Anion mediated diversity in the H-bonded assembly of a series of heteronuclear copper(II)/sodium(I) compounds

Article abstract of DOI:10.1016/j.ica.2012.03.044

Three heteronuclear Cu(II)/Na(I) compounds, [Cu(vanpn)Na(NO ₃)(H₂O)] (1), [Cu(vanpn)Na(N₃)(CH ₃OH)] (2) and [Cu(vanpn)Na(NCS)(H₂O)] (3) where H ₂vanpn = N,N′-(1,3-propylene)-bis(3-methoxysa

Full text of DOI:10.1016/j.ica.2012.03.044

Inorganica Chimica Acta 390 (2012) 53–60
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Anion mediated diversity in the H-bonded assembly of a series
of heteronuclear copper(II)/sodium(I) compounds
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 700032, 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
Article history:
3 2 3 3
Three heteronuclear Cu(II)/Na(I) compounds, [Cu(vanpn)Na(NO )(H O)] (1), [Cu(vanpn)Na(N )(CH OH)]
Received 1 December 2011
Received in revised form 21 February 2012
Accepted 23 March 2012
0
2 2
(2) and [Cu(vanpn)Na(NCS)(H O)] (3) where H vanpn = N,N -(1,3-propylene)-bis(3-methoxysalicylide-
neimine), a well known compartmental Schiff base ligand, have been prepared and characterized by ele-
mental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. Compound 1
Available online 4 April 2012
ꢀ
crystallises in monoclinic space group P2
1
/n, compound 2 in triclinic P1 and compound 3 in orthorhombic
space group Pbca. In all the compounds, Cu atoms assume distorted square planar geometries whereas Na
atoms exhibit distorted octahedral geometry. In compound 1, the nitrate ion is coordinated as a chelating
ligand and essentially both the O atoms of the nitrate occupy one axial site. Variation of the counter
anions leads to considerable change in the H-bonded supramolecular structures of the compounds. Com-
pound 1 forms a dimer, compound 2 constitutes a chain and compound 3 forms a helix. Electrochemical
electron transfer study reveals Cu(II)Cu(I) reduction in acetonitrile solution.
Keywords:
Heteronuclear Cu(II)/Na(I)
Compartmental Schiff base
H-bonded architecture
Cyclic voltammetry
Ó 2012 Elsevier B.V. All rights reserved.
1
. Introduction
Supramolecular systems based on coordination compounds
good classes of complexing agents for alkali metal ions, there
are many other simpler and certainly more affordable ligands
that are also extremely effective in this respect. One such ligand
0
have received much attention because of their potential use as
sensors, probes, photonic devices, and catalysts and in host–guest
chemistry [1–7]. A significant number of supramolecular metal
complexes have been synthesized in the last several years [8–
is
H
2
vanpn {=N,N -(1,3-propylene)-bis(3-methoxysalicylidenei-
mine)}, produced by the condensation of 3-methoxysalicalde-
hyde and 1,3-diaminopropane. This compartmental Schiff base
has already been used exhaustively to prepare heterometallic
3d/4f compounds [19]. Structure determination showed that
1
2]. The two most commonly used approaches for engineering
the crystal structure of such complexes employ either coordina-
tive bonds [13–15] or hydrogen bonds [16–18]. Both approaches
and their combinations have resulted in the construction of pre-
designed 2D or 3D supramolecular architectures. Hydrogen bonds
have attracted considerable interest due to their relative strength,
directionality, and ability to act synergically, thus providing a
directing force for the organization of individual molecules into
well-defined supramolecular assemblies. In this regard, it seemed
interesting to conduct a systematic investigation on a designed
series of transition metal complexes with the intention to under-
stand the way in which H-bonding interactions cooperate and di-
rect the supramolecular assembly of the molecular building
blocks.
the 3d metals were placed in the N
gand whereas lanthanide ions were placed in the O
2
O
2
compartment of the li-
compart-
2 2
O
ment in all the compounds without exception. Interestingly,
reports on the preparation of 3d/alkali metal compounds with
this ligand are relatively scanty and to the best to our knowl-
edge, only three compounds are reported in the literatures
which contain a transition metal and Na [20]. Of these three
compounds, one is Cd/Na compound and the other two are Ni/
Na compounds. No heteronuclear Cu/Na compounds with this li-
gand were reported in the literature till date. Furthermore, there
is only one report of the preparation of Cu/alkali metal com-
pound with this ligand in the CSD, where the alkali metal is
potassium [21]. The diversity in the H bonding assembly of such
3d/alkali metal compounds with varying counter anions were
also not studied systematically before the present work. Herein,
we report the facile syntheses, crystal structures, spectroscopic
and electrochemical studies and Hirshfeld analyses of three
new heteronuclear Cu/Na compounds.
Structural studies have focused strongly on crown ethers,
cryptands, and related ligands. Although these are particularly
⇑
Corresponding author. Tel.: +91 9903756480.
E-mail address: shouvik.chem@gmail.com (S. Chattopadhyay).
0
020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.03.044

5
4
P. Bhowmik et al. / Inorganica Chimica Acta 390 (2012) 53–60
2
. Experimental
(1200–350 nm) were recorded in a Hitachi U-3501 spectropho-
tometer. Electrochemical measurements were performed in aceto-
nitrile solution under a dry nitrogen atmosphere in conventional
three-electrode configurations using a Pt diskworking electrode,
Pt auxiliary electrode and Ag/AgCl reference electrode, with tetra-
butylammonium hexafluorophosphate as supporting electrolyte in
the potential range from ꢀ2 to 2 V, and were uncorrected for junc-
tion contribution. The value for the Fc–Fc+ couple under our condi-
tions is 0.5 V. The magnetic susceptibility measurements were
done with an EG & PAR vibrating sample magnetometer, model
2
.1. Materials
All starting materials were commercially available, reagent
grade, and used as purchased without further purification.
