing diagram reveals that
[Mn2(btec)(H2O)10] H2O.28 Similar molecular struc-
6 3.5H2O exists in a three-dimensional network, which
3
3
tures of [M2(btec)(H2O)10] are also observed in
can be described in terms of two building subunits: 2D
[NiII(btec)]-based layers and octahedral NiII hinges. Within
the former building subunit, each trans-Ni(OCO)4(OH2)2
center acts as a square-planar 4-connector, whereas the btec
ligands serve as linear linkers, in spite of the fact that the
organic multicarboxylate ligand is coordinated to four NiII
ions (i.e., the 4-coordinated organic ligand as a pseudo-2-
connecting linear linker), leading to the formation of a (4,4)-
net (Figure 3). Interestingly, the [Ni(btec)]-based layer is
hinged by the trans-Ni(OCO)2(OH2)4 centers as linear
2-connecting octahedral hinges, as shown in Figure 4,
with the further carboxylate groups of the btec ligand
through nickel-carboxylate-directed coordination bonds
[M2(btec)(H2O)10] 6H2O (M=Co, Ni).29 For 5 H2O,
3
3
in which each CoII ion is coordinated by one mono-
dentate carboxylate group of a btec ligand (Co-O =
˚
2.1003(19)-2.101(2) A) and five water molecules (Co-
˚
O = 2.081(2)-2.120(2) A), each btec ligand is para-
bridged to two CoII ions. Crystal packing is stabilized
by numerous intermolecular O-H
O hydrogen-
3 3 3
bonding interactions (Figure 2a). Interestingly, a hex-
americ water cluster consisting of a cyclic water tetra-
mer in an uudd fashion30 and two pendent water
molecules is formed from two free (O19) and four
coordinated (O9 and O16) water molecules. These
interactions assist a hydrogen-bonded supramolecular
synthon {(CoO6)4(H2O)2}, extending to a supramole-
˚
(2.075(5) A). This results in the combination of the two
building subunits to generate a three-dimensional polymeric
structure with a novel (2,4,4)-connected network. The 3D
net contains one-dimensional rectangular-shaped channels
cular pseudo-(4,4)-layer structure (Figure 2b). The
˚
average water water separation of ca. 2.735 A within
the tetrameric water aggregate is comparable to that
3 3 3
˚
with an effective window size of approximately 3.8ꢀ3.6 A
31
for liquid water (2.85 A) and for other H2O clusters
˚
along the crystallographic a axis, which accommodates
lithium ions and free water molecules (Figure 5).
˚
(2.768-2.834 A) hosted by metal-organic frame-
works.30b,32
{Li2[Ni3(btec)2(H2O)10] 3.5H2O}n (6 3.5H2O). In 6 3.5-
[Na2Co(btec)(H2O)8]n (7). Compound 7 is isostructural
and isomorphous with the Ni analogue, [Na2Ni(btec)-
(H2O)8]n.33 There is a quarter of a CoII ion, half of a
NaI ion, a quarter of a btec ligand, and half of a cobalt-
bonded water molecule in the asymmetric unit, as well
as one and one-half sodium-bonded water molecules.
Each CoII center adopts an octahedral geometry with
3
3
3
H2O, there are two crystallographically distinct nickel ions:
one adopts a distorted trans-Ni(OCO)4(OH2)2 octahedron
˚
with two water molecules (Ni-O = 2.065(7) A) and four
˚
monodentate carboxylate groups (Ni-O=2.045(5) A), and
the other consists of four water molecules (Ni-O=2.046
˚
˚
(5)-2.057(5) A) in the basal plane and two monodentate
two water molecules (Co-O=2.135(2) A) at the apical
positions and four monodentate carboxylate groups
˚
carboxylate groups (Ni-O=2.075(5) A) at axial positions,
˚
(Co-O = 2.1070(16) A) in the basal plane, while each
btec ligand is bridged to four CoII ions via 1,2,4,5-
coordination, leading to the formation of a 2D (4,4)-net
by regarding both CoII ions and btec ligands to be four-
connectors (Figure 6a,b). The overall negative charge of
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7460 Inorganic Chemistry, Vol. 48, No. 15, 2009
Ding et al.
