Hirshfeld surface analysis of some new heteroleptic Copper(I) complexes

Article abstract of DOI:10.1016/j.molstruc.2019.05.011

Seven new coordination complexes namely, [Cu(T1) (I) (PPh₃)₂] (CT1), [Cu(T2) (I) (PPh₃)₂] (CT2), [Cu(T3) (I) (PPh₃)₂] (CT3), [Cu(T4) (I) (PPh₃)₂] (CT4), [Cu(T5) (I) (P

Full text of DOI:10.1016/j.molstruc.2019.05.011

Accepted Manuscript
Hirshfeld surface analysis of some new heteroleptic Copper(I) complexes
Mohamad Zarif Mohd Zubir, Nazzatush Shimar Jamaludin, Siti Nadiah Abdul Halim
PII:
S0022-2860(19)30563-0
DOI:
https://doi.org/10.1016/j.molstruc.2019.05.011
MOLSTR 26518
Reference:
To appear in: Journal of Molecular Structure
Received Date: 15 January 2019
Revised Date: 30 April 2019
Accepted Date: 6 May 2019
Please cite this article as: M.Z. Mohd Zubir, N.S. Jamaludin, S.N. Abdul Halim, Hirshfeld surface
analysis of some new heteroleptic Copper(I) complexes, Journal of Molecular Structure (2019), doi:
https://doi.org/10.1016/j.molstruc.2019.05.011.
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ACCEPTED MANUSCRIPT
HIRSHFELD SURFACE ANALYSIS OF SOME NEW HETEROLEPTIC COPPER(I)
COMPLEXES
Mohamad Zarif Mohd Zubira, Nazzatush Shimar Jamaludina, Siti Nadiah Abdul Halima
aDepartment of Chemistry, Faculty of Science, University Malaya, 50603 Kuala Lumpur, Malaysia
Abstract
Seven new coordination complexes namely, [Cu(T1)(I)(PPh3)2] (CT1), [Cu(T2)(I)(PPh3)2]
(CT2), [Cu(T3)(I)(PPh3)2] (CT3), [Cu(T4)(I)(PPh3)2] (CT4), [Cu(T5)(I)(PPh3)2] (CT5),
[Cu(T6)(I)(PPh3)2] (CT6) and [Cu(T7)(I)(PPh3)2] (CT7), were synthesized and characterized by
using spectroscopic and crystallographic methods. The results from spectroscopic data and crystal
structure analysis showed that in all complexes, the acylthiourea ligands coordinated as monodentate
S-donor mode. All of the complexes displayed distorted tetrahedral geometry with one iodide anion,
two triphenylphosphine ligands and one acylthiourea ligand (N-benzoyl-N’-(substituted
phenyl)thiourea bearing different ortho/meta-substituents; R- H, 3-Me, 3-OMe, 3-OH, 3-Cl, 2-Me and
2-OMe, T1-T7 respectively) attached to the Cu(I) central metal atom. The acylthiourea ligands
behaved as a monodentate S-donor ligand instead of its common O, S-bidentate nature due to the
tetrahedrally favored geometry of the copper(I) metal and the presence of two bulky group of
triphenylphosphine ligand as the co-ligand. Interestingly, CT1-CT4 and CT7 crystals are isostructural
and crystallized in the monoclinic P21/c crystal system whereas CT5 and CT6 are also isostructurally
ꢀ
crystallized in the triclinic P1 crystal system. Isostructural structures of these two crystal systems
illustrated almost similar crystal packing but with significantly different interactions as determined by
Hirshfeld surface analysis which is discussed herein.
Keywords: Copper(I) Complexes, Acylthiourea, Hirshfeld Surface Analysis, Crystallography.
Author to whom correspondence should be addressed Associate Prof. Dr. Siti Nadiah Abdul Halim
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(UM), Tel: +603-79674248; Fax:+60379674193; email: nadiahhalim@um.edu.my
1. Introduction
Thiourea has interesting behavior because of their unique combinations of functional groups
that include amino, imino, and thiol [1-2]. This series of ligands showed bonding to the metal centers
via the S atom and is known to be favorable [3]. Thus, the chemistry of acylthiourea derivatives in
coordination complexes has become an interest because of its interesting backbone of
C(O)N(H)C(S)N, bearing O, N, N’ and S donor atoms within it [1-3]. This has led to research far and
wide on the study of the versatility of acylthiourea to form complexes of d-block elements with its
remarkable applications in biological sciences [4, 5], luminescent studies [6], electrochemical
investigations [7] and catalytic properties [8].