2
2
.2. Synthesis
0
.2.1. SynthesisoftheligandN,N -propylene-bis(3-methoxysalicylideneimine)
vanpn)
The hexadentate Schiff base ligand, H
1
55 at room temperature and diamagnetic corrections were made
(H
2
using Pascal’s constants.
2
vanpn, was synthesized
by refluxing 1,3-diaminopropane (10 mmol, 0.84 mL) with 3-
methoxysalicyldehyde (20 mmol, 3.04 g) in methanol (20 ml) for
ca. 1 h.
2.4. X-ray crystallography
Crystals of compounds 1 and 3 were 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 (1) or at 100 K on a STOE
2
.2.2. Synthesis of [Cu(vanpn)Na(NO
A methanol solution (15 ml) of Cu(II) acetate monohydrate
1 mmol, 0.2 g) was added to the methanol solution (15 ml) of
vanpn (1 mmol, 0.342 g) and refluxed for 1 h. A solution of so-
3 2
)(H O)] (1)
(
H
IPDS 2T diffractometer (3) using graphite monochromated Mo K
a
2
radiation, and have been corrected for absorption effects using
multiscanned reflections (1, 3). Non-hydrogen atoms were refined
anisotropically. C bonded hydrogen atoms have been included on
calculated positions and refined using the ‘riding model’. O bonded
hydrogens were located and refined isotropically. Programs used:
SIR92 [22], SHELXL-97 [23,24], PLATON [25], and XAREA [26].
dium nitrate (1 mmol, 0.085 g) in water (5 ml) was then added to
it and stirred for 15 min. A green colored compound was precipi-
tated out and was recrystallized from acetonitrile solution to ob-
tain prismatic dark green single crystals suitable for X-ray
diffraction.
Yield: 0.34 g (67%). Anal. Calc. for C19
3 8
H22CuN NaO (506.93): C,
On the other hand, single crystals of
2 having suitable
4
5.02; H, 4.37; N, 8.29; Found: C, 45.4; H, 4.8; N, 8.3%. IR (KBr,
dimensions for the compound was used for data collection using
a ‘Bruker SMART APEX II’ diffractometer equipped with graphite-
ꢀ
3
1
cm ): 1598
(
c
@
C N
), 1468
dm mol cm )) (acetonitrile), 609 (175), 375 (4616), Magnetic
moment = 1.72 BM.
(cNO3). UV–Vis, kmax (nm) (e
max
ꢀ1
ꢀ1
(
monochromated Mo K
a radiation (k = 0.71073 Å) at 293 K. The
molecular structure was solved by direct methods and refinement
2
by full-matrix least squares on F using the SHELX-97 package
2
.2.3. Synthesis of [Cu(Vanpn)Na(N
It was prepared in a similar method to that of compound 1, ex-
cept that a solution of sodium azide (1 mmol, 0.065 g) in water
5 ml) was used instead of sodium nitrate. X-ray diffraction quality
3 3
)(CH OH)] (2)
[
25,26]. Non-hydrogen atoms were refined with anisotropic
thermal parameters. H atoms of water molecules were located
by difference Fourier maps and were kept fixed. All other
(
single crystals were obtained from the filtrate by slow evaporation
in air.
Table 1
Crystal data and refinement details of compounds 1–3.
5 5
Yield: 0.37 g (74%). Anal. Calc. for C20H24CuN NaO (500.98): C,
4
7.95; H, 4.83; N, 13.98; Found: C, 47.9; H, 4.8; N, 13.6%. IR (KBr,
Compound 1
22CuN NaO
506.93
Compound 2
24CuN NaO
500.98
Compound 3
5
22CuN NaO S
ꢀ
1
cm ): 1615
(
c
C
@
N
), 2044
dm mol cm )) (acetonitrile), 552 (290), 370 (3912), Magnetic
moment = 1.71 BM.
(cN3). UV–Vis, kmax (nm) (e
max
Formula
Formula
weight
C
19
H
3
8
C
20
H
5
5
C
20
H
3
3
ꢀ1
ꢀ1
(
503
Crystal size
0.26 ꢁ 0.24 ꢁ 0.21 0.3 ꢁ 0.2 ꢁ 0.2
0.10 ꢁ 0.08 ꢁ 0.05
(
mm)
2
.2.4. Synthesis of [Cu(Vanpn)Na(NCS)(H
To prepare compound 3, the acetonitrile solution (10 ml) of
Cu(II) acetate monohydrate (1 mmol, 0.2 g) was added to the ace-
tonitrile solution (10 ml) of H vanpn (1 mmol, 0.342 g) and re-
fluxed for 1 h and a solution of sodium thiocyanate (1 mmol,
.081 g) in water (5 ml) was then added to it. The mixture was stir-
2
O)] (3)
T (K)
193
monoclinic
293
100
orthorhombic
Pbca
Crystal system
Space group
a (Å)
b (Å)
c (Å)
triclinic
P2
1
/n
P1
ꢀ
7.0672(10)
24.537(2)
12.0489(17)
–
98.579(17)
–
7.2590(2)
11.0904(3)
13.5757(3)
96.854(1)
101.099(1)
93.095(1)
2
1.567
1.093
518
15802
13.1161(4)
13.6814(5)
24.0413(8)
–
–
–
8
1.549
1.167
2072
23177
2
0
a
(°)
red for about half an hour and filtered to remove a small amount of
precipitate that appeared immediately. The filtrate was left at
room temperature. Diffraction quality single crystals were ob-
tained by slow evaporation of the filtrate in open atmosphere.
b (°)
c
Z
d
(°)
4
calc (g cmꢀ3)
(mm
1.630
1.132
1044
17321
ꢀ1
l
)
Yield: 0.36 g (71.6%). Anal. Calc. for C20
3
H22CuN NaO
5
S (503): C,
F(000)
Total
reflections
Unique
reflections
4
7.76; H, 4.41; N, 8.35; Found: C, 47.8; H, 4.4; N, 8.6%. IR (KBr,
ꢀ
3
1
cm ): 1620
(
c
@
C N
), 2079
dm mol cm )) (acetonitrile), 565 (124), 366 (4557), Magnetic
moment = 1.72 BM.
