Analysis of energies of halogen and hydrogen bonding interactions in the solid state structures of vanadyl Schiff base complexes

Article abstract of DOI:10.1039/c8ra09947b

Two mononuclear and two dinuclear vanadium(v) complexes, [VO₂L¹] (1), [VO₂L²] (2), (μ-O)₂[V(O)(L³)]₂ (3) and (μ-O)₂[V(O)(L⁴)]₂·2H₂O (4

Full text of DOI:10.1039/c8ra09947b

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PAPER
Analysis of energies of halogen and hydrogen
bonding interactions in the solid state structures of
vanadyl Schiff base complexes†
Cite this: RSC Adv., 2019, 9, 4789
a
b
c
Snehasish Thakur, Michael G. B. Drew, Antonio Franconetti,
c
a
Antonio Frontera * and Shouvik Chattopadhyay
*
1
2
3
Two mononuclear and two dinuclear vanadium(V) complexes, [VO
2
L ] (1), [VO
2
L ] (2), (m-O)
2
[V(O)(L )]
2
(3)
2
4
1
and (m-O)
2
[V(O)(L )]
2
$2H
2
O (4), where HL ¼ 4-bromo-6-[(2-phenylaminoethylimino)methyl]phenol, HL
3
¼
4
2-((2-(diethylamino)ethylimino)methyl)-4-chlorophenol, HL ¼ 2-((2-(ethylamino)ethylimino)methyl)-
4
-chlorophenol and HL ¼ 2-(1-(2-(ethylamino)ethylimino)ethyl)phenol have been synthesized and
Received 3rd December 2018
Accepted 21st January 2019
characterized. Structures of all complexes have been confirmed by single crystal X-ray diffraction
studies. Complexes 1, 2, and 3 exhibit significant halogen bonding interactions in their solid state
structures. The energies associated to the supramolecular interactions have been explored using Density
Functional Theory (DFT) calculations, and further confirmed with non-covalent interaction (NCI) plots.
DOI: 10.1039/c8ra09947b
rsc.li/rsc-advances
bonding interactions in the supramolecular systems generated
by vanadyl Schiff base complex building blocks.
1
. Introduction
Supramolecular chemistry is enriched by the participation of
Recently, we have reported the synthesis and characteriza-
carbon-bound halogen atoms (acting as electron acceptors), tion of few vanadyl Schiff base complexes along with the anal-
forming short contacts with both neutral and negatively ysis of supramolecular interactions in their solid state
1
8
charged species, having abilities to act as electron donors. This structures. Supramolecular interactions in those complexes
type of supramolecular interaction is commonly known as were mainly governed by C–H/p, p/p (chelate ring) and
‘
halogen bonding’ to indicate their similarity with hydrogen hydrogen bonding interactions. In the present work, we have
1b,1e
bonding interactions.
These non-covalent interactions have designed the Schiff bases in such a way that supramolecular
been shown to have signicant contribution in controlling the systems could be generated with the help of halogen bonding
2
3
aggregation of different organic molecules in solid, liquid, and interactions along with conventional hydrogen bonding inter-
1
4
gases. Supramolecular chemists are very much interested in actions. Four tridentate N
2
O donor Schiff bases, HL (4-bromo-
2
5
analyzing the nature of these halogen bonding interactions.
6-[(2-phenylaminoethylimino)methyl]phenol),
HL
2-((2-
3
Although hydrogen bonding interactions are the most (diethylamino)ethylimino)methyl)-4-chlorophenol, HL 2-((2-
frequently used means to assemble molecules in solid, liquid, (ethylamino)ethylimino)methyl)-4-chlorophenol and HL 2-(1-
4
and gas phases, and play important roles in stabilizing supra- (2-(ethylamino)ethylimino)ethyl)phenol have been used to
1
2
6
molecular aggregates even in water, the literature shows prepare four complexes, [VO
2
L ] (1), [VO
2
L ] (2), (m-
3
4
examples where ‘halogen bonding’ interactions may dominate O)
2
[V(O)(L )]
2
(3) and (m-O)
2
[V(O)(L )]
2
$2H
2
O (4). Signicant
over the hydrogen bonding interactions, depending upon the halogen bonding interactions have been observed in the solid
type of substituents and orientation of the responsible atoms state structures of complexes 1, 2 and 3. The energies involved
7
with respect to the electron donor groups. However, there is no in these interactions have been examined using DFT calcula-
report in the literature regarding the analysis of halogen tions, and further conrmed with NCI plots. The ndings are
impressive and hopefully encouraging for coordination as well
as supramolecular chemists working in related areas.
a
Department of Chemistry, Inorganic Section, Jadavpur University, Kolkata 700 032,
India. E-mail: shouvik.chem@gmail.com
b
School of Chemistry, The University of Reading, P. O. Box 224, Whiteknights, Reading
RG6 6AD, UK
2
. Experimental section
c
Departament de Qu ´ı mica, Universitat de les Illes Balears, Crta. De Valldemossa km
7
.5, 07122 Palma, Baleares, Spain. E-mail: toni.frontera@uib.es
VOSO $5H O was purchased from Loba Chemie Pvt. Ltd. and
4
2
†
Electronic supplementary information (ESI) available. CCDC 1879191–1879194
was of reagent grade. All other starting materials were
commercially available, reagent grade, and used as purchased
from Sigma-Aldrich without further purication.
contain the supplementary crystallographic data for complexes 1–4 respectively.
For ESI and crystallographic data in CIF or other electronic format see DOI:
1
0.1039/c8ra09947b
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2
.1 Preparation
.1.1 Preparation
phenylaminoethylimino)methyl]phenol
Elmer Spectrum Two spectrophotometer. Electronic spectrum
of complex 1 (in DMF) and that of complexes 2–4 (in CH CN)
3
2
of
ligands,
4-bromo-6-[(2-
1
were recorded on a Shimadzu UV-1700 UV-Vis spectrophotom-
eter. The magnetic susceptibility measurements were per-
formed with an EG and PAR vibrating sample magnetometer,
model 155 at room temperature (300 K) in a 5000 G magnetic
eld, and diamagnetic corrections were performed using
Pascal's constants.
