Syntheses, characterization and crystal structures of potassium and barium complexes of a Schiff base ligand with different anions

Article abstract of DOI:10.1007/s12039-014-0701-1

New pseudopolymorph of a O,N,N'-donor hydrazone ligand, 2-pyridylcarboxaldehyde isonicotinoylhydrazone (L) and its discrete complexes with K⁺ and Ba²⁺ have been reported. L forms isostructural dinuclear complexes with K⁺ when bromide and iodide were employed as counter anions. However, a monomeric complex in the case of Ba²⁺ with existence of coordinated as well as lattice perchlorate counter anions was observed. All compounds were characterized by single crystal X-ray analysis and other physicochemical techniques. Structural analysis and spectral features of all compounds are described in detail.

Full text of DOI:10.1007/s12039-014-0701-1

J. Chem. Sci. Vol. 126, No. 5, September 2014, pp. 1373–1384. ꢀc Indian Academy of Sciences.
Syntheses, characterization and crystal structures of potassium
and barium complexes of a Schiff base ligand with different anions
a
a,b
c
a,b,
BHAVESH PARMAR , KAMAL KUMAR BISHT , PRATYUSH MAITI , PARIMAL PAUL
a,b,∗
and ERINGATHODI SURESH
Analytical Discipline and Centralized Instrument Facility, Academy of Scientific and Innovative Research
AcSIR), Scale-up and Process Engineering Unit, CSIR–Central Salt and Marine Chemicals Research
a
b
c
(
Institute, Council of Scientific and Industrial Research, G B Marg, Bhavnagar 364 002, Gujarat, India
e-mail: esuresh@csmcri.org; sureshe123@rediffmail.com
MS received 5 April 2014; accepted 1 September 2014
Abstract. New pseudopolymorph of a O,N,N’-donor hydrazone ligand, 2-pyridylcarboxaldehyde isonicoti-
+
2+
noylhydrazone (L) and its discrete complexes with K and Ba have been reported. L forms isostructural din-
+
uclear complexes with K when bromide and iodide were employed as counter anions. However, a monomeric
2+
complex in the case of Ba with existence of coordinated as well as lattice perchlorate counter anions was
observed. All compounds were characterized by single crystal X-ray analysis and other physicochemical
techniques. Structural analysis and spectral features of all compounds are described in detail.
Keywords. Potassium; Barium; Schiff base; dinuclear complex; 2-pyridylcarboxaldehyde isonicotinoylhy-
drazone; single crystal x-ray analysis.
1
. Introduction
co-crystals/salts and coordination compounds with dif-
4
,5
ferent transition metal ions. An oxidized derivative of
L (N-(isonicotinoyl)-N’-(picolinoyl)hydrazine), which
has been obtained in presence Fe(III) ions has also been
Crystal engineering utilizes intermolecular interactions
and offers the synthesis of molecular solids from neutral
or ionic building blocks. Supramolecular assemblies
1
5
reported. Moreover, Bernhardt et al. have explored the
involving O,N,N’-donor organic molecules and coordi-
nation compounds thereof have been of much research
interest owing to their potent biological activity as well
notable iron chelator efficacy of numerous transition
metal complexes of L and derivative ligands.
6
Recently, L has been utilized to fabricate extended
2
as variety of structural diversity. Significant structural
materials such as coordination polymers or metal
7
differences observed in various complexes involving
O,N,N’-donor molecules have shown to impart diverse
features such as catalytic property and second harmonic
organic frameworks. Dehnen et al. reported mixed lig-
and In(III) helical coordination polymers in its neu-
tral as well as anionic forms involving aryl thiolates
and L. Interestingly, the coordination polymer pos-
sessing anionic form showed a centrosymmetric struc-
ture, whereas, the one comprising neutral hydrazone
revealed non-centrosymmetric structure exhibiting sec-
3
generation.
O,N,N’-donor hydrazone ligands which are often
synthesized by Schiff base condensation have been
excellent supramolecular precursors for their ability to
exist in keto- and enol- tautomeric forms (scheme 1).
Interestingly, hydrazone ligands can coordinate with
metal centres either as neutral molecule or depro-
tonated anionic form, which enhances the coordina-
tion diversity in the resulting architectures (scheme 1).
A large number of mono- and dinuclear metal com-
plexes are available in literature involving hydrazone
ligands and transition metal ions. In fact, the Schiff
base, 2-pyridylcarboxaldehyde isonicotinoylhydrazone
8
ond harmonic generation (SHG) effect.
On the contrary, variation in the solid state forms
of biologically active substances remains of significant
9
interest. Different solid state forms of any molecule
of interest; typically, an active pharmaceutical ingredi-
ent may exhibit different stability, dissolution or sol-
ubility behaviour. Thus, the studies on the polymor-
phic and pseudopolymorphic forms of potent organic
molecules remain the subject of interest among crys-
9
(L), has been exploited to realize a range of organic
tal engineers. We have been involved in the stud-
ies on crystal engineering aspects and supramolecular
interactions of self assembled systems including hybrid
∗
For correspondence
1
373