Figure 2. (a) Perspective view of the packing diagrams of 5 H2O. The two crystallographically distinct dinuclear [Co2(btec)(H2O)10] molecules, shown in
light- and medium-gray colors, and free water molecules are represented as space-filling models. (b) The hydrogen-bonded supramolecular pseudo-(4,4)-
layer structure containing cyclic water tetramers in 5 H2O. Its arrangement and immediate environment are highlighted within the circle.
3
3
Figure 4. The 2-connecting octahedral metallic hinge of the trans-Ni-
(OCO)2(OH2)4 center in 6 3.5H2O, shown as ball-and-stick, polyhedron,
and schematic representations.
3
ion, two NaI ions, two halves of the btec ligand, and nine
metal-bonded water molecules as well as one and a half
free water molecules. Each NiII center is coordinated by
Figure 3. Schematic representations of (a) the metallic and (b) the organic
4-connected nodes in 6 3.5H2O. (c) Perspective view and schematic
representation of the [Ni(btec)]-based 2D layer in a (4,4)-topology, formed
by 4-connecting metallic nodes and pseudo-2-connecting organic linkers.
3
˚
˚
one monodentate carboxylate group (Ni-O=2.032(3) A)
and five water molecules (Ni-O=2.016(3)-2.104(3) A)
in an octahedral geometry, of which three water mole-
cules are further bonded to NaI ions (Na-O=2.419(3)-
2.573(3) A). Both of the crystallographically distinct Na
the [CoII(btec)]-based layer is balanced by NaI ions. The
octahedrally coordinated NaI ion is surrounded by three
paired monodentate carboxylate groups (Na-O=2.3379
I
˚
ions show a distorted octahedral NaO6 core: one being
surrounded by one terminal and one bridged water
˚
˚
(19) A), bridged water molecules (Na-O=2.5805(12) A),
˚
˚
molecule at cis positions (Na-O=2.336(4)-2.460(3) A)
as well as four monodentate carboxylate groups from
and terminal water molecules (Na-O = 2.412(2) A) at
trans positions, forming 1D [(H2O)2Na(μ-H2O)]n chains
˚
˚
with a Na Na separation of ca. 4.78 A. As a result of
two btec ligands (Na-O = 2.303(3)-2.5481(3) A), and
the other surrounded by three terminal and two cis-
3 3 3
these sodium-btec contacts, compound 7 possesses a
three-dimensional polymeric structure, which can be
described in terms of two building subunits: a cationic
1D sodium-hydrate chain of {[(H2O)2NaI(μ-H2O)]þ}n
and an anionic 2D (4,4)-layer of a {[CoII(btec)]2-}n-net.
Nevertheless, it can also be regarded as the result of two
types of intercrossed (4,4)-layers, a [CoII(btec)]-based
layer and a [NaI(btec)]-based layer, in a nearly perpendi-
cular orientation (ca. 87°; Figure 6).
positioned bridged water molecules (Na-O=2.332(4)-
2.573(3) A) as well as one monodentate carboxylate
˚
˚
group (Na-O = 2.402(3) A). One of the two crystal-
lographically distinct btec ligands is bridged to two NaI
ions via a bis(ortho-chelating) mode, while the other, in
addition to the bis(ortho-chelating) bridged NaI ions, is
para-bridged to two further NaI ions and two CoII ions
(Figure 7). Through three bridged water molecules
and one μ,η1-carboxylate group, one Ni(O2C)(H2O)5,
one Na(O2C)(H2O)5, and one cis-Na(O2C)4(H2O)2 core
{[Na4Ni2(btec)2(H2O)18] 3H2O}n (8 3H2O). In com-
3
3
pound 8 3H2O, the asymmetric unit contains one NiII
3

Article
Inorganic Chemistry, Vol. 48, No. 15, 2009 7461
Figure 5. Perspective view and schematic representation of the three-dimensional (2,4,4)-connected network of 6 3.5H2O along the crystallographic
(a) [100] and (b) [101] directions. Light-gray polyhedron and 2-connector, trans-Ni(OCO)2(H2O)4; dark-gray 4-connector; trans-Ni(OCO)4(H2O)2; white
4-connector, btec ligand.