(cNCS). UV–Vis, kmax (nm) (e
max
ꢀ1
ꢀ1
3648
2654
308
15 287
10031
300
3803
2716
290
(
Observed data
[
I > 2
No. of
parameters
r(I)]
2.3. Physical measurements
R
int
0.0641
0.0538, 0.0675
0.0374
0.0749,0.1245
0.0688
0.0755, 0.0637
Elemental analysis (carbon, hydrogen, and nitrogen) was per-
R1, wR2 (all
data)
R1, wR2
formed using a Perkin–Elmer 240C elemental analyzer. IR spectra
ꢀ1
0.0318, 0.0632
0.0417, 0.1095
0.0408, 0.0569
in KBr (4500–500 cm ) were recorded using a Perkin–Elmer RXI
FT-IR spectrophotometer. Electronic spectra in acetonitrile
[
I > 2r(I)]

P. Bhowmik et al. / Inorganica Chimica Acta 390 (2012) 53–60
55
hydrogen atoms were placed in their geometrically idealized
positions and constrained to ride on their parent atoms. Empirical
absorption corrections were carried out with the ABSPACK program
[
27]. A summary of the crystallographic data are given in Table 1.
CCDC reference numbers are 841558 (for 1), 837600 (for 2) and
41559 (for 3).
8
2.5. Hirshfeld surface analysis
Hirshfeld surfaces [28–30] and the associated 2D-fingerprint
[
31–33] plots were calculated using CrystalExplorer [34] which ac-
cepts a structure input file in CIF format. Bond lengths to hydrogen
atoms were set to standard values. For each point on the Hirshfeld
isosurface, two distances d , the distance from the point to the
e
nearest nucleus external to the surface and di, the distance to the
nearest nucleus internal to the surface, are defined. The normalized
e i
contact distance (dnorm) based on d and d is given by
À
Á
À
Á
vdw
vdw
d
i
ꢀ ri
d
e
ꢀ re
D
norm
¼
þ
vdw
i
vdw
e
r
r
where r vi dW and r ev dW are the van der Waals radii of the atoms. The
value of dnorm is negative 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 spherical atomic electron densities, the Hirsh-
feld surface is unique [35], and it is this property that suggests
the possibility of gaining additional insight into the intermolecular
interaction of molecular crystals.
3
. Results and discussion
3.1. Syntheses
Scheme 1. Formation of the compounds.
2
The ligand (H vanpn) was prepared by the 1:2 condensation of
the 1,3-diaminopropane with 3-methoxysalicyldehyde in metha-
nol following the literature method [36]. H vanpn was then made
3.2. Description of structures
2
to react with Cu(II) acetate monohydrate and stirring with sodium
azide to prepare compound 1. Compounds 2 and 3 were produced
similarly by using sodium thiocyanate and sodium nitrate, respec-
tively, instead of sodium azide. It is to be noted that in absence of
3.2.1. [Cu(vanpn)Na(NO
The molecular structure of 1 is built from isolated dinuclear
molecules of [Cu(vanpn)Na(NO )(H O)]. A perspective view of this
compound with the corresponding labeling scheme is depicted in
Fig. 1. This structure is very similar to the analogous 3d–4f Schiff
base compounds studied earlier [39,40]. In each bimetallic unit,
3 2
)(H O)] (1)
3
2
2
any Na salt, [Cu(vanpn)(OH )] is produced where Cu(II) assumes a
square pyramidal geometry. The X-ray structure of this compound
is reported elsewhere [37]. This compound can also be used as the
starting material in producing compounds 1–3 (Scheme 1). The
2 2 2 2
the Cu(II) and Na(I) atoms occupy the inner N O and outer O O
sites, respectively. The coordinating atoms N(8), N(12), O(1) and
O(3), deviate 0.236(2), ꢀ0.234(2), ꢀ0.283(2) and 0.280(2) Å,
respectively from the mean square plane and the Cu(II) atom is
0.015 Å away from the same plane. The conformation of the satu-
rated six-membered ring {Cu(1)–N(8)–C(9)–C(10)–C(11)–N(12)} is
closer to screw boat with the puckering parameters [41,42]
2
coordinated water in the compound [Cu(vanpn)(OH )] is involved
in H-bonding with the methoxy oxygen of a second, thereby form-
ing a H-bonded dimer. When Na(I) is incorporated in the system,
the geometry of Cu(II) ion is changed from square pyramidal to
square planar. The H-bonding framework changes drastically on
the incorporation of Na(I) in the O
tate Schiff Base. The formation of compounds 1–3 is shown in
Scheme 1. [Cu(vanpn)(OH )] can also be prepared by refluxing
Cu(ClO O with H vanpn in 1:1 ratio. It is very important to
ꢂ6H
maintain the metal:ligand ratio in this synthetic procedure, be-
cause, on refluxing Cu(ClO O with H vanpn in 3:2 ratio, a
ꢂ6H
tri-nuclear compound [Cu(vanpn)Cu(vanpn)Cu](ClO was pro-
duced, the structure of which is reported by a different group
38]. Once this tri-nuclear compound is formed, heteronuclear
Cu(II)/Na(I) compounds could not be prepared.
