Unique example of a T3(2)4(2)3(2)6(2) water tape containing acetate-water hybrid hexamer in a heterometallic schiff base complex host

Article abstract of DOI:10.1016/j.inoche.2012.01.008

The novel T3(2)4(2)3(2)6(2) tape, constructed by acetate-water hybrid hexamer [(H₂O)₄(CH₃COO)₂] ^2-, water trimers and tetramer, has been observed for the first time in a heterometallic Schiff base com

Full text of DOI:10.1016/j.inoche.2012.01.008

Inorganic Chemistry Communications 18 (2012) 50–56
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Unique example of a T3(2)4(2)3(2)6(2) water tape containing acetate–water hybrid
hexamer in a heterometallic schiff base complex host
a
a
b
b
a,
Prasanta Bhowmik , Subrata Jana , Partha Pratim Jana , Klaus Harms , Shouvik Chattopadhyay ⁎
a
Department of Chemistry, Inorganic Section, Jadavpur University, Kolkata, 700 032, India
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
b
a r t i c l e i n f o
a b s t r a c t
The novel T3(2)4(2)3(2)6(2) tape, constructed by acetate–water hybrid hexamer [(H O) (CH COO) ]2−,
Article history:
2
4
3
2
Received 28 November 2011
Accepted 6 January 2012
Available online 13 January 2012
water trimers and tetramer, has been observed for the first time in a heterometallic Schiff base complex
host, [Cu(vanpn)Na(CH COO)(H O)]. 2H O, {H vanpn=N,N′-propylene-bis(3-methoxysalicylideneimine}.
3
2
2
2
The present findings provide insight and serve as a prototype for stabilizing other pure and hybrid water
clusters.
Keywords:
©
2012 Elsevier B.V. All rights reserved.
T3(2)4(2)3(2)6(2) tape
Water-trimer
Water-tetramer
Acetate–water hybrid hexamer
Schiff base
Copper(II)
Because water is so essential to life on Earth, water clusters have
been the subject of extensive experimental and theoretical research
may be fused to form T4(2)6(2) tape [17], four-membered rings may
be connected by sharing a water to form a T4(1) tape [18] etc. There
are also some interesting examples, where a four-membered ring is
fused with a ten-membered ring or with a eight-membered ring to
form a T10(2)4(2) tape [19] or a T8(1)4(1) tape [20] respectively. In
order to retrieve a sample of hydrated structures, we used the CSD
search program ConQuest (version 5.32, November 2010; last updates
Feb 2011). We included only those structures that have at least one
acetate/water contact with an O⋯O distance less than the sum of their
van der Waals radii and R-factorb10% (266 hits on May 18, 2011).
In the present paper, we report for the first time, the synthesis and
[1,2]. A number of discrete water clusters including tetramers [3],
pentamers [4], hexamers [5,6], octamers [7], decamers [8,9], and
higher order clusters [10] have been identified. Despite of many the-
oretical and experimental efforts, understanding the behavior of solid
and liquid water at the molecular level still remains a challenge [11].
At the molecular level, water clusters are thought to facilitate the
transfer of a proton along the hydrogen bonded chain [12], which is
not only a fundamental biological process [13], but also a key mecha-
nism for the generation of electrical power in hydrogen fuel cells [14].
Interestingly, this area continues to intrigue the scientific community
both in terms of basic research and technological applications [15]. In
particular, the structural characterization of water clusters is crucial
in correlating and predicting the properties of bulk water at a molec-
ular level. It is known that, in the solid state, most of the organic hosts
forming water clusters are directly linked to water molecules via
hydrogen bonding interactions [4].
2−
2 4 3 2
characterization of a new type of hybrid hexamer [(H O) (CH COO) ]
fused with water trimers and tetramer to form a one-dimensional
T3(2)4(2)3(2)6(2) tape (Chart 1). Although the finding was totally
serendipitous and not designed, the unique tape is expected to draw
attention for the presence of fused tetracyclic moiety containing water
trimer, tetramer and acetate–water hybrid hexamer in the same tape.
This unique tape is stabilized in a heterometallic Schiff base complex
It is possible to classify a number of common aggregation states
adopted by hydrogen-bonded water molecules as: D (discrete chains),
R (discrete rings), C (infinite chains in one dimension involving no
rings), T (infinite tapes in one dimension involving rings), L (infinite
layers in two dimensions), and U (unclassified structures) [16]. Many
infinite water tapes in one dimension involving rings are reported in
the literature. For example, six-membered and four-membered rings
host, [Cu(vanpn)Na(CH
propylene-bis(3-methoxysalicylideneimine}. The hybrid hexamer
bears a similar structural topology as the cyclic hexamer, (H O) [21]
or cyclohexane. The participation of two oxygen atoms from two
carboxylate groups with four water molecules in forming a six-
membered ring has not been found in the aforementioned search [22]
to form a T3(2)4(2)3(2)6(2) tape.