1
374
Bhavesh Parmar et al.
Scheme 1. Neutral keto-enol tautomers and anionic enolate form of O,N,N’-donor, L.
organic materials, discrete metal complexes and coordi- (L) was synthesized by adopting a reported procedure
10
11
nation polymers. Despite the rich literature reports on with slight modifications. Pyridine-2-carboxaldehyde
the coordination compounds of L with transition met- (1.0 mL, 10 mmol) and isonicotinohydrazide (1.37 gm,
als, coordination behaviour of L towards the alkali and 10 mmol) were dissolved in 25 mL of ethanol and few
alkaline earth metal ions are scantly investigated. The drops of acetic acid were added. Resulted solution was
present study is outlined to understand the crystal engi- refluxed with continuous stirring for 8 h and then the
neering aspects of Schiff base ligand L and its coordi- solvent was reduced by rotator evaporation to 10 mL
nation behaviour towards the alkali and alkaline metal which on cooling to room temperature yielded white
+
+2
ions K and Ba . Thus, a new polymorphic form of precipitate. The precipitate thus obtained was washed
ligand L has been crystallized and complexes 1, 2 and 3 with cold methanol and recrystallized in ethanol.
1
have been synthesised by treatment of the metal precur- Yield = 85%. H NMR (DMSO- ): δ 7.46 (m,1H),
d6
sors with L in appropriate stoichiometry. L and all three 7.93 (m,4H), 8.50 (d,1H), 8.65 (d,1H), 8.81(d, 2H),
complexes have been characterized by single crystal X-ray 12.26(s,1H). Elemental analysis (%) calc.: C, 63.71; H,
diffraction analysis and other physicochemical techniques. 4.46; N, 24.76; found: C, 63.32; H, 4.72; N, 24.14; IR
−1
cm (KBr): 3446 (br), 3174 (w), 2998 (m), 2365 (w),
665 (s), 1549 (s), 1472 (m), 1407 (w), 1346 (w), 1286
s), 1148 (m), 1073 (m), 997 (w), 956 (w), 849 (w),
1
(
2. Experimental
787 (w), 749 (w), 688 (m), 628 (w), 512(w).
2.1 Materials and methods
All reagents and solvents were purchased from com-
mercial sources and were used without further purifica-
tion. Distilled water was used for synthetic manipula-
2
.3 Crystallization of 2-pyridylcarboxaldehyde
isonicotinoylhydrazone dihydrate (L.2H O)
2
tions. CHNS analyses were done using a Perkin-Elmer L (23 mg, 0.10 mmol) and KNO (11 mg, 0.10 mmol)
3
1
13
2
400 CHNS/O analyzer. H and C NMR spectra for were dispersed in 7 mL of water-methanol solvent mix-
the ligands and complexes were recorded on Bruker AX ture (water : methanol = 1 : 2.5) and heated for 6 h at
◦
◦
5
00 spectrometer (500 MHz at temperature 25 C and 75−80 C then cooled down to ambient temperature and
was calibrated with respect to internal reference TMS). allowed to evaporate slowly. X-ray quality fibrous nee-
IR spectra were recorded using KBr pellets on a Perkin- dle shaped crystals were harvested in ca 2 months time.
Elmer GX FTIR spectrometer. For each IR spectra 10 Yield = 70.5%. Elemental analysis (%) calc.: C, 54.96;
−1
scans were recorded at 4 cm resolution. TGA was car- H, 5.38; N, 21.36; found: C, 54.77; H, 5.78; N, 20.87;
−1
ried out using Mettler Toledo Star SW 8.10. Absorp- IR cm (KBr): 3450 (s), 3069 (m), 2928 (w), 2850 (w),
tion spectra were recorded using Shimadzu UV-3101PC 2362 (m), 1665 (s), 1567 (s), 1471 (w), 1437 (m), 1415
spectrometer. X-ray powder diffraction data were col- (m), 1363 (m), 1291 (s), 1146 (w), 1067 (m), 1001 (w),
lected using a Philips X-Pert MPD system with CuKα 949 (w), 855 (w), 784 (w), 748 (w), 689 (s), 522 (w),
radiation. Single crystal structures were determined 460 (w).
using BRUKER SMART APEX (CCD) diffractometer.
2
.4 Synthesis of [K L (H O) ]Br .6H O(1)
2
4
2
2
2
2
2
.2 Synthesis of 2-pyridylcarboxaldehyde
L (23 mg, 0.10 mmol) and KBr (12 mg, 0.10 mmol)
isonicotinoylhydrazone (L)
were dispersed in a mixture of 2 mL H O and 5 mL
2
2-pyridylcarboxaldehyde isonicotinoylhydrazone or methanol and then refluxed for 6 h. The reaction mix-
(E)-N’-(pyridin-2-ylmethylene) isonicotinohydrazide ture was cooled to room temperature, filtered and

