Synthesis, Single Crystal X-ray Structure Analysis and Computational Electronic Structure Investigations of 2-amino-7,7-dimethyl-4-(4-(methylthio)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile

Article abstract of DOI:10.1007/s10870-019-00778-5

A clean, efficient and mild method is presented for one-pot three-component synthesis of 2-amino-7,7-dimethyl-4-(4-(methylthio)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile using nickel ferrite magnetic nanoparticles as a recyclable catalyst in green solvent at 40?°C. The structure of the target product was confirmed by FT-IR, ¹HNMR, ¹³CNMR and single crystal X-ray structure analysis. In the present work, the quantum theoretical calculations of the molecular structure of this new compound have been predicted using Density Functional Theory in the solvent DMSO. The geometries of the title compound were optimized by B3LYP/6-31+G* and B3LYP/6-311++G** levels of theory. The electronic spectrum of the title compound in the solvent DMSO was carried out by TDB3LYP/6-311++G** method. Frontier molecular orbitals, molecular electrostatic potential, electronic properties, natural charges and natural bond orbital analysis of the mentioned compound were investigated and discussed by theoretical calculations. Graphical Abstract: [Figure not available: see fulltext.] In the present work, the frontier molecular orbitals, molecular electrostatic potential, electronic properties, natural charges and Natural Bond Orbital (NBO) analysis of the mentioned compound were investigated and discussed by theoretical calculations.

Full text of DOI:10.1007/s10870-019-00778-5

Journal of Chemical Crystallography
https://doi.org/10.1007/s10870-019-00778-5
ORIGINAL PAPER
Synthesis, Single Crystal X-ray Structure Analysis and Computational
Electronic Structure Investigations of 2-amino-7,7-dimethyl-4-(4-
(methylthio)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-
carbonitrile
Ali Ramazani1,2 · Hamideh Ahankar3 · Katarzyna Ślepokura4 · Tadeusz Lis4 · Pegah Azimzadeh Asiabi1 ·
Masoome Sheikhi5 · Farideh Gouranlou6 · Hooriye Yahyaei7
Received: 10 November 2017 / Accepted: 23 March 2019
© Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract
A clean, efcient and mild method is presented for one-pot three-component synthesis of 2-amino-7,7-dimethyl-4-(4-
(methylthio)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile using nickel ferrite magnetic nanoparticles as a
recyclable catalyst in green solvent at 40 °C. The structure of the target product was confrmed by FT-IR, 1HNMR, 13CNMR
and single crystal X-ray structure analysis. In the present work, the quantum theoretical calculations of the molecular structure
of this new compound have been predicted using Density Functional Theory in the solvent DMSO. The geometries of the
title compound were optimized by B3LYP/6-31+G* and B3LYP/6-311++G** levels of theory. The electronic spectrum of
the title compound in the solvent DMSO was carried out by TDB3LYP/6-311++G** method. Frontier molecular orbitals,
molecular electrostatic potential, electronic properties, natural charges and natural bond orbital analysis of the mentioned
compound were investigated and discussed by theoretical calculations.
Graphical Abstract
In the present work, the frontier molecular orbitals, molecular electrostatic potential, electronic properties, natural charges and
Natural Bond Orbital (NBO) analysis of the mentioned compound were investigated and discussed by theoretical calculations.
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s10870-019-00778-5) contains
supplementary material, which is available to authorized users.
Extended author information available on the last page of the article
Vol.:(0123456789)
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Journal of Chemical Crystallography
Keywords 4H-chromene · X-ray single crystal · Nickel ferrite · Magnetic nanoparticles · Green solvent
this study we report an efcient and mild method for the syn-
thesis of 2-amino-7,7-dimethyl-4-(4-(methylthio)phenyl)-
5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile in the
presence of nickel ferrite magnetic nanoparticles (NiFe2O4
MNPs) in a green solvent at 40 °C (Scheme 1).
Introduction
One of the most important of the class of polycyclic organic
compounds is benzopyran, which has two isomers that are
named 1-benzopyran (chromene) and 2-benzopyran (isoch-
romene). Some structural frameworks containing the ben-
zopyran nucleus with biological and pharmaceutical proper-
ties are chromane, 2H-chromene and specially 4H-chromene
(Fig. 1) [1].
In recent years, with the advances of quantum chemistry
and development of fast computers, a new branch in chem-
istry has emerged, called computational chemistry. One of
computational chemistry’s main purpose is to create a com-
puter program to calculate molecules properties including
total energy, dipole moments, vibration frequencies and
other known molecule properties. It can also be used in
nuclear magnetic spectrometry.
Diferent chromenes, such as vitamin E [2], cromakalim
[3], conrauinone A [4], uvafzlelin [5] and erysenegalensein
C [6], are marvelous class of compounds that are found in
plenty of pharmaceuticals and active natural products. In
addition, substituted chromenes have been known as inter-
esting heterocyclic compounds with attractive pharmaco-
logical and biological properties as, e.g., anti-oxidant [2],
anti-microbial and anti-fungal [7], anti-HIV [8], anti-tumor
[9], anti-coagulant [10], anti-infammatory [11], and diuretic
[12] agents. Plus, some drugs with chromene moiety have
been utilized for medical treatment of neurodegenerative
diseases such as Alzheimer’s, Down’s syndrome and Par-
kinson’s disease [13]. Moreover, compounds with chromene
moiety are mostly employed in the arena of cosmetic and
pigments industries [14].
Theoretical quantum chemistry methods is an important
area in determining the mechanisms of chemical reactions
[27], especially catalysis [28], and structural determination
of organic compounds [29]. Also, this method used for the
prediction of spectroscopic data such as 1H NMR and 13
C
NMR chemical shifts [30], FT-IR, UV/Vis, and properties
calculation of organic molecules [31].
In this research, we report the results of density functional
theory (DFT) calculations to investigate absorption spec-
trum, UV/Vis, frontier molecular orbitals (FMO), molecu-
lar electrostatic potential (MEP), and natural bond orbital
(NBO) of the new compound 2-amino-7,7-dimethyl-4-(4-
(methylthio)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-
3-carbonitrile. UV/Vis computations of new compound in
the ground state were calculated by TD-DFT in a solvent
DMSO.
Organic compounds containing sulfur are very numer-
ous in the nature and often play an important role in various
biochemical processes. The synthesis of a variety of sulfur-
containing compounds have been investigated [15–22]. As
part of our ongoing program to use of ferrite magnetic nano-
particles in multi-component reactions (MCRs) [23–26], in
Results and Discussion
Fig. 1 Structure of
4H-chromene
The synthesis of 2-amino-7,7-dimethyl-4-(4-(methylthio)
phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbon-
itrile in the presence of prepared NiFe2O4 MNPs [23] in a
O
Scheme 1 Synthesis of
2-amino-7,7-dimethyl-
4-(4-(methylthio)phenyl)-
5-oxo-5,6,7,8-tetrahydro-
4H-chromene-3-carbonitrile
1 3