(HL ),
2-((2-
2
(
(
(
diethylamino)ethylimino)methyl)-4-chlorophenol (HL ), 2-((2-
ethylamino)ethylimino)methyl)-4-chlorophenol (HL ) and 2-(1-
2-(ethylamino)ethylimino)ethyl)phenol (HL ). The tridentate
3
4
1
Schiff base ligand, HL , was prepared by reuxing 5-bromosa-
licylaldehyde (201 mg, 1 mmol) with N-phenylethylenediamine
2
(0.13 mL, 1 mmol) in CH CN (10 mL) for ca. 1 h. HL was
3
1
prepared in a similar method to that of HL , except that N,N-
diethylethylenediamine (0.14 mL, 1 mmol) and 5-chlor-
osalicylaldehyde (156 mg, 1 mmol) were used instead of N-
phenylethylenediamine and 5-bromosalicylaldehyde, respec-
tively. The tridentate ligands, HL and HL , were synthesized by
reuxing N-ethylethylenediamine (0.11 mL, 1 mmol) with 5-
chlorosalicylaldehyde (156 mg,
yacetophenone (136 mg, 1 mmol), respectively in CH CN (10
mL) for ca. 1 h 30 min. All these ligands were not isolated and
were directly used for the synthesis of their respective
complexes.
2.3 X-ray crystallography
For each complex, a suitable single crystal was picked and
mounted on a glass ber, and diffraction intensities were
measured with an Oxford Diffraction X-Calibur diffractometer,
3
4
˚
equipped with Mo K
a
radiation (l ¼ 0.71073 A, 50 kV, 40 mA) at
0
temperature 150 K. Data collection and reduction were per-
formed with the Oxford Diffraction Crystalis system. Structures
of the complexes were solved by direct method and rened by
full-matrix least squares on F , using the SHELX-2016/6
package. The absorption correction type is empirical with
1
mmol) and 2 -hydrox-
3
2
9
1
2
ABSPACK program of Oxford Diffraction Ltd. Non-hydrogen
atoms were rened anisotropically. Hydrogen atoms attached
to nitrogen and oxygen atoms were located by difference Fourier
maps. All other hydrogen atoms were placed in their geomet-
rically idealized positions and constrained to ride on their
2
.1.2 Preparation of complexes [VO
2
L ] (1), [VO
$2H O (4). All complexes
were prepared in a general synthetic procedure. DMF or CH CN
10 mL) solution of VOSO $5H O (253 mg, 1 mmol) was added
2
L ] (2), (m-
3
4
O)
2
[V(O)(L )]
2
(3) and (m-O)
2
[V(O)(L )]
2
2
3
(
4
2
to the CH CN solution (20 mL) of the synthesized tridentate
3
9
10
parent atoms. Programs used: SHELX-2016/6, PLATON,
ligand and the resulting solution was then reuxed for ca. 3 h.
Subsequently, it was cooled to room temperature, ltered and
kept for crystallization. Single crystals, suitable for X-ray
diffraction, were obtained aer 3–7 days on slow evaporation
11
12
13
WINGX, ORTEP, and MERCURY. Signicant crystallo-
graphic data are summarized in Table 1. Selected bond lengths
and bond angles are gathered in Tables 2 and 3, respectively.
of the ltrate in open atmosphere.
1
[VO
2
L ] (1). Yield: 289 mg (72%); anal. calc. for C15
H14BrN
2
-
2
.4 Theoretical methods
O V (FW ¼ 401.12) C, 44.91; H, 3.52; N, 6.98%. Found: C, 44.8;
3
ꢀ
1
The geometries of the complexes included in this study were
computed at the M06-2X/def2-TZVP level of theory using the
crystallographic coordinates. Therefore, the interaction ener-
gies were calculated using the frozen monomers as they are in
the dimers. For all calculations, the GAUSSIAN-09 program has
been used. The Grimme's dispersion correction has also
been used as implemented in GAUSSIAN-09 program since it is
adequate for the evaluation of non-covalent interactions where
dispersion effects are relevant like s-hole interactions. The
basis set superposition error for the calculation of interaction
H, 3.4; N, 7.1%; FT-IR (KBr, cm ): 3077(n ), 1630(n
), 925,
C]N
N–H
ꢀ
1
ꢀ1
8
(
25(nV]O), UV-Vis, lmax (nm), [3max (L mol cm )] (DMF), 334
3
4.1 ꢁ 10 ). Magnetic moment ¼ diamagnetic.
2
[VO
2 2
L ] (2). Yield: 229 mg (68%); anal. calc. for C13H18ClN -
O
3
V (FW ¼ 336.68): C, 46.37; H, 5.39; N, 8.32%. Found: C, 46.3;
14
15
ꢀ
1
H, 5.2; N, 8.4%; FT-IR (KBr, cm ): 1627 (nC]N), 935, 819 (nV]O),
UV-Vis, lmax (nm), [3max (L mol cm )] (CH
ꢀ1
ꢀ1
3
CN): 331 (3.8 ꢁ
3
10 ). Magnetic moment ¼ diamagnetic.
3
(
m-O) [V(O)(L )] (3). Yield: 219 mg (71%); anal. calc. for C -
2
2
22
H Cl N O V (FW ¼ 617.26): C, 42.81; H, 4.57; N, 9.08%;
2
8
2 4 6 2
16
ꢀ
1
energies has been corrected using the counterpoise method.
Found: C, 42.7; H, 4.4; N, 9.1%; FT-IR (KBr, cm ): 1641 (nC]N),
29, 836 (nV]O). UV-Vis, lmax (nm), [3max (L mol
CH
3
(
17
ꢀ
1
ꢀ1
The NCI plot isosurfaces have been used to characterize non-
covalent interactions. They correspond to both favorable and
unfavorable interactions, as differentiated by the sign of the
second density Hessian eigenvalue and dened by the isosur-
face color. The color scheme is a red-yellow-green-blue scale
with red for rcut (repulsive) and blue for rcut (attractive).