Alkali and alkaline earth metal complexes with O,N,N’-donor hydrazone ligand
1375
2
allowed to evaporate slowly when fibrous needle refined on F by the full-matrix least-squares technique
14,15
shape crystals suitable for single crystal analysis were using the program SHELXL-97.
Hydrogen atoms
obtained after 40–45 days. Yield = 74.2%. Elemental attached to the organic ligand is either located from
analysis (%) calc.: C, 44.79; H, 4.39; N, 17.41; found: the difference Fourier map or fixed stereochemically
−1
C, 43.96; H, 5.01; N, 16.82; IR cm (KBr): 3456 (br), in all the compounds. Hydrogen atoms of the coordi-
3
2
163 (w), 3056 (w), 3008 (m), 2925 (w), 2849 (w), nated/lattice water molecules are located from the dif-
360 (w), 2208 (w), 1664 (s),1560 (s), 1480 (w), 1437 ference Fourier map and kept fixed using DFIX card.
(w), 1409 (w), 1361 (m), 1300 (s), 1154 (m), 1065 (m), In the case of Ba complex 3 some oxygen atoms of
9
48 (w), 850 (w), 775 (w), 686 (m), 520 (w).
both perchlorate anions showed extensive disorder. The
site and occupancy factor for the disordered oxygen
atoms were determined using PART and FVAR cards
of SHELXL-97 package. All non-hydrogen atoms were
refined anisotropically till convergence is reached.
2.5 Synthesis of [K L (H O) ]I .6H O (2)
2
4
2
2
2
2
Method was same as adopted for 1 except KI (17 mg,
.10 mmol) was used instead of KBr. Yield = 78.4%.
Elemental analysis (%) calc.: C, 41.74; H, 4.09; N,
0
3. Results and Discussion
−1
16.23; found: C, 40.92; H, 4.24; N, 15.62; IR cm
(
(
1
KBr): 3476 (br), 3173 (s), 3035 (m), 2866 (w), 2367
w), 2215 (w), 1678 (s),1547 (s), 1471 (w), 1430 (w),
409 (w), 1361 (w), 1292 (s), 1147 (m), 1065 (m), 999
Conformational flexibility of ligand L makes it interest-
ing and suitable for the crystal engineering studies. In
fact, the O,N,N’-donor sites can presume syn and anti
conformation as depicted in scheme 2. Structure of L
reported by Richardson et al. revealed anti conforma-
tion by the pyridyl nitrogen with respect to the imine
(w), 847 (w), 776 (w), 692 (m), 480(w).
2
.6 {[Ba(L) (H2O) (ClO )].(ClO )} (3)
2 2 4
4
4
nitrogen. Interestingly, syn conformation is espoused
by the ligand moiety in pseudopolymorph L.2H O with
Ba(ClO ) (168 mg, 0.5 mmol) was dissolved in 5 mL
2
4
2
water of crystallization which is reported in present
work. This is attributable to the supramolecular inter-
actions of L with lattice water molecules in the pseu-
dopolymorph. It is worthy to mention that Cambridge
Structure Database (CSD version 5.35) search involv-
ing L and transition metal ions showed 6 complexes
involving keto tautomer and 12 complexes involving
H O then 5 mL methanol was layered carefully over
2
which L (112 mg, 0.5 mmol) dissolved in ethanol
were layered. The container was covered and kept for
slow diffusion of reactants at room temperature which
afforded white crystals within 45–50 days. Yield =
7
1.2%. Elemental analysis (%) calc.: C, 34.95; H, 2.93;
−1
N, 13.59; found: C, 35.11; H, 2.878; N, 14.17; IR cm
7
,8
enol or enolate tautomers of L. However, no struc-
(
(
KBr): 3546 (m), 3265 (s), 2932 (w), 2857 (w), 2364
w), 1665 (s), 1552 (s), 1477 (w), 1438 (w), 1369 (w),
+
+2
tural report on the K and Ba complexes of L is avail-
able in CSD and literature. Evidently, the current study
presents first report on the complexation between L and
alkali and alkaline earth metal ions. Complexes 1, 2
and 3 reveal the syn conformation of ligand moiety in
keto tautomeric form which is attributable to the wrap-
ping of ligand around the cations to facilitate effective
tridentate chelation. Keto tautomeric form of L in all
complexes as well as in its free states was established
1
6
293 (s), 1089 (s), 928 (w), 849 (w), 781 (w), 750 (w),
94 (w), 627 (m), 514 (w).
2.7 X-ray crystallography
Summary of crystallographic data and details of data
collection for L and 1–3 is given in table 1. Single
crystals with suitable dimensions were chosen under
an optical microscope after immersing in paratone oil
and mounted on a glass fibre for data collection. Inten-
sity data for all the crystals were collected using MoKα
1
13
by H and C NMR spectra (figure S4). Structural fea-
tures of ligand as well as all complexes are discussed in
following sections.
(
λ = 0.71073 Å) radiation on a Bruker SMART APEX
diffractometer equipped with CCD area detector at 150
3
.1 Crystal and molecular structure of L.2H O
2
K except for complex 3 for which data was collected
at room temperature (296 K). The data integration Ligand L was appropriately prepared by Schiff base
12
and reduction were processed with SAINT software.
condensation between pyridine-2-carboxaldehyde and
An empirical absorption correction was applied to the isonicotinohydrazide. Crystal structure of the unhy-
13
collected reflections with SADABS. Structures were drated form of ligand L was previously reported by
solved by direct methods using SHELXTL and were Richardson et al. in Fdd2 space group of orthorhombic

1
376
Bhavesh Parmar et al.
[a]
Table 1. Crystal data and refinement parameters for L and 1–3 .
Identification code
L.2H2O
1
2
3
Chemical formula
Formula weight
Crystal Colour
Crystal Size (mm)
Temperature (K)
Crystal System
Space Group
a(Å)
C12H14N4O3
262.27
Colourless
0.25 × 0.05 × 0.04
150(2)
K2C48H56Br2N16O12
1287.11
Pale-White
0.11 × 0.08 × 0.05
150(2)
K2C48H56I2N16O12
1381.09
BaC24H24Cl2N8O12
824.75
Yellow
White
0.26 × 0.08 × 0.07
0.60 × 0.40 × 0.30
150(2)
296(2)
Monoclinic
P21/n
7.077(4)
14.237(8)
12.632(7)
90
Triclinic
P-1
Triclinic
P-1
Triclinic
P-1
10.1656(13)
12.7671(16)
13.0956(17)
111.469(2)
102.801(2)
106.544(2)
1
1411.5(3)
1.514
1.657
10.2966(9)
12.7918(11)
13.2334(11)
110.6820(10)
102.7650(10)
106.8600(10)
1
1455.2(2)
1.576
1.295
9.8642(17)
10.8398(19)
15.784(3)
84.846(3)
74.006(2)
87.718(3)
2
1615.6(5)
1.695
1.466
b(Å)
c(Å)
α( )
◦
◦
β( )
98.248(12)
90
◦
γ ( )
Z
V(Å )
4
3
1259.5(13)
1.383
3
Density (Mg/m )
−1
μ (mm
)
0.102
F(000)
552
6176
2204
0.0852
660
11807
6031
0.0376
696
12117
6210
0.0196
820
13325
6916
0.0177
Reflections Collected
Independent Reflections
Rint
Number of parameters
GOF on F
226
1.122
401
1.111
402
1.156
496
1.035
2
FinalR1/wR2(I ≥ 2σ(I)
Weighted R1/wR2 (all data)
CCDC number
0.0792/0.1536
0.1183/0.1700
992911
0.0597/0.1163
0.0780/0.1227
992912
0.0349/0.0805
0.0382/0.0821
992913
0.0286/0.0787
0.0301/0.0800
992914
[a]
2
2 2
2 2 1/2
R = ꢀꢁFo| − |Fcꢁ/ꢀ|Fo|; wR = [ꢀw(Fo –Fc ) /ꢀw(Fo ) ]
chelation in wrapping around the metal upon coordi-
nation. In an attempt to understand the supramolecular
interactions we have analyzed the packing and hydro-
gen bonding interactions in detail. Packing diagram
with hydrogen bonding interactions viewed down a-
axis is depicted in figure 1c. Pairs of π stacked L
moieties in opposite orientations are engaged along
b-axis with the centroid· · · centroid stacking distance
between the pyridyl rings are 3.45Å and 3.56Å respec-
tively. Lattice water molecules are positioned between
the π stacked L layers and involved in extensive hydro-
Scheme 2. Syn- and anti-conformations of O,N,N’-donor
L.
system.4 However, colourless shiny single crystals gen bonding interactions generating a two dimensional
of new pseudopolymorph L.2H O suitable for X-ray network.
2
crystallography were harvested from slow evaporation
Close up view of the various hydrogen bonding
of methanol/water mixture in presence of potassium contacts are depicted in figure 1b. Thus, O2 and O3
nitrate. Pseudopolymorph L crystallized along with two are involved as a donor and making O-H· · · O and
water molecules as solvent of crystallization in mon- O-H· · · N interactions with water oxygen O3, pyridyl
oclinic system with P2 /n Space group (figure 1a). nitrogen N4 and amide oxygen O1 and pyridyl nitro-
1
Crystal structure revealed that L moiety is almost pla- gen N1 respectively. Lattice water molecules O2, is
nar with the syn conformation adopted by the pyridyl involved as acceptor in C-H· · · O interaction with imine
nitrogen N1 with respect to the imine nitrogen N2 hydrogen H6, pyridyl hydrogen H9 and N-H· · · O con-
which is the favourable conformation to make tridentate tact with amide hydrogen H1C. Nevertheless, O3 is