Journal of Chemical Crystallography
green solvent at 40 °C was tested (Scheme 1). The proposed
mechanism for the synthesis of 2-amino-7,7-dimethyl-4-(4-
(methylthio)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-
3-carbonitrile is shown in Scheme 2. First, Knoevenagel
reaction in the presence of NiFe2O4 MNPs, then, Michael
addition and at the end, an intra-molecular cyclization of
intermediate cause the target product.
The structure of the product was confrmed by 1H NMR,
13C NMR, and FT-IR spectroscopy. Melting points was
also measured. Finally, single-crystal X-ray analysis of the
product conclusively confrmed its structure (Fig. 2). The
crystal of 2-amino-7,7-dimethyl-4-(4-(methylthio)phenyl)-
5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile was
found to be isomorphous with the 4-(3-(trifuoro)phenyl)
[32] and 4-(3,4-methylenedioxylphenyl) [33, 34] deriva-
tives deposited at the CSD (Ver. 5.37, Feb. 2016) [35]
with the refcodes MEWNAF and XOXZIT, XOXZIT01,
XOXZIT02, respectively. Therefore, the molecular geometry
of the title compound, as well as the packing of its crystal
are very close to previously reported. The fused cyclohex-
ene and pyran rings in 5,6,7,8-tetrahydro-4H-chromene
moiety adopt envelope puckering (Cremer&Pople param-
eters [36] Q = 0.465(2) Å, θ = 124.0(2)°, Φ = 351.0(3)°)
Fig. 2 X-ray structure of 2-amino-7,7-dimethyl-4-(4-(methylthio)
phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile show-
ing the atom-numbering scheme. The S enantiomer is shown. Dis-
placement ellipsoids are drawn at the 50% probability level
Scheme 2 The proposed mechanism for the synthesis of target product
1 3

Journal of Chemical Crystallography
and almost planar conformation (nearest puckering: skew;
Q=0.168(2) Å, θ=105.9(5)°, Φ=351.0(6)°). In the crystal
lattice, molecular dimers are formed by the use of two cen-
trosymmetric N–H⋯N interactions. Inter-dimeric N–H⋯O
contacts provide further stabilization of the crystal and give
rise to corrugated layers parallel to the (100) plane, as shown
in Fig. 3. The methylthio groups are pointed towards the
interlayer space.
GaussView 05 program [43]. Also the electronic structure of
the title compound were studied by NBO analysis [42] using
B3LYP/6-311++G** level of theory in order to understand
hyperconjugative interactions and charge delocalization.
Optimized Structure of the Title Compound
We carried out the DFT calculations for the title compound
by B3LYP/6-31+G* and B3LYP/6-311++G** levels of
theory in a solvent DMSO. The optimized molecular struc-
ture of the title compound is shown in Fig. 4. The quantum
calculations were performed using the Gaussian 09 software
package and GaussView 05 visualization programs on a Pen-
tium IV/4.02 GHz personal computer. The integral equa-
tion formalism PCM (IEFPCM) coupled to UAKS radii is
a method that was used to calculate the solvent (DMSO)
efect. The IEFPCM, by Cances, Mennucci and Tomasi
is the most popular PCM version. It employs a molecule
shaped cavity composed of spheres centered on the nuclei,
while the reaction feld is modeled by placing charges on
the cavity surface. The selected experimental and calculated
geometrical parameters such as bond lengths (Å) and bond
angles (°) of the investigated structure have been obtained by
B3LYP/6-31+G* and B3LYP/6-311++G** levels of theory
and they are listed in Table 1.
Computational Methods
In this work, we have carried out quantum calculations and
have optimized structure of the title compound using the
DFT method with 6-31+G* and 6-311++G** basis sets
by the Gaussian 09W program package [41] on a Pentium
IV/4.28 GHz personal computer. We were also used from
the Time Dependent Density Functional Theory (TD-DFT)
for calculation of the electronic transitions of the title com-
pound. The Polarized Continuum Model (PCM) [42] was
used for calculations of solvent efect. Theoretical absorption
spectrum of the structure in a solvent DMSO was calculated
using the TD-DFT method. The electronic properties such
as EHOMO, ELUMO, energy gap between HOMO and LUMO,
dipole moment (µD), point group and natural charge of the
title structure were calculated [30]. The optimized molecular
structure, HOMO and LUMO surfaces were visualized by
Fig. 3 Hydrogen bonds (dashed
lines) in the crystal of 2-amino-
7,7-dimethyl-4-(4-(methylthio)
phenyl)-5-oxo-5,6,7,8-tetrahy-
dro-4H-chromene-3-carboni-
trile: centrosymmetric molecu-
lar dimers formed by the use
of two N–H⋯N interactions,
and the inter-dimeric N–H⋯O
contacts. Geometry of H-bonds
(D–H/Å, H⋯A/Å, D⋯A/Å,
D–H⋯A/º) for N1–H1N⋯O2i:
0.81(2), 2.09(2), 2.9031(19),
178(2); for N1–H2N⋯N2ii:
0.86(3), 2.15(3), 3.008(2),
177(2). Symmetry codes: (i) x,
−y+1, z−1/2; (ii)−x, −y, −z
1 3