Molecular Electrostatic Potential surfaces have been computed
at the M06-2X/6-31+G* level using the SPARTAN'10 program
version 1.1.0. The SAPT (symmetry adapted perturbation
9
(
cm )]
3
CN): 382 (6.8 ꢁ 10 ). Magnetic moment ¼ diamagnetic.
4
m-O)
2
[V(O)(L )]
2 2
$2H O (4). Yield: 211 mg (69%); anal. calc. for
C
24 38 4 8 2
H N O V
(FW ¼ 612.46): C, 47.07; H, 6.25; N, 9.15%;
ꢀ
1
Found: C, 47.0; H, 6.1; N, 9.2%; FT-IR (KBr, cm ): 3212 (n ),
N–H
+
ꢀ
1
606 (n
), 930 (nV]O). 464 (nV–O), UV-Vis, l
(nm), [3max (L
max
C]N
ꢀ1
ꢀ
1
3
mol cm )] (CH CN): 352 (7.0 ꢁ 10 ). Magnetic moment ¼
3
diamagnetic.
18
theory) has been used to decompose the interaction energy
into well-dened components (electrostatic, exchange, induc-
2.2 Physical measurements
Elemental analyses (carbon, hydrogen and nitrogen) were per- tion, and dispersion terms). The DFT-SAPT calculations have
formed using a Perkin Elmer 240C elemental analyzer. IR been performed using the PBE0/def2-TZVP level of theory and
ꢀ
1
19
spectra in KBr (4500–500 cm ) were recorded with a Perkin the MOLPRO program.
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Table 1 Crystal data and refinement details of complexes 1–4
Complex
1
2
3
4
Formula
15
C H
14BrN
2
O
3
V
C
13
2
H18ClN O
3
V
C
22
H28Cl
2
N
4
O
6
V
2
24 38 4 8 2
C H N O V
Formula weight
Temperature (K)
Crystal system
Space group
401.12
150
Monoclinic
Pc
12.7168(14)
6.1962(5)
9.6410(11)
90
91.74(1)
90
336.68
150
617.26
150
Monoclinic
I2/a
22.194(2)
7.5879(7)
15.5112(12)
90
97.479(10)
90
612.46
150
Monoclinic
P2 /n
Monoclinic
P2 /n
1
1
˚
a (A)
14.1152(7)
6.9353(3)
15.1466(7)
90
106.842(5)
90
8.9266(4)
6.9648(3)
21.9606(12)
90
96.547(4)
90
˚
b (A)
˚
c (A)
a (deg)
b (deg)
g (deg)
Z
2
4
4
2
ꢀ3
d
calc (g cm
)
1.754
3.297
400
1.576
0.895
696
1.583
0.973
1264
1.500
0.743
640
ꢀ
1
m (mm
F(000)
)
Total reections
4316
9618
7844
8667
Unique reections
Observed data [I > 2s (I)]
No. of parameters
3000
2678
199
4096
3498
183
3726
3036
167
3873
3256
182
R
R
R
(int)
0.053
0.0693, 0.1446
0.0609, 0.1345
0.030
0.0464, 0.0947
0.0377, 0.0911
0.030
0.0595, 0.1075
0.0443, 0.1015
0.035
0.0604, 0.1072
0.0476, 0.1091
1
1
, wR
, wR
2
(all data)
[I > 2s (I)]
2
in Fig. 1. Complex 2 has a very similar structure (Fig. S1, ESI†).
The vanadium(V) center is ve coordinated in each complex.
The basal plane in each complex is composed of one imine
3
. Results and discussions
3.1 Synthesis
1
2
3
4
Four Schiff bases, HL , HL , HL and HL , have been prepared nitrogen atom, N(19), one amine nitrogen atom, N(22), one
by the condensation of appropriate diamines and salicylalde- phenoxo oxygen atom, O(11), of a deprotonated Schiff base
2
0
hyde derivatives in CH
The ligands were not isolated and were reacted with VOSO
3
CN, following the literature methods.
ligand and an oxo group [O(1) for 1 and O(2) for 2]. The apical
positions are occupied by a second oxo group, i.e. O(2) for 1 and
4
-
$
5H O (dissolved either in DMF or CH CN) in open atmosphere O(1) for 2. The geometry of any penta-coordinated metal center
2
3
1
to synthesize two mononuclear vanadium(V) complexes, [VO L ] is generally measured by the Addison parameter (s) [s ¼ (a ꢀ b)/
2
2
(
(
1) and [VO L ] (2) and two dinuclear vanadium(V) complexes, 60, where a and b are the two largest ligand–metal–ligand
2
3
4
1
2
m-O)
L
2
[V(O)(L )]
2
(3) and (m-O)
2
[V(O)(L )]
2
$2H
2
O (4), where L , L , angles in the coordination sphere (s ¼ 0 infers an ideal square
3
4
and L are the deprotonated mono-anionic forms of the
respective Schiff bases. The effort to prepare these complexes
under N environment was unsuccessful. This is because all the
ꢂ
a
Table 3 Selected bond angles ( ) for complexes 1–4
2
syntheses involves the oxidation of vanadium from +4 (in
Complex
1
2
3
4
starting material) to +5 (in complexes 1–4). The oxidation of
vanadium centers may therefore be caused by aerial oxygen. O(1)–V(1)–O(2)
110.4(4)
96.1(3)
137.4(4)
90.1(3)
102.8(4)
111.1(3)
96.0(4)
83.8(3)
156.7(3)
76.6(3)
—
—
—
—
—
—
—
—
—
110.67(7)
102.95(6)
113.96(6)
93.96(6)
96.96(6)
134.29(6)
90.68(6)
82.50(5)
157.52(5)
77.09(5)
—
—
—
—
—
—
—
—
—
106.99(7)
101.45(7)
97.03(7)
91.50(7)
99.22(7)
154.28(7)
92.65(7)
84.56(7)
158.96(6)
77.38(6)
—
107.49(7)
97.02(7)
152.91(7)
92.46(7)
102.64(7)
98.56(7)
93.06(7)
84.16(6)
158.22(6)
78.58(6)
77.94(6)
170.29(7)
84.36(6)
75.24(5)
78.49(6)
—
O(1)–V(1)–O(11)
Synthetic route to the complexes is outlined in Scheme 1.