3 2 2 2
COO)(H O)].2H O, {Where H vanpn is N,N′-
2
6
2
The reaction of copper(II) acetate monohydrate with H vanpn and
sodium acetate at ambient temperature produces green precipitate of
the complex [23]. Diffraction quality single crystals [24] are grown
⁎
Corresponding author. Tel.: +91 9903756480.
E-mail address: shouvik.chem@gmail.com (S. Chattopadhyay).
2
from the acetonitrile solution. The ligand (H vanpn) is prepared by
1387-7003/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2012.01.008

P. Bhowmik et al. / Inorganic Chemistry Communications 18 (2012) 50–56
51
3 2 2
Chart 1. Coexistence of water trimer, tetramer and acetate–water hybrid hexamer in [Cu(vanpn)Na(CH COO)(H O)]. 2H O forming a T3(2)4(2)3(2)6(2) tape.
the 1:2 condensation of the 1,3-propanediamine with 3-
methoxysalicyldehyde in methanol following the literature method
The structure determination reveals that the complex crystallizes
in the monoclinic space group P2 /c with the asymmetric unit con-
sisting of hetero-metallic complex [Cu(vanpn)Na(CH COO)(H O)]
1
[
25]. H
drate and stirring with sodium acetate to prepare the complex. When
copper(II) acetate is refluxed with H vanpn only, a different complex
Cu(vanpn)(OH )] is produced, where copper(II) assumes a square-
2
vanpn is then made to react with copper(II) acetate monohy-
3
2
and two lattice water molecules. A representative ORTEP diagram is
shown in Fig. 1. The central copper atom is coordinated by the two ni-
trogen atoms, N(8) and N(12), and two phenoxo oxygen atoms, O(2)
and O(3), forming the distorted square planner geometry. There is a
slight distortion to the square plane and the deviations of the coor-
dinating atoms N(8),N(12),O(2) and O(3) from the least-square
mean plane through them are 0.162(2), −0.161(2), −0.193(2) and
0.192(1) Å respectively and that of copper atom from the same
plane is 0.046 Å. The conformation of the saturated six-membered
ring {Cu(1)–N(8)–C(9)–C(10)–C(11)–N(12)} is closer to screw boat
with the puckering parameters [28] Q=0.610(2) Å, θ=116.99(19)°,
φ=332.2(2)°. The N(8)–Cu(1)–N(12) angle is 96.45(7)° as expected
for a typical six-membered chelate [29]. On the other hand, the
sodium ion is surrounded by two phenoxo oxygen atoms, {O(2),
O(3)} and two methoxy oxygen atoms {O(1), O(4)} of the Schiff
base, one oxygen atom, O(100), of water molecule and one oxygen
atom, O(11), from acetate group, to form a distorted octahedral geom-
etry. The distance of Na-O(methoxy) is larger than that of Na-
O(phenolate). The Cu(1)⋯Na(1) intra-molecular distance is 3.476 Å.
The bridging angles Cu(1)–O(2)–Na(1) and Cu(1)–O(3)–Na(1) are
107.88(7)° and 108.01(6)°, respectively. The Cu(1)–O(2)–O(3)–
Na(1) core is almost planar, the dihedral angles between the O(2)
Cu(1)O(3) and O(2) Na(1)O(3) planes being 5.23°.
2
[
2
pyramidal geometry. The X-ray structure of this complex is reported
elsewhere [26]. The coordinated water in the complex
2
[Cu(vanpn)(OH )] is involved in H-bonding with the methoxy
oxygen of a second, thereby forming a H-bonded dimer. When
sodium ion is incorporated in the system, the geometry of copper(II)
ion is changed from square pyramidal to square planer. The H-
bonding framework changes drastically on the incorporation of sodium
in the O
complex [Cu(vanpn)(OH
4
compartment of the tetradentate Schiff Base. The mononuclear
)] can also be prepared by refluxing
vanpn in 1:1 ratio, but, in this synthetic
O and H vanpn ratio must be maintained to
2
Cu(ClO
4
)
2
·6H
2
O with H
·6H
2
procedure, Cu(ClO
4
)
2
2
2
3
4 2
:2; otherwise a trinuclear complex [Cu(vanpn)Cu(vanpn)Cu](ClO )
is produced. The structure of this is reported by a different group [27].
The formation of the complexes is shown in Scheme 1.