Journal of Chemical Crystallography
Table 1 Selected optimized geometrical parameters [Bond lengths
(Å) and Bond angles (°)] of the title compound calculated by
B3LYP/6-31+G* and B3LYP/6-311++G** methods
Parameter
Experimental Calculated
B3LYP/6-31+G* B3LYP/6-
311++G**
Bond lengths (Å)
C1–C2
C1–C6
C2–C3
C3–C4
C4–C5
C5–C6
C4–O7
O7–C8
C8–C9
C5–C10
C9–C10
C2–C20
C2–C21
C6–O18
C8–N19
C9–C23
C23–N24
C10–C11
C11–C12
C11–C16
C12–C13
C13–C14
C14–C15
C15–C16
C14–S17
1.538 (2)
1.506 (2)
1.532 (2)
1.490 (2)
1.338 (2)
1.469 (2)
1.376 (18)
1.371 (17)
1.364 (2)
1.501(2)
1.519 (2)
1.534 (2)
1.528 (2)
1.227 (18)
1.332 (2)
1.414 (2)
1.150 (2)
1.525 (2)
1.393 (2)
1.391(19)
1.386 (2)
1.401 (19)
1.393 (2)
1.395 (2)
1.763 (16)
1.7974 (17)
1.545
1.519
1.547
1.497
1.351
1.473
1.374
1.366
1.367
1.516
1.528
1.538
1.543
1.234
1.359
1.412
1.170
1.533
1.401
1.399
1.394
1.405
1.402
1.397
1.785
1.824
1.543
1.516
1.545
1.495
1.346
1.472
1.373
1.364
1.363
1.514
1.526
1.536
1.541
1.226
1.354
1.408
1.161
1.531
1.398
1.396
1.390
1.401
1.399
1.394
1.784
1.822
Fig. 4 Optimized molecular structures of the title compound
From the Table 1, it has been observed that the calculated
parameters show good approximation and can be used as
a foundation to calculate the other parameters for the title
compound. As can be seen from Table 1, the average difer-
ences of the theoretical parameters from the experimental
for bond lengths of the title compound were found to be
low. We found that most of the calculated bond lengths are
slightly longer than X-ray values that it is due to the fact that
experimental result corresponds to interacting molecules
in the crystal lattice, whereas computational method deals
with an isolated molecule in solvent phase [44]. The calcu-
lated C14–S17 bond length by 6-31+G* and 6-311++G**
basis sets is 1.785 Å and 1.784 Å respectively, which are
in good agreement with experimental value (1.763 Å). The
calculated C8–N19 bond length in NO2 group by 6-31+G*
and 6-311++G** basis sets is 1.359 Å and 1.354 Å respec-
tively and the experimental value is 1.332 Å, whereas the
experimental C23–N24 bond length is 1.150 Å and the cal-
culated values are 1.170 Å (by 6-31+G*) and 1.161 Å (by
6-311++G**). The C23–N24 bond length is shorter than the
C8–N19 bond length that it is due to the C23–N24 bond is
partly a triple bond, whereas the C8–N19 bond is doublet.
The C13–C14–S17–C22 dihedral angle in the X-ray struc-
ture is 171.00° and the calculated bond angle by 6-31+G*
and 6-311++G** basis sets is − 179.67° and − 179.76°
respectively, therefore S–CH3 group in the title compound
with phenyl ring is in one plan.
S17–C22
Bond angles (°)
C1–C2–C3
C3–C4–C5
C3–C4–O7
C4–C5–C6
C4–O7–C8
O7–C8–C9
C5–C6–O18
O7–C8–N19
C9–C8–N19
C9–C10–C11
C8–C9–C23
C9–C23–N24
C11–C12–C13
C13–C14–C15
C13–C14–S17
C15–C14–S17
C14–S17–C22
C20–C2–C21
108.28 (12)
125.64 (13)
111.11 (12)
118.74 (13)
118.62 (12)
121.17 (13)
119.68 (14)
110.74 (13)
128.09 (14)
109.70 (12)
119.22 (13)
177.33 (15)
121.56 (13)
118.91 (13)
116.20 (12)
124.85 (11)
103.65 (8)
108.19
126.19
111.45
118.40
119.68
121.77
120.93
110.39
127.80
111.69
118.92
179.09
121.25
118.74
116.88
124.36
104.06
109.05
108.21
126.15
111.47
118.59
119.66
121.78
120.96
110.45
127.74
111.70
118.99
179.23
121.23
118.83
116.87
124.29
104.01
109.13
109.27 (12)
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Journal of Chemical Crystallography
Table 1 (continued)
(Table 2). The calculated electronic absorption spectrum
(UV/Vis) of the title compound in a solvent (DMSO) is
observed in Fig. S4 in Supplementary Information.
Parameter
Experimental Calculated
B3LYP/6-31+G* B3LYP/6-
311++G**
115.86
H34–N19–H35
Torsion angels (°)
C4–C5–C6–O18
C10–C5–C6–O18
C4–O7–C8–C9
C4–O7–C8–N19
C6–C5–C10–C11
N19–C8–C9–C23
C5–C10–C11–C16 −40.73 (19)
C9–C10–C11–C12 −92.78 (16)
C13–C14–S17–C22 171.00 (12) −179.67
C15–C14–S17–C22 −6.70 (15) 0.43
114.83
FMO Analysis of the Title Compound
178.77 (13) −173.17
−172.79
5.97
7.81
−173.69
71.31
6.30
51.11
106.28
−179.76
0.36
The FMO analysis plays an signifcant role in the electronic
and optical properties, as well as in UV/Vis spectrum and
chemical reactions [42]. FMO analysis was done for the
title compound by B3LYP/6-311++G** level of theory.
The FMO results of the title compound are summarized in
Table 3.
0.82 (19)
−6.58 (19)
5.83
7.56
173.52 (12) −174.33
−74.13 (16)
−0.8 (2)
71.15
6.48
51.96
107.17
The HOMO and LUMO orbitals act as electron donor
and electron acceptor, respectively. As can be seen from
Table 3, the energy values of the HOMO and LUMO of the
title compound is − 5.96 eV and − 1.92 eV, respectively.
Total electronic densities of states (DOSs) [45] of the title
compound were computed (Fig. 6). The DOS analysis indi-
cates that the energy gap between LUMO and HOMO of the
title compound is about 4.04 eV.
Electronic Structure and Excited States
of the Title Compound
A detail of quantum molecular descriptors of the title
compound consist of ionization potential (I = − EHOMO),
electron afnity (A=−ELUMO), global hardness (η=I−A/2),
electronegativity (χ=I+A/2), electronic chemical potential
[µ=−(I+A)/2], electrophilicity (ω=µ2/2η) [30] and chemi-
cal softness (S=1/η) [42] are calculated and are reported in
Table 3. The energy of HOMO is directly related to the ioni-
zation potential (I), while the energy of LUMO is related to
the electron afnity (A). The global hardness (η) corresponds
to the energy gap between LUMO and HOMO. Electronega-
tivity (χ) is a measure of the power of an atom or a group
of atoms to attract electrons and the chemical softness (S)
describes the capacity of an atom or a group of atoms to
receive electrons [42].
We used the TD-DFT for predicting the absorption spectra
of the title compound. The theoretical absorption spectrum
of the optimized compound were calculated in a solvent
DMSO by TDB3LYP/6-311++G** method. 20 excited
states considered for the calculation equations that were per-
formed using the IEFPCM method coupled to UAKS radii.
The exact amount of the maximum absorption wavelength
(λmax) to the title compound is obtained using the TD-DFT
method.
20 excited states and wavelengths of electronic absorption
spectrum of the title compound is reported in Table 2. As
can be seen, the strong absorption at λmax =226 nm and the
oscillator strength f=0.18 is due to charge transfer of elec-
tron into the excited state S0→S16 with wave function includ-
ing nine confgurations [(H-1→L), (H-1→L), (H-1→L),
(H→L + 1), (H→L + 2), (H→L + 3), (H-1→L + 4),
(H→L + 6), (H→L + 8)]. The transition from HOMO to
LUMO + 3 (H→L + 3) is main responsible for formation
maximum wavelength at 226 nm (Table 2). Figure 5 shows
shape molecular orbitals participants at λmax = 226 nm.
According to Fig. 2, the electron density of the HOMO is
mainly focused on –C=C– in phenyl ring, the sulfur atom
and methyl group (in S–CH3 group), whereas the LUMO is
mainly focused on –NH2, –CN, –C=O groups. Therefore
the electronic transition from the HOMO to LUMO+3 is
mainly due to the contribution of pi (π) bonds. The other
important excited state is S0→S5 at 266 nm (f=0.17) with
two confgurations for electronic excitations [(H-4→L),
(H-1→L + 1), (H→L + 1), (H→L + 2)]. The other excited
states of the title compound have very small intensity (f≈0)
that is nearly forbidden by orbital symmetry considerations
The dipole moment parameter is used for investigation of
intermolecular interactions and study of asymmetric nature
of compounds [30]. The high amounts of dipole moment
lead to stronger intermolecular interaction [46]. As can be
seen from Table 5, dipole moment value of the title com-
pound is about 12.1621 Debye. The value of the dipole
moment is related to the composition and dimensionality of
the 3D compounds. The point group of the title compounds
is C1, which refers to their high asymmetry. When the atoms
in compound are irregularly arranged leads to the increasing
dipole moment.
MEP of the Title Compound
MEP maps show the electronic density in the molecules.
The MEP maps are also used to identify sites of negative
and positive electrostatic potentials for electrophilic attack
1 3