Theoretically, acylthiourea was expected to behave exclusively as a multidentate ligand yet it
showed coordination through less than the maximum number of potential donor atoms. Hence, the
term ‘hypodentate’ was used to describe this type of coordination behaviour [9, 10]. These
hypodentate manners of acylthiourea were also observed with other metals such as platinum[9],
palladium [11] and silver [12]. To observe this manner in detail, here we embark the challenge to
conduct the Hirshfeld surface analysis apart from discussing the preparation, characterization and
crystal structures of a series of new noble mixed copper(I) complexes of acylthiourea derivatives
(Figure 1) with iodine and triphenylphosphine moiety as co-ligand.
N
N’
R=H, 3-Me, 3-OMe, 3-OH, 3-Cl, 2-Me, 2-OMe
Figure 1: N-benzoyl-N’-(substituted phenyl)thiourea. (T1-T7).
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The Hirshfeld surface analysis was developed to explain the space occupied by a molecule in
a crystal structure by partitioning the crystal electron density into molecular fragments. Hirshfeld
surfaces were named in honor of F. L. Hirshfeld, who proposed the stockholder partitioning scheme
for defining atoms in molecules, consequently, lead to the extension of expressing a molecule in a
crystal space [13, 14].
Hirshfeld surface has since become a unique tool in the prediction and study of crystal
structure and its packing behavior. This method is so-called analysis; because it has proven to be a
better method in uncovering the minute factors and features that contribute to a specific crystal
characteristic, unlike by just examining the classical crystal packing diagrams [15]. Clearer rationale
for distinguishing various types of non-bonding interactions (such as; van der Waals forces, hydrogen
bonding, intermolecular contacts to halogen atoms, πꢀꢀꢀπ stacking interaction and so on [16]) and their
impact within the crystal system can be understood. Each molecule has its own unique set of spherical
atomic electron densities; thus, no two molecules have the same Hirshfeld surface. Spackman and co-
worker also stated that:
“… the Hirshfeld surface envelops the molecule and defines the volume of space where the
promolecule electron density exceeds that from all neighboring molecules. It guarantees maximum
proximity of neighboring molecular volumes, but the volumes never overlap because of the nature of
the weight function.” [13]
2. Experimental Section
2.1. Materials and Measurements
All the chemicals were obtained from commercial sources and used as received. The IR
measurement was conducted via the attenuated total reflection (ATR) technique in the frequency
1
13
range of 450-4000 cm-1 using a Perkin Elmer FTIR-Spectrum 400. The H NMR and C{1H} NMR
1
spectra of ligand (TI-T7) were recorded in deuterated dimethyl sulfoxide, DMSO-d6. The H NMR,
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13C{1H} NMR and 31P NMR spectra of the copper(I) phosphine complexes, CT1-CT7 were recorded
1
in deuterated chloroform, CDCl3. The H NMR and 13C{1H} NMR were referenced to internal
31
tetramethylsilane (TMS) whereas the P NMR was internally referred to 85 % phosphoric acid. All
NMR experiments were conducted on a JEOL ECA 400 MHz instrument. The compositions of C, H,
and N were analyzed on a Perkin Elmer CHN Analyzer 2400. The samples were packed in a standard
size solid sample tin capsule. The melting point was measured with MEL-TEMP II melting point
apparatus.
X-ray single crystal determinations of complexes (CT1-CT7) were carried out using the
Agilent Oxford Supernova Single Crystal Dual Wavelength X-ray Diffractometer and XtaLAB
Synergy, Dualflex, AtlasS2 Rigaku Oxford Diffractometer using CuKα (λ = 1.54184 Å) radiation.