4
compartment of the hexaden-
Q = 0.643(3) Å, h = 67.95(18)°, u = 151.1(2)°. The N(8)–Cu(1)–
N(12) angle is 97.57(9)° and is typical of six-membered chelate
[43]. Cu(II) and Na(I) are doubly bridged to each other by two
phenoxo oxygen atoms, O(1) and O(3), with Cu(1)ꢂ ꢂ ꢂNa(1) distance
of 3.462(12) Å. The Na(I) is surrounded by four oxygen atoms, O(1),
O(2), O(3), and O(4) of the Schiff base and a oxygen atom, O(100) of
water moiety and two O atoms, O(11) and O(12) of the nitrate. The
small value (50.5°) of the angle [O(11)–Na(1)–O(12)], subtended
by the two O atoms at the metal, traces on the point that the
two oxygen atoms are sharing one axial site, i.e. the nitrate group
2
4
)
2
2
2
4
)
2
2
2
4 2
)
[

5
6
P. Bhowmik et al. / Inorganica Chimica Acta 390 (2012) 53–60
Fig. 1. Perspective view of compound 1 along with the atom numbering of all non-
carbon non-hydrogen atoms. Disordered oxygen atom is not shown for clarity.
Selected bond distances (Å): Cu(1)–N(8) 1.944(2), Cu(1)–N(12) 1.978(2), Cu(1)–
O(1) 1.917(17), Cu(1)–O(3) 1.8993(18), l Na(1)–O(1) 2.385(2), Na(1)–O(2) 2.515(2),
Na(1)–O(3) 2.357(2), Na(1)–O(4) 2.552(2), Na(1)–O(11) 2.505(2), Na(1)–O(12)
2
S1.
.488(15), Na(1)–O(100) 2.352(2). Bond angles are given in Supplementary Table
Fig. 2. Perspective view of compound 2 showing the atom numbering of relevant
atoms. Selected bond distances (Å): Cu(1)–N(8) 1.9934(10), Cu(1)–N(12) 1.9664(9),
Cu(1)–O(1) 1.9184(8), Cu(1)–O(2) 1.9181(8), Na(1)–O(3) 2.4602(11), Na(1)–O(1)
2.3743(9), Na(1)–O(4) 2.4479(11), Na(1)–O(2) 2.3375(9), Na(1)–O(100) 2.3894(15),
Na(1)–N(1) 2.4118(17) Bond angles are given in Supplementary Table S2.
is better thought of as a single entity occupying just one stereo-
chemical site in the coordination sphere of the metal instead of
as a bidentate ligand. Thus the geometry around the Na atom is
distorted octahedral. The bridging angles Cu(1)–O(1)–Na(1) and
Cu(1)–O(3)–Na(1) are 106.65(8) and 108.38(8) respectively. The
dihedral angle between the Cu(1)O(1)O(2) and O(1)O(2)Na(1)
planes is equal to 1.65°. The Cu(1)O(1)O(2)Na(1) core is thus pla-
nar. The distance of Na–O(methoxy) is also larger than that of
Na–O(phenolate). The selected bond lengths and bond angles are
given in Table S1.
Na(1)O(3) planes being 6.830. The selected bond lengths and bond
angles are given in Table S2.
2
3.2.3. [Cu(vanpn)Na(NCS)(H O)] (3)
Compound 3 crystallises in the orthorhombic space group Pbca.
The molecular structure of 3 in Fig. 3 reveals a heteronuclear com-
pound which is similar to that in compounds 1 and 2 with the
coordination of thiocyanate to Na(I) instead of nitrate (as in 1) or
azide (as in 2). Cu(1) has a four-coordinate distorted square plan-
ner geometry in which O(1), O(2), N(8), and N(12) atoms of depro-
3.2.2. [Cu(vanpn)Na(N
3 3
)(CH OH)] (2)
2
ꢀ
The structure determination reveals that the compound crystal-
tonated di-Schiff base (vanpn) constitute the equatorial plane.
There is a slight distortion to the square plane and the deviations
of the coordinating atoms N(8), N(12), O(1), and O(2) from the
least-square mean plane through them are ꢀ0.152(3), 0.153(3),
0.183(2) and ꢀ0.184(2) Å, respectively, and that of Cu atom from
the same plane is 0.045 Å. The conformation of the saturated six-
membered ring {Cu(1)–N(8)–C(9)–C(10)–C(11)–N(12)} is closer
to envelope with the puckering parameters Q = 0.566(4) Å,
ꢀ
lizes in the triclinic space group P1 with the asymmetric unit con-
sisting of heteronuclear compound [Cu(vanpn)Na(N )(CH OH)]. A
3
3
structural diagram is shown in Fig. 2. This structure is very similar
to that of compound 1. In each bimetallic unit, the Cu(II) and Na(I)
atoms occupy the inner N O and outer O O sites, respectively.