Journal of Chemical Crystallography
Table 2 Electronic absorption spectrum of the title compound calculated by TDB3LYP/6-311++G**
Excited State Wave-
Excitation Confgurations composition (corresponding transition orbitals)
Oscillator
length
(nm)
energy
(eV)
strength (f)
S1
S2
S3
S4
S5
S6
S7
S8
355
323
315
277
266
261
255
250
3.48
3.83
3.93
4.47
4.65
4.73
4.86
4.94
0.68(H→L)
0.68(H-1→L)
0.05
0.02
0.00
0.05
0.17
0.08
0.05
0.08
−0.13(H-4→L)+0.41(H-3→L)+0.49(H-2→L)+0.10(H-1→L) −0.13(H→L)
−0.10(H-2→L)+0.52(H→L+1) −0.40(H→L+2)
0.10(H-4→L)+0.10(H-1→L+1) −0.41(H→L+1)+0.52(H→L+2)
−0.21(H-4→L)+0.44(H-3→L) −0.43(H-2→L)+0.14(H-1→L+1) −0.17(H→L+1)
0.51(H-4→L)+0.12(H-3→L)+0.42(H-1→L+1) −0.15(H→L+2)
0.21(H-4→L) −0.29(H-1→L+1)+0.14(H-
1→L+2)+0.36(H→L+3)+0.30(H→L+4)+0.26(H→L+5)
S9
249
4.96
−0.29(H-4→L)+0.33(H-1→L+1) −0.27(H-1→L+2) −0.24(H→L+3)+0.32(H→L+4 0.02
)+0.12(H→L+5)
S10
S11
247
244
5.01
5.08
−0.14(H-4→L)+0.27(H-1→L+1) −0.41(H-1→L+2)+0.43(H→L+3)
0.06
−0.22(H-1→L+2)+0.12(H-1→L+4) −0.10(H-1→L+8)+0.45(H→L+4) −0.30(H→L 0.00
+5)+0.11(H→L+6)+0.25(H→L+7) −0.11(H→L+9)
S12
S13
S14
S15
S16
241
234
233
229
226
5.13
5.29
5.30
5.41
5.48
−0.14(H-4→L) −0.12(H-3→L)+0.16(H-1→L+1)+0.33(H-1→L+2) −0.31(H-
1→L+3)+0.27(H-1→L+8)+0.16(H→L+3)+0.20(H→L+4)+0.16(H→L+8)
0.06
0.00
0.06
0.26(H-1→L+3) −0.32(H-1→L+4) −0.15(H-1→L+6)+0.17(H-
1→L+8)+0.12(H→L+5)+0.41(H→L+7)+0.15(H→L+8)+0.11(H→L+10)
0.11(H-4→L) −0.16(H-1→L+1) −0.29(H-1→L+2)+0.13(H-1→L+4)+0.41(H-
1→L+8) −0.12(H→L+7)+0.30(H→L+8)
−0.25(H-1→L+3)+0.25(H-1→L+4)+0.12(H-1→L+6) −0.24(H→L+4)+0.18(H→L 0.00
+5)+0.26(H→L+6)+0.33(H→L+7)+0.20(H→L+10)
0.23(H-1→L) −0.35(H-1→L) −0.11(H-
0.18
1→L)+0.13(H→L+1)+0.28(H→L+2)+0.43(H→L+3)+0.22(H-
1→L+4)+0.12(H→L+6)+0.10(H→L+8)
S17
S18
223
222
5.53
5.56
−0.15(H-5→L) −0.34(H-1→L+4)+0.54(H→L+6) −0.14(H→L+7)+0.10(H→L+9)
0.00
0.05
0.57(H-5→L)+0.10(H-3→L+1)+0.13(H-2→L+1)+0.12(H-2→L+2) −0.16(H-
1→L+3) −0.15(H-1→L+4)
S19
S20
220
219
5.62
5.65
−0.19(H-5→L)+0.16(H-3→L+1)+0.59(H-2→L+1)+0.13(H-
2→L+2)+0.11(H→L+8)
0.03
−0.19(H-1→L+8) −0.15(H→L+5) −0.12(H→L+6)+0.29(H→L+8)+0.46(H→L+9) 0.00
+0.17(H→L+10) −0.14(H→L+13)
H HOMO, L LUMO
and nucleophilic reactions. The diference of the electro-
static potential at the surfaces is represented by diferent
colors. The negative regions of MEP with red, orange and
yellow color have the high electron density, while the posi-
tive regions with blue color have the low electron density.
Also, the green color is shown neutral regions. The MEPs
of the title compound was obtained by theoretical calcula-
tions (Fig. 7).
regions with green color of the title compound indicate
areas with zero potential (neutral sites).
Natural Charge Analysis of the Title
Compound
We calculated the charge distributions for equilibrium geom-
etry of the investigated compound by the NBO (natural
charge) charges [30] using B3LYP/6-31+G* and B3LYP/6-
311++G** levels of theory. The calculated natural charges
are listed in Table 4 (Atoms labeling is according to Fig. 7).
The total charge of the investigated compound is equal
to zero. Also, Fig. 7 shows results of natural charges
in graphical form. The results of natural charge (NBO)
As shown in Fig. 7, the negative regions (red color) of
the title compound are mainly focused on O18 atom, N24
atom and phenyl ring. Therefore, these regions are suit-
able for electrophilic attack. According to MEP map, the
hydrogen atoms are the positive potential sites (blue color)
and the most positive potential is mainly focused on H34
atom, therefore it is suitable for nucleophilic attack. The
1 3