High-quality crystals were chosen using a polarizing microscope and carefully mounted on glass
fibers. Data processing and absorption correction were performed using a multi-scan method within
CrysAlis PRO. Empirical absorption correction using spherical harmonics, as implemented in the
SCALE3 ABSPACK scaling algorithm, [17] was carried out. The structures were solved by the direct
method using SHELXS. All data were refined by full matrix least-squares refinement against |F2|
using SHELXL 2017, [18] and the final refinements include atomic positions for all the atoms,
anisotropic thermal parameters for all the non-hydrogen atoms, and isotropic thermal parameters for
the hydrogen atoms. The programs Olex2 [19], PLATON, [20] and Mercury [21] were used to
process the data. Hirshfeld surface analysis was conducted and their 2D fingerprint plots were
obtained using CrystalExplorer17 software [22].
2.2. Synthesis of Acylthiourea Ligands (T1-T7)
The
acylthiourea
ligand
N-benzoyl-N’-phenylthiourea
(T1),
N-benzoyl-N’-(3-
methylphenyl)thiourea (T2), N-benzoyl-N’-(3-methoxyphenyl)thiourea (T3), N-benzoyl-N’-(3-
hydroxyphenyl)thiourea (T4), N-benzoyl-N’-(3-chlorophenyl)thiourea (T5), N-benzoyl-N’-(2-
methylphenyl)thiourea (T6), and N-benzoyl-N’-(2-methoxyphenyl)thiourea (T7), were prepared by
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reacting potassium isothiocyanate with benzoyl chloride in acetone and formed benzoyl
isothiocyanate, followed by the addition of aniline or other substituted aniline to form the acylthiourea
derivatives [23].
2.3. Synthesis of Phosphanecopper(I) Complexes (CT1-CT7)
Seven novel phosphanecopper(I) complexes of N-benzoyl-N’-(substituted phenyl)thiourea
(CT1-CT7) were synthesized by adapting previously described procedure [10, 24] by reacting
acylthiourea derivatives (T1-T7) respectively with copper(I) iodide and triphenylphosphine (Scheme
1).
CuI
2
+
MeCN, rt., 1h
R= H, 3-Me, 3-OMe, 3-OH, 3-Cl, 2-Me, 2-OMe
Scheme 1: Preparation of phosphanecopper(I) complexes (CT1-CT7).
The CT1 complexes were prepared by modifying a previously described procedure [8, 24].
Triphenylphosphine (20 mmol) was dissolved in acetonitrile (10 ml) and was stirred vigorously before
copper(I) iodide solid (10 mmol) was added into the stirring solution. The reaction mixture was left to
stirred for 1 hour and the solid formed (phosphanecopper(I) precursor) was isolated upon filtration
with excess acetonitrile and methanol. The dried phosphanecopper(I) precursor, without any
purification or characterization, was directly reacted with the solid thiourea (T1) (10 mmol) in-situ
followed by addition of acetonitrile (5 ml) to give a yellow precipitate in a clear yellow solution. The
clear yellow solution was allowed to stand at room temperature, for a day up to a week to form pure
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yellow, prismatic crystals. A similar method was applied to obtained CT2-CT7.
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3. Results and discussion
3.1. Synthesis
All complexes yielded yellow crystals and were structurally characterized and tabulated in Table 1. The crystals were air-stable, non-hygroscopic in
nature, and soluble in common solvents such as dichloromethane, acetone, acetonitrile, dimethylformamide and dimethylsulfoxide. All compounds were
characterized using FTIR and (1H, 13C{1H},31P) NMR. Single crystal X ray diffraction crystallography studies revealed that complexes CT1-CT7 contained
one molecule of acylthiourea derivatives T1-T7, respectively, with two molecules of triphenylphosphine and one iodine. All acylthiourea ligands exhibited
neutral monodentate coordination with copper(I) through the sulfur atom.
Table 1: Physical data of the phosphanecopper(I) complexes (CT1-CT7).