Alkali and alkaline earth metal complexes with O,N,N’-donor hydrazone ligand
1377
Figure 1. (a) ORTEP digam of L.2H2O with atom numbering scheme; (b) close-up view
of various Hydrogen bonding interactions between the organic moiety and the lattice water
molecules (turquoise dotted lines); (c) packing diagram viewed down a-axis showing the
various supramolecular interactions in the two dimensional H-bonded network.
involved as acceptor in making C-H· · · O interaction 3.2 Crystal and molecular structures of [K L
2
4
with the pyridyl hydrogen H2 and O-H· · · O interac- (H O) ]Br .6H O (1) and [K L (H O) ]I .6H O (2)
2
2
2
2
2
4
2
2
2
2
tion with water hydrogen H4D respectively in making
the two dimensional sheet like hydrogen bonded nets. Compound 1 and 2 are isostructural dimers crystallized
Details of these H-bonding interactions with symmetry in triclinic system with P-1 space group and the struc-
code are summarised in table 2.
tural description is limited to 1. Cationic part of the

1
378
Bhavesh Parmar et al.
Table 2. Details of hydrogen bonding interactions observed in L.2H2O and 1-3.
L.2H2O
◦
D-H · · · A
d(H· · · A) (Å)
d(D· · · A) (Å)
2.848(5)
2.945(4)
2.939(4)
2.871(4)
2.785(4)
3.416(5)
3.345(5)
3.255(4)
∠D-H· · ·A ( )
1
2
2
N(3)-H(1C)· · ·O(2)
O(3)-H(3C)· · ·N(1)
1.94(4)
172(4)
161(5)
164(5)
171(4)
165(4)
155(3)
138(2)
158(3)
2.07(5)
2.10(6)
2.05(4)
1.75(4)
2.57(3)
2.58(3)
2.37(3)
O(3)-H(3D)· · ·O(1)
3
O(2)-H(4C)· · ·N(4)
4
O(2)-H(4D)· · ·O(3)
5
C(2)-H(2)· · ·O(3)
1
C(6)-H(6)· · ·O(2)
1
C(9)-H(9)· · ·O(2)
Symmetry code: 1. 1/2-x,-1/2+y,1/2-z; 2. 1/2+x,3/2-y,1/2+z; 3. x,1+y,z; 4. -1+x,y,z; 5. 1-x,2-y,-z
Complex 1
◦
D-H· · · A
d(H· · · A) (Å)
2.13(5)
2.16(6)
2.65(4)
2.04(5)
2.02(5)
2.14(5)
2.58(5)
1.93(7)
2.61(5)
2.06(4)
2.4824
d(D· · · A) (Å)
2.892(5)
2.862(5)
3.414(3)
2.784(6)
2.748(5)
2.859(6)
3.363(4)
2.707(6)
3.372(4)
2.835(5)
3.154(5)
3.721(4)
3.414(5)
3.203(5)
∠D-H· · ·A ( )
168(5)
168(7)
168(4)
174(5)
156(5)
160(6)
165(5)
163(5)
174(5)
171(4)
129.33
148.15
156.44
133.63
1
O(3)-H(3A)· · ·N(4)
2
O(3)-H(3B)· · ·N(5)
3
N(3)-H(3N)· · ·Br(1)
2
O(4)-H(4A)· · ·O(3)
2
O(4)-H(4B)· · ·O(6)
4
O(5)-H(5A)· · ·N(8)
5
O(5)-H(5B)· · ·Br(1)
3
O(6)-H(6A)· · ·O(5)
O(6)-H(6B)· · ·Br(1)
6
4
N(7)-H(7N)· · ·O(4)
2
C(1)-H(1)· · ·O(2)
5
C(14)-H(14)· · ·Br(1)
2.8987
2.5405
2.4894
4
C(18)-H(18)· · ·O(6)
4
C(21)-H(21)· · ·O(4)
Symmetry code: 1. 1-x,-y,1-z; 2. x, y, z; 3. 1-x,1-y,1-z; 4. -x,1-y,1-z; 5. x,-1+y,z; 6. x,y,1+z
Complex 2
◦
D-H· · · A
d(H· · · A) (Å)
2.14(5)
2.2762
2.07(4)
2.08(5)
1.93(6)
2.05(7)
2.89(4)
1.92(5)
2.81(5)
2.88(3)
3.0188
2.56(4)
2.555
d(D· · · A) (Å)
2.912(4)
2.861(3)
2.842(4)
2.792(4)
2.731(4)
2.800(5)
3.576(4)
2.690(5)
3.571(3)
3.643(3)
3.843(4)
3.411(5)
3.421(4)
3.167(3)
3.196(4)
∠D-H· · ·A ( )
1
O(3)-H(3A)· · ·N(8)
170(5)
128.64
168(4)
174(4)
162(7)
164(7)
166(4)
167(6)
180(5)
166(4)
148.53
152(3)
154.93
131.51
129.85
2
2
2
O(3)-H(3B)· · ·N(1)
N(3)-H(3C)· · ·O(4)
O(4)-H(4A)· · ·O(3)
2
O(4)-H(4B)· · ·O(6)
O(5)-H(5A)· · ·N(4)
2
2
O(5)-H(5B)· · ·I(1)
3
O(6)-H(6A)· · ·O(5)
4
O(6)-H(6B)· · ·I(1)
3
N(7)-H(7C)· · ·I(1)
2
C(2)-H(2)· · ·I(1)
4
C(3)-H(3)· · ·O(5)
2
C(6)-H(6)· · ·O(6)
2
5
C(12)-H(12)· · ·O(4)
C(13)-H(13)· · ·O(1)
2.4725
2.5203
Symmetry code: 1. 1+x,y,z; 2. x, y, z; 3. -1+x,y,z; 4. 1-x,1-y,-z; 5. 1-x,1-y,1-z
Complex 3
◦
D-H· · · A
d(H· · · A) (Å)
2.1646
d(D· · · A) (Å)
2.996(3)
3.231(6)
2.855(4)
3.032(5)
2.809(4)
2.916(6)
3.264(4)
∠D-H· · ·A ( )
1
N(2)- H(3C)· · ·O(5)
162.27
164(2)
168.4(19)
146(3)
166(2)
144.04
156.46
2
O(3)-H(3D)· · ·O(9)
2.33(2)
1.93(2)
2.26(2)
1.93(2)
2.1759
3
O(3)-H(3E)· · ·N(5)
O(4)-H(4D)· · ·O(9)
2
4
O(4)-H(4E)· · ·N(1)
5
N(6)-H(6C)· · ·O(10)
1
C(4)-H(4)· · ·O(5)
2.3913
Symmetry code: 1. -x,1-y,1-z; 2. -1+x,1+y,z; 3. 1-x,2-y,-z; 4. -1-x,1-y,1-z; 5. x, y, z