O(1)–V(1)–N(19)
O(1)–V(1)–N(22)
3.2 Description of structures
O(2)–V(1)–O(11)
O(2)–V(1)–N(19)
O(2)–V(1)–N(22)
O(11)–V(1)–N(19)
O(11)–V(1)–N(22)
N(19)–V(1)–N(22)
1
2
3.2.1 [VO
2
L ] (1) and [VO
2
L ] (2). A perspective view of
complex 1 with the selective atom numbering scheme is shown
ꢀ
a
Table 2 Selected bond lengths (A) for complexes 1–4
b
O(1)–V(1)–O(1 )
b
Complex
1
2
3
4
O(1 )–V(1)–O(2)
—
—
—
—
b
O(1 )–V(1)–O(11)
b
V(1)–O(1)
V(1)–O(2)
V(1)–O(11)
V(1)–N(19)
V(1)–N(22)
1.628(7)
1.625(8)
1.903(8)
2.118(8)
2.159(9)
—
1.6228(13)
1.6215(14)
1.9160(13)
2.1424(14)
2.2021(14)
—
1.6159(14)
1.6773(15)
1.9150(15)
2.1637(17)
2.1554(18)
2.3096(15)
—
1.6812(15) O(1 )–V(1)–N(19)
1.6100(15) O(1 )–V(1)–N(22)
1.9033(16) O(1)–V(1)–O(2 )
2.1703(18) O(2)–V(1)–O(2 )
b
a
169.79(7)
78.78(6)
85.63(6)
76.15(6)
79.68(6)
a
—
—
—
—
a
2.1300(18) O(2 )–V(1)–O(11)
a
a
V(1)–O(2 )
V(1)–O(1 )
—
O(2 )–V(1)–N(19)
b
a
—
—
2.4008(15) O(2 )–V(1)–N(22)
—
—
a
a
Symmetry transformations: a ¼ 1 ꢀ x, 2 ꢀ y, ꢀz, b ¼ ꢀx, 1 ꢀ y, ꢀz.
Symmetry transformations: a ¼ 1 ꢀ x, 2 ꢀ y, ꢀz, b ¼ ꢀx, 1 ꢀ y, ꢀz.
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Scheme 1 Synthetic route to complexes 1–4.
2
1
a
b
pyramid and s ¼ 1 infers a perfect trigonal bipyramid)]. The s atoms; O(1), O(2 ) [a ¼ 1 ꢀ x, 2 ꢀ y, ꢀz] (for complex 3) and O(1 )
value is found to be ꢃ0.3 in each complex, indicating a severely [b ¼ ꢀx, 1 ꢀ y, ꢀz], O(2) (for complex 4). In the V
2 2
O core of each
distorted square pyramidal geometry around the vanadium(V) dimer, one vanadium(V)–oxygen distance is shorter [V(1)–O(2) ¼
22
˚
˚
centers. In 1, the coordinating atoms, N(19), N(22), O(11), and 1.681(1) A for complex 3, V(1)–O(1) ¼ 1.677(1) A for complex 4]
O(1), deviate from the mean plane passing through them by
˚
˚
˚
˚
–
0.171(4) A, 0.170(4) A, 0.172(4) A, –0.171(4) A with the metal
˚
0
.487(5) A from the plane in the direction of terminal O(2). In 2,
the geometry is slightly more distorted. With O(1) chosen as the
axial atom, the deviations for N(19), N(22), O(11), O(2) are
˚
˚
˚
˚
0
.2147(7) A, –0.2086(7) A, –0.2183(8) A, 0.2131(8) A with the
˚
metal 0.4925(8) A from the plane in the direction of O(1). The
˚
V(1)–O(1) and V(1)–O(2) distances are ꢃ1.62 A in both
23
complexes, as expected for typical V]O double bonds. The
bond distances and angles in both complexes are similar to
those observed in analogous vanadium(V) complexes with Schiff
24
bases. Saturated ve membered chelate ring, V(1)–N(19)–
C(20)–C(21)–N(22), assumes a half-chair conformation with
˚
ꢂ
Fig. 1 Perspective view of complex 1 with selective atom numbering
scheme.
puckering parameters q ¼ 0.411(12) A and 4 ¼ 282.1(11) in
complex 1, and an envelope conformation with puckering
˚
ꢂ
parameters q ¼ 0.4482(17) A and 4 ¼ 104.78(17) in complex 2.
3
4
3
.2.2 (m-O) [V(O)(L )] (3) and (m-O) [V(O)(L )] $2H O (4).
2 2 2 2 2
Both complexes 3 (Fig. 2) and 4 (Fig. S2, ESI†) are double oxo-
bridged centrosymmetric dimers containing V cores. Vana-
2 2
O
dium(V) centers in them are six coordinate and distorted octa-
hedral. The crystallographic asymmetric unit in each complex
consists of one vanadium atom, V(1), two oxo groups, O(1) and
O(2), and one tridentate (deprotonated) Schiff base ligand
binding to the vanadium(V) center via imine nitrogen atom,
N(19), amine nitrogen atom, N(22), and the phenolate oxygen
atom, O(11). The asymmetric unit of complex 4 contains
a lattice water molecule. The equatorial plane is dened with
phenolic oxygen atom, O(11), imine nitrogen atom, N(19), and
an amine nitrogen atom, N(22), of the Schiff base ligand and
one oxo oxygen atom, O(2) for complex 3 and O(1) for complex 4,
Fig. 2 Perspective view of complex 3 with selective atom numbering
respectively. Two axial positions are occupied by two oxo oxygen scheme. Symmetry transformation: a ¼ 1 ꢀ x, 2 ꢀ y, ꢀz.