C (%)
H (%)
N (%)
Compound
Chemical Formula
R
Molecular Weight (g/mol)
Yield (%)
Melting Point ( )
Calc
61.82
62.16
61.25
60.84
59.71
62.16
61.25
Found Calc Found Calc Found
CT1
CT2
CT3
CT4
CT5
CT6
CT7
C50H42CuIN2OP2S
C51H44CuIN2OP2S
C51H44CuIN2O2P2S
C50H42CuIN2O2P2S
C50H41ClCuIN2OP2S
C51H44CuIN2OP2S
C51H44CuIN2O2P2S
H
971.36
985.38
1000.09
987.08
1005.80
985.38
1000.09
81
79
82
85
89
75
80
154-156
155-158
152-154
156-158
166-168
172-174
171-173
61.53
61.96
61.38
60.93
59.91
62.30
61.11
4.36
4.50
4.43
4.29
4.11
4.50
4.43
4.37
4.37
4.29
4.02
4.01
4.48
4.37
2.88
2.84
2.8
2.87
2.66
2.71
2.73
2.79
2.65
2.69
3-Me
3-OMe
3-OH
3-Cl
2.84
2.79
2.84
2.80
2-Me
2-OMe
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3.2 IR Spectroscopic Characterization
The IR spectra for all the free ligands (T1-T7) presented strong vibrational bands in the wave
number at around 3350-3200 cm-1 regions, attributable to ν(N—H) stretching modes [25]. The
thiourea derivatives (T1-T7) can exist in the thiocarbonyl or thiol forms. In the solid state of these
compounds, the absence of the ν(S—H) band at about 2570 cm-1 and the presence of the ν(N—H)
bands in the range of 3000-3300 cm-1 in the IR spectra revealed the evidence for thiocarbonyl
tautomer formation [26].
The coordination of the ligands (T1-T7) with phosphanecopper(I) was confirmed by
comparing the IR spectra of the free ligands with those of the complexes (Table 2). The IR vibrational
bands for the complexes show obvious changes of the ν(C=S) bands at the region 1400-1200 cm-1 [8].
This is a significant indication that the sulfur atom of the thiourea involved in coordination with
copper(I). Another noticeable observation is that the IR bands at region 3300-3400 cm-1 and 1670-
1690 cm-1 attributed to ν(N—H) and ν(C=O) respectively [27, 28], which are all similar in the IR
spectra of the ligands and complexes. This ruled out the involvement of the thiocarbonyl nor the
amine group in coordination with the copper(I) metal.
The four characteristic thioamide bands (I-IV) of the free ligands which contributed from the
thioamide group HN-C=S, namely I; (ν(C—N) + δ(N—H) at about 1600-1500 cm-1), II; (ν(C=S) +
ν(C—H) at about 1400-1200 cm-1), III; (ν(C—N) + ν(C—S) at about 1200-1050 cm-1) and IV; (ν(C—
S)) at about 800-700 cm-1 [29, 30], have considerable changes in frequency upon coordination with
copper(I). Based on the four (I-IV) thioamide bands, they indicated an exclusive S-coordination mode
due to the coordination. Consequently, thioamide II, containing a contribution from the ν(C=S)
stretching vibration, generally appears to have reduced in intensity in the spectra of the complexes,
compared to the spectra of the respective free ligands. The absorptions at 800-780 cm-1 in the spectra
of free ligands (T1-T7) was attributed to the ν(C—S) stretching vibrations and it had shown some
shifting consistently to the range of 741-743 cm-1 in the spectra of the complexes. This slight changes
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supported the coordination through the sulfur atom with the copper(I) metal center [29]. However, the
bands of thioamide I and thioamide II, as expected, their changes in terms of the shifting and intensity
are less significant [31].
Table 2: IR spectral assignments for the acylthiourea (T1-T7) and their phosphanecopper(I)
complexes (CT1-CT7) (cm-1).