3
aggregate together to produce a linear heterometal-
lic trinuclear cluster of Na2Ni(O2C)5(H2O)9 with two
8 3H2O (Figure S2, Supporting Information) and an
3
elemental analysis (see the Experimental Section).
Furthermore, the single-crystal X-ray diffraction analysis
also supports this conclusion.
˚
Ni Na separations of 3.5053(19) and 3.5160(18) A.
3 3 3
Such a heterometallic trinuclear cluster is a secondary
building unit (SBU) that is linked to three neighboring
SBUs via the benzene ring of the btec ligands, forming a
two-dimensional sheet network, as shown in Figure 8.
Discussion. Structural changes in the Co- and Ni-con-
taining CPs, driven by the presence of alkali-metal ions via
a dissolution/reorganization process, are observed in the
present study.26b This phenomenon is significantly differ-
ent from the solid-state transformations of metal-organic
frameworks which show thatthe structural transformation
occurred from one crystalline state to another state with-
out dissolution and recrystallization of the dynamic multi-
functional materials. This study initially involved CP 1-4
systems and aqueous solutions of KCl or CsCl. The results
were the formation of only 3D porous frameworks of
{K2[M3(btec)2(H2O)4]}n (M = Co (1), Ni (20)) and only
1D zigzag chains of {Cs2[M(btec)2(H2O)4]}n (M=Co (9);
Ni (10)) in the presence of KCl and CsCl, respectively.26b
Interestingly, a remarkable reversible destruction/con-
structionstructuraltransformation between the 3Dporous
framework and the 1D zigzag chain structure was demon-
strated in the case of Co-containing species. When lithium
chloride and sodium chloride are used, instead of potas-
sium chloride and cesium chloride, CPs 1-4 undergo
dissolution/reorganization case by case, giving rise to
extremely rich and diverse structural rearrangements.
The metal-carboxylate materials reorganized from aqu-
eoussystems of CP 1/LiCl, CP 2/LiCl, CP1 or 3/NaCl, and
CP 2 or 4/NaCl are structurally characterized as a 0D
˚
Each sheet is hydrogen-bonded (2.58-2.86 A) to neigh-
boring sheets to produce a three-dimensional supramo-
lecular network.
Examination of the Dissolution/Reorganization Behav-
iors for {Cs2[M3(btec)2(H2O)4]}n (M=Co (3), Ni (4)) in
an Aqueous Solution of Sodium Chloride. In addition to
the potassium salts of [M3(btec)2(H2O)4]2- (M=Co, Ni),
related investigations involving the cesium salts (3 3H2O
and 4 3H2O) were also performed in the case of sodium
3
3
chloride under the same conditions.
When suitable amounts of 3 3H2O were added to an
3
aqueous solution of sodium chloride, the red crys-
tals dissolved. Evaporation of the solvent gave reddish
block-shaped crystals, along with a large amount of
colorless crystals of alkali chloride salts. The red species
were identified by a single-crystal X-ray diffraction ana-
lysis (INDEX data), indicating that the cell parameters
were similar to those of 7. This result was also confirmed
by the powder X-ray diffraction (PXRD) pattern of
the reddish-colored samples that had been reassembled
from an aqueous solution of 3 3H2O and NaCl, which
3
is in good agreement with the simulated and experi-
mental PXRD patterns for 7 (Figure S1, Supporting
Information).