Elemental analysis (carbon, hydrogen and nitrogen) was performed
using a Perkin–Elmer 240C elemental analyzer. IR spectra in KBr
−
1
(
4500–500 cm ) were recorded using a Perkin–Elmer RXI FT-IR spec-
trophotometer. Electronic spectra in acetonitrile (1200–350 nm) were
recorded in a Hitachi U-3501 spectrophotometer. The magnetic sus-
ceptibility measurements were done with an EG & PAR vibrating sample
magnetometer, model 155 at room temperature and diamagnetic
corrections were made using Pascal's constants. The thermal behavior
of the complex was studied in a dynamic nitrogen atmosphere
The enclathrated and coordinated water molecules as well as ace-
tate groups are self-assembled through hydrogen bonds along the b
axis to form a complex 1D network. The hydrogen bonding geometry
and the water network are shown in Fig. 2 and hydrogen bond dis-
tances are given in Table S2. The most striking feature of the present
system is that it contains cyclic water trimers, tetramers and hexam-
ers fused with one another. Cyclic water tetramers (Fig. 3a) are
formed by two types of water molecules, the lattice water molecules
−
1
−1
(
150 mL min ) at a heating rate of 10 °C min
using thermogravi-
metric (TG) and derivative thermogravimetric (DTG) techniques in a
Perkin Elmer (SINGAPORE) Pyris Diamond TG/DTA instrument. Electro-
chemical measurements were performed in acetonitrile solution under
a dry nitrogen atmosphere in conventional three-electrode configura-
tions using a Pt diskworking electrode, Pt auxiliary electrode and Ag/
AgCl reference electrode, with tetrabutylammonium hexafluoropho-
sphate as supporting electrolyte in the potential range from −2 to
i
W1 and its symmetry related counterpart W1 , the coordinated water
i
molecule W2 and symmetry related W2 , the corresponding oxygen
i
atoms of which are represented by O(100), O(100 ), O(102) and
i
2
V, and were uncorrected for junction contribution. The value for the
O(102 ) respectively. The average hydrogen bond distance within
Fc–Fc+ couple under our conditions is 0.5 V. The magnetic susceptibil-
ity measurements were done with an EG & PAR vibrating sample
magnetometer, model 155 at room temperature and diamagnetic
corrections were made using Pascal's constants.
the water tetramer is 2.8321 Å, which is closer to the respective
distance of bulk liquid water (2.85 Å) [30] than to that of ice (2.76 Å
i
for ice Ih at 90 K) [31]. O(102) and O(102 ) act as two hydrogen
i
bond acceptors and O(100) and O(100 ) as hydrogen bond donors

52
P. Bhowmik et al. / Inorganic Chemistry Communications 18 (2012) 50–56
Scheme 1. Synthesis of the complex.
j
j
to form the cyclic water tetramer. The four oxygen atoms within the
cyclic tetramer lie in a plane. Interestingly, the individual water tetra-
O(102 ) as hydrogen bond donors where as O(101) and O(101 )
involve in both hydrogen bond acceptor and donor. The average
hydrogen bond distance within the acetate–water hybrid hexamer
is 2.736 Å, which is closer to the respective distance of ice (2.76 Å
for ice Ih at 90 K) [21] than to that of bulk liquid water (2.85 Å)
[22]. Hydrogen bonded acetate–water hybrid hexamer is in a chair
conformation.
Although the role of water has been extensively analyzed in the
assembly of crystalline materials, no concrete rule has yet been estab-
lished. However, it is generally assumed that water normally plays
two types of role: firstly, it fills the void space in porous materials
and secondly, it acts as balancing agent for the number of donors
and acceptors when there is a mismatch between a set of hydrogen-
bonding partners [33]. In recent years, there have been a number of
reports of crystalline materials encapsulating water clusters of various
nuclearities [34] and morphologies [4], either remaining in the void
mer is hydrogen bonded to two neighboring free water molecules
i
(
W3and W3 ) [32] yielding an extended hexamer (Fig. 3b). Instead
of describing this water cluster as hexamer, however, one can also
think of the formation of two trimeric water clusters (Fig. 3c) (by
i
i
i
W1, W2, W3; and W1 , W2 , W3 ) fused with the water tetramer.
The bond angle between the planes of trimer and tetramer is found
to be 65.98°. All the oxygen atoms act as both hydrogen bond accep-
tors and hydrogen bond donors alternatively. The water trimer
clusters lie in the plane. This fused system of trimers with tetramer
is linked among themselves again through a fused hexa nuclear ring
formed by two lattice water, (W2 and W3) and an oxygen atom
(
O12) of the acetate group and obviously their symmetry-related
j
j
j
counterparts (W2 , W3 and O12 ) (Fig. 3d). In that hexamer, O(12)
and O(12 ) act as hydrogen bond acceptors with O(102) and
j

P. Bhowmik et al. / Inorganic Chemistry Communications 18 (2012) 50–56
53
Fig. 1. ORTEP3 diagram of the complex with 25% ellipsoid probability. Hydrogen atoms and lattice water molecules are not shown for clarity. Selected bond distances (Å): Cu(1)\
O(2) 1.9288(15), Cu(1)\O(3) 1.9238(14), Cu(1)\N(8) 1.9705(19), Cu(1)\N(12) 1.9778(17), Na(1)\O(1) 2.4831(18), Na(1)\O(2) 2.3601(17), Na(1)\O(3) 2.3613(16), Na(1)\
O(4) 2.4953(16), Na(1)\O(11) 2.2690(2), Na(1)\O(100) 2.3350(2). Bond angles are given in supplementary Table S1.
space or as a constituent of the supramolecular network itself. The
water tetramers are one of the important water motifs that have been
observed in crystalline materials in more instances than the other
water motifs [2]. This suggests that water molecules have an inherent
tendency to self-organize themselves especially in the form of the
water tetramer even in the presence of other molecular building blocks.