Journal of Chemical Crystallography
Fig. 5 Form of the MO participant in formation of absorption spectrum of the title compound at λmax =226 nm calculated by B3LYP/6-
311+G** method
analysis show that carbon atoms have both positive and
negative charges values. According to results, the positive
carbons are observed for the carbons atoms attachment to
the electron-withdrawing nitrogen and oxygen atoms. The
C4, C6, C8, C10, C23 atoms have the positive charge and
the other carbon atoms have negative charge. The oxy-
gen and nitrogen atoms have negative charge. The highest
positive charge of the compound is observed for C8 atom
(0.583e by 6-31+G* and 0.579e by 6-311++G**) due
to attachment to the electron-withdrawing O7 and N19
atoms. The C22 atom in the S–CH3 group has the high-
est negative charge (− 0.840e by 6-31+G* and − 0.706e
by 6-311++G**) rather than the other carbon atoms due
to hyperconjugation efect. According to Natural charge’s
plot (Fig. S5 in Supplementary Information), all hydrogen
atoms have the positive charge. The H34 and H35 atoms of
Table 3 Electronic properties of the title compound calculated by
B3LYP/6-311++G** method
Property
HOMO (eV)
ELUMO (eV)
Energy gap (eV)
B3LYP/6-
311++G**
E
−5.96
−1.92
4.04
Ionisation potential, I (eV)
Electron afnity, A (eV)
Electronegativity, χ (eV)
Global hardness, η (eV)
Chemical potential, µ (eV)
Global electrophilicity, ω (eV)
5.96
1.92
3.94
2.02
−3.94
3.84
0.49
12.1621
C1
Chemical softness, S (eV−1
Dipole moment (Debye)
Point group
)
1 3

Journal of Chemical Crystallography
Fig. 6 Calculated DOS plots of the compound
electron-withdrawing nature of the N19, therefore they
are acidic hydrogens.
NBO Analysis of the Title Compound
NBO analysis is important method for studying intra- and
inter-molecular bonding and interaction between bonds in
molecular systems [47]. Electron donor orbitals, acceptor
orbitals and the interacting stabilization energy (E(2)) result-
ing from the second-order micro disturbance theory for the
investigated compound are reported in Table 5.
The electron delocalization from flled NBOs (donor
orbitals) to the empty NBOs (acceptor orbitals) describes
a conjugative electron transfer process between them. For
each donor (i) and acceptor (j), the stabilization energy E(2)
associated with the delocalization i→j is estimated [42]:
Fig. 7 MEP map of the title compound
F(i, j)2
the NH2 group have the highest positive charge (0.459e)
rather than the other hydrogen atoms due to the
E(2) = ΔEij = qi
(1)
ꢀj − ꢀi
where qi is the donor orbital occupancy, εj and εi are diago-
nal elements and F(i,j) is the of diagonal NBO Fock matrix
1 3

Journal of Chemical Crystallography
Table 4 Natural Charges
distribution (NBO charges, e)
of the title compound using
B3LYP/6-31+G* and B3LYP/6-
311++G** methods
B3LYP/6-31+G*
B3LYP/6-311++G**
Atoms
Charge
Atoms
Charge
Atoms
Charge
Atoms
Charge
C1
C2
C3
C4
−0.533
−0.098
−0.501
0.424
C23
N24
H25
H26
H27
H28
H29
H30
H31
H32
H33
H34
H35
H36
H37
H38
H39
H40
H41
H42
H43
H44
0.310
−0.423
0.268
0.276
0.280
0.275
0.286
0.252
0.255
0.253
0.249
0.449
0.450
0.242
0.245
0.244
0.244
0.245
0.241
0.276
0.259
0.259
C1
C2
C3
C4
−0.466
−0.065
−0.433
0.422
C23
N24
H25
H26
H27
H28
H29
H30
H31
H32
H33
H34
H35
H36
H37
H38
H39
H40
H41
H42
H43
H44
0.307
−0.432
0.229
0.237
0.240
0.236
0.228
0.215
0.218
0.220
0.213
0.414
0.415
0.204
0.208
0.207
0.207
0.208
0.205
0.232
0.215
0.215
C5
C6
−0.195
0.571
C5
C6
−0.407
0.564
O7
C8
−0.499
0.583
O7
C8
−0.518
0.579
C9
−0.325
−0.268
−0.051
−0.218
−0.250
−0.201
−0.261
−0.218
0.249
−0.619
−0.835
−0.674
−0.682
−0.840
C9
−0.758
0.576
C10
C11
C12
C13
C14
C15
C16
S17
O18
N19
C20
C21
C22
C10
C11
C12
C13
C14
C15
C16
S17
O18
N19
C20
C21
C22
−0.143
−0.187
−0.223
−0.178
−0.238
−0.193
0.239
−0.619
−0.764
−0.569
−0.579
−0.706
element. The resonance energy (E(2)) detected the quantity
of participation of electrons in the resonance between atoms
of molecule [42]. The larger E(2) value, the more intensive
is the interaction between electron donors and acceptor, i.e.
the more donation tendency from electron donors to electron
acceptors and the greater the extent of conjugation of the
whole system. Delocalization of electron density between
occupied Lewis-type (bond or lone pair) NBO orbitals and
formally unoccupied (antibond or Rydberg) non Lewis NBO
orbitals correspond to a stabilization donor–acceptor inter-
action. NBO analysis has been performed for the title com-
pound by B3LYP/6-311++G** method in order to elucidate
the intramolecular, rehybridization, and delocalization of
electron density within the title compound. We reported the
highest strong intramolecular hyperconjugative interactions
of the title compound such as π→π*, π*→π*, σ→σ*, n→σ*
and n→π* transitions in Table 5. The π(C14–C15) orbital
in phenyl ring participates as donor and the anti-bonding
π*(C11–C16), π*(C12–C13) and π*(C23–N24) orbitals act
as acceptor with resonance energies (E(2)) 18.41 kcal/mol,
16.96 kcal/mol, and 109.33 kcal/mol, respectively. These val-
ues indicate π(C14–C15)→π*(C23–N24) transition has the
highest resonance energy (109.33 kcal/mol) compared with
π(C14–C15)→π*(C11–C16) and π(C12–C13)→π*(C11–C16)
transitions. The π(C12–C13)→π*(C23–N24) transition
has the highest resonance energy (156.29 kcal/mol) rather
than other π→π* transitions of the title compound. As can
be seen from Table 6, the intramolecular hyperconjuga-
tive interactions of the σ→π* transitions have the higher
resonance energy (E(2)) rather than the π→π* transitions.
The σ(C22–H42)→π*(C23–N24) transition has the highest
resonance energy (992.48 kcal/mol) rather than other σ→π*
transitions of the title compound. The σ(C6–O18) orbital
participates as donor and the anti-bonding σ*(C14–S17),
σ*(C21–H41), σ*(C22–H44) orbitals act as acceptor with
resonance energies (E(2)) of 92.42 kcal/mol, 57.50 kcal/
mol and 562.58 kcal/mol, respectively. These values indi-
cate σ(C6–O18)→σ*(C22–H44) transition has the high-
est resonance energy (562.58 kcal/mol) rather than the
σ(C6–O18)→σ*(C14–S17) and σ(C6–O18)→σ*(C21–H41)
transitions. The highest resonance energy of the title com-
pound is observed for π*(C14–C15)→π*(C23–N24)
transition in with resonance energy (E(2)) 16475.83 kcal/
mol that lead to most stability of the title compound. The
most important transitions n→π* and n→σ* is observed
for n2(O7)→π*(C8–C9) and n1(N19)→π*(C8–C9) with
resonance energies (E(2)) 30.50 kcal/mol and 44.49 kcal/
mol respectively. Also, the n2(O18)→σ*(C1–C6) and
n2(O18)→σ*(C5–C6) transitions have the highest reso-
nance energies about 17.61 kcal/mol and 17.89 kcal/mol
respectively rather than other σ→σ* transitions of the title
compound.
1 3