Alkali and alkaline earth metal complexes with O,N,N’-donor hydrazone ligand
1379
+
dimeric compound 1 with atom numbering scheme is to bridge the adjacent K along with one coordinated
depicted in figure 2a. Asymmetric unit of 1 is com- water molecule. K-O distances in ranges from 2.787(3)
+
−
posed of one K centre, one Br anion, two molecules to 2.945(2) / 2.815(3) to 3.026(2) Å and K-N distance
of L, one coordinated water molecule and three water is in the range 2.843(3) to 3.275(3)/2.856(2) to 3.302(2)
molecules as solvent of crystallization.
Å respectively for 1 and 2 (Table S1).
+
Each symmetrically disposed K in the dimeric unit
Diverse supramolecular interactions are anticipated
is wrapped around by two L moieties. One of the L due to the presence of amide group in the ligand moi-
act as a tridentate ligand via N O coordination with ety and lattice/coordinated water molecules in 1 & 2.
2
+
K through its imine and pyridyl nitrogens (N6, N5) Packing diagram viewed down a-axis with hydrogen
and the amide oxygen (O2), while from the second L bonding interactions are depicted in figures 2b and S1.
moiety the amide oxygen (O1) is making a μ type Symmetrically disposed water molecule O4 positioned
2
−
+
coordination with the symmetrically disposed K gen- between the dimers are involved in bridging the adja-
erating the centrosymmetric dimeric compound. Each cent dimeric unit to from a hydrogen bonded layers
+
K is involved in an octa coordination provided by the along b-axis. Thus, symmetrically placed water (O4)
imine/pyridyl nitrogen and amide oxygen atoms from acts as a donor through O-H· · ·O contact with the coor-
two different L moieties in which amide oxygen O1 dinated water O3 and an acceptor via N-H· · ·O con-
from one of the L is making μ2 type coordination tacts with the amide hydrogen H7N in the formation
−
Figure 2. (a) ORTEP diagram of 1 depicting 50% probability for thermal
ellipsoids with atom numbering scheme (Some of the hydrogen atoms, bromide
anions and lattice water molecules have been omitted for clarity); (b) packing
diagram presenting the hydrogen bonded 2D sheets spreading along bc-plane;
−
(
c) centrosymmetric hexameric [(H2O)4(Br )2] cluster observed in 1.

