Synthesis, Spectral Characterization, Crystal Structure, Thermal Studies and Hirshfeld Surface Analysis of Novel Dichlorodi-(E)-N′-(4-methoxybenzylidene)benzohydrazide Manganese(II) Complex

Article abstract of DOI:10.14233/ajchem.2020.22750

A novel dichlorodi(E)-N′-(4-methoxybenzylidene)benzohydrazide manganese(II) (ENMB-Mn) complex has been successfully synthesized using (E)-N′-(4-methoxybenzylidene)benzohydrazide (ENMB) as ligand. The structure of the ENMB-Mn complex was studied by single crystal X-ray diffraction, UV-Visible, FTIR, thermogravimetric analysis (TGA) and Hirshfeld surface analysis. Results of single crystal X-ray diffraction found that the structure of ENMB-Mn complex crystal is triclinic with space group P-1 and lattice parameters of unit cell a, b and c values were 7.1900 ?, 8.9094 ? and 11.8130 ?, respectively. The structure of ENMB-Mn complex clearly indicates complete octahedral geometry [Mn(ENMB)2Cl2] with manganese(II) ion, where the ENMB and chlorine atoms ratio is 1:2:2, respectively. Further, the molecular properties like Hirshfeld surface analysis mapping are reported.

Full text of DOI:10.14233/ajchem.2020.22750

Asian Journal of Chemistry; Vol. 32, No. 9 (2020), 2213-2221
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2020.22750
Synthesis, Spectral Characterization, Crystal Structure, Thermal
Studies and Hirshfeld Surface Analysis of Novel Dichlorodi-(E)-N′-
(
4-methoxybenzylidene)benzohydrazide Manganese(II) Complex
1
2
3,
4
5,*,
G. KAVITHA , M. UTHAYAKUMAR , VANDANA SHINDE , T. CHANDRASEKARAN and M. SURESH
1
2
3
4
5
Department of Chemistry, Rajalakshmi Institute of Technology, Kuthambakkam, Chennai-600124, India
Department of Physics, Jayarani Arts and Science college for Women, Salem-636002, India
Department of Physics, Kavayitri Bahinabai Chaudhari North Maharashtra University, Jalgaon-425001, India
Sir Sivaswamy Iyer Higher Secondary School, Thirukattupalli, Thanjavur-613104, India
Department of Chemistry, Pachaiyappa′s College for Men, Kanchipuram-631501, India
*
Corresponding author: E-mail: mscsuresh2@gmail.com
Received: 31 March 2020; Accepted: 27 May 2020;
Published online: 20 August 2020;
AJC-20015
A novel dichlorodi(E)-N′-(4-methoxybenzylidene)benzohydrazide manganese(II) (ENMB-Mn) complex has been successfully synthesized
using (E)-N′-(4-methoxybenzylidene)benzohydrazide (ENMB) as ligand. The structure of the ENMB-Mn complex was studied by single
crystal X-ray diffraction, UV-Visible, FTIR, thermogravimetric analysis (TGA) and Hirshfeld surface analysis. Results of single crystal
X-ray diffraction found that the structure of ENMB-Mn complex crystal is triclinic with space group P-1 and lattice parameters of unit cell
a, b and c values were 7.1900 Å, 8.9094 Å and 11.8130 Å, respectively. The structure of ENMB-Mn complex clearly indicates complete
octahedral geometry [Mn(ENMB)
2
2
Cl ] with manganese(II) ion, where the ENMB and chlorine atoms ratio is 1:2:2, respectively. Further,
the molecular properties like Hirshfeld surface analysis mapping are reported.
Keywords: Benzohydrazide manganese(II) complex, Schiff base, Single crystal XRD, Hirshfeld surface analysis.
with co-centered metal complexes are the interest of research
INTRODUCTION
since they possess important superior catalytic behaviour,
biological activities and second order non-linear optical prop-
erties, etc. The purpose of metal incorporation in structure is
similar to metal organic frameworks such as metal centers and
organic linkers, which have remarkable capability to dominate
and alter their properties superior way like gas sorption/separa-
tion, water sorption/desorption, proton conductivity and drug
delivery [17,18]. In this way, symmetrical and unsymmetrical
Schiff bases contributing the progress in coordination chemistry
of transition metals and major group elements.