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a
compared to the other vanadium(V)–oxygen distance [V(1)–O(2 ) distribution around the Br atom (it is represented only for the Br
b
˚
˚
¼
2.401(1) A for complex 3, V(1)–O(1 ) ¼ 2.310(1) A for complex atom in Fig. 3a, right). The MEP value at the s-hole of Br is
ꢀ1 ꢀ1
4
]. The short vanadium-oxygen distance corresponds to a V]O +8 kcal mol and at the belt is ꢀ15 kcal mol . A dimer,
25
double bond. The V–O and V–N bond lengths in the complexes retrieved from the innite chain, has been computed and the
ꢀ
1
are comparable to the corresponding values observed in other formation energy is moderately strong, DE
similar oxovanadium(V) complexes with Schiff bases.
1
¼ ꢀ4.3 kcal mol
.
24a,26
The The DFT-SAPT computed for this dimer shows that the inter-
chelating angles, N(19)–V(1)–N(22) and N(19)–V(1)–O(22) have action is dominated by induction and dispersion effects that
ꢂ
the values in the range 78–84 , indicating distortion of the represent the 75% of the sum of the attractive terms followed by
27
octahedron around vanadium(V) centers. The intramolecular the electrostatic term. The ‘non-covalent interaction plot’ (NCI
˚
˚
V/V separations are 3.107(5) A (complex 3) and 3.206(5) A plot) index has also been computed in order to characterize the
(
complex 4), which fall within the range of known V/V Br/p interaction in the dimer of 1. The NCI plot is an intuitive
28
distances in double-bridged vanadium polynuclear systems.
visualization index that enables the identication of non-
Depending on the orientation of V]O groups with respect to covalent interactions easily and efficiently. This plot is conve-
the plane through two vanadium centers and two bridging oxo- nient to analyze host–guest interactions since it clearly shows
2
+
groups, the {V
2
O
4
}
core can have ve different congurations which molecular regions interact. The colour scheme is a red-
(
syn and anti-orthogonal, syn- and anti-coplanar, twist) in yellow-green-blue scale with red (repulsive) and blue (attrac-
2
+
29
complexes constructed from two cis-VO (pervanadyl) units.
tive). Yellow and green surfaces correspond to weak repulsive
Both these complexes may be termed as anti-coplanar, as the and weak attractive interactions, respectively. The representa-
two terminal V]O bonds in both complexes are oriented in an tion of the NCI plot is shown in Fig. 3c. As noted, the halogen
anti arrangement with respect to the {V O } plane. The coordi- bond is characterized by a green isosurface that covers the
2
2
nation environment may then be best described as two edge- aromatic C]C bond and thus conrming the existence of the
shared vanadium octahedra that are signicantly distorted. Br/p interaction.
The assignment of the +5 oxidation state for the vanadium
A partial view of the X-ray structure of 2 is given in Fig. 4a,
centers in both complexes is conrmed by the bond valence where an innite one dimensional supramolecular chain is
30
sum calculations, which give 4.946 and 4.943 valence units for represented. In this supramolecular assembly, the halogen
vanadium centers in complexes 3 and 4, respectively.
bonding is established between the Cl atom and one O atom of
the VO2 moiety, which is a better electron donor compared to
+
the p-system. The MEP surface of complex 2 also shows an
3.3 Theoretical studies on supramolecular interactions in
anisotropic distribution around the Cl atom; however, the MEP
complexes 1, 2 and 3
ꢀ
1
value at the s-hole of Cl is very small, i.e. +2 kcal mol and at
+
Four new Schiff base complexes of VO
2
have been synthesized
ꢀ1
the belt is ꢀ17 kcal mol . A dimer, retrieved from the innite
and characterized by X-ray crystallography. Some of them
contain halogen atoms in the structure (Br or Cl), that partici-
pate in halogen bonding or hydrogen bonding interactions. The
theoretical study is devoted to analyze the energy associated to
the halogen bonding or hydrogen bonding interactions
involving the halogen atoms in complexes 1, 2 and 3.
In Fig. 3a, a partial view of the X-ray structure of 1 is pre-
sented, where an innite supramolecular chain is formed that is
governed by the formation of Br/p interactions and where the
p-system corresponds to a C]C bond of the aromatic ring. First
of all, the molecular electrostatic potential (MEP) surface in
complex 1 has been computed and it reveals an anisotropic
chain, has been computed and the formation energy is similar
ꢀ1
to that computed above for complex 1 (DE
2
¼ ꢀ4.6 kcal mol
,
Fig. 4b), which is likely due to a compensating effect (worse s-
hole donor and better s-hole acceptor compared to complex 1).
The DFT-SAPT in this case shows that the interaction is domi-
nated by electrostatic effects that represent the 55% of the sum
of the attractive terms followed by the induction and dispersion
terms (45%). The NCI plot index has also been calculated in
order to characterize the halogen bonding interaction in the
dimer of 2 (Fig. 4c). The halogen bond is characterized by
a small green isosurface that is located between the Cl and O
Fig. 3 (a) One dimensional supramolecular chain observed in the X-ray solid state structure of 1 and the MEP surface (isodensity ¼ 0.001 a.u.)
around the Br atom. Hydrogen atoms have been omitted for clarity. (b) Theoretical model used to evaluate the interaction energy. (c) NCI surface
of the dimer of complex 1. The gradient cut-off is s ¼ 0.35 a.u., and the colour scale is ꢀ0.04 < r < 0.04 a.u.
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Fig. 4 (a) One dimensional supramolecular chain observed in the X-ray solid state structure of 2 and the MEP surface (isodensity ¼ 0.001 a.u.)
around the Cl atom. Hydrogen atoms have been omitted for clarity. (b) Dimer retrieved from the crystal structure of complex 2. Distances in A˚ . (c)
NCI surface of the dimer of complex 2. The gradient cut-off is s ¼ 0.35 a.u., and the color scale is ꢀ0.04 < r < 0.04 a.u.