2 2 2 2
The distortion of the coordinating atoms N(8), N(12), O(1) and
O(2) from the least-square mean plane through them are
ꢀ
0.108(1), 0.108(1)–0.130(1) and ꢀ0.129(1) Å, respectively, and
h = 125.4(3)°, u = 348.9(4)° [44,45]. The N(8)–Cu(1)–N(12) angle
that of Cu atom from the same plane is 0.026 Å. The conformation
of the saturated six-membered ring {Cu(1)–N(8)–C(9)–C(3)–C(2)–
N(12)} is in between screw boat and envelope with the puckering
is 97.29(10)° and is typical of six-membered chelate [44,45]. The
coordination environment around Na(I) shows a distorted octahe-
dral geometry involving O2O2 donors in the basal plane {phenoxo
oxygen atoms, O(1) and O(2); and methoxy oxygen atoms, O(3) and
O(4)}. One oxygen atom, O(100), from a water molecule and one
nitrogen atom, N(1), from a thiocyanate, are attached to the sodium
to fill its two axial sites. The distance of Na–O(methoxy) is larger
than that of Na–O(phenolate). The Cu(1)ꢂ ꢂ ꢂNa(1) intra-molecular
distance is 3.479(11) Å. The bridge angles Cu(1)–O(1)–Na(1) and
Cu(1)–O(2)–Na(1) are 107.18(9)° and 108.34(9)°, respectively. The
Cu(1)O(1)O(2)Na(1) core is almost planar, the dihedral angles
between the O(1)Cu(1)O2) and O(1) Na(1)O(2) planes being
5.130. The selected bond lengths and bond angles are given in
Table S2.
parameters 53 Q = 0.5845(14) Å, h = 116.53(12)°,
u = 18.17(14)°.
The N(8)–Cu(1)–N(12) angle is 96.74(4)° and is typical of six-mem-
bered chelate [43]. The Na(I) is octahedrally surrounded by NO5
moiety. The two phenoxo oxygen atoms, O(1) and O(2), two meth-
oxy oxygen atoms, O(3) and O(4) of the deprotonated di-Schiff base
constitute the equatorial plane around Na(I). O(100) from a meth-
anol and N(1) from an azide are coordinated in the axial positions.
The two different geometries of Cu and Na share a common edge
defined by the bridging phenolate oxygen atoms O(1) and O(2).
The bridging Na–O(phenolate) bonds (av. 2.355 Å) are longer than
the Na–O(phenolate) bonds (av.1.918 Å). Also the Na–O(methoxy)
distances (av. 2.454 Å) are larger than that of Na–O(phenolate). The
intra-molecular Cu(1)ꢂ ꢂ ꢂNa(1) distance is 3.463 Å. The bridge an-
gles Cu(1)–O(1)–Na(1) and Cu(1)–O(2)–Na(1) are 107.08(4)° and
3.2.4. H bonded network in compounds 1–3
The hydrogen atom, H(101), attached with O(100) of the coordi-
nated water molecule in 1 is engaged in hydrogen bond formation
with the symmetry related (# = 2 ꢀ x, 1 ꢀ y, 2 ꢀ z) oxygen atom,
1
08.53(4)°, 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)

P. Bhowmik et al. / Inorganica Chimica Acta 390 (2012) 53–60
57
1
) in the bottom right (acceptor) region of fingerprint plot, where
nitrate/acetate oxygen also acts as acceptor to the H atoms of the
O molecule and these oxygen-based interactions represent the
H
2
closest contacts in the structures and can be viewed as a pair of
large red spots on the dnorm surface (Fig. S1a). The proportion of
Nꢂ ꢂ ꢂH/Hꢂ ꢂ ꢂN interactions comprises 20.40% of the Hirshfeld sur-
faces for each molecule of compound 2. The Nꢂ ꢂ ꢂH interactions
i e
are represented by a spike (d = 0.746, d = 1.127 Å) in the bottom
left (donor) area of the fingerprint plot (Fig. S3a), indicating H-
atoms of H O molecule are interacting with N-atom of the azide
group. The Hꢂ ꢂ ꢂN interactions are represented by another spike
= 0.746, d = 1.127 Å) in the bottom right (acceptor) region of
fingerprint plot (Fig. S3a), where azide nitrogen also acts as accep-
tor to the H atoms of the H O molecule and these nitrogen-based
2
(d
e
i
2
interactions represent the closest contacts in the structures and
can be viewed as a pair of large red spots on the dnorm surface
(
Fig. S1b) The proportion of Sꢂ ꢂ ꢂH/Hꢂ ꢂ ꢂS interactions comprises
3.2% of the Hirshfeld surfaces for each molecule of compound 3.
The Sꢂ ꢂ ꢂH interactions are represented by a spike (d = 0.866,
= 1.503 Å) in the bottom left (donor) area of the fingerprint plot
(Fig. S3b), indicating H-atoms of H O molecule are interacting with
S-atom of the thiocyanate group, whereas the Hꢂ ꢂ ꢂS interactions
are represented by another spike (d = 0.866, d = 1.503 Å) in the
bottom right (acceptor) region of fingerprint plot (Fig. S3b), where
thiocyanate sulfur acts as acceptor to the H atoms of the H O mol-
ecule and these sulfur-based interactions represent the closest
contacts in the structures and can be viewed as a pair of large
red spots on the dnorm surface (Fig. S1c). The relative contribution
of the different interactions to the Hirshfeld surface was calculated
for compounds 1–3 and some similar compounds (Fig. S4) avail-
able in the CSD.
1
i
Fig. 3. Perspective view of compound 3. Selected bond distances (Å): Cu(1)–N(8)
.977(3), Cu(1)–N(12) 1.989(2), Cu(1)–O(1) 2.427(3), Cu(1)–O(2) 1.920(2), Na(1)–
O(1) 2.383(2), Na(1)–O(2) 2.359(2), Na(1)–O(3) 2.471(2), Na(1)–O(4) 2.448(3),
Na(1)–O(100) 2.310(3), Na(1)–N(1) 1.9267(18). Selected bond distances (Å): Bond
angles are given in Supplementary Table S2.