The significant characteristic of these materials are they
show the ''breathing effect" which means it capture metal cations
as host in organic frameworks and it have flexible periodic
structure which shows deformation in structure by external
agency. Therefore, it is used for wide range of applications, which
make these compounds as a versatile [19,20]. In brief, Shakdofa
et al. [21] reported a review article on the metal complexes of
The label 'Schiff base' contains two words, the first word
represents the name of German chemist Hugo Schiff, who has
synthesized Schiff base for the first time and second word
indicates its base type nature [1]. These types of compounds
have wide range of applications from biological to electronics
2]. Condensation reactions between ketone or aldehyde with
primary amines resulting the Schiff base compounds.
In order to develop new coordination compounds, various
research groups have tried to synthesis of Schiff base ligands
using transition metals which results outstanding and tunable
properties related to stereo-electronic structure [3]. Such kind
of new compounds are highly useful in various fields like gas
sensors, catalysis, electroluminescence, photoluminescence,
drug delivery and membranes [4-16]. Therefore numerous
researchers are motivated towards these types of compounds.
In last two-three decades, symmetrically-substituted Schiff base
[
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2
214 Kavitha et al.
Asian J. Chem.
hydrazones with the variety of applications. Hosseini-Monfareda
et al. [22] reported the synthesis of ONN and ONO hydrazone
Schiff base ligands. Further their crystal structure and catalytic
activity of complexation with manganese metal ion also investi-
gated. Rathi et al. [23] also reported the synthesis of few Mn(II)
complexes of tridentate NNN donor ligands and their DNA
interaction, nuclease and protease activities are explained. The
Mn(II) triazamacrocyclic complexes synthesized and its structural,
spectroscopic, electrochemical and magnetic properties have
been investigated by Banerjee et al. [24].
In recent years, several works reported the hydrolysis of
phosphoric and carboxyl esters based Schiff bases and their
applications in the field of environment and biological fields
are also analyzed [25]. Variety of metals incorporated Schiff
bases catalysts are found in literature but Mn(II) and Co(II)
incorporated catalysts are the cost effective and more effective
catalysts species in hydrolysis of phosphoric and carboxyl
esters [26,27]. The synthesis and characterization of four Mn(II)
and Co(II) complexes incorporated by unsymmetrically substi-
tuted tetradentate Schiff base ligands are also reported by Li
et al. [28]. These complexes have excellent catalytic activities
for hydrolysis reactions. They observed that with increase in
pH, the reaction rate also increased. Shaabani et al. [29] studied
antimicrobial behaviour and crystal structure of hydrazone
Schiff base and azide ligands incorporated by Cr(III), Mn(II)
and Fe(III). Boutar et al. [30] also reported Zn(II) and Mn(II)
incorporated calix[4]arene functionalized with carboxylates
complexation.
interaction of title compound also studied by TGA and Hirsh-
feld surface analysis.
EXPERIMENTAL
A.R. grade anisaldehyde, benzohydrazide, hydrochloric
acid, manganese(II) chloride, ethanol and ether were purchased
from Merck and Sigma-Aldrich suppliers and used without
any purification. Analytical TLC was carried on silica coated
glass plates.
Synthesis of dichlorodi(E)-N′-(4-methoxybenzylidene)-
benzohydrazide (ENMB) ligand: Initially, an ethanolic
solution of anisaldehyde (3.4 mL, 0.025 mol) was measured
in flask, after then benzohydrazide (3.4 g, 0.025 mol) and a
little drops of hydrochloric acid were mixed into the solution.
This reaction mixture was stirred well keeping in an ice bath
for 3 h. After completion of the reaction that was checked by
TLC. The colourless solid formed was filtered, washed several
times with petroleum ether (40-60%).The crude solid ENMB
ligand, thus obtained was dried over in vacuum and recrystal-
lized using ethanol (Scheme-I).