Journal of Chemical Crystallography
Table 5 Signifcant donor–
acceptor interactions and second
order perturbation energies of
the title compound calculated
using the B3LYP/6-311+G**
level of energy
Donor (i)
Occupancy Acceptor (j)
Occupancy E(2)a kcal/mol E(j)–E(i)b a.u. F(i, j)c a.u.
0.18223
π(C4–C5)
π(C8–C9)
π(C11–C16)
π(C12–C13)
1.83628
1.84351
1.66707
1.68333
π*(C6–O18)
22.70
104.29
21.24
20.48
156.29
18.41
16.96
109.33
852.54
412.24
3119.71
16475.83
10.82
161.60
116.50
19.22
92.42
57.50
562.58
19.97
26.93
703.62
178.92
78.43
31.87
716.90
33.59
142.02
992.48
5.32
0.31
0.09
0.29
0.28
0.05
0.29
0.30
0.06
0.52
0.77
0.39
0.07
0.50
0.31
1.17
0.94
0.18
0.44
0.06
1.03
0.72
0.08
0.09
0.55
3.54
0.35
0.86
0.54
0.35
1.20
1.15
0.39
0.37
1.19
0.99
3.22
0.03
1.09
1.16
0.67
0.73
0.88
0.31
1.06
0.075
0.086
0.070
0.069
0.085
0.066
0.064
0.077
1.260
1.102
2.140
2.051
0.067
0.204
0.334
0.123
0.117
0.141
0.161
0.129
0.125
0.207
0.113
0.186
0.300
0.466
0.152
0.249
0.542
0.071
0.068
0.094
0.098
0.060
0.065
0.048
0.10
π*(C23–N24) 0.14349
π*(C12–C13) 0.32038
π*(C11–C16) 0.02584
π*(C23–N24) 0.14349
π*(C11–C16) 0.02584
π*(C12–C13) 0.32038
π*(C23–N24) 0.14349
σ*(C14–S17) 0.03284
σ*(C21–H41) 0.00625
σ*(C22–H44) 0.00469
π*(C23–N24) 0.14349
σ*(C20–H36) 0.00615
σ*(C23–N24) 0.14349
π(C14–C15)
1.66907
π*(C14–C15) 0.41042
σ(C1–H26)
σ(C5–C10)
σ(C6–O18)
1.95369
1.83317
1.99420
σ*(C9–C10)
0.12094
σ*(C10–C11) 0.05634
σ*(C14–S17) 0.03284
σ*(C21–H41) 0.00625
σ*(C22–H44) 0.01575
σ*(C16–H33) 0.01478
σ*(C20–H36) 0.00615
σ*(C21–H41) 0.00625
σ*(C21–H41) 0.00625
σ*(C20–H36) 0.00615
σ*(C21–H39) 0.00580
σ*(C23–N24) 0.14349
σ*(C16–H33) 0.01478
σ*(C20–H36) 0.00615
σ*(C23–N24) 0.14349
σ(C11–C12)
1.96893
σ(C14–C15)
σ(S17–C22)
1.97774
1.98926
σ(C22–H42)
1.98862
n1(O7)
1.96004
1.77969
1.98126
1.85599
1.97796
1.89924
1.76465
1.97087
σ*(C4–C5)
σ*(C8–C9)
π*(C4–C5)
π*(C8–C9)
σ*(C14–C15) 0.02719
σ*(C20–H37) 0.00562
σ*(C21–H39) 0.00580
π*(C23–N24) 0.14349
σ*(C1–C6)
σ*(C5–C6)
σ*(C1–C6)
σ*(C5–C6)
σ*(C8–C9)
π*(C8–C9)
σ*(C9–C23)
0.03145
0.03012
0.18247
0.34016
5.10
n2(O7)
27.80
30.50
3.79
5.31
0.84
n1(S17)
n2(S17)
n1(O18)
n2(O18)
n1(N19)
n1(N24)
3.42
1.93
1.67
17.61
17.89
0.82
44.49
10.63
0.05531
0.06540
0.05531
0.06540
0.03012
0.34016
0.02941
0.041
0.041
0.098
0.103
0.025
0.108
0.095
aE(2) Energy of hyperconjucative interactions
bEnergy diference between donor and acceptor i and j NBO orbitals
cF(i, j) Is the Fock matrix element between i and j NBO orbitals
1 3