1
d
e
2
e
i
2
O(11), to form a dimer (Fig. 4). In this dimer, a chair is formed by
Na(1), O(11), O(100) and their symmetry-related counter parts. In
compound 2, the hydrogen atom, H(39), attached with O(100) of
the coordinated methanol molecule is engaged in hydrogen bond
formation with the symmetry related (ꢃ = 1 + x, y, z) nitrogen atom,
N(3) to form a chain (Fig. 5). S atom of NCS ligand in compound 3 is
hydrogen-bonded with the symmetry related hydrogen atoms
(
u = ꢀ1/2 + x, 1/2 ꢀ y, 2 ꢀ z and v = 1/2 ꢀ x, ꢀ1/2 + y, z) of the water
3
.4. IR and electronic spectra and magnetic properties
moiety of another molecule of same compound to form helical
structure (Fig. 6). The details of H bonding are given in Table 2.
In the IR spectra of compounds 1–3, distinct bands due to the
ꢀ1
azomethine (C@N) group within 1649–1573 cm are customarily
noticed [46]. Broad bands around 3400 cm
ꢀ1
3
.3. Hirshfeld surfaces
in IR spectra of
compounds 1 and 3 are assigned to the OH stretching vibration
The Hirshfeld surfaces of the compounds are illustrated in
Fig. S1, showing surfaces that have been mapped over a dnorm
of the coordinated water molecule, which is involved in hydrogen
ꢀ1
bonding [47]. The bands in the range of 2929–2930 cm are due
to alkyl C–H bond stretching of methoxy groups [48]. The presence
as well as coordination mode of azide to a transition metal can be
(
range of ꢀ0.5 to 1.5 Å), shape index and curvedness. The surfaces
are shown as transparent to allow visualization of the molecular
moiety, in a similar orientation for all structures, around which
they were calculated.
detected by the intense IR band due to
within 2000–2055 cm for terminal azide [49]. In the IR spectrum
of 2, the appearance of strong band at 2044 cm indicates the
m
N
3
that usually appears
ꢀ1
ꢀ1
The dominant interactions between Nꢂ ꢂ ꢂH, Oꢂ ꢂ ꢂH and Sꢂ ꢂ ꢂH
atoms in the compounds 1–3 can be seen in the Hirshfeld surface
as the red areas in Fig. S1. Other visible spots in the Hirshfeld sur-
faces correspond to Hꢂ ꢂ ꢂH contacts. The small extent of area and
light color on the surface indicates weaker and longer contact other
than hydrogen bonds. The Oꢂ ꢂ ꢂH/Hꢂ ꢂ ꢂO intermolecular interactions
appear as distinct spikes in the 2D fingerprint plot for compound 1
presence of monodentate azide [50]. Similarly, a band at 2079
ꢀ1
cm in compound 3 is indicative of the presence of the N-coordi-
ꢀ
1
nated thiocyanate where as twin bands at 1320 and 1468 cm
indicates unsymmetrical chelating nitrate group in compound 1
[50].
The electronic spectra in acetonitrile solution have been re-
corded for the three compounds. The appearance of two bands at
606 and 373 nm (compound 1), 552 and 370 nm (compound 2),
565 and 366 nm (compound 3) in the absorption spectra are
consistent with the square planar geometry of Cu(II) [51].
Room temperature magnetic susceptibility measurements
show that all the compounds have magnetic moments close to
1.73 BM.
(
Fig. S2). The Nꢂ ꢂ ꢂH and Sꢂ ꢂ ꢂH intermolecular interactions appear as
two distinct spikes in the 2D fingerprint plots (Fig. S3), in com-
pounds 2 and 3, respectively. Complementary regions are visible
in the fingerprint plots where one molecule act as donor (d
e i
> d )
and the other as an acceptor (d < d ). The fingerprint plots can be
e
i
decomposed to highlight particular atoms pair close contacts. This
decomposition enables separation of contributions from different
interaction types, which overlap in the full fingerprint. The propor-
tion of Oꢂ ꢂ ꢂH/Hꢂ ꢂ ꢂO interaction are comprising of 33.0% of the
Hirshfeld surfaces for each molecule of compound 1. The Oꢂ ꢂ ꢂH
3.5. Thermo-gravimetric analysis
interaction is represented by a spike (d
i
= 0.756, d
e
= 1.102 Å in
Thermo-gravimetric analyses of compounds 1 and 3 show a
weight loss of ꢄ3.75% and 3.85%, respectively in the temperature
range 80–150 °C, which corresponds to the loss of one water mol-
ecule (Calc. 3.55%). Compound 2 shows a weight loss of ꢄ7% in the
temperature range 50–110 °C which corresponds to the loss of a
compound 1) in the bottom left (donor) area of the fingerprint plot
Fig. S2), indicating H-atoms of H O molecule are interacting with
O-atom of the nitrate/acetate group. The Hꢂ ꢂ ꢂO interaction is also
represented by another spike (d = 0.756, d = 1.102 Å in compound
(
2
e
i

5
8
P. Bhowmik et al. / Inorganica Chimica Acta 390 (2012) 53–60
Fig. 4. H-bonded dimer of compound 1.
Fig. 5. H-bonded chain of compound 2.
methanol molecule (Calc. 6.4%). The dehydrated species does not
absorb any water molecules on exposure to open atmosphere. In
the IR spectra of the dehydrated species, the broad band at ca.
reaction following the electron transfer process. Reversible behav-
ior can only be seen in cases where the geometry of the Cu com-
pound 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 systems Cu(I) may have regular tetrahe-
dral coordination sphere but Cu(II) always involves a compressed
tetrahedral or square planar geometry. In the present study, the
compounds 1 and 2 exhibit reversible signals whereas compounds
3 exhibit quasi-reversible signals. The single-electron nature of the
voltammograms has been confirmed by the comparison of current
ꢀ1
3
490 cm is missing, confirming the elimination of the water mol-
ecule on heating.