Synthesis of ENMB-Mn complex: Ethanolic solution of
ENMB ligand (2.15 g, 0.01 mol) and manganese(II) chloride
(0.85 g, 0.005 mol) were mixed in flask. This reaction mixture
kept stirring and refluxed at 85 ºC for 8 h. Then after, solution
kept stable for three days at room temperature. On the fourth
day, a pale violet coloured crystalline solid of ENMB-Mn was
observed. The product solution was filtered from the reaction
mixture, washed several times with petroleum ether and dried
at room temperature. The product was recrystallized using
ethanol and dried in vacuum (Scheme-II).
The literature survey indicates that the synthesis, charact-
erization including single crystal XRD (SCXRD) and Hirshfield
studies have not been documented of the title compound so
far. The present work reports the synthesis of manganese(II)
complex of (E)-N′-(4-methoxybenzylidene)benzohydrazide
Characterization: FTIR spectra were recorded in the
-1
frequency range of 4000-400 cm using Shimadzu FTIR 400
spectrophotometer, by KBr pellet technique. The UV-Visible
absorption spectra were measured using Perkin-Elmer Lambda
35 model spectrophotometer in the wavelength range 190-1100
(ENMB-Mn) and characterized by FTIR, UV-Visible absor-
ption spectroscopy, SCXRD analysis. The structure of ENMB
1
13
1
13
ligand is evaluated using FTIR, UV-visible, H & C NMR and
mass spectral studies. The thermal properties and intramolecular
nm. H & C NMR spectra of samples were recorded at 300
MHz and 100 MHz, respectively using DMSO-d as solvent
6
H
CHO
H
N
273-278 K/H+
N
N
H2N
O
O
O
O
Scheme-I: Synthesis of ENMB ligand
H
N
N
O
O
H
N
C H OH
Mn
N
Cl
2
5
Cl
N
MnCl ·4H O
2 2
+
O
O
O
O
N
H
Scheme-II: Synthesis of ENMB-Mn complex

Vol. 32, No. 9 (2020)
Studies of Novel Dichlorodi-(E)-N′-(4-methoxybenzylidene)benzohydrazide Manganese(II) Complex 2215
at room temperature by Bruker NMR Spectrometer. A mass
spectrum was measured by using JEOL mass spectrometer,
operating at an ionization potential of 70 eV. Bruker Kappa
diffractometer with X-ray source Mo (wavelength of Kα line
C=C stretching, NH bending modes and other modes are not
having considerable change in the both complex and ligand.
The assigned values are given in Table-1 [35-40].
=
0.71073 Å) using in the ω/2θ scan mode at room temperature
TABLE-1
FT-IR ASSIGNMENTS FOR LIGAND (ENMB)
AND ITS TITLE COMPOUND (ENMB-Mn)
was used to collect the crystal structure data of ENMB-Mn
crystal. The thermal behaviour of ENMB-Mn complex was
studied by TGA using thermogravimetric analyzer TGA 4000-
Perkin-Elmer model temperature varied from room temperature
to 900 ºC keeping a heating rate of 15 ºC/min in a nitrogen
atmosphere. The Hirshfeld surfaces of ENMB-Mn crystal were
generated using Crystal Explorer 3.1 software using the Crystallo-
graphy Informative File (CIF) [31].
–1
Frequency (ν, cm )
ENMB ENMB-Mn
430
Assignments
3
3422
2902.70
N-H symmetric stretching
Aromatic C-H stretching
Aliphatic CH stretching
C=O stretching
2902.55
2846.58
1675.64
1594.78
2846.50
1678.12
1592.84
NH bending
1
492.53, 1447.95
1492.62, 1445.94
1255.50
C=C bending
C=N stretching
RESULTS AND DISCUSSION
1249.62
–
–
459.24
409.38
Mn-N bending
Mn-Cl bending
FT-IR studies: FTIR spectra of ENMB and ENMB-Mn
complex are shown in Fig. 1. The band appeared at 1668 cm
-1
indicates the ν(-C=N) stretching of azomethine moiety of the
ENMB ligand. This band observed to be shifted to the lower
frequency in the manganese complex (ENMB-Mn) at 1645
cm by nearly 23 cm . This suggests that the coordination is
observed through N-atom of azomethine (-CH=N-) linkage
UV-visible studies:The UV-visible spectra of ENMB and
ENMB-Mn are shown in Fig. 2. The broad peak with small
absorbance observed at 206 nm indicates that high energy π-π*
transitions. This peak suggesting that the presence of delocali-
zation of π electron from the benzene rings of ligand ENMB.