Fig. 5 Partial view of the X-ray solid state structure of 3 (a) and the theoretical model (b). Distances in A˚ .
atoms. Moreover, an additional green isosurface is located vanadium(V) Schiff base complexes. Sharp bands around
ꢀ
1
between the aliphatic hydrogen atoms of one methyl group and 3310 cm may be assigned to n(N–H) stretching vibrations in
3
4
ꢀ1
the negative belt at the Cl atoms, thus also contributing to the complexes 3 and 4. Bands in the range of 2998–2806 cm due
stabilization of the dimer and also explaining the larger binding to alkyl C–H bond stretching vibrations are customarily noticed
energy obtained for 2 compared to 1.
35
in the IR spectra of all the complexes.
Electronic spectrum of each complex shows an absorption
Complex 3 also has a chlorine atom as substituent; however,
it does not participate in halogen bonding interactions. Instead, band around 350 nm. This band may be assigned as a ligand-to-
it establishes several C–H/Cl interactions. In fact, its solid metal charge transfer (LMCT) transition, originating from the
state structure (Fig. 5a) shows that each dinuclear complex p orbital on the phenolate oxygen to the empty d orbitals of the
p
3
6
0
establishes four sets of C–H/Cl interactions: two as donor and vanadium(V). As all these vanadium(V) complexes has a 3d
two as acceptors, generating a two dimensional sheet. The conguration, d–d bands are not expected to appear in their
37
interaction energy of the hydrogen bonded dimer is modest, electronic spectra.
ꢀ1
DE
3
¼ ꢀ3.7 kcal mol and smaller than the halogen bonding
All these complexes are diamagnetic as expected for mono-
computed for 1 and 2, thus suggesting that the halogen bond is nuclear and dinuclear vanadium(V) complexes with d cong-
0
favoured in these vanadium systems. The DFT-SAPT computed uration, as also observed for other similar vanadium(V)
38
for this interaction shows that it is dominated by electrostatic complexes.
effects that represent the 75% of the sum of the attractive terms.
4. Conclusion
3.4 IR, electronic spectra and magnetic moments
+
Four new VO
2
complexes with Schiff base ligands have been
Strong and sharp bands due to azomethine (C]N) groups in prepared and structurally characterized. Supramolecular inter-
ꢀ
1
the range 1600–1640 cm have been customarily noticed in the actions were investigated in details. An innite one dimen-
3
1
ꢀ1
IR spectra of these complexes. Strong bands around 930 cm
sional supramolecular chain is formed in complex 1, governed
ꢀ
1
and 825 cm in all complexes may be assigned to asymmetric by the formation of Br/p interactions (where the p-system
32
and symmetric n(O]V]O) vibrations of cis-VO groups present.
corresponds to a C]C bond of the aromatic ring). A dimer,
2
ꢀ
1
The n(V–O) bands can be monitored around 460 cm for all retrieved from the innite chain, has been computed and the
complexes. These values are in good agreement with similar formation energy is moderately strong, DE
33
ꢀ1
1
¼ ꢀ4.3 kcal mol
.
4794 | RSC Adv., 2019, 9, 4789–4796
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In the supramolecular assembly of complex 2, the halogen
1157; (b) A. C. Legon, Angew. Chem., 1999, 111, 2850–2880;
(c) A. C. Legon, Chem.–Eur. J., 1998, 4, 1890–1897.
bonding is established between the Cl atom and one O atom of
+
the VO2 moiety, which is a better electron donor compared to
5 (a)
A.
M.
Maharramova,
N.
Q.
Shikhaliyeva,
the p-system. A dimer, retrieved from the innite chain, has
G. T. Suleymanovaa, A. V. Gurbanova, G. V. Babayevaa,
G. Z. Mammadovaa, F. I. Zubkovc, V. G. Nenajdenkod,
K. T. Mahmudov and A. J. L. Pombeiro, Dyes Pigm., 2018,
159, 135–141; (b) D. Franchinia, F. Dapiaggia,
S. Pieraccinia, A. Fornib and M. Sironi, Chem. Phys. Lett.,
2018, 712, 89–94; (c) J. M. Guevara-Vela, D. Ochoa-
Resendiz, A. Costales, R. Hern ´a ndez-Lamoneda and
A. M. Pend ´a s, ChemPhysChem, 2018, 19, 2512–2517.
6 (a) L. Brunsveld, J. A. J. M. Vekemans, J. H. K. K. Hirschberg,
R. P. Sijbesma and E. W. Meijer, Proc. Natl. Acad. Sci. U. S. A.,
2002, 99, 4977–4982; (b) C. M. A. Leenders, L. Albertazzi,
T. Mes, M. M. E. Koenigs, A. R. A. Palmans and
E. W. Meijer, Chem. Commun., 2013, 49, 1963–1965; (c)
M. Henry, ChemPhysChem, 2002, 3, 607–616; (d)
C. Schmuck and W. Wienand, Angew. Chem., Int. Ed., 2001,
40, 4363–4369; (e) F. Wang, M. A. J. Gillissen, P. J. M. Stals,
A. R. A. Palmans and E. W. Meijer, Chem.–Eur. J., 2012, 18,
been computed and the formation energy is similar to that
ꢀ1
computed for complex 1 (DE
2
¼ ꢀ4.6 kcal mol ), which is likely
due to a compensating effect (worse s-hole donor and better s-
hole acceptor compared to complex 1). Complex 3 has a chlo-
rine atom in the ligand part; however, it does not participate in
halogen bonding interactions. Instead, it establishes several C–
H/Cl interactions. In fact, its solid state structure shows that
each dinuclear complex establishes four sets of C–H/Cl
interactions: two as donor and two as acceptors, generating
a two dimensional sheet. The interaction energy of the
ꢀ
1
hydrogen bonded dimer is modest, DE
3
¼ ꢀ3.7 kcal mol and
smaller than the halogen bonding computed for 1 and 2, thus
suggesting that the halogen bond is favoured in these vanadium
systems. All these results were further corroborated with the
molecular electrostatic potential (MEP) surface calculation and
NCI plot index computational tool.