discrete molecule (5 H2O), a 3D porous framework
(6 3.5H2O), a 3D regular network (7), and a 2D sheet
(8 3H2O), respectively. The reasons for the richness of the
3
3
3
On the other hand, when Ni analogue 4 3H2O was used
to replace the Co derivative 3 3H2O in an aqueous
3
structural transformations for CPs 1-4 in the presence of
LiCl or NaCl in water are unclear but may be related to
simple structural changes in CPs 1-4 and the KCl or CsCl
systems. This could, however, be attributed to the nature
of the d-electron configurations of transition metal ions
3
solution of sodium chloride, greenish-colored crystals
were produced. This product was characterized as
8 3H2O on the basis of a comparison of PXRD patterns
3
with patterns simulated from the single-crystal data for

7462 Inorganic Chemistry, Vol. 48, No. 15, 2009
Ding et al.
Figure 6. Perspective views of(a) the [CoII(btec)]-based(4,4)-layer and (c) the [NaI(btec)]-based (4,4)-layer in 7. Schematic representations are simplified in
b and d, respectively. (e) Schematic view of the three-dimensional polymeric architecture of 7. Dark-gray 4-connector, trans-Co(O2C-)4(H2O)2 core; white
4-connector, btec ligand; light-gray 2-connector, (H2O)2Na(μ-H2O) core.
Figure 7. Coordination modes of the two crystallographically distinct btec ligands in 8 3H2O.
3
(d7 for CoII and d8 for NiII)34 and the size of the alkali-
1-4 are the result of the rearrangement of transition
metal-carboxylate building blocks. The building blocks
in 1-4 are trinuclear 8-connectors of M3(O2C)8(H2O)4,
which are coverted to a mononuclear 1-connector (M-
(O2C)(H2O)5) in 5 and 8 as a terminal node, both a
linear 2-connector (trans-M(O2C)2(H2O)4) and a dis-
torted square-planar 4-connector trans-(M(O2C)4-
(H2O)2) in 6, and a distorted square-planar 4-connector
(trans-M(O2C)4(H2O)2) in 7 as well as a bent 2-con-
nector (cis-M(O2C)2(H2O)4) in {Cs2[M(btec)2(H2O)4]}n
3
metal ions (2 A for Li , 3 A for Na , 10 A for K , and
I
3
I
3
I
˚
I 35
˚
˚
3
19 A for Cs ).
˚
It is noteworthy that the dissolution/reorganization
processes leading to the structural conversion of CPs
ꢁ
(34) (a) Guillou, N.; Livage, C.; Ferey, G. Eur. J. Inorg. Chem. 2006, 4963.
ꢁ
(b) Livage, C.; Forster, P. M.; Guillou, N; Tafoya, M. M.; Cheetham, A. K.; Ferey,
G. Angew. Chem., Int. Ed. 2007, 46, 5877.
(35) Mingos, D. M. P.; Rohl, A. L. Inorg. Chem. 1991, 30, 3769.

Article
Inorganic Chemistry, Vol. 48, No. 15, 2009 7463
Figure 8. (a) Heterometallic trinuclear SBU of Na2Ni(O2C)5(H2O)9 in 8 3H2O, shown as ball-and-stick and edge-sharing polyhedra representa-
3
tions. (b) Views of the two-dimensional sheet network with SBUs linked together via the benzene ring of the btec ligand along the crystallograp-
hic a (left), b (middle), and c axes (right). Color scheme: medium gray, O; light gray, C; dark-gray polyhedron, CoO6 core; light-gray polyhedron,
NaO6 core.
Figure 9. Schematic representations of 1- (terminal, M(O2C)(H2O)5), 2- (linear, trans-M(O2C)2(H2O)4, and bent, cis-M(O2C)2(H2O)4), 4- (distorted
square-planar, trans-M(O2C)4(H2O)2), and 8-connected (trinuclear cluster, M3(O2C)8(H2O)4) transition metal-carboxylate building blocks.