An another one peak observed at 230 nm, arises due to n-σ*
transition indicating that the non-bonding electrons on nitrogen
atom in amines are loosely bound as compared to n-electrons
on oxygen atom in the ligand ENMB.
-1
-1
[
12]. The carbonyl group (C=O) stretching frequency of ENMB
-1
ligand was observed at 1675 cm while the same was observed
-
1
at 1678 cm for ENMB-Mn complex, which suggests the
oxygen atom included in carbonyl group of ligand bounds with
Mn(II) ions. The amide group in ligand exhibits a peaks at 3322
and 3150 cm , which corresponds to NH symmetric and asym-
metric stretching modes, respectively, while ENMB-Mn complex
has been found stretching bands at 3325 and 3152 cm , which
indicates that there is absence of nitrogen atom of amide group
in ligand binding with Mn(II) ions [32-34]. The bands for CH,
-1
0.8
ENMB
ENMB-Mn
-1
0
.6
ENMB-Mn
0.4
0.2
0.0
200
400
600
800
1000
Wavelength (nm)
Fig. 2. UV-visible spectrum of ligand ENMB and ENMB-Mn complex
ENMB
In the coordination compound, the maximum absorption
band is ascertained to be at 329 nm, which may arise due to
n→π* transition corresponds to the promotion of an electron
from a bonding orbital to an antibonding π* orbital available
in ligand compound with unsaturated centers. While on the
other hand, UV-visible spectrum of ENMB-Mn shows the
maximum absorption band at 343 nm, which may arise due to
n→π* transition corresponds originated from the ligand metal
charge transfer (LMCT) interactions. In the coordination comp-
ound, the maximum absorption band is ascertained to be at
243 nm, which may arise due to n→π* transitions [41,42].
4000
3200
2400
Wavenumber (cm )
Fig. 1. FT-IR spectrum of ENMB and ENMB-Mn complex
1600
800
400
–1

2
216 Kavitha et al.
Asian J. Chem.
1
NMR studies: The H NMR spectrum of ENMB ligand
least squares refinement results are given in Table-2. The some
selected bond lengths and bond angles are shown in Tables 3
and 4, respectively.The solved final molecular structure (ORTEP)
and crystal packing diagram with hydrogen bonding interaction
of grown ENMB-Mn crystal are shown in Figs. 3 and 4.
The ENMB-Mn crystal belongs to the triclinic system
corresponding from the space group P-1, which is recognized
shows a singlet 11.8 ppm with their characteristic proton coup-
lings indicate the presence of amide protons (CONH), but it
exist keto-enolic tautomer form in DMSO-d
1
6
solvent. The H
NMR chemical shift at 8.4 ppm with sharp singlet indicates
the presence of azomethine proton (CH=N). One doublet is
appeared at δ7.9 ppm which corresponds to two aromatic ortho-
CH proton of phenyl ring of benzohydrazide part. Doublet
signals appeared at δ 7.7 ppm and 7.0 ppm corresponds to
four aromatic CH protons of aldehyde part of the compound.
Two triplets appeared at about δ 7.6 and 7.5 ppm indicating
three aromatic CH protons of the para and meta-position of
benzo-hydrazide phenyl ring. Further one sharp singlet peak
at δ 3.8 ppm suggesting the methyl protons of the ligand.