3.6. Cyclic voltammetry
The redox properties of the Cu(II) compounds exhibit more or
less similar features consisting of a reversible or quasi-reversible
Cu(II)/Cu(I) reduction. The criteria of reversibility were checked
2+
heights for the compounds and that of a simple [Fe(bipy)
3
]
com-
by observing constancy of peak-peak separation (
D
E
p
= Epa ꢀ Epc
)
pound under identical conditions [53]. It has been observed that no
well defined oxidative or reductive responses could be observed on
running further in the positive or negative potential. The E1/2 and
and the ratio of peak heights (ipa/ipc ꢄ 1) with variation of scan
rates [52]. Only very few Cu(II)/Cu(I) couples exhibit truly revers-
ible electrochemical behavior because Cu(II) has a tendency to-
ward six-coordinate tetragonal geometries while Cu(I) appears to
prefer four-coordinate tetrahedral geometries. The subsequent
rearrangement of the Cu coordination sphere upon the reduction
of the Cu(II) species typically leads to a relatively slow chemical
D
E
p
values for these redox couples are given in Table 3. All the re-
dox signals remain virtually invariant under different scan rates
ꢀ1
(0.01–1.0 V s ) in the temperature range 300–280 K. Solvent
dependent shift and change in electrochemical reversibility of re-
dox couples are not significant.

P. Bhowmik et al. / Inorganica Chimica Acta 390 (2012) 53–60
59
Fig. 6. H-bonded helix of compound 3.
Table 2
Appendix A. Supplementary material
H-bond distances in compounds 1–3.
D–Hꢂ ꢂ ꢂA
D–H
Dꢂ ꢂ ꢂA
Hꢂ ꢂ ꢂA
\D–Hꢂ ꢂ ꢂA
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.ica.2012.03.044.
#
1
2
3
O(100)–H(101)ꢂ ꢂ ꢂO(11)
0.81(4)
0.89(3)
0.77(5)
0.82(5)
2.03(4)
1.97(3)
2.59(5)
2.54(5)
2.834(3)
2.844(2)
3.313(4)
3.361(3)
171(4)
168(3)
158(4)
173(5)
⁄
u
O(100)–H(39)ꢂ ꢂ ꢂN(3)
O(100)–H(101)ꢂ ꢂ ꢂS(1)
References
v
O(100)–H(102)ꢂ ꢂ ꢂS(1)
Symmetry element # = 2 ꢀ x, 1 ꢀ y, 2 ꢀ z, ꢃ = 1 + x, y, z, u = ꢀ1/2 + x, 1/2 ꢀ y, 2 ꢀ z
and
= 1/2 ꢀ x, ꢀ1/2 + y, z.
[1] J.M. Lehn, Angew. Chem., Int. Ed. Engl. 27 (1988) 89.
[
[
[
[
[
2] H.J. Schneider, Angew. Chem., Int. Ed. Engl. 30 (1991) 1417.
3] D.J. Braga, J. Chem. Soc., Dalton Trans. (2000) 3705.
4] H. Li, M. Eddaoudi, M. O’Keeffe, O.M. Yaghi, Nature 402 (1999) 276.
5] D.J. Stufkens, A. Vleck Jr., Coord. Chem. Rev. 177 (1998) 127.
6] J.L. Atwood, J.E.D. Davies, D.D. MacNicol, F. Vogtle, J.M. Lehn, in: J.M. Lehn (Ed.),
v
Table 3
Comprehensive Supramolecular Chemistry, vol. vols.
Oxford, 1996.
6 and 9, Pergamon,
Electrochemical data for compounds 1–3.
[
7] M.J. Blanco, M.C. Jimenez, J.C. Chambron, V. Heitz, M. Linke, J.P. Sauvage, Chem.
Soc. Rev. 28 (1999) 293.
Compound
Cu(II)/Cu(I)
pa (V)
E
E
pc (V)
E
1/2 (V)
D
E
p
(mV)
[8] M. Fujita, Chem. Soc. Rev. 27 (1998) 417.
9] P.K. Iyer, J.B. Beck, C. Weder, S.J. Rowan, Chem. Commun. (2005) 319.
[
1
2
3
ꢀ1.62
ꢀ1.54
ꢀ1.55
ꢀ1.68
ꢀ1.58
ꢀ1.63
ꢀ1.65
ꢀ1.56
ꢀ1.59
60
40
80
[
[
[
10] G.R. Whittell, M.D. Hager, U.S. Schubert, I. Manners, Nat. Mater. 10 (2011) 176.
11] M. Albrecht, Naturwissenschaften 94 (2007) 951.
12] E. Pardo, R. Ruiz-García, J. Cano, X. Ottenwaelder, R. Lescoue’zec, Y. Journaux, F.
Lloret, M. Julve, Dalton Trans. (2008) 2780.
13] A.J. Blake, N.R. Champness, P. Hubberstey, W.S. Li, M.A. Withersby, M.
Schro’der, Coord. Chem. Rev. 183 (1999) 117.
E
1/2 is calculated as the average of anodic (Epa) and cathodic (Epc) peak potentials;
= (Epa ꢀ Epc).
[
DE
p
[
[
[
[
14] R. Robson, Dalton Trans. (2000) 3735.
15] B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1629.
16] R.E. Mele’ndez, A.D. Hamilton, Top. Curr. Chem. 198 (1998) 97.
17] C.B. Aakero’y, A.M. Beatty, Aust. J. Chem. 54 (2001) 409.
4
. Conclusion
The syntheses and characterization of three iso-structural com-
[18] A.D. Burrows, Struct. Bonding (Berlin) 108 (2004) 5595.
[19] CSD search file 1.pdf (Supporting Information).
0
pounds [Cu(II)(vanpn)Na(I)X] (X = NO
enebis(3-ethoxysalicylaldiimine) (H
3
, N
3
, NCS) with N,N -propyl-
[
[
20] CSD search file 2.pdf (Supporting Information).