1
380
Bhavesh Parmar et al.
of the hydrogen bonded layers along b−axis. Exten-
sive hydrogen bonding interactions do exist in 1 &
2
between the lattice water molecules O5 and O6
with the bromide/iodide anions in generating a hybrid
water-bromide puckered ring with chair conformation
as depicted in figure 2c. Lattice Water molecules O5
and O6 are mutually involved in O-H· · ·O hydrogen
bonding in which O6 acts as a donor and O5 as accep-
tor. Thus, H6A attached to O6 render as the donor and
involved in O–H· · ·O interactions with O5 and H6B
and H5B from O6 and O5 respectively are drawn into
−
O–H· · ·Br contacts generating a cyclic centrosym-
−
metric hexameric [(H O) (Br ) ] cluster (figure 2c).
2
4
2
The O· · ·O distances, O–H· · ·O and angles within this
−
basic centrosymmetric [(H O) (Br ) ] unit generat-
2
4
2
Figure 3. ORTEP diagram depicting of the monocationic
part of 3 with atom numbering scheme (50% probability
for thermal ellipsoids; only amide hydrogen atoms and one
ing a eleven membered cyclic ring are O(5)· · ·O(6)
◦
=
2.707(6) Å, with ∠O(6)–H(6A)· · ·O(5) = 163(5)
−
and; the O· · ·Br1 distances and O–H· · ·Br angles are of the disordered position for the coordinated perchlorate
moiety is shown).
(
Br1· · ·O5 = 3.363(4) Å, Br1· · ·O6 = 3.372(4) Å
◦
and ∠O5–H5B· · ·Br1 = 165(5) , ∠O6–H6B· · ·Br1 =
◦
1
[
74(5) ) respectively. Centrosymmetric six membered
−
(H O) (Br ) ] rings are placed between the hydro-
2
4
2
hydrogen bonding interaction in detail. Packing dia-
gram with hydrogen bonding interaction viewed down
b-axis is depicted in figure 4a and shows that the
monomeric cations are oriented along c-axis. Detailed
analysis of observed hydrogen bonding interaction
gen bonded 1D layers and involved in O-H· · · O, N-
H· · ·O and N-H· · ·Br contacts along c-axis generat-
ing a two dimensional hydrogen bonded network (fig-
ure 2b). In addition to the above mentioned hydrogen
bonds inter and intra molecular C-H· · ·O as well as C-
(figure 4b) expose that the 2D supramolecular sheet
−
H· · · Br contacts are also observed in supramolecular
is stabilized by several weak molecular contacts. N-
H· · · O, O-H· · · O and C-H· · ·O interactions involving
the coordinated/lattice perchlorate anion with complex
moiety play a crucial role for the association of the
discrete complex entities generating a layered motif
along c-axis. Thus, amide hydrogen atoms H6C and
H3C from N6/N2, water hydrogen H3D and H4D from
O3/O4 and pyridyl hydrogen H4C from C4 is involved
in intermolecular contacts with perchlorate oxygen
atoms as cited [N6-H6C· · ·O10: H6C· · ·O10 = (2.18
Å), N(2)-H3C· · ·O(5): H3C· · ·O(5) = (2.16 Å), O3-
H3D. . . O9: H3D· · ·O9 = (2.33(2) Å, O4-H4D· · ·O9:
assembly resulting in the stabilisation of molecules in
crystal lattice. Similar molecular interactions are persis-
tent in the isostructural compound 2 with counter anion
−
I (figure S1). Details of all the hydrogen bonding inter-
actions present in 1 and 2 with symmetry codes are
given in table 2.
3
.3 Crystal and molecular structure
of [Ba(L) (H O) (ClO )]ClO (3)
2
2
2
4
4
Complex 3 crystallized in triclinic system with P-1 H4D· · ·O9 = (2.26(2) Å), C4-H4· · ·O5: H4· · ·O5 =
space group. ORTEP diagram for mono-cationic com- (2.39 Å)]. Intermolecular O-H· · ·N interactions involv-
plex part of 3 is depicted in figure 3. Nona coordi- ing coordinated water hydrogen (H4E and H3E) and
+2
nation adopted by Ba is provided by two L moi- terminal pyridine nitrogen of ligand L [(O4-H4E· · · N1:
eties in chelated tridentate fashion through its pyridyl, H4E· · ·N1 = 1.93(2) Å and O3-H3E· · ·N5: H3E· · ·N5
imine nitrogen atoms (N4, N8 and N3, N7), amide = 1.93(2) Å] from neighbouring units of layered hydro-
oxygen atoms (O1 and O2), two water molecules (O3 gen bonded motif extending the supramolecular array
and O4) and one perchlorate oxygen (O5). Ba-O dis- along a-axis generating a two dimensional hydro-
tances involving the amide oxygen and water molecules gen bonded network in 3. In addition to the above
ranges from 2.714(2) to 2.956(3) Å and Ba-N distances mentioned hydrogen bonding interactions the pyridyl
involving the pyridyl/amide nitrogen is in the range of rings (N(5)-C(13) to C(17)) of the ligand moieties are
2
.893(2) to 2.965(2) Å respectively.
In an attempt to understand the supramolecular along a-axis with centroid· · · centroid distance between
interaction in 3 we have analysed the packing and the pyridyl rings 3.68 Å [symmetry code 1-x,2-y,-z].
involved in intermolecular π· · ·π stacking interactions

Alkali and alkaline earth metal complexes with O,N,N’-donor hydrazone ligand
1381
Figure 4. (a) Packing diagram viewed down b- and a- axes for 3; (b) close-up
view of the various H-bonding (Black dotted lines) present in 3.
3.4 TGA and PXRD analyses
two coordinated water molecules (calc. 4.36%). Com-
plex 3, exhibits thermal stability up 285 C and further
◦
The lattice guests and composition of L and 1–3 were
estimated and ascertained by thermal, elemental and
single crystal analyses. Lattice water molecules in case
increase in temperature cause rapid decomposition of
compound. Experimental PXRD data obtained for bulk
samples of L.2H O as well as complexes corroborate
2
of L.2H O (C H N O.(H O) ) escape from the crys-
2
12 10
2
2
2
well with those simulated from respective single crystal
data (figures S2 and S3) confirming the phase purity of
synthesized samples.
◦
tal lattice in the temperature range 40−128 C, evi-
dent from the thermogram showing ca 9% weight loss
(calc. 13.73%) in the mentioned temperature range
(
figure 5). Dehydrated ligand L thus obtained exhibits
◦
thermal stability up to 200 C and further increment
in temperature resulted in the decomposition of lig-
3.5 FTIR and absorption spectra
and. Complex 1, ([K L (H O) ]Br .6H O) lose lat- FTIR spectra for both pseudopolymorphs and all three
2
4
2
2
2
2
tice water molecules at ambient conditions; however, complexes were recorded at room temperature by
expulsion of coordinated water molecules (obs. ca dispersing minute amount of solids in KBr pellets
◦
3
%; calc. 2.8%) in temperature range 70 − 165 C (figure 6). FTIR spectra of ligand pseudopolymorphs
was observed. Compound 1 decomposes at temper- featured comparable bands for carbonyl and imine
ature higher than 200 C. Lattice (calc. 7.82%) and stretching modes at 1665 and 1549 cm for L and at
coordinated (calc. 2.60%) water molecules in case 1665 and 1567 cm for L.2H O. Presence of water
◦
−1
−1
2
of complex 2, ([K L (H O) ]I .6H O) escape step- molecules in psuedopolymorph L.2H O was revealed
2
4
2
2
2
2
2
◦
wise manner in the temperature range 30−165 C for by broad band for OH stretching mode observed in
−1
which 9.2% weight loss was observed. Complex 3, 3200–3550 cm range. Carbonyl and imine stretch-
BaL (H O) (ClO )].(ClO ) exhibit 3.10% weight loss ing bands in case of complexes 1–3 were observed at
[
2
2
2
4
4
◦
−1
when heated up to 150 C which is attributable to the ca 1665 and 1550 cm whereas all three complexes