Wavenumber, v (cm-1)
Compound
Thioamide bands
N-H
C=O
I
II
III
IV
T1
CT1
T2
3257.25 (m)
3049.03 (w)
3323.81 (m)
3048.65 (w)
3270.57 (m)
3206.26 (w)
3320.67 (m)
3051.29 (w)
3287.13 (m)
3051.11 (w)
3258.02 (m)
3053.36 (w)
3267.41 (m)
3047.42 (w)
1671.54 (m)
1669.47 (m)
1667.59 (m)
1667.60 (m)
1671.77 (m)
1668.63 (m)
1670.54 (m)
1670.69 (m)
1668.87 (m)
1667.26 (m)
1668.63 (m)
1667.53 (m)
1674.35 (m)
1673.41 (m)
1526.39 (s)
1517.77 (s)
1519.09 (s)
1514.77 (s)
1522.07 (s)
1518.13 (s)
1518.50 (s)
1514.88 (s)
1516.94 (s)
1508.62 (s)
1517.80 (s)
1510.84 (s)
1538.75 (s)
1503.31 (s)
1357.40 (s)
1141.92 (s)
1143.89 (s)
1137.99 (s)
1139.24 (s)
1140.08 (s)
1142.55 (s)
1140.23 (s)
1138.95 (s)
1140.86 (s)
1146.98 (s)
1151.07 (s)
1148.00 (s)
1151.26 (s)
1148.48 (s)
793.27 (m)
741.63 (s)
792.57 (m)
741.79 (s)
784.87 (m)
742.00 (s)
735.15 (m)
741.94 (s)
792.00 (m)
742.84 (s)
742.56 (s)
740.11 (s)
750.70 (s)
742.12 (s)
-
1353.65 (s)
CT2
T3
-
1357.38 (s)
CT3
T4
-
1327.19 (s)
CT4
T5
-
1344.28 (s)
CT5
T6
-
1337.59 (s)
CT6
T7
-
1353.68 (s)
-
CT7
*w = weak, m = medium, s = strong
3.3 NMR Spectroscopic Characterization
1
The H NMR spectrum of complex CT1 showed multiplets at the aromatic region, which
integrated as 40 hydrogens at 8.04-7.19 ppm due to the aromatic protons of two phenyl rings of the
ligand and the aromatic protons of two triphenylphosphine molecules attached to the metal. Similar
multiplicities were also observed in the 1H NMR spectra of complexes CT2-CT7, which integrated as
1
39 hydrogens at the range of 8.52-6.80 ppm, as presented in Table 3. In the H NMR spectra of
complexes, the N(1)H appeared at the range of 10.00-9.60 ppm and has shifted downfield compared
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to the free ligands at the range of 11.70-11.40 ppm. This is due to the changes in the molecular
environment as a result of complexation with the metal, based on consistent observation of all the
complexes [32].
13
The C{1H} NMR spectra of these complexes showed the presence of 13 carbon signals in
complex CT1 and 17 carbon signals in complexes CT2, CT3, CT6 and CT7, while complexes CT4
and CT5 only had 16 carbon signals. These data are coherent with the formulation of each complex
containing one acylthiourea ligand molecules and two triphenylphosphine molecules in accordance
with the proposed structure of the mixed ligand copper(I) iodide complexes. The C=S carbon atom
resonance was observed in the farthest low field at a range between 178.49-180.56 ppm in the
13C{1H} spectrum of the free ligands, resultant of the conjugative effect of the thiourea skeleton. This
signal underwent a slight upfield shift to 176.58-179.15 ppm in all complexes. This is possibly due to
the electron delocalization induced from the coordination of copper(I) with the ligand through the
thiourea sulfur [10]. The carbon atoms of the phenyl rings in triphenylphosphine are observed in the
aromatic region with a higher abundance. It was also noticed that the signals split into doublets by the
magnetic field of phosphorus atoms. This splitting occurred even in the proton-decoupled spectrum,
this is expected because the carbon-phosphorus coupling is not turned off [33]. Meanwhile, the other
signals observed in the aromatic region were carbons due to the acylthiourea ligands.
The 31P NMR spectrum of the complexes in CDCl3 exhibited only one signal at around -5.00
ppm indicating the presence of the triphenylphosphine [34]. A single resonance signal was observed
because the chemical environment of the phosphorus atom from all of the triphenylphosphine are
similar [35]. These results are in good agreement suggesting that the nitrogen is not involved in
coordination with Cu(I) for all of the complexes. Hence, leaving the coordination occur only through
the
sulfur
atom.
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Table 3: 1H NMR assignments of acylthiourea (T1-T7) and their phosphanecopper(I) complexes (CT1-CT7) (ppm).