The isolation and crystal structure of the complex unambiguously show
not only the presence of fused trimers and tetramer but also the
presence of an acetate–water hybrid hexamer to form a T3(2)4(2)
3(2)6(2) tape.
The bidentate ligand, acetate, has extensively been used to link the
transition metal ion and Na by coordination driven self-assembly to
form discrete 2-D and 3-D species with well defined shape and sizes
[35,36]. But, surprisingly, in all the complexes containing both copper
Fig. 2. T3(2)4(2)3(2)6(2) tape containing water trimers, tetramers and acetate–water hybrid hexamer.

54
P. Bhowmik et al. / Inorganic Chemistry Communications 18 (2012) 50–56
Fig. 3. ORTEP3 diagrams showing (a) cyclic water tetramer (b) extended hexamer (c) cyclic water trimer (d) acetate water hybrid hexamer.
and sodium, acetate is acting as bridging ligand [37] and among them,
only one complex contains a Schiff base [36a]. Most interestingly, best
to our knowledge, there is no report of crystal structure of a complex
containing copper, sodium and acetate where acetate is used as a
terminal ligand and attached with sodium only [37].
The Hirshfeld surfaces [38] of the complex are illustrated in Fig. 4a,
showing surfaces that have been mapped over a dnorm (range of −0.5
to 1.5 Å), shape index and curvedness. The surface is shown as trans-
parent to allow visualization of the molecular moiety, in a similar
orientation for all structures, around which they are calculated.
Fig. 4. (a) Hirshfeld surface mapped with dnorm (left), shape index (middle), and curvedness (right). (b) Fingerprint plot: Full (left) and resolved into O⋯H/H⋯O (right) contact showing
the percentage of contact contributed to the total Hirshfeld Surface area of molecule.

P. Bhowmik et al. / Inorganic Chemistry Communications 18 (2012) 50–56
55
The dominant interaction between O⋯H atoms can be seen in the
Hirshfeld surface as the red areas in Fig. 4a. Other visible spots in
the Hirshfeld surfaces correspond to H⋯H contacts. The small extent
of area and light color on the surface indicates weaker and longer
contact other than hydrogen bonds. The O⋯H/H⋯O intermolecular
interactions appear as distinct spikes in the 2D fingerprint plot
different scan rates (0.01–1.0 V s−1) in the temperature range
300–280 K. Solvent dependent shift and change in electrochemical re-
versibility of redox couples are not significant.
Although there is an abundance of discrete water clusters reported
in the literature, the formation of the acetate–water hybrid hexamer
described in this work has not been observed before in a metal organic
framework host. The coexistence of water trimers and tetramers with
this hybrid-hexamer forming a T3(2)4(2)3(2)6(2) tape makes the
system unique. Given the novel role of water clusters in chemical and
biological systems, the present findings provide insight and serve as a
prototype for stabilizing other pure and hybrid water clusters.
(
Fig. 4b). Complementary regions are visible in the fingerprint plots
where one molecule act as donor (d >d ) and the other as an acceptor
bd ). The fingerprint plots can be decomposed to highlight particular
e
i
(
d
e
i
atoms pair close contacts. This decomposition enables separation
of contributions from different interaction types, which overlap in the
full fingerprint. The proportion of O⋯H/H⋯O interaction are comprising
of 22.4% of the Hirshfeld surfaces for each molecule of the complex.
Acknowledgment
The O⋯H interaction is represented by a spike (d
.026 Å) in the bottom left (donor) area of the fingerprint plot
Fig. 4b), indicating H-atoms of H O molecule are interacting with O-
atom of the acetate group. The H⋯O interaction is also represented by
another spike (d =0.676, d =1.026 Å) in the bottom right (acceptor)
region of fingerprint plot, where acetate oxygen also acts as acceptor
to the H atoms of the H O molecule and these oxygen-based interac-
i e
=0.676, d =
1
This work was supported by CSIR, India (Fellowship for Prasanta
Bhowmik, Sanction No. 09/096(0607)/2010-EMR-I, dated 27.1.10,
and for Subrata Jana, Sanction No. 09/096(0659)/2010-EMR-I, dated
(
2
e
i
1
8.1.11) and University Grants Commission, CAS-UGC, New Delhi.