11761–11770; (f) T. Kato, N. Mizoshita and K. Kanie,
Macromol. Rapid Commun., 2001, 22, 797–814; (g)
C. M. Paleos and D. Tsiourvas, Liq. Cryst., 2001, 28, 1127–
1161; (h) F. C. Gozzo, L. S. Santos, R. Augusti,
C. S. Consorti, J. Dupont and M. N. Eberlin, Chem.–Eur. J.,
Conflicts of interest
There are no conicts of interest to declare.
2004, 10, 6187–6193.
Acknowledgements
7
(a) P. Metrangolo and G. Resnati, Chem.–Eur. J., 2001, 7,
2511–2519; (b) E. Corradi, S. V. Meille, M. T. Messina and
G. Resnati, Angew. Chem., Int. Ed., 2000, 39, 1782–1786; (c)
C. B. Aaker ¨o y, M. Fasulo, N. Schultheiss, J. Desper and
C. Moore, J. Am. Chem. Soc., 2007, 129, 13772–13773; (d)
G. C. Cole, A. C. Legon and P. Ottaviani, J. Chem. Phys.,
2002, 117, 2790.
8 (a) S. Thakur, S. Roy, A. Bauz ´a , A. Frontera and
S. Chattopadhyay, Inorg. Chim. Acta, 2017, 467, 212–220; (b)
S. Thakur, N. Sarkar, M. G. B. Drew, A. Bauz ´a , A. Frontera
and S. Chattopadhyay, Polyhedron, 2018, 142, 83–92.
S. T. thanks the DST, India, for awarding a Junior Research
Fellowship (IF160359). A. Frontera and A. Franconetti gratefully
acknowledge the nancial support of this work by the MINECO
of Spain (project CTQ2017-85821-R, FEDER funds). In addition,
AF thanks the MINECO/AEI from Spain for a “Juan de la Cierva”
contract. They thank the CTI (UIB) for free allocation of
computer time. M. G. B. D. thanks the University of Reading and
the EPSRC (U. K.) for funds for the diffractometer.
Notes and references
9
(a) G. M. Sheldrick, Acta Crystallogr., Sect. A: Found.
Crystallogr., 2008, 64, 112–122; (b) G. M. Sheldrick, Acta
Crystallogr., Sect. C: Struct. Chem., 2015, 71, 3–8.
1
(a) J. P. M. Lommerse, A. J. Stone, R. Taylor and F. H. Allen, J.
Am. Chem. Soc., 1996, 118, 3108–3116; (b) P. Politzer, P. Lane,
M. C. Concha, Y. Ma and J. S. Murray, J. Mol. Model., 2007, 13, 10 A. L. Spek, Acta Crystallogr., 2009, D65, 148–155.
05–311; (c) P. Metrangolo, F. Meyer, T. Pilati, G. Resnati and 11 J. L. Farrugia, J. Appl. Crystallogr., 2012, 45, 849–854.
G. Terraneo, Angew. Chem., Int. Ed., 2008, 47, 6114–6127; (d) 12 M. N. Burnett and C. K. Johnson, ORTEP-3: Oak Ridge
3
P. Politzer, J. S. Murray and M. C. Concha, J. Mol. Model.,
007, 13, 643–650; (e) P. Politzer, J. S. Murray and T. Clark,
Phys. Chem. Chem. Phys., 2010, 12, 7748–7757.
Thermal Ellipsoid Plot Program for Crystal Structure
Illustrations, Report ORNL-6895, Oak Ridge National
Laboratory, Oak Ridge, TN, USA, 1996.
2
2
(a) A. Farina, S. V. Meille, M. T. Messina, P. Metrangolo, 13 C. F. Macrae, I. J. Bruno, J. A. Chisholm, P. R. Edgington,
G. Resnati and G. Vecchio, Angew. Chem., Int. Ed., 1999, 38,
433–2436; (b) T. Caronna, R. Liantonio, T. A. Logothetis,
P. Metrangolo, T. Pilati and G. Resnati, J. Am. Chem. Soc.,
004, 126, 4500–4501.
(a) M. T. Messina, P. Metrangolo, W. Panzeri, E. Ragg and
G. Resnati, Tetrahedron Lett., 1998, 39, 9069–9072; (b)
H. L. Nguyen, P. N. Horton, M. B. Hursthouse, A. C. Legon
and D. W. Bruce, J. Am. Chem. Soc., 2004, 126, 16–17.
P. McCabe, E. Pidcock, L. R. Monge, R. Taylor,
J. V. D. Streek and P. A. Wood, J. Appl. Crystallogr., 2008,
41, 466–470.
2
2
14 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng,
J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota,
R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery Jr,
3
4
(a) O. Dumele, B. Schreib, U. Warzok, N. Trapp, C. A. Schalley
and F. Diederich, Angew. Chem., Int. Ed., 2017, 56, 1152–
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 4789–4796 | 4795

View Article Online
RSC Advances
Paper
J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers,
K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand,
K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar,
919; (b) S. Mondal, M. Mukherjee, K. Dhara, S. Ghosh,
J. Ratha, P. Banerjee and A. K. Mukherjee, Cryst. Growth
Des., 2007, 7, 1716–1721.
J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, 27 Z.-L. You, D.-H. Shi, J.-C. Zhang, Y.-P. Maa, C. Wang and
J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, K. Li, Inorg. Chim. Acta, 2012, 384, 54–61.
R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, 28 (a) C. A. Root, J. D. Hoeschele, C. R. Cornman, J. W. Kampf
R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin,
K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador,
and V. L. Pecoraro, Inorg. Chem., 1993, 32, 3855–3861; (b)
S. Pal and S. Pal, J. Chem. Crystallogr., 2000, 30, 329–333.
¨
J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, 29 (a) Y. Zhang, R. C. Haushalter and J. Zubieta, Inorg. Chim.