1
382
Bhavesh Parmar et al.
Figure 5. TGA traces for ligand pseudopolymorph L.2H2O and complexes 1-3.
exhibit broad OH stretching bands for coordinated
−1
and/or lattice water molecules at ca 3475 cm . Cl-O
−1
stretching band was distinctly observed at ca 1100 cm
in case of complex 3.
Absorption behaviour of both psuedopolymorphic
forms (L and L.2H O) of ligand and synthesized com-
2
plexes 1–3 was studied in solid state at room tem-
perature (figure 7). L revealed two overlapping bands
at ca 326 and 261 nm which can be ascribed as π-
π* and π-n transitions. However, these bands were
much diffused in case of L.2H O and appeared as a
2
broad band spanning in 360–233 nm range. Complexes
1–3 showed similar absorption spectral feature as of
Figure 6. FTIR spectra recorded by KBr pellet method for Figure 7. Solid state absorption spectra for pseudopoly-
L.2H2O and complexes 1–3. morphs L, L.2H2O and complexes 1-3.

Alkali and alkaline earth metal complexes with O,N,N’-donor hydrazone ligand
constituting ligand, suggesting the persistent intraligand References
1383
or metal perturbed intraligand electronic transitions.
1
. (a) Desiraju G R 2007 Angew. Chem. Int. Ed. 46 8342;
(
b) Vantomme G and Lehn J M 2013 Angew. Chem. Int.
Ed. 52 3940
2
. (a) Fahmi N, Shrivastava S, Meena R, Joshi S C and
Singh R V 2013 New J. Chem. 37 1445; (b) Armstrong
C M, Bernhardt P V, Chin P and Richardson D R 2003
Eur. J. Inorg. Chem. 1145; (c) Singh N, Watts S, Joshi
S C and Singh R V 2013 Appl. Organometal. Chem.
27 269; (d) Ababei L V, Kriza A, Andronescu C and
Musuc A M 2012 J. Therm. Anal. Calorim. 107 573;
4
. Conclusions
We have reported a new psuedopolymorph of a O,N,N’-
donor hydrazone ligand, 2-pyridylcarboxaldehyde ison-
icotinoylhydrazone (L) and its discrete complexes with
K and Ba which present as first examples of com-
plexes between L and alkali or alkaline earth metal
ions. All compounds were characterized by single crys-
tal X-ray structural analysis and other physicochemical
techniques such as FTIR, TGA, PXRD and solid state
absorption spectra. L formed isostructural dinuclear
complexes with K when bromide and iodide were
employed as counteranion, whereas, a mononuclear
complex with Ba was formed which showed coor-
dinated as well as uncoordinated perchlorate counter
anion. Various structural aspects including hydrogen
+
2+
(
e) Shahverdizadeh G H, Tiekink E R T and
Mirtamizdoust B 2011 Acta Crystallogr., Sect. E: Struct.
Rep. Online 67 m1727
3
. (a) Bernhardt P V, China P and Richardson D R 2004
Dalton Trans. 3342; (b) Sharma V K, Srivastava S and
Srivastava A 2006 J. Coord. Chem. 59 1321; (c) Sastry
P S S J and Rao T R 1995 Proc. Indian Acad. Sci.
+
(
Chem. Sci.) 107 25; (d) Bikas R, Hosseini-Monfared H,
Zoppellaro G, Herchel R, Tucek J, Owczarzak A M,
Kubicki M and Zboril R 2013 Dalton Trans. 42 2803
. Richardson D R, Becker E and Bernhardt P V 1999 Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 55 2102
. Bernhardt P V, Chin P and Richardson D R 2001 J. Biol.
Inorg. Chem. 6 801
2
+
4
5
6
bonding interactions and spectral features of L.2H O
and 1-3 have been studied in detail.
2
. (a) Bernhardt P V, Caldwell L M, Chaston T B, Chin P
and Richardson D R 2003 J. Biol. Inorg. Chem. 8 866;
(
b) Bernhardt P V, Chin P, Sharpe P C and Richardson
D R 2007 Dalton Trans. 3232; (c) Bernhardt P V,
Mattsson J and Richardson D R 2006 Inorg. Chem. 45
Supplementary Information
7
52; (d) Kalinowski D S, Sharpe P C, Bernhardt P V and
Crystallographic data of for the psuedopolymorhic
Richardson D R 2008 J. Med. Chem. 51 331
form of L.2H O, complexes 1, 2 and 3 has been
7. (a) Shin H and Min B 2013 J. Inorg. Organomet.
Polym. 23 1305; (b) Li D Q, Liu X and Zhou J 2008
Inorg. Chem. Commun. 11 367; (c) Xua C, Maoa H,
Shena X, Zhanga H, Liua H, Wua Q, Houa H and
Zhua Y 2007 J. Coord. Chem. 60 193; (d) Shaabani B,
Khandar A A, Kazemi S S, Shaghaghi Z, Boudalis A K,
Psycharis V and Raptopoulou A 2013 Polyhedron 49 61;
(e) Hanifehpour Y, Saraei N, Asl S M and Joo S W 2012
J. Inorg. Organomet. Polym. 22 1271; (f) Ni W X, Li M,
Zhan S Z, Hou J Z and Li D 2009 Inorg. Chem. 48 1433;
2
deposited at the Cambridge Crystallographic Data Cen-
tre with CCDC nos. 992911 to 991914 respectively.
Copies of this information can be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 IEZ, UK (Fax: +44-1223-336033;
Email: deposit@ccdc.cam.ac.uk or http://www.ccdc.
cam.ac.uk). Characterization data for the ligand and
complexes such experimental and simulated PXRD for
(
g) Yu Q, Zhu L G, Bian H G, Deng G H, Bao X G and
L.2H O (figure S2), Experimental and simulated PXRD
2
Liang H 2007 Inorg. Chem. Commun. 10 437; (h) He Z,
He C, Gao E Q, Wang Z M, Yang X F, Liao C S and
Yan C H 2003 Inorg. Chem. 42 2206; (i) Li D Q, Liu X
and Zhou J 2010 Z. Naturforsch. B: Chem. Sci. 65 1084;
1
13
for 1-3 (figure S2), H and C NMR Spectra of ligands
and complexes (figure S4) and ORTEP diagram and
crystal structure for complex 2 (figure S1) and selected
bond lengths and angles (table S1) are available in the
supporting information (www.ias.ac.in/chemsci).
(
j) Li G, Yan W B, He C, Duan C Y, Meng Q J and Li
Y Z 2008 Chin. J. Inorg. Chem. 24 1767; (k) Li D Q,
Liu X and Zhou J 2008 Z. Naturforsch. B: Chem. Sci.
6
2
3 1343; (l) Cai T J, Long Y F, Deng Q and Peng Z S
005 Z. Kristallogr. New Cryst. Struct. 220 506; (m) Cai
Acknowledgement
T J, Peng Z S, Deng Q, Long Y F, Deng T T and Yu K B
2
004 Chin. J. Inorg. Chem. 20 731; (n) Hanifehpour
Authors acknowledge the CSIR, India (K-TEN Project,
Grant no. CSC 0105) for financial support, Mrs.
Monika Gupta for TGA data, Ms. Riddhi Laiya for
XRPD data, Mr. Satyaveer Gothwal for elemental data,
Mr. Viral Vakani for IR data. BP and KKB acknowl-
edge CSIR (India) for research fellowships. Publication
Registration Number: CSIR-CSMCRI No. : 066/2014.
Y, Khanalilou S, Paknahad E, Joo S W, Sadr M H and
Soltani B 2012 J. Inorg. Organomet. Polym. Mater. 22 1248
. Heine J, Hoły n´ ska M, Reuter M, Haas B, Chatterjee S,
Koch M, Gries K I, Volz K and Dehnen S 2013 Cryst.
Growth Des. 13 1252
. (a) Rodríguez-Spong B, Price C P, Jayasankar A,
Matzger A J and Rodríguez-Hornedo N. 2004 Adv.
Drug Deliv. Rev. 56 241; (b) Mukherjee A, Tothadi S,
8
9