The results of C NMR of ENMB ligand analysis provide
information regarding the twelve peaks of the carbon atom
with different electronic environments. The signal appears at
the chemical shift (δ) 168 ppm is correspond to carbonyl carbon
and the signals exhibit at δ 163, 148, 137, 129, 128, 127 and
14 ppm are attributed to benzene ring carbons of both anisal-
dehyde and benzohydrazide part. A peak signal appeared at δ
52 ppm, which is corresponding to azomethine carbon. At
lower chemical shift 57 ppm one more signal observed which
indicates carbon of methoxy group [43,44].
Mass studies: Mass spectrum of ENMB ligand was recorded
by electron ionization method and its fragmentation pattern is
shown in Scheme-III. The calculated molecular weight of the
synthesized ENMB ligand is 254 and the mass spectrum also
displays a peak at m/z 254, which supports the synthesized
TABLE-2
CRYSTALLOGRAPHIC DATA OF
THE ENMB-Mn COMPOUND
Empirical formula
Formula weight
C H N O Cl Mn
30 28 4 4 2
634.40
Temperature
296(2) K
Wavelength
0.71073 Å
13
Crystal system, space group
Unit cell dimensions
Triclinic, P-1
a = 7.1900(4) Å α = 94.064(4)°
b = 8.9094(5) Å β = 101.718(3)°
c = 11.8130(7) Å γ = 101.485(3)°
3
Volume
721.21(7) Å
3
1
Z, Calculated density
Absorption coefficient
F(000)
2, 1.461 Mg/m
-1
0.686 mm
327
1
Crystal size
Theta range for data collection
Limiting indices
0.35 × 0.30 × 0.25 mm
1.77 to 28.27°
-9<=h<=9, -11<=k<=11,
-15<=l<=15
Reflections collected / unique
Completeness to theta = 28.27
Absorption correction
Max. and min. transmission
Refinement method
5620 / 3421 [R(int) = 0.0140]
95.4%
Semi-empirical from equivalents
0.8472 and 0.7953
2
Full-matrix least-squares on F
ENMB ligand (C16
48, which is due to the structure C
m/z 133 is corresponds to the fragment of C
A peak with high intensity appears at m/z 105 corresponds to
H
14
N
2
O
4
(I)). Further, a peak appears at m/z
Data / restraints / parameters
Goodness-of-fit on F
3421 / 0 / 195
1.129
1
8
H
8
N
2
O (II). And a peak at
2
+
7 5 2
H N O ion (III).
R1 = 0.0314, wR2 = 0.0912
Final R indices [I>2σ(I)]
R indices (all data)
Largest diff. peak and hole
R1 = 0.0430, wR2 = 0.1074
+
-3
C
7
H
5
O ion (IV) which is known as base peak and further it
0.338 and -0.351 e.A
will disintegrate to give two peaks at m/z 91 and 77 which is
+
+
due to the C
7
H
7
(V) and C
7
H (VI) ions, respectively. Thus
5
TABLE-3
SELECTED BOND LENGTHS (Å) OF ENMB-Mn COMPLEX
mass spectrum clearly shows the formation of ENMB ligand
via various intermediate cations, which will finally results to
the stable ligand.