2
tions represent the closest contacts in the structures and can be viewed
as a pair of large red spots on the dnorm surface (Fig. 4a). The relative
contribution of the different interactions to the Hirshfeld surface is cal-
culated for this complex as well as some similar complexes (Fig. S1)
available in the CSD.
Appendix A. Supplementary data
Crystallgraphic data for the analysis have been deposited with the
Cambridge Crystallographic data Centre, CCDC No 814315. Copies of
this information may be obtained free of charge from CCDC, 12 Union
Road, Cambridge, CB21EZ, UK (fax: +44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk). Supple-
mentary data to this article can be found online at doi:10.1016/j.inoche.
In the IR spectrum of the complex, distinct bands due to the
−
1
azomethine (C\N) group within 1649–1573 cm
are customarily
noticed [39]. The spectrum exhibits a broad band centered at
−
1
3
401 cm
water cluster, which is similar to that of liquid water (3490 cm
40]. Thermogravimetric analysis shows a weight loss of ~10% in the
attributable to the O-H stretching frequency of the
2
012.01.008.
−
1
)
[
References
temperature range 80–110°C which corresponds to the loss of 3
water molecules (calc. 10%). In the DTA curve, there is an endotherm
peak, corresponding to the release of water molecule (Fig. S2). The
dehydrated species does not absorb any water molecules on exposure
to open atmosphere. In the IR spectrum of the dehydrated species, the
[
[
[
1] R. Ludwig, Water: from clusters to the bulk, Angew. Chem. Int. Ed. 40 (2001)
1808–1827.
2] M. Mascal, L. Infantes, J. Chisholm, Water oligomers in crystal hydrates—what's
news and what isn't? Angew. Chem. Int. Ed. 45 (2006) 32–36.
3] M. Zuhayra, W.U. Kampen, E. Henze, Z. Soti, L. Zsolnai, G. Huttner, F. Oberdorfer, A
planar water tetramer with tetrahedrally coordinated water embedded in a hydro-
−
1
broad band at ca. 3490 cm
is missing, confirming the elimination of
4 3 4 2
gen bonding network of [Tc (CO)12\(μ \OH) ·4H O], J. Am. Chem. Soc. 128
the water molecule on heating.
The redox property of the complex exhibits a quasi-reversible
copper(II)/copper(I) reduction. The criteria of reversibility are checked
(2006) 424–425.
[
4] B.-Q. Ma, H.-L. Sun, S. Gao, Cyclic water pentamer in a tape-like structure, Chem.
Commun. (2004) 2220–2221.
by observing constancy of peak–peak separation (ΔE
p
=Epa−Epc) and
[5] P. Rodríguez-Cuamatzi, G. Vargas-Díaz, H. Höpfl, Modification of 2D water that
contains hexameric units in chair and boat conformations—a contribution to the
structural elucidation of bulk water, Angew. Chem. Int. Ed. 43 (2004) 3041–3044.
[6] Y.-C. Liao, Y.-C. Jiang, S.-L. Wang, Discrete water hexamers and template-assisted
molecular recognition in an elastic zincophosphate lattice, J. Am. Chem. Soc. 127
the ratio of peak heights (ipa/ipc ~1) with variation of scan rates [41].
Only very few copper(II)/copper(I) couples exhibit truly reversible elec-
trochemical behavior because copper(II) has a tendency toward six-
coordinate tetragonal geometries while copper(I) appears to prefer
four-coordinate tetrahedral geometries. The subsequent rearrangement
of the copper coordination sphere upon the reduction of the copper(II)
species typically leads to a relatively slow chemical reaction following
the electron transfer process. Reversible behavior can only be seen in
cases where the geometry of the copper complex is essentially the
same before and after the reduction. The only coordination number
that is common to both oxidation states is four, and even in these sys-
tems copper(I) may have regular tetrahedral coordination sphere but
copper(II) always involves a compressed tetrahedral or square planer
geometry. In the present study, complex exhibit quasi-reversible sig-
nals. It has been observed that no well defined oxidative or reductive re-
sponses could be observed on running further in the positive or
(
2005) 12794–12795.
7] J.L. Atwood, L.J. Barbour, T.J. Ness, C.L. Raston, P.L. Raston, A well-resolved ice-like
O) cluster in an organic supramolecular complex, J. Am. Chem. Soc. 123
[
(H
2
8
(2001) 7192–7193.
[
8] U. Mukhopadhyay, I. Bernal, A self-assembled, decameric water cluster stabilized
by a cyano-bridged copper(ii) complex, Cryst. Growth Des. 6 (2006) 363–365.
9] M. Yoshizawa, T. Kusukawa, M. Kawano, T. Ohhara, I. Tanaka, K. Kurihara, N.