Journal of Chemical Crystallography
Table 6 Calculated NBO and the polarization coefcient for each hybrid in selected bonds of the title compound using the B3LYP/6-311++G**
level of theory
Occupancy (a.u.) Bond (A–B)a Energy (a.u.) EDA (%) EDB (%) NBO
S(%) (A) S(%) (B) P(%) (A) P(%) (B)
1.96598
1.97429
1.83628
σ(C1–C2)
σ(C4–C5)
π(C4–C5)
−0.60386
−0.77641
−0.30223
49.88
49.78
43.96
50.12
50.22
56.04
0.7063 (sp2.39)+0.7080 (sp3.70
0.7055 (sp1.41)+0.7087 (sp1.72
0.6630 (sp1.00)+0.7786
)
)
29.52
41.52
0.00
24.54
36.73
0.04
70.44
58.45
99.90
75.41
63.22
99.89
(sp99.99
)
1.98775
1.99420
1.97373
σ(C4–O7)
σ(C6–O18) −1.09043
π(C6–O18) −0.38549
−0.94006
30.46
34.56
30.65
69.54
65.44
69.35
0.5519 (sp3.38)+0.8339 (sp1.93
0.5879 (sp2.28)+0.8089 (sp1.35
0.5536 (sp99.99)+0.8328
)
)
22.75
30.39
0.02
34.09
42.46
0.02
77.00
69.44
99.55
65.85
57.43
99.87
(sp99.99
)
1.98587
1.98502
1.89568
1.96893
1.97984
1.98926
1.97472
1.99243
1.97462
1.95369
1.98276
1.98216
1.97792
1.98862
1.96004
1.77969
1.98126
1.85599
1.97796
1.89924
1.76465
1.97087
σ(O7–C8)
−0.93825
68.37
40.83
46.17
50.47
53.65
48.91
52.07
42.60
41.82
61.47
70.86
70.74
60.84
61.64
–
–
–
–
–
–
–
–
31.63
59.17
53.83
49.53
46.35
51.09
47.93
57.40
58.18
38.53
29.14
29.26
39.16
38.36
–
–
–
–
–
–
–
–
0.8269 (sp2.18)+0.5624 (sp3.15
0.6390 (sp2.17)+0.7692 (sp1.66
0.6795 (sp2.79)+0.7337 (sp2.26
0.7104 (sp1.89)+0.7038 (sp1.77
0.7325 (sp2.92)+0.6808 (sp4.49
0.6994 (sp5.03)+0.7148 (sp3.48
0.7216 (sp2.85)+0.6923 (sp2.31
0.6527 (sp1.12)+0.7576 (sp1.12
0.6467 (sp1.00)+0.7627 (sp1.00
0.7840 (sp3.69)+0.6207 (s)
0.8418 (sp2.62)+0.5398 (s)
0.8411 (sp2.54)+0.5409 (s)
0.7800 (sp2.54)+0.6258 (s)
0.7851 (sp3.00)+0.6193 (s)
sp1.92
)
)
)
)
)
)
)
)
)
31.41
31.54
26.33
34.59
25.50
16.50
25.97
47.17
0.00
21.29
27.58
28.21
28.21
24.97
34.23
0.25
24.01
37.51
30.62
36.12
18.11
22.30
30.22
47.01
0.00
99.97
99.93
99.92
99.95
99.96
–
–
–
–
–
–
–
–
68.52
68.38
73.52
65.37
74.36
82.95
73.99
52.81
99.91
78.64
72.37
71.74
71.74
74.96
65.73
99.70
34.06
99.97
42.47
99.94
93.35
46.95
75.74
62.42
69.36
63.84
81.28
77.52
69.75
52.63
σ(C8–N19) −0.87377
σ(C10–C11) −0.54672
σ(C11–C12) −0.73061
σ(C14–S17) −0.65693
σ(S17–C22) −0.56433
σ(C2–C20) −0.60350
σ(C23–N24) −1.06669
σ(C23–N24) −0.35259
σ(C1–H26) −0.51647
σ(N19–H34) −0.67544
σ(N19–H35) −0.68052
σ(C12–H30) −0.51726
σ(C22–H42) −0.55653
99.70
–
–
–
–
–
–
–
–
–
–
–
–
–
n1(O7)
n2(O7)
−0.57894
−0.36830
−0.63186
−0.24453
−0.70231
−0.27804
−0.30724
−0.52478
sp99.99
n1(S17)
n2(S17)
n1(O18)
n2(O18)
n1(N19)
n1(N24)
sp0.25
65.92
0.00
57.51
0.00
6.62
52.98
sp1.00
sp0.74
sp1.00
sp14.10
sp0.89
aA–B is the bond between atom A and atom B. (A: natural bond orbital and the polarization coefcient of atom; A–B: natural bond orbital and
the polarization coefcient of atom B)
The results of NBO analysis such as the occupation num-
bers with their energies for the interacting NBOs [interaction
between NBO A and NBO B (A–B)] and the polarization
coefcient amounts of atoms in the title compound are pre-
sented using the B3LYP/6-311++G** method is summa-
rized in Table 6 (Atoms labeling is according to Fig. 7).
The size of polarization coefcients shows the impor-
tance of the two hybrids in the formation of the bond in
molecules. The diferences in electronegativity of the atoms
involved in the bond formation are refected in the larger dif-
ferences in the polarization coefcients of the atoms (C–O,
C–N, C–S, C–H bonds) [42]. As can be seen from Table 6,
the calculated bonding orbital for the σ(C4–O7) bond is
the σ=0.5519(sp3.38)+0.8339(sp1.93) with high occupancy
1.98775 a.u. and low energy −0.94006 a.u. The polariza-
tion coefcients of C4 = 0.5519 and O7 = 0.8339 shows
importance of O7 in forming σ(C4–O7) bond compared
with C4 atom. As seen from Table 6, the calculated bond-
ing orbital for the σ(C14–S17) bond is σ=0.7325(sp2.92)+0
.6808(sp4.49) is formed from sp2.92 and sp4.49 hybrids on C14
and S17 atoms which is the mixture of s(25.50%) p(74.36%)
for C14 and s(18.11%) p(81.28%) for S17. The natural
hybrid orbital n2(O18) with high occupancy 1.89924 a.u.
and high energy − 0.27804 a.u. has p-character (99.94%).
Therefore pure p-type lone pair orbital n2(O18) partici-
pates as electron donation to σ*(C1–C6) and σ*(C5–C6)
in the n2(O18)→σ*(C1–C6) and n2(O18)→σ*(C5–C6)
interactions with resonance energies (E(2)) 17.61 kcal/mol
and 17.89 kcal/mol respectively (see Table 5). According to
NBO analysis, the natural hybrid orbital n1(N19) occupy a
high energy orbital (−0.30724 a.u), high occupation num-
ber (1.76465 a.u) and high p-character (93.35%). Therefore
1 3