Mn1-O2
Mn1-N1
Mn1-N1
Mn1-Cl1
Mn1-Cl1
N1-C8
2.1347 (12)
2.3728 (14)
2.3728(14)
2.4967 (4)
2.4967 (4)
1.279 (2)
1.3889 (18)
1.241 (2)
1.359 (2)
1.413 (3)
1.340 (2)
1.385 (2)
1.389 (2)
C10-C9
C11-C12
C15-C14
C8-C5
C7-C2
C7-C6
C5-C6
C5-C4
C2-C3
C4-C3
C14-C13
C13-C12
–
1.482 (2)
1.381 (3)
1.386 (3)
1.452 (2)
1.379 (3)
1.380 (3)
1.384 (2)
1.396 (2)
1.385 (3)
1.368 (3)
1.375 (3)
1.371 (3)
–
Single crystal XRD study of ENMB-Mn: The single
crystal XRD has been carried out to investigate structure and
the lattice parameter for the grown ENMB-Mn crystal. The
collected crystal structural data of ENMB-Mn was deposited
in Cambridge Crystallographic Data Centre (CCDC) with
CCDC number is 1901365. The lattice parameters of ENMB-
Mn crystal are a = 7.1900(4) Å, b=8.9094(5) Å, c = 11.8130(7)
N1-N2
O2-C9
O1-C2
O1-C1
3
Å and volumeV = 721.21(7) Å . The minimum and maximum
N2-C9
C10-C15
C10-C11
-3
value of residual electron density was -0.351 and 0.338e Å
respectively and the final R-factor were 0.0430. The full-matrix
H
N
H
N
N
N
N
N
O
III
O
O
O
O
I
II
IV
C H O
V
VI
+
+
+
+
C16H14N O2
C H N O
C H N O
C H
C H
7 5
2
8
8
2
7
5
2
7
5
7
7
(
m/z=254)
(m/z=148)
(m/z=133)
(m/z=105)
(m/z=91)
(m/z=77)
Scheme-III: Mass fragmentation of ENMB-Mn complex

Vol. 32, No. 9 (2020)
Studies of Novel Dichlorodi-(E)-N′-(4-methoxybenzylidene)benzohydrazide Manganese(II) Complex 2217
TABLE-4
BOND ANGLES (°) OF ENMB-Mn COMPLEX
O2-Mn1-O2
O2-Mn1-N1
O2-Mn1-N1
O2-Mn1-N1
O2-Mn1-N1
N1-Mn1-N1
O2-Mn1-Cl1
O2-Mn1-Cl1
N1-Mn1-Cl1
N1-Mn1-Cl1
O2-Mn1-Cl1
O2-Mn1-Cl1
N1-Mn1-Cl1
N1-Mn1-Cl1
C8-N1-N2
180.00(5)
107.92(5)
72.08(5)
C15-C10-C9
C11-C10-C9
C10-C15-C14
N1-C8-C5
N1-C8-H8
C5-C8-H8
C2-C7-C6
C6-C5-C4
C6-C5-C8
C4-C5-C8
116.91(15)
123.49 (16)
119.78(19)
123.78(16)
121.8(15)
72.08(5)
107.92(5)
180.00(1)
90.71(4)
89.29(4)
87.42(3)
92.58(3)
89.29(4)
90.71(4)
92.58(3)
114.5(15)
119.95(18)
118.24(17)
123.06(16)
118.67(16)
124.34(19)
115.82(18)
119.82(17)
120.95(17)
121.36(15)
120.40(15)
118.24(15)
121.01(18)
120.10(2)
O1-C2-C7
O1-C2-C3
C7-C2-C3
87.42(3)
C7-C6-C5
114.79(14)
138.76(12)
105.48(10)
118.20 (11)
118.39(18)
118.60(14)
127.3(18)
113.8(18)
O2-C9-N2
O2-C9-C10
N2-C9-C10
C3-C4-C5
C13-C14-C15
C4-C3-C2
C8-N1-Mn1
N2-N1-Mn1
C9-O2-Mn1
C2-O1-C1
C9-N2-N1
C9-N2-H2
120.01(18)
120.41(18)
120.09(19)
C12 C13 C14
C13 C12 C11
N1-N2-H2
Fig. 4. Packing of ENMB-Mn complex viewed down ‘a’ axis. Hydrogen
bonds are shown as dashed lines
TABLE-5
HYDROGEN BOND DATA (Å) OF
THE COMPOUND (ENMB-Mn)
D–H···A
D–H
H···A
D···A
DHA
C6-H6...Cl1
0.93(1)
0.80(3)
0.87(2)
0.93(1)
0.93(1)
2.72(2)
2.45(3)
2.76(2)
2.68(2)
2.53(2)
3.6389(19)
3.2380(15)
3.5260(18)
3.606(2)
171.4(2)
169.0(2)
148.0(2)
172.5(2)
174.7(2)
i
N2-H2...Cl1
Fig. 3. ORTEP diagram of ENMB-Mn complex
i
C8-H8...Cl1
C11-H11...Cl1
i
ii
as centro-symmetric system. The structure consists of a unique
manganese atom at center surrounded by two chlorine atoms
and an independent free two ENMB molecules placed in front
positions of central manganese atom. ENMB molecule exists
as neutral (act as Lewis base) by coordinate covalent bonds
with the central manganese cation (act as Lewis acid) in the
complex stable molecule. The hydrogen bonding interactions
are listed in Table-5. The two ENMB molecules are interlinked
covalently with central manganese atom through nitrogen and
oxygen atom with bond length is 2.37 and 2.13 Å, respectively.