Niimura, M. Fujita, Endohedral clusterization of ten water molecules into a
[
“
molecular ice” within the hydrophobic pocket of
a self-assembled cage,
J. Am. Chem. Soc. 127 (2005) 2798–2799.
[
10] (a) P.S. Lakshminarayanan, E. Suresh, P. Ghosh, A hybrid water–chloride struc-
ture with discrete undecameric water moieties self-assembled in a heptapro-
tonated octaamino cryptand, Angew. Chem. Int. Ed. 45 (2006) 3807–3811;
(
b) P.S. Lakshminarayanan, E. Suresh, P. Ghosh, Formation of an infinite 2D-
layered water of (H2O)45 cluster in a cryptand−water supramolecular
complex: a template effect, J. Am. Chem. Soc. 127 (2005) 13132–13133.
[11] M.H. Mir, J.J. Vittal, Phase transition accompanied by transformation of an elusive
discrete cyclic water heptamer to a bicyclic (H O) cluster, Angew. Chem. Int. Ed.
6 (2007) 5925–5928.
2
7
p
negative potential. The E1/2 and ΔE values for these redox couples are
given in Table 1. All the redox signals remain virtually invariant under
4
[
12] Z. Sun, C.-K. Siu, O.P. Balaj, M. Gruber, V.E. Bondybey, M.K. Beyer, Proton transfer
in ionic water clusters, Angew. Chem. Int. Ed. 45 (2006) 4027–4030.
[
13] S. Taraphder, G. Hummer, Protein side-chain motion and hydration in proton-
transfer pathways. Results for cytochrome P450cam, J. Am. Chem. Soc. 125
Table 1
Electrochemical data.
(
2003) 3931–3941.
14] K.-D. Kreuer, Proton conductivity: materials and applications, Chem. Mater.
(1996) 610–641.
[
[
II
I
Cu /Cu
8
15] (a) C. Massera, M. Melegari, F. Ugozzoli, E. Dalcanale, Formation of tetrameric
water clusters driven by a cavitand template, Chem. Commun. 46 (2010)
E
pa(V)
E
pc(V)
E
1/2(V)
p
ΔE (mV)
80
−
1.51
−1.59
−1.55
88–90;

56
P. Bhowmik et al. / Inorganic Chemistry Communications 18 (2012) 50–56
(
b) A. Gutberlet, G. Schwaab, O. Birer, M. Masia, A. Kaczmarek, H. Forbert, M.
Havenith, D. Marx, Aggregation-Induced Dissociation of HCl(H O) Below 1
K: The Smallest Droplet of Acid, Science 324 (2009) 1545–1548.
[35] F. Yuksel, Y. Chumakov, D. Luneau, The chiral Zn(II)–Na(I) coordination polymer:
2
4
Synthesis, crystal structure, thermal and optical properties, Inorg. Chem.
Commun. 11 (2008) 749–753.
[
[
16] L. Infantes, S. Motherwell, Water clusters in organic molecular crystals, CrystEng-
Comm 4 (2002) 454–461.
17] R. Custelcean, C. Afloroaei, M. Vlassa, M. Polverejan, Formation of extended tapes
of cyclic water hexamer in a organic molecular crystal host, Angew. Chem. Int. Ed.
[36] (a) M.E. Bluhm, M. Ciesielski, H. Gorls, O. Walter, M. Doring, Complexes of Schiff
bases and intermediates in the copper-catalyzed oxidative heterocyclization
by atmospheric oxygen, Inorg. Chem. 42 (2003) 8878–8885;
4 2
(b) C. Nather, J. Greve, I. Jess, Poly[di-μ -acetato-di-μ -azido-copper(II)diso-
3
9 (2000) 3094–3096.
dium(I)] at 150 K, Acta Crystallogr., Sect. E: Struct. Rep. Online 61 (2005)
m314–m316;
(c) B. Kozlevcar, A. Golobic, P. Gamez, I.A. Koval, W.L. Driessen, J. Reedijk, A
tridentate bis(pyrazolyl) ligand binds to Cu(II), without using the pyrazole
[
18] S. Pal, N.B. Sankaran, A. Samanta, Structure of a self-assembled chain of water
molecules in a crystal host, Angew. Chem. Int. Ed. 42 (2003) 1741–1743.
19] L. Infantes, J. Chisholm, S. Motherwell, Extended motifs from water and chemical
[
functional groups in organic molecular crystals, CrystEngComm
80–486.
20] A.M. Voutchkova, L.N. Appelhans, A.R. Chianese, R.H. Crabtree, Disubstituted
imidazolium-2-carboxylates as efficient precursors to N-heterocyclic carbene
complexes of Rh, Ru, Ir, and Pd, J. Am. Chem. Soc. 127 (2005) 17624–17625.