Chemical shifts, δ (ppm)
1H
13C{1H}
31P
Compound
Aromatic due to
PPh3
N(1)H
Aromatic
Others
-
C=S
C=O
Aromatic due to acylthiourea
Others
-
PPh3
9.86
(s, 1H)
9.92
8.04-7.19 (m,
40H)
137.36, 133.88, 133.32, 133.06, 131.31, 127.12,
124.67
134.18, 129.69,
128.94, 128.47
134.18, 129.68,
128.74, 128.56
134.17, 129.72,
129.05, 128.58
134.16, 129.78,
129.13, 128.63
134.16, 129.71,
129.06, 128.57
134.22, 129.76,
128.94, 128.57
134.19, 129.76,
128.99, 128.58
CT1
CT2
CT3
CT4
CT5
CT6
CT7
178.24 168.01
178.09 168.09
177.92 168.96
177.91 167.73
178.33 168.15
179.15 168.10
176.58 167.63
-5.38
-5.41
-5.3
8.04-7.18 (m,
39H)
2.34 (s, 3H)
-Me
138.92, 137.22, 133.85, 133.36, 133.09, 131.30,
128.99, 127.93, 125.20, 121.77
21.49 -
Me
(s, 1H)
9.81
8.03-6.80 (m,
39H)
3.76 (s, 3H)
-OMe
159.93, 138.43, 133.90, 133.25, 132.99, 131.31,
129.64, 116.60, 113.18, 109.74
55.51 -
OMe
(s, 1H)
9.61 (s,
1H)
7.98-6.74 (m,
39H)
5.14 (s, 1H)
-OH
155.95, 138.51, 133.16, 132.89, 131.35, 130.01,
128.25, 116.52, 114.14, 111.37
-
-
-5.09
-5.38
-5.33
-5.41
9.93 (s,
1H)
8.05-7.19 (m,
39H)
138.44, 134. 43, 133.29, 133.03, 131.09, 129.89,
128.61, 127.14, 124.64, 122.71
-
9.95 (s,
1H)
8.05-7.19 (m,
39H)
2.28 (s, 3H)
-Me
136.00, 133.91, 133.63, 133.08, 132.79, 131.19,
130.86, 127.91, 126.61, 126.48
18.09 -
Me
9.61 (s,
1H)
8.52-7.21 (m,
39H)
3.92 (s, 3H)
-OMe
151.16, 134.05, 133.12, 132.85, 131.58, 128.21,
127.14, 126.88, 123.73, 120.20
56.07 -
OMe
*s= single, d= doublet, t= triplet, m=multiplet
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3.4 X-ray Crystallography
The single crystal X-ray diffraction studies of phosphanecopper(I) complexes with substituted
acylthiourea ligand have been conducted to evaluate the coordination behavior of these polyfunctional
group ligands when forming complexes with copper(I) metal center. The steric effect of the bulky
phosphine co-ligands, which can modify the compound geometry and behavior was also explored
[36].
Prismatic yellow-colored crystals of CT1-CT7 were grown from its acetonitrile solution by
slow evaporation method at ambient atmosphere and collected to conduct the SCXRD analysis. The
crystallographic data and structural refinement details and parameters obtained from X-ray diffraction
analysis for all the crystals CT1-CT7 are listed in Table 4. The result revealed that all the
phosphanecopper(I) complexes, CT1-CT7 are isostructural, adopting the geometry of a distorted
tetrahedral geometry with one monodentate acylthiourea ligand, an iodine atom and two PPh3
moieties. Compounds CT1, CT2, CT3, CT4, CT7 shows isomorphism as they crystallized in the
monoclinic system with space group P21/c, while CT5 and CT6 crystallized in the triclinic system
ꢀ
with space group P1. Significant bond lengths and angles are shown in Table 5 and Table 6
respectively.
3.4.1 Crystal Structure of CT1- CT7
The molecular structure obtained for complex CT1 and CT5 is depicted in Figure 2 and
Figure 3 respectively, the H atoms of the PPh3were omitted for clarity. CT1 is a monomeric
compound, crystallizes in the monoclinic space group P21/c, that consists of four independent
[Cu(TI)(I)(PPh3)2] molecular units accommodated per cell. Whereas CT5 crystallizes in the triclinic
ꢀ
space group P1, that consists of two independent [Cu(T5)(I)(PPh3)2] molecular units accommodated
per cell. The asymmetric unit of complex CT1 showed that it is a mononuclear and four-coordinated
with one iodine, two triphenylphosphine units and one acylthiourea ligand, that is N-benzoyl-N’-
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phenylthiourea (T1), as a monodentate ligand coordinating via the sulfur, (S1) atom to the copper(I),
(Cu1) atoms. Again, CT1 is isostructural with CT2, CT3, CT4 and CT7, while CT5 is isostructural
with CT6.
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Table 4: Crystal data and refinement details for phosphanecopper(I) complexes (CT1-CT7).