(M=Co (9), Ni (10)) (Figure 9).26b As a result, the rear-
rangement of transition metal-carboxylate building
blocks accompanies the metal-carboxylate-donating
Scheme 2. Changes in Transition Metal-Carboxylate Building
Blocks for the Structural Transformation of CPs 1-4 Induced by
Alkali-Metal Ions in Aqueous Solutions
bond cleavage/formation during dissolution/reorganiza-
tion. Scheme 2 summarizes the changes in transition
metal-carboxylate building blocks in Co- and Ni-
carboxylate coordination networks induced by alkali-
metal ions (LiI, NaI, KI, and CsI) via the dissolution/
reorganization process, some of the results are presented
from our previous investigations,26b which demonstrated
the structural transformations in CPs.
Thermal Properties. Thermogravimetric (TG) analysis
results for compounds 5 H2O, 7, and 8 3H2O measured
3
3
under N2 are shown in Figure S3 (Supporting Informa-
tion) and are in agreement with microanalytical data. The
TG curves reveal that the main weight loss occurs be-
tween room temperature and 250 °C, corresponding
to the loss of free and coordinated water molecules (T e
170 °C for 5 H2O, T e 157 °C for 7, and T e 232 °C for
3
8 3H2O), before the compounds decompose under N2 at
ca. 430, 370, and 440 °C for 5 H2O, 7, and 8 3H2O,
respectively. Detailed TG data for the crystalline samples
3
3
3

7464 Inorganic Chemistry, Vol. 48, No. 15, 2009
Ding et al.
Table 1. Crystallographic Data for 5 H2O, 6 3.5H2O, 7, and 8 3H2O
3
3
3
5 H2O
6 3.5H2O
7
8 3H2O
3
3
3
empirical formula
Mw
cryst syst
C
10H24Co2O19
C20H31Li2Ni3O29.5
933.46
monoclinic
C2/m
9.540(2)
19.812(5)
11.151(3)
90
113.684(10)
90
1930.2(8)
2
293(2)
0.71073
1.606
1.546
954
0.959
0.0629
0.1784
C10H18CoNa2O16
499.15
monoclinic
C2/m
15.723(3)
9.5571(19)
6.1123(12)
90
92.83(3)
90
917.4(3)
2
293(2)
0.71073
1.807
1.066
510
1.123
0.0294
0.0753
C20H46Na4Ni2O37
1087.95
triclinic
P1
9.6710(7)
10.2810(7)
11.1449(7)
114.761(4)
92.333(4)
93.158(4)
1002.22(12)
1
566.15
triclinic
P1
space group
˚
a (A)
9.4058(19)
10.215(2)
11.096(2)
87.82(3)
77.29(3)
70.21(3)
977.8(3)
2
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
T (K)
293(2)
293(2)
˚
λ (A)
0.71073
1.923
1.793
580
1.052
0.0295
0.0779
0.0450
0.0847
0.431/-0.499
0.71073
1.803
1.104
562
0.777
0.0516
0.0890
0.1469
0.1030
Dcalcd (g cm-3
)
μ (mm-1
F000
)
GOF
R1a (I > 2σ (I))
wR2b (I > 2σ (I))
R1a (all data)
0.1117
0.1887
1.049/-0.542
0.0329
0.0775
0.243/-0.431
wR2b (all data)
ΔFmax/ΔFmin (e A
-3
˚
)
0.415/-0.528
P
P
P
P
a R1 =
||Fo - Fc||/ |Fo|. b wR2 = { [w(Fo2 - Fc2)2]/ [w(Fo2)2]}.
of 5 H2O, 7, and 8 3H2O are summarized in Table S1
(Supporting Information).
Dissolution/Reorganization of Porous CPs 1 and 2 in Aqueous
Solutions of Lithium Chloride. Entry 1: [Co2(btec)(H2O)10]
3
3
3
H2O (5 H2O). CP 1 6H2O (28.0 mg, 3.0 ꢀ 10-2 mmol) was
3
3
dissolved in an aqueous solution of lithium chloride (1.0 M,
Conclusions
5 mL, 5 mmol). Pink crystals of 5 H2O (9.0 mg, 1.6ꢀ10-2 mmol,
3
35% based on Co2þ) appeared after the solution was allowed to
stand for ca. 60 days. Anal. found: C, 21.02; H, 4.15%. Calcd for
C10H24Co2O19: C, 21.22; H, 4.27%.