Journal of Chemical Crystallography
n1(N19) participates as electron donation to π*(C8–C9) in
the n1(N19)→π*(C8–C9) interaction with high resonance
energy (E(2)) 44.49 kcal/mol in the title compound (see
Table 5).
X-ray Crystallography
After recrystallization, pure solid of the title compound was
dissolved in hot ethanol. X-ray crystals of desired product
were obtained in excellent yield after evaporation of part of
solvent at room temperature.
Experimental
The crystallographic measurement was performed on an
Xcalibur R κ-geometry automated four-circle difractometer
equipped with a CCD camera Ruby and graphite-monochro-
matized MoKα radiation (λ=0.71073 Å). The data were col-
lected at 80(2) K by using the Oxford-Cryosystems cooler.
Data were corrected for Lorentz and polarization efects.
Data collection, cell refnement, data reduction and analy-
sis, and empirical (multi-scan) absorption correction were
carried out with Xcalibur R software, CrysAlisPro [37]. As
the title crystal is isomorphous with the crystals of 4-(3-(tri-
fuoro)phenyl) [32] and 4-(3,4-methylenedioxylphenyl) [33,
34] derivatives (CSD refcodes MEWNAF and XOXZIT,
XOXZIT01, XOXZIT02, respectively) [35], the refnement
of its structure was started by using the coordinates of non-H
atoms (except one O) taken from XOXZIT. The structure
was refned by a full-matrix least-squares technique with
SHELXL2014 [38] and anisotropic thermal parameters for
non-H atoms. All H atoms were found in diference Fourier
maps and were refned isotropically. In the fnal refnement
cycles, the C-bonded H atoms were repositioned in their
calculated positions and refned using a riding model, with
C–H = 0.95–1.00 Å, and with Uiso(H) = 1.2Ueq(C) for CH
and CH2 groups, or 1.5Ueq(C) for CH3. Amine H atoms were
refned freely. Figures were made with the DIAMOND pro-
gram [39]. Cremer–Pople puckering parameters were calcu-
lated using the PLATON program [40] Details of the condi-
tions for the data collection and the structures refnements
are given in Table 7 and the crystallographic information
fle (CIF) deposited with The Cambridge Crystallographic
Data Centre (http://www.ccdc.cam.ac.uk/; deposition
number CCDC-1564673) and provided as Supplementary
Information.
General
Starting materials were obtained from sigma-Aldrich,
Merck, and Fluka were used without further purifcation.
The method used to follow the reactions was TLC with UV
light. Melting points were measured on an Electrothermal
9100 apparatus (LABEQUIP LTD., Markham, Ontario, Can-
ada). 1H and 13C NMR (DMSO-d6) spectra were recorded
on a Bruker DRX-250 Avance spectrometer at 250.13 and
62.90 MHz, respectively. FT-IR spectrum was measured on
a Jasco 6300 FT-IR spectrometer.
Representative Procedure for Synthesis of 2-amino-7,7-di-
methyl-4-(4-(methylthio) phenyl)-5-oxo-5,6,7,8-tetrahy-
dro-4H-chromene-3-carbonitrile
A solution of 4-(methylthio) benzaldehyde (152 mg,
1 mmol), dimedone (140 mg, 1 mmol), malononitril (66 mg,
1 mmol) and ethanol (2 ml) was magnetically stirred at room
temperature. To the mixture, prepared NiFe2O4 MNPs [23]
(5 mol %) was added and the content was heated at 40 °C for
60 min. The progress of the reaction was checked by TLC
(n-hexane: EtOAc, 10:6). After completion, the resulting
product was heated in ethanol. The catalyst was magneti-
cally removed from the mixture and washed several times
with acetone for reuse. The pure product was collected from
the fltrate after cooling to room temperature with ice bath.
The yield of isolated product was 90%. The pure product
was obtained by recrystallization from hot ethanol. The Sup-
plemental Information of sample, contain FT-IR (Fig. S1),
1H and 13C NMR spectra (Figs. S1 and S2), other Figs. and
X-ray crystallography data.
Spectral Data of Target Product
Conclusions
Colorless crystal (yield: 90%) M. P.: 239–242 °C. IR (KBr)
νmax/cm−1: 3355, 3257, 3188, 2963, 2192, 1683, 1652, 1369.
1H NMR (DMSO-d6, 250.13 MHz;): δH (ppm) 0.94 (s, 3H,
CH3), 1.01 (s, 3H, CH3), 2.08 (d, J=15.25 Hz, 1H, CH2),
2.23 (d, J=14.26 Hz, 1H, CH2), 2.42 (s, 2H, CH2), 2.48 (s,
3H, SCH3), 4.14 (s, 1H, CH), 6.98 (s, 2H, NH2), 7.15 (d,
J=7.25 Hz, 2H, Arom.), 7.09 (d, J=7.00 Hz, 2H, Arom.).
13C NMR (DMSO-d6, 62.90 MHz,): δC (ppm) 15.19, 27.27,
28.84, 32.22, 35.58, 50.44, 58.66, 113.09, 120.13, 126.43,
128.29, 136.55, 141.98, 144.19, 158.91, 162.84, 196.08.
Briefy, an easy and convenient method was reported for
the synthesis of 2-amino-7,7-dimethyl-4-(4-(methylthio)
phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carboni-
trile under mild conditions in the presence of NiFe2O4 MNPs
as a nanocatalyst. It should be noted, some signifcant advan-
tages of this procedure are use of green solvent and catalyst,
clean and environmentally benign conditions and clean.
From the other important superiorities of this method are
operational simplicity, easy work-up, non-chromatographic
purifcation technique, short reaction time, and high yield.
1 3

Journal of Chemical Crystallography
Table 7 Experimental details for the crystal
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Afliations
Ali Ramazani1,2 · Hamideh Ahankar3 · Katarzyna Ślepokura4 · Tadeusz Lis4 · Pegah Azimzadeh Asiabi1 ·
Masoome Sheikhi5 · Farideh Gouranlou6 · Hooriye Yahyaei7
4
* Ali Ramazani
Faculty of Chemistry, University of Wrocław, 14 Joliot-Curie
aliramazani@gmail.com; aliramazani@znu.ac.ir
St, 50-383 Wrocław, Poland
5
6
7
* Hamideh Ahankar
Young Researchers and Elite Club, Gorgan Branch, Islamic
Azad University, Gorgan, Iran
hahankar@gmail.com
Department of Bioscience and Biotechnology, Malek Ashtar
University of Technology, Tehran, Iran
1
Department of Chemistry, University of Zanjan, P O
Box 45195-313, Zanjan, Iran
Department of Chemistry, Zanjan Branch, Islamic Azad
2
Research Institute of Modern Biological Techniques,
University, Zanjan, Iran
University of Zanjan, P O Box 45195-313, Zanjan, Iran
3
Department of Chemistry, Abhar Branch, Islamic Azad
University, P O Box 22, Abhar, Iran
1 3