Further the coordination complex has five intermolecular H-
C14-H14...O1
3.453(3)
Symmetry elements: (i) X+1, Y, Z (ii) X, Y+1, Z-1
atoms. Therefore, conclusion is that the ligand ENMB have
neutral bidentate nature and it coordinate through N and O of
ENMB to Mn(II) ions.
Thermal studies: In TGA analysis, the rate of heating
-1
was maintained at 15 ºC min under inert atmosphere. The
weight loss was measured from room temperature to 900 ºC.
The ENMB-Mn complex has been degradation into three steps.
The first step is removal of water molecule of ENMB-Mn from
temperature 150 ºC to 300 ºC, which is 10% (Fig. 5). Second
step involves maximum (50%) weight loss indicates that removal
of all organic moieties like ENMB ligand in temperature range
from 300 ºC to 600 ºC. The third step shows the 30% weight
loss corresponding to elimination of chlorine ligand in between
temperature range from 650 ºC to 750 ºC. Finally, the residue
was estimated as pure MnO at above 750 ºC [45-48].
bonding interactions are C
6
H
1
6
…Cl
and the distance between inter-
action of donor (hydrogen) and acceptor atom are observed
.72, 2.45, 2.76, 2.68 and 2.53 Å, respectively. Mn(II) is in a
1
, N
2
H
2
…Cl
1
, C
8
H
8
…Cl
1
,
C
11
H11…Cl
1
and C14
H14…O
2
slightly distorted octahedral environment, which is connected to
one nitrogen atoms N1, one oxygen atom O1 from two chelating
bidentate Schiff base ligand ENMB and two unidendate chlorine

2
218 Kavitha et al.
Asian J. Chem.
2
.1
The red region indicates that the closer contacts with
negative dnorm value. White region indicates that contact at van
der Waals separation with zero value. While the blue region
indicates that the longer contacts with positive dnorm value. In
ENMB-Mn crystal, the huge circular red patches on dnorm surfaces
suggests the hydrogen bonding while other patches suggests
the oxygen bonded with other atoms. Further, the red and blue
areas indication of the negative and positive electrostatic
potentials, respectively. This electrostatic potentials related to
the acceptor and donor atoms in the interactions during crystal
formations [49].
Shape index on the Hirshfeld surface can be used to find
interpretation of π-π stacking. Neighboring red and blue
triangles are observed in present ENMB-Mn crystal surfaces,
which suggest that π-π interaction is observed. UV-Visible
spectrum results also agreement to each other. Hollow region
indicated by red patches and bump region indicated by blue
patches via these molecular surfaces touches each other [50,51].
The construction of two-dimensional fingerprint graphs are
5
0%
2.0
1.6
1.2
3
0%
0.8
1
0%
0
.4
.0
0
3
0
100
200 300 400 500
Temperature (°C)
Fig. 5. TGA curve of ENMB-Mn complex
600 700 800
900
Hirshfeld surface studies: Hirshfeld 3D surfaces of dnorm
, shape index curveness for ENMB-Mn compound are
,
d
i
, d
e
carried by collecting (d
i
, d ) pairs. The corresponding 2-D finger-
e
shown in Fig. 6. Mapping of dnorm over the Hirshfeld surface
in the range −0.7681 to 1.4425 is shown in Fig. 6c. It shows
the intermolecular interactions with the adjacent molecules.