21] T. Steiner, Water molecules which apparently accept no hydrogen bonds are
5
(2003)
group: a very unusual coordination mode of the ligand Hbdmpb, 1,3-
bis(3,5-dimethylpyrazol-1-yl)-2-butanoic acid, Inorg. Chim. Acta 358
(2005) 1135–1140;
4
[
(d) A.C. Warden, M.T.W. Hearn, L. Spiccia, Novel acetate binding modes in [Na2-
3 4 2 2
Cu(CH COO) (H O)]·H O, Inorg. Chem. 42 (2003) 7037–7040;
[
(e) C.-D. Wu, C.-Z. Lu, W.-B. Yang, H.-H. Zhuang, J.-S. Huang, A three-dimentional
framework of dimeric copper(II) acetate linked by coordinated sodium cat-
ions, Inorg. Chem. Commun. 4 (2001) 504–506.
systematically involved in C–H⋯O interactions, Acta Crystallogr., Sect.
1995) 93–97.
22] CSD search file 1.pdf (Supporting Information).
23] The Schiff base ligand, H vanpn, was synthesized by refluxing 1,3-diaminopro-
D 51
(
[
[
[37] CSD search file 2.pdf (Supporting Information).
2
[38] Hirshfeld surfaces [42–44] and the associated 2D-fingerprint [45–47] plots were
calculated using Crystal Explorer [48], which accepts a structure input file in CIF
format. Bond lengths to hydrogen atoms were set to standard values. For each
pane (10 mmol, 0.84 mL) with 3-methoxysalicyldehyde (20 mmol, 3.04 g) in
methanol (20 ml) for ca. 1 h. To prepare the complex, a methanol solution of
copper(II) acetate monohydrate (1 mmol, 0.2 g) was added to the methanol solu-
point on the Hirshfeld isosurface, two distances d
to the nearest nucleus external to the surface and d
e
, the distance from the point
, the distance to the nearest
tion of H
acetate (1 mmol, 0.085 g) in methanol was then added to it and stirred for
5 mins. A green colored complex was precipitated out and was recrystallized
from acetonitrile solution to obtain prismatic dark green single crystals suitable
for X-ray diffraction. Yield: 0.34 g (61%). Anal. Calc. for C22 32CuN NaO (540):
2
vanpn (1 mmol, 0.342 g) and refluxed for 1 hr. A solution of sodium
i
nucleus internal to the surface, are defined. The normalized contact distance
vdw
i
vdw
ðdi−r
Þ
ðde −re Þ where rvdw
1
(d
norm) based on de and d
vdw
i
is given by dnorm ¼
vdw
þ
vdw
i
r
re
i
and r
e
are the van der Waals radii of the atoms. The value of dnorm is negative
H
2
9
or positive depending on intermolecular contacts being shorter or longer than the
van der Waals separations. The parameter dnorm displays a surface with a red-
white-blue color scheme, where bright red spots highlight shorter contacts
white areas represent contacts around the van der Waals separation, and blue
regions are devoid of close contacts. For a given crystal structure and set of spher-
ical atomic electron densities, the Hirshfeld surface is unique [49], and it is the
property that suggests the possibility of gaining additional insight into the inter-
molecular interaction of molecular crystals.
C, 40.40; H, 5.04; N, 4.32; Found: C, 40.3; H, 4.9; N, 4.4; UV–Vis, λmax(nm)
3
−1
−1
(ε
max (dm mol
cm )) (acetonitrile), 565 (130), 366 (4355), Magnetic
moment=1.74 BM.
[
24] A crystal of dimensions 0.34×0.32×0.14 mm3 was mounted in inert oil and
transferred to the cold gas stream of the cooling device. Data have been collected
at 193 K on a STOE IPDS diffractometer using graphite monochromated Mo-
Kαradiation and corrected for absorption using indexed faces. Programs used:
SIR92 — A program for crystal structure solution. A. Altomare, G. Cascarano, C.
Giacovazzo, A. Guagliardi, J. Appl. Crystallogr. 1993, 26, 343–350. SHELXL-97 —
A program for crystal structure refinement. G. M. Sheldrick, Acta Cryst., 2008,
[
39] P. Bhowmik, S. Chattopadhyay, M.G.B. Drew, C. Diaz, A. Ghosh, Synthesis, struc-
ture and magnetic properties of mono- and di-nuclear nickel(II) thiocyanate
complexes with tridentate N3 donor Schiff bases, Polyhedron 29 (2010)
A64, 112–122. Crystal data: Fw-539.99; monoclinic, P2 /c, a=11.4435(8),
1
−
3
b=8.7183(6), c=23.3113(17) Å, β=92.062(8)°,dcalc (g cm )=1.543, F(000)
1124, Z=4. 334 parameters were fit to 4052 unique reflections to give R1,
2637–2642.
=
[
40] S.K. Ghosh, P.K. Bharadwaj, Octameric water clusters of staircase structure
present in a metal-organic framework built from helical lanthanide coordination
polymers, Eur. J. Inorg. Chem. (2005) 4886–4889.