1
384
Bhavesh Parmar et al.
Chakraborty S, Ganguly S and Desiraju G R 2013 Crys-
tEngComm 15 4640; (c) Bhargavi G, Rajasekharan M V,
Costes J P and Tuchagues J P 2013 Dalton Trans. 42
Solanki J, Brahmbhatt H R, Chunawala J R, Suresh E
and Paul P 2013 PCT Int. Appl. WO 2013150363 A1
20131010; (c) Ramakrishna V, Patra S, Suresh E, Bhatt
A K, Bhatt P A, Hussain A and Paul P 2012 Inorg.
Chem. Commun. 22 85; (d) Patra S, Suresh E and Paul
P 2007 Polyhedron 26 4971; (e) Bisht K K, Rachuri Y,
Parmar B and Suresh E 2014 J. Solid State Chem. 213
43; (f) Kathalikkattil A C, Damodaran S, Bisht K K and
Suresh E 2011 J. Mol. Struct. 985 361; (g) Kathalikkattil
A C, Bisht K K, Subramanian P S and Suresh E 2010
Polyhedron 29 1801; (h) Bisht K K, Patel P, Rachuri Y
and Suresh E 2014 Acta Crystallogr. Sect. B-Struct. Sci.
70 63; (i) Bisht K K, Rachuri, Y, Parmar B and Suresh E
2014 RSC Adv. 4 7352
8
2
113; (d) Grobelny P, Mukherjee A and Desiraju G R
012 CrystEngComm 14 5785; (d) Aravinda S, Shamala
N, Karle I L and Balaram P 2012 Pept. Sci. 98 76;
e) Aitipamula S, Banerjee R, Bansal A K, Biradha K,
(
Cheney M L, Choudhury A R, Desiraju G R, Dikundwar
A G, Dubey R, Duggirala N, Ghogale P P, Ghosh S,
Goswami P K, Goud N R, Jetti R K R, Karpinski P,
Kaushik P, Kumar D, Kumar V, Moulton B, Mukherjee
A, Mukherjee G, Myerson A S, Puri V, Ramanan
A, Rajamannar T, Reddy C M, Rodriguez-Hornedo N,
Rogers R D, Row T N G, Sanphui P, Shan N, Shete G,
Singh A, Sun C C, Swift J A, Thaimattam R, Thakur T S, 11. (a) Aakeröy C B, Forbes S and Desper J 2012 Cryst.
Thaper R K, Thomas S P, Tothadi S, Vangala V R,
Vishweshwar P, Weyna D R and Zaworotko M J 2012
Eng. Comm. 14 2435; (b) Johnson D K, Murphy T B and
Rose N J 1982 Inorg. Chim. Acta 67 159
Cryst. Growth Des. 12 4290; (f) Mukherjee A, Grobelny 12. Sheldrick G M SAINT 5.1 ed., Siemens Industrial
P, Thakur T S and Desiraju G R 2011 Cryst. Growth Automation Inc., Madison, WI, 1995
Des. 11 2637; (g) Chieng N, Rades T and Aaltonen J 13. SADABS, Empirical Absorption Correction Program,
011 J. Pharm. Biomed. Anal. 55 618; (h) Thakur T S, University of Göttingen, Göttingen, Germany, 1997
Sathishkumar R, Dikundwar A G, Row T N G and 14. Sheldrick G M SHELXTL Reference Manual: Version
Desiraju G R 2010 Cryst. Growth Des. 10 4246; 5.1, Bruker AXS, Madison, WI, 1997
2
(
i)NangiaAand Desiraju G R 1999 Chem. Commun. 605 15. Sheldrick G M SHELXL–97: Program for Crystal Struc-
1
0. (a) Patidar R, Paul P and Ganguly B 2013 J. Mol. Graph.
Model. 46 22; (b) Maiti P, Ghosh P K, Ghara K K,
ture Refinement, University of Göttingen, Göttingen,
Germany, 1997