J. B. Foresman, J. V. Ortiz, J. Cioslowski and D. J. Fox,
Gaussian 09, Gaussian, Inc., Wallingford CT, 2009.
Acta, 1997, 260, 105–110; (b) W. Plass, Angew. Chem., Int.
Ed. Engl., 1996, 35, 627–631.
15 S. Grimme, J. Antony, S. Ehrlich and H. Krieg, J. Chem. Phys., 30 (a) R. Codd, T. W. Hambley and P. A. Lay, Inorg. Chem., 1995,
2010, 132, 154104.
34, 877–882; (b) H. H. Thorp, Inorg. Chem., 1992, 31, 1585–
1
1
6 S. F. Boys and F. Bernardi, Mol. Phys., 1970, 19, 553–566.
7 J. Contreras-Garc ´ı a, E. R. Johnson, S. Keinan, R. Chaudret, 31 (a) P. Bhowmik, S. Chattopadhyay, M. G. B. Drew, C. Diaz
1588.
J.-P. Piquemal, D. N. Beratan and W. Yang, J. Chem. Theory
Comput., 2011, 7, 625–632.
8 B. Jeziorski, R. Moszynski and K. Szalewicz, Chem. Rev., 1994,
and A. Ghosh, Polyhedron, 2010, 29, 2637–2642; (b)
P. Bhowmik, H. P. Nayek, M. Corbella, N. Aliaga-Alcalde
and S. Chattopadhyay, Dalton Trans., 2011, 40, 7916–7926;
(c) F. H. Suydam, Anal. Chem., 1963, 35, 193–195; (d)
1
1
2
94, 1887–1930.
9 MOLPRO, A package of ab initio programs, version 2010.1;
Molpro, Cardiff, U.K., 2010.
0 (a) L. Sacconi and I. Bertini, Inorg. Chem., 1966, 5, 1520–
S.
Chattopadhyay,
M.
S.
Ray,
S.
Chaudhuri,
G. Mukhopadhyay, G. Bocelli, A. Cantoni and A. Ghosh,
Inorg. Chim. Acta, 2006, 359, 1367–1375.
1522; (b) M. S. Shongwe, U. A. Al-Zaabi, F. Al-Mjeni, 32 (a) M. R. Maurya, A. Kumar, M. Abid and A. Azam, Inorg.
C. S. Eribal, E. Sinn, I. A. Al-Omari, H. H. Hamdeh,
D. Matoga, H. Adams, M. J. Morris, A. L. Rheingold, E. Bill
and D. J. Sellmyer, Inorg. Chem., 2012, 51, 8241–8253; (c)
Chim. Acta, 2006, 359, 2439–2447; (b) E. Kwiatkowski,
G. Romanowski, W. Nowicki, M. Kwiatkowski and
K. Suwi n´ ska, Polyhedron, 2007, 26, 2559–2568.
Y.-Q. Cui, Z.-L. You, X.-F. Li, X.-L. Wang, Y.-P. Ma, C. Wang 33 X. Wang, X. M. Zhang and H. X. Liu, Inorg. Chim. Acta, 1994,
and C.-L. Zhang, Transition Met. Chem., 2010, 35, 159–163. 223, 193–197.
1 A. W. Addison, T. N. Rao, J. Reedijk, J. V. Rijn and 34 (a) S. Rayati, N. Sadeghzadeh and H. R. Khavasi, Inorg. Chem.
2
2
2
2
G. C. Verschoor, J. Chem. Soc., Dalton Trans., 1984, 1349.
2 C. R. Cornman, K. M. Geiser-Bush, S. P. Rowley and
P. D. Boyle, Inorg. Chem., 1997, 36, 6401–6408.
3 G. Asgedom, A. Sreedhara, J. Kivikoski, E. Kolehmainen and
C. P. Rao, J. Chem. Soc., Dalton Trans., 1996, 93–97.
Commun., 2007, 10, 1545–1548; (b) G. F. Svatos, C. Curran
and J. V. Quagliano, J. Am. Chem. Soc., 1955, 77, 6159–6163.
35 G. Grivani, A. D. Khalaji, V. Tahmasebi, K. Gotoh and
H. Ishida, Polyhedron, 2012, 31, 265–271.
36 (a) R. Dinda, P. Sengupta, S. Ghosh and T. C. W. Mak, Inorg.
Chem., 2002, 41, 1684–1688; (b) G. Asgedom, A. Sreedhara,
J. Kivikoski, E. Kolehmainen and C. P. Rao, J. Chem. Soc.,
Dalton Trans., 1996, 93–97.
4 (a) L. M. Mokry and C. J. Carrano, Inorg. Chem., 1993, 32,
6
119–6121; (b) E. Kwiatkowski, G. Romanowski,
W. Nowicki, M. Kwiatkowski and K. Suwi n´ ska, Polyhedron,
003, 22, 1009–1018.
5 (a) G. Romanowski, E. Kwiatkowski, W. Nowicki,
2
37 M. R. Maurya, A. Kumar, A. R. Bhat, A. Azam, C. Bader and
D. Rehder, Inorg. Chem., 2006, 45, 1260–1269.
2
M. Kwiatkowski and T. Lis, Polyhedron, 2008, 27, 1601– 38 (a) J. Dai, S. Akiyama, M. Munakata and M. Mikuriya,
1
1
609; (b) A. Sarkar and S. Pal, Polyhedron, 2007, 26, 1205–
210.
Polyhedron, 1994, 13, 2495–2499; (b) T. Ghosh, B. Mondal,
T. Ghosh, M. Sutradhar, G. Mukherjee and M. G. B. Drew,
Inorg. Chim. Acta, 2007, 360, 1753–1761.
2
6 (a) C. A. Duncan, E. P. Copeland, I. A. Kahwa, A. Quick and
D. J. Williams, J. Chem. Soc., Dalton Trans., 1997, 6, 917–
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