41] D.H. Evans, K.M. O'Connell, R.A. Petersen, M.J. Kelly, Cyclic voltammetry, J. Chem.
Educ. 60 (1983) 290–293.
42] M.A. Spackman, D. Jayatilaka, Hirshfeld surface analysis, CrystEngComm 11
wR2 [I>2 σ (I)]=0.0295, 0.0606.
[
[
[
25] P. Bhowmik, H.P. Nayek, M. Corbella, N. Aliaga-Alcalde, S. Chattopadhyay, Control
of molecular architecture by steric factors: mononuclear vs polynuclear manga-
[
[
[
[
nese(III) compounds with tetradentate N
0 (2011) 7916–7926.
2 2
O donor Schiff bases, Dalton Trans.
4
26] S. Thakurta, J. Chakraborty, G. Rosair, R.J. Butcher, S. Mitra, The interplay of O–
H⋯O hydrogen bonding in the generation of three new supramolecular
(2009) 19–32.
43] F.L. Hirshfeld, Bonded-atom fragments for describing molecular charge densities,
Theor. Chim. Acta 44 (1977) 129–138.
44] H.F. Clausen, M.S. Chevallier, M.A. Spackman, B.B. Iversen, Three new co-crystals
of hydroquinone: crystal structures and Hirshfeld surface analysis of intermole-
cular interactions, New J. Chem. 34 (2010) 193–199.
45] A.L. Rohl, M. Moret, W. Kaminsky, K. Claborn, J.J. McKinnon, B. Kahr, Hirshfeld
surfaces identify inadequacies in computations of intermolecular interactions in
crystals: pentamorphic 1,8-dihydroxyanthraquinone, Cryst. Growth Des.
II
II
III
complexes of Cu , Ni and Co
: syntheses, characterization and structural
aspects, Inorg. Chim. Acta 362 (2009) 2828–2836.
27] S. Thakurta, C. Rizzoli, R.J. Butcher, C.J. Gómez-García, E. Garribba, S. Mitra, Sterically-
controlled nuclearity in new copper(II) complexes with di-compartmental ligands:
formation of antiferromagnetically coupled angular trimer and mononuclear inclu-
sion complex, Inorg. Chim. Acta 363 (2010) 1395–1403.
28] D. Cramer, J.A. Pople, General definition of ring puckering coordinates, J. Am.
Chem. Soc. 97 (1975) 1354–1358.
29] M.S. Ray, R. Bhattacharya, S. Chaudhuri, L. Right, G. Boceli, G. Mukhopadhyay, A.
Ghosh, Synthesis, characterisation and X-ray crystal structure of copper(II)
complexes with unsymmetrical tetradentate Schiff base ligands: first evidence
of Cu(II) catalysed rearrangement of unsymmetrical to symmetrical complex,
Polyhedron 22 (2003) 617–624.
[
[
8
(2008) 4517–4525.
[
[
46] A. Parkin, G. Barr, W. Dong, C.J. Gilmore, D. Jayatilaka, J.J. McKinnon, M.A. Spackman,
C.C. Wilson, Comparing entire crystal structures: structural genetic fingerprinting,
CrystEngComm 9 (2007) 648–652.
47] M.A. Spackman, J.J. McKinnon, Fingerprinting intermolecular interactions in
molecular crystals, CrystEngComm 4 (2002) 378–392.
48] S.K. Wolff, D.J. Grimwood, J.J. McKinnon, D. Jayatilaka, M.A. Spackman, Crystal
Explorer 2.0; University of Western Australia: Perth, Australia, http://hirshfeld
surfacenet.blogspot.com/2007.
49] J.J. McKinnon, M.A. Spackman, A.S. Mitchell, Novel tools for visualizing and
exploring intermolecular interactions in molecular crystals, Acta Crystallogr.,
Sect. B 60 (2004) 627–668.
[
[
[
[
[
[
30] T. Head-Gordon, G. Hura, Water structure from scattering experiments and
[
simulation, Chem. Rev. 102 (2002) 2651–2670.
31] W.F. Kuhs, M.S. Lehman, The structure of the ice Ih by neutron diffraction, J. Phys.
Chem. 87 (1983) 4312–4313.
[
i
32] The corresponding oxygen atoms are representated as O(101) and O(101 ) in
Figure 5.
33] G.R. Desiraju, Hydration in organic crystals: prediction from molecular structure,
J. Chem. Soc. Chem. Commun. (1991) 426–428.
34] M.T. Ng, T.C. Deivaraj, W.T. Klooster, G.J. McIntyre, J.J. Vittal, Hydrogen-bonded
2 2
polyrotaxane-like structure containing cyclic (H O)4 in [Zn(OAc)2(m-bpe)]·2H O:
X-ray and neutron diffraction studies, Chem. Eur. J. 10 (2004) 5853–5859.