In this study, dissolution/reorganization toward the struc-
tural transformation of CPs {A2[M3(btec)2(H2O)4]}n (A=K,
Cs; M = Co, Ni), accompanied by the rearrangement of
transition metal-carboxylate building blocks via bond clea-
vage/formation, occurred in the presence of alkali-metal
chloride (LiCl and NaCl) in water, leading to the formation
of new metal-carboxylate species. Taking a simple survey,
dissolution/reorganization processes reveal the results, case
by case in the work presented here (LiCl or NaCl); therefore,
CPs 1-4 would give rise to extremely rich and diverse
structural rearrangements. The resulting metal-carboxylate
materials are a 0D discrete molecule (5 H2O), a 3D porous
(2,4,4)-connected framework (6 3.5H2O), a 3D regular net-
work (7), and a 2D sheet (8 3H2O). In comparison, the
results regarding aqueous systems of CPs 1-4 and KCl or
CsCl are relatively simple and afforded only a 3D porous
framework of {K2[M3(btec)2(H2O)4]}n and only a 1D zigzag
chain of {Cs2[M(btec)2(H2O)4]}n, respectively. This may be
attributed to the nature of the d-electron configurations of
transition metal ions (CoII and NiII) and the size of the alkali-
metal ions (LiI, NaI, KI, and CsI) used.
Entry 2: {Li2[Ni3(btec)2(H2O)10] 3.5H2O}n (6 3.5H2O). CP
3
3
2 4H2O (34.6 mg, 3.9ꢀ10-2 mmol) was dissolved in an aqueous
3
solution of lithium chloride (1.0 M, 5 mL, 5 mmol). Green
crystals of 6 3.5H2O appeared after the solution was allowed to
3
stand for ca. 90 days.
Dissolution/Reorganization of Porous CPs 1-4 in Aqueous
Solutions of Sodium Chloride. Entry 1: [Na2Co(btec)(H2O)8]n
(7). CP 1 6H2O (31.3 mg, 3.3ꢀ10-2 mmol) was dissolved in an
3
aqueous solution of sodium chloride (1.0 M, 5 mL, 5 mmol).
Red crystals of 7 (18.7 mg, 3.7 ꢀ 10-2 mmol, 56% based on
btec4-) appeared after the solution was allowed to stand for ca.
60 days. Anal. found: C, 24.05; H, 3.50%. Calcd for C10H18Co-
Na2O16: C, 24.06; H, 3.63%.
3
3
3
Entry 2: {[Na4Ni2(btec)2(H2O)18] 3H2O}n (8 3H2O). CP
3
3
2 4H2O (72.5 mg, 8.1ꢀ10-2 mmol) was dissolved in an aqueous
3
solution of sodium chloride (1.0 M, 5 mL, 5 mmol). Green
crystals of 8 3H2O (20.7 mg, 1.9ꢀ10-2 mmol, 24% based on
3
btec4-) appeared after the solution was allowed to stand for ca.
30 days. Anal. found: C, 22.47; H, 3.91%. Calcd for C20H46Na4-
Ni2O37: C, 22.08; H, 4.26%.
Entry 3. CP 3 3H2O (36.6 mg, 3.4ꢀ10-2 mmol) was dissolved
3
Experimental Section
in an aqueous solution of sodium chloride (1.0 M, 7 mL,
7 mmol). After the solution was allowed to stand for ca. 40
days, red crystals of 7, identified by PXRD analysis and a
comparison of cell parameters (INDEX data) from a single-
crystal X-ray diffraction analysis, were obtained. Yield: 65%
based on btec4- (22.3 mg, 4.5ꢀ10-1 mmol). Anal. Found: C,
23.96; H, 3.60. Calcd for C10H18CoNa2O16 (7): C, 24.06; H, 3.63.