The dnorm map values over the Hirshfeld surface, are shown by
a red-white-blue colour pattern. These coloured regions have
specific indicative meaning.
print plots for Hirshfeld surfaces of the ENMB-Mn molecule
showing significant intermolecular interactions. The percen-
tage of involvements of various bonding to the total Hirshfeld
surface area are given in Fig. 7. It is observed that H···H inter-
actions in ENMB-Mn molecule, which is a notable contribution
among all the total Hirshfeld surfaces. This clearly replicating
di
de
d norm
Curveness
Shape index
Fig. 6. 3D-Hirshfeld images d norm, de, di, shape index, curvedness ENMB-Mn complex

Vol. 32, No. 9 (2020)
Studies of Novel Dichlorodi-(E)-N′-(4-methoxybenzylidene)benzohydrazide Manganese(II) Complex 2219
de
de
de
2
2
2
1
1
1
1
1
0
0
.4
.2
.0
.8
.6
.4
.2
.0
.8
.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
2.4
2
2
.2
.0
1.8
1.6
1
1
.4
.2
1.0
0.8
All interactions
00%
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
H···H
40%
C···H
0
.6
1
di
16.5%
di
di
0
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
de
de
de
2.4
2
2
2
1
1
1
1
1
0
0
.4
.2
.0
.8
.6
.4
.2
.0
.8
.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
2.2
2.0
1.8
1.6
1
1
1
0
.4
.2
.0
.8
O···H
H···Cl
13.5%
N···H
.5%
10.5%
di
0.6
di
3
di
0
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
de
de
de
2
2
2
1
1
1
1
1
0
0
.4
2.4
2
.4
.2
.0
.8
.6
.4
.2
.0
.8
.6
.4
.2
.0
.8
.6
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
2
2
1
1
1
1.2
1.0
0.8
0.6
C···N
.2%
O···Mn
1.6% di
Mn···N
1.4% di
1
di
0
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
de
de
de
2
2
2
1
1
1
1
1
0
0
.4
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
2.4
2.2
.2
.0
.8
.6
.4
.2
.0
.8
.6
2
1
1
1
1
1
0
0
.0
.8
.6
.4
.2
.0
.8
.6
C···C
.7%
C···O
0.8%
Mn···Cl
7
di
di
1.3% di
0
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
de
de
de
2
2
2
1
1
1
1
1
0
0
.4
.2
.0
.8
.6
.4
.2
.0
.8
.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
2
2
.4
.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
Mn···H
Cl···N
0.6%
O···Cl
0.4%
0.7%
di
di
di
0
.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Fig. 7. 2D Hirshfeld fingerprint images of ENMB-Mn complex for all elements

2
220 Kavitha et al.
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that focus of scattered points in the 2-D fingerprint plot is H···H
interaction. These graphs indicates the involvements of selected
some intermolecular contacts to the Hirshfeld surfaces. The
all interactions in percentage for ENMB-Mn complex showing
H···H, C···H, O···H, H···Cl, N···H, C···N, O···Mn, Mn···N, C···C,
C···O, Mn···Cl, Mn···H, Cl···N and O···Cl are 100, 40,
1
1
1
0
6.5,10.5,13.5, 3.5, 1.2, 1.6, 1.4 , 7.7 ,0.8, 1.3, 0.7, 0.6 and
.4, respectively.
1
1
1
Conclusion
In the present study, novel ENMB-Mn complex of the
ligand, dichlorodi(E)-N′-(4-methoxybenzylidene)benzohydr-
azide (ENMB) with Mn(II)ion was synthesized. The molecular
structures of ligand and manganese complex were confirmed
by spectroscopic techniques. The single crystal XRD analysis
of ENMB-Mn indicates that crystal structure is to be triclinic
with space group P-1, the structure is complete octahedral geo-
metry and the ratio of manganese(II) ion, ENMB and chlorine
ratio is 1:2:2, respectively. Thermal behaviour of ENMB-Mn
shows that the crystal can withstand at high temperature.
Hirshfeld surface study clearly supports the maximum crystal
voids are present since packing density is half than total volume
of unit cell of title crystal compound, which is helpful for charge
transfer and it will be used as a non-linear optical materials.
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CONFLICT OF INTEREST
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The authors declare that there is no conflict of interests
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