Parameter
CCDC No
CT1
CT2
CT3
CT4
CT5
CT6
CT7
1865948
1865949
1875061
1874984
1865944
1865945
1865946
Empirical
C50H42CuIN2OP2S C51H44CuIN2OP2S C51H44CuIN2O2P2S C50H42CuIN2O2P2S C50H41Cl1CuIN2OP2S C51H44CuIN2OP2S
C51H44CuIN2O2P2S
formula
Formula weight
Temperature/ K
971.30
293(2)
985.32
293(2)
1005.75
293(2)
987.30
293(2)
1976.03
293(2)
985.33
293(2)
1001.32
293(2)
CuKα
CuKα
CuKα
CuKα
CuKα
CuKα
CuKα
Wavelength
(λ = 1.54178)
Monoclinic
P21/c
(λ = 1.54178)
Monoclinic
P21/c
(λ = 1.54178)
Monoclinic
P21/c
(λ = 1.54178)
Monoclinic
P21/c
(λ = 1.54178)
Triclinic
P-1
(λ = 1.54178)
Triclinic
P-1
(λ = 1.54178)
Monoclinic
P21/c
Crystal system
Space group
a/ Å
10.4262(3)
22.6541(6)
18.8774(6)
90.000
10.7295(5)
22.7196(10)
18.6290(8)
90.000
10.2510
22.8713(10)
19.0029(10)
90.000
10.3834(10)
22.3572(10)
18.7591(10)
90.000
11.7876(10)
12.7342(12)
17.6274(15)
79.475(7)
74.273(7)
65.999(9)
2318.8(4)
2
11.6335(6)
12.5117(6)
18.0259(8)
88.279(4)
71.833(4)
67.611(5)
2293.3(2)
2
10.4317(5)
22.8237(12)
19.1489(10)
90.000
b/ Å
c/ Å
α/ ˚
β/ ˚
90.491(3)
90.000
91.489(4)
90.000
91.230
91.400
90.266(5)
90.000
γ/ ˚
Volume/ Å3
90.000
90.00
4458.60(2)
4
4539.70(4)
4
4454.44(3)
4
4353.51(5)
4
4559.1(4)
4
Z
ρcalc, g/cm3
ꢁ/ mm-1
F (000)
2Θ range for
data collection/°
Reflections
1.536
1.536
1.495
1.506
1.412
1.395
1.459
7.583
7.583
7.585
7.753
7.790
7.324
7.411
2088
2088
2036
2000
995
980
2032
7.80 to 148.02
19369
7.78 to 148.34
19651
6.04 to 153.08
57755
6.16 to 153.2
56828
7.62 to 147.78
16134
7.68 to 148.044
15880
7.74 to 147.66
11884
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collected
7863
8943
9308
9073
9097
8904
7312
Independent
reflections
[Rint = 0.0385,
[Rint = 0.0525,
[Rint = 0.0287,
[Rint =0.0320,
Rsigma = 0.0194]
[Rint = 0.0918,
Rsigma =0.0827]
[Rint = 0.0859,
Rsigma = 0.0789]
[Rint = 0.0292,
Rsigma =0.0417]
Rsigma = 0.0365] Rsigma = 0.0558]
Rsigma = 0.0179]
Data/ restraints/
parameters
Goodness-of-fit
on F2
7863/0/524
1.023
8943/0/534
1.021
9308/0/542
1.046
9073/0/529
0.990
9097/0/533
1.033
8904/0/534
1.136
7312/0/543
1.028
Final R indices
[I>=2σ (I)]
Final R indices
(all data)
R1 = 0.0557,
wR2 = 0.1480
R1 = 0.0592,
wR2 = 0.1535
R1 = 0.0588,
wR2 = 0.1529
R1 = 0.0649,
wR2 = 0.1622
R1 = 0.0207,
wR2 = 0.0517
R1 = 0.0212,
wR2 = 0.0520
R1 = 0.0274,
wR2 = 0.0738
R1 = 0.0283,
wR2 = 0.0747
R1 = 0.0745,
wR2 = 0.1848
R1 = 0.0819,
wR2 = 0.1982
R1 = 0.0782,
wR2 = 0.2036
R1 = 0.0858,
wR2 = 0.2221
R1 = 0.0457, wR2 =
0.1249
R1 = 0.0504, wR2 =
0.1319
Largest diff.
peak/
1.20/-1.94
1.31/-1.98
0.28/-0.89
1.44/-1.23
2.45/-1.91
2.12/-2.80
1.10/-1.18
hole/ e.Å-3
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Table 5: Selected bond lengths (Å) for phosphanecopper(I) complexes (CT1- CT7).