Materials and Instruments. Chemical reagents were pur-
chased commercially and were used as received without further
purification. Solvated CPs {A2[M3(btec)2(H2O)4] xH2O}n
(1 6H2O, A=K, M=Co, x=6; 2 4H2O, A=K, M=Ni, x=
3
3
3
4; 3 3H2O, A=Cs, M=Co, x=3; and 4 3H2O, A=Cs, M=Ni,
3
3
x = 3) were prepared following literature procedures.26 TG
analyses were performed under nitrogen with a Perkin-Elmer
TGA-7 TG analyzer. PXRD measurements were recorded on a
Siemens D-5000 diffractometer at 40 kV, 30 mA for Cu KR (λ=
Entry 4. CP 4 3H2O (31.2 mg, 2.9ꢀ10-2 mmol) was dissolved
3
in an aqueous solution of sodium chloride (1.0 M, 12 mL, 12
mmol). After the solution was allowed to stand for ca. 80 days,
green crystals of 8 3H2O, identified by PXRD analysis and a
˚
1.5406 A), with a step size of 0.02° in θ and a scan speed of 1 s per
step size. Elemental analyses were carried out on a Perkin-Elmer
2400 CHN elemental analyzer.
3
comparison of cell parameters (INDEX data) from a single-
crystal X-ray diffraction analysis, were obtained. Yield: 82%

Article
Inorganic Chemistry, Vol. 48, No. 15, 2009 7465
based on btec4- (25.9 mg, 2.4ꢀ10-1 mmol). Anal. Found: C,
located from difference Fourier maps and refined isotropically.
No attempt was made to locate the hydrogen atoms of the free
water molecules in 6 3.5H2O. Lithium metal ions were assigned
22.31; H, 3.90. Calcd for C20H46Na4Ni2O37 (8 3H2O): C, 22.08;
H, 4.26.
3
3
for the charge compensation in 6 3.5H2O. The defined Li ion is
Crystallographic Determination. Single-crystal X-ray diffrac-
tion analysis was performed by using an Enraf Nonius CAD4
diffractometer for 5 H2O and 7 and a Bruker P4 diffractometer
3
located at a special position with a site of occupancy of 0.5,
which fully meets the requirements for charge compensation. In
addition, the thermal factor of the defined Li ion is more
reasonable than that of a water oxygen atom. The disorder of
lithium ions is possible considering the high anisotropy of
thermal motion. Experimental details for X-ray data collection
and the refinements are summarized in Table 1.
3
for 6 3.5H2O and 8 3H2O equipped with graphite monochro-
3
3
˚
matized Mo KR radiation (λ=0.71073 A). The structures were
solved by direct methods and refined by the full-matrix least-
squares method on F2 values using the WINGX36 and SHELX-
9737 program packages. Anisotropic thermal factors were
assigned to non-hydrogen atoms, except the oxygen atoms of
Acknowledgment. We thank Academia Sinica and the
National Science Council of Taiwan for financial support.
the free water molecules in 6 3.5H2O. Hydrogen atoms were
placed in calculated positions with isotropic displacement para-
3
meters. The aqua hydrogen atoms in 5 H2O, 7, and 8 3H2O as
well as those of coordinated water molecules in 6 3.5H2O were
3
3
Supporting Information Available: Full crystallographic de-
tails (CIF) for 5 H2O, 6 3.5H2O, 7, and 8 3H2O are provided.
Powder X-ray diffractions patterns, TG diagrams, and data
3
3
3
3
(36) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(37) Sheldrick, G. M. SHELX-97 (including SHELXS and SHELXL);
University of Gottingen: Gottingen, Germany, 1997.
analyses for 5 H2O, 7, and 8 3H2O. This material is available
free of charge via the Internet at http://pubs.acs.org.
3
3