2
vanpn) have been described
21] D.G. Branzea, A. Guerri, O. Fabelo, C. Ruiz-Perez, L.-M. Chamoreau, C.
Sangregorio, A. Caneschi, M. Andruh, Cryst. Growth Des. 8 (2008) 941.
22] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, J. Appl. Crystallogr. 26
in the present paper. It has been presented that the reaction of
Cu(II)and Na(I) salts with a compartmental Schiff base can afford
interesting heteronuclear compounds with different H-bonded
supramolecular assembly varying from dimer to helical chain.
The representative anions are applied to construct these H-bonded
architectures. Thus, this work gives rise to a promising method for
rationally designing and controlling structural assemblies of re-
lated coordination species.
[
(
1993) 343.
[
23] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
[24] G.M. Sheldrick, SHELXS-97 and SHELXL-97, University of Göttingen, Germany,
997.
1
[
[
25] A.L. Spek, Acta Crystallogr., Sect. A 46 (1990) C34.
26] X-AREA, version 1.56, STOE & Cie GmbH, Darmstadt, 2011.
[27] ABSPACK, version 1, Oxford Diffraction, Abingdon, 2005.
[28] M.A. Spackman, D. Jayatilaka, CrystEngCommun. 11 (2009) 19.
[
[
29] F.L. Hirshfeld, Theor. Chim. Acta 44 (1977) 129.
30] H.F. Clausen, M.S. Chevallier, M.A. Spackman, B.B. Iversen, New J. Chem. 34
(2010) 193.
Acknowledgements
[
[
31] A.L. Rohl, M. Moret, W. Kaminsky, K. Claborn, J.J. McKinnon, B. Kahr, Cryst.
Growth Des. 8 (2008) 4517.
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, da-
ted 18.1.11) and University Grants Commission, CAS-UGC, New
Delhi.
32] A. Parkin, G. Barr, W. Dong, C.J. Gilmore, D. Jayatilaka, J.J. McKinnon, M.A.
Spackman, C.C. Wilson, CrystEngCommun. 9 (2007) 648.
33] M.A. Spackman, J.J. McKinnon, CrystEngCommun. 4 (2002) 378.
34] S.K. Wolff, D.J. Grimwood, J.J. McKinnon, D. Jayatilaka, M.A. Spackman, Crystal
Explorer 2.0, University of Western Australia, Perth, Australia, 2007. <http://
hirshfeldsurfacenet.blogspot.com/>.
[
[

6
0
P. Bhowmik et al. / Inorganica Chimica Acta 390 (2012) 53–60
[
[
[
[
35] J.J. McKinnon, M.A. Spackman, A.S. Mitchell, Acta Crystallogr., Sect. B 60 (2004)
27.
36] P. Bhowmik, H.P. Nayek, M. Corbella, N. Aliaga-Alcalde, S. Chattopadhyay,
Dalton Trans. 40 (2011) 7916.
[45] I.R. Laskar, A. Ghosh, G. Mostafa, D. Das, A. Mondal, N. Ray Chaudhuri,
Polyhedron 19 (2000) 1015.
[46] P. Bhowmik, S. Chattopadhyay, M.G.B. Drew, C. Diaz, A. Ghosh, Polyhedron 29
(2010) 2637 (and references there in).
[47] M.S. Ray, S. Chattopadhyay, M.G.B. Drew, A. Figuerola, J. Ribas, C. Diaz, A.
Ghosh, Eur. J. Inorg. Chem. (2005) 4562.
[48] C.J. Cooper, M.D. Jones, S.K. Brayshaw, B. Sonnex, M.L. Russell, M.F. Mahon, D.R.
Allan, Dalton Trans. 40 (2011) 3677.
6
37] S. Thakurta, J. Chakraborty, G. Rosair, R.J. Butcher, S. Mitra, Inorg. Chim. Acta
3
62 (2009) 2828.
38] S. Thakurta, C. Rizzoli, R.J. Butcher, C.J. Gómez-García, E. Garribba, S. Mitra,
Inorg. Chim. Acta 363 (2010) 1395.
[
[
[
[
[
39] J.-P. Costes, F. Dahan, A. Dupuis, J.-P. Laurent, Inorg. Chem. 35 (1996) 2400.
40] J.-P. Costes, F. Dahan, A. Dupuis, J.-P. Laurent, New J. Chem. (1998) 1525.
41] D. Cramer, J.A. Pople, J. Am. Chem. Soc. 97 (1975) 1354.
42] J.C.A. Boyens, J. Cryst. Mol. Struct. 8 (1978) 317.
43] S. Chattopadhyay, M.G.B. Drew, A. Ghosh, Inorg. Chim. Acta 359 (2006) 4519
[49] S.S. Tandon, L.K. Thompson, M.E. Manuel, J.N. Bridson, Inorg. Chem. 33 (1994)
5555.
[50] K. Nakamoto, Infrared Spectra of Inorganic Compounds, Wiley, New York, 1970.
[51] S. Chattopadhyay, M.S. Ray, S. Chaudhuri, G. Mukhopadhyay, G. Bocelli, A.
Cantoni, A. Ghosh, Inorg. Chim. Acta 359 (2006) 1367.
[52] D.H. Evans, K.M. O’Connell, R.A. Petersen, M.J. Kelly, J. Chem. Educ. 60 (1983)
290.
(
and the references there in).
[
44] I.R. Laskar, D. Das, G. Mostafa, T.H. Lu, T.C. Keng, J.C. Wang, A. Ghosh, N. Ray
Chaudhuri, New J. Chem. 25 (2001) 764.
[53] K. Mitra, S. Biswas, C.R. Lucas, B. Adhikary, Inorg. Chim. Acta 359 (2006) 1997.