Length/Å
Atom
Atom
CT1
CT2
CT3
CT4
CT5
CT6
CT7
Cu1
Cu1
Cu1
Cu1
S1
I1
2.3745(9)
2.6350(6)
2.2883(9)
2.2840(9)
2.3588(9)
2.6369(6)
2.2886(10)
2.2833(9)
2.3266(4)
2.6106(2)
2.2912(4)
2.2801(4)
2.3426(5)
2.6520(3)
2.2786(5)
2.2730(5)
2.4089(14)
2.6462(8)
2.2836(13)
2.2989(13)
2.4095(16)
2.6349(8)
2.2870(15)
2.2915(16)
2.3550(10)
2.6330(6)
2.3061(10)
2.2966(10)
P1
P2
Table 6: Selected bond angles (˚) for phosphanecopper(I) complexes (CT1- CT7).
Angle/˚
Atom
Atom
Atom
CT1
CT2
CT3
CT4
CT5
CT6
CT7
P1
P1
P1
P2
P2
S1
Cu1
Cu1
Cu1
Cu1
Cu1
Cu1
S1
I1
99.71(3)
104.93(3)
123.46(4)
104.14(4)
109.07(3)
115.84(3)
101.52(3)
105.92(3)
123.37(4)
103.73(4)
108.63(3)
113.75(3)
99.93(15)
105.03(13)
124.24(16)
106.88(16)
107.83(12)
112.88(12)
99.77(2)
108.50(5)
104.02(4)
123.42(6)
102.19(6)
110.62(4)
107.26(4)
106.69(6)
99.62(4)
106.16(3)
123.52(4)
106.87(4)
107.50(3)
113.18(3)
103.73(17)
124.12(2)
104.75(2)
108.85(16)
116.06(16)
101.49(4)
122.53(6)
103.75(6)
115.58(5)
115.58(5)
P2
S1
I1
I1
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It is noted that the angle between the phenyl rings of the acylthiourea ligands shows some
differences i.e. the phenyl ring appeared to be planar in CT5 and CT6, while perpendicular in the
others. The presence of intramolecular hydrogen bond N—HꢀꢀꢀO=C (with the formation of a '6-
membered ring' ), explained the stability of the complex in forming a monodentate S behaviour of the
acylthiourea ligand [37].
Figure 2: Three-dimensional structure of CT1 complex.
Coordination bonds are listed in Table 5. It shows that the range for Cu—S bond distance are
from (2.2832(14)-2.6456(9)) Å, are consistent with the distances usually found for tetrahedrally
coordinated copper(I) complexes with S-donors ligands [8, 31, 34]. The Cu—P distances ranges from
(2.2730 (5)-2.3061 (10)) Å are similar to Cu—P distances in previous reported analogous complexes
[10, 36]. The Cu—I bond ranges from (2.6106 (2)-2.6520 (3)) Å is less than the sum of the ionic radii
of Cu and I, that is 2.97 Å, agrees to other reported copper(I) halide complexes [24, 38-40].
The bond angles around the copper(I) atom is in the range of (99.62 (4)-124.24 (16))˚
deviated from the ideal tetrahedral bond angle of 109.5˚ as shown in Table 6. It is significant to
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observe the P1—Cu1—P2 angle, that is above 120˚; (122.53–124.24)˚, subtended by the bulky
triphenylphosphine ligands [24]. This reveals a distorted tetrahedral coordination environment around
each copper(I) atom in the phosphanecopper(I) complex. The distorted tetrahedral geometry is also
reported in the copper(I) halide complexes with mixed PPh3/sulfur-based ligands [24, 41, 42]. This
demonstrated that the two triphenylphosphine ligands exerted significant steric effects on the
coordination geometry of the complexes [24].
Figure 3: Three-dimensional structure of CT5 complex.
3.5 Hirshfeld Surface Analysis
In order to exemplify the interactions of the crystal structures in this series of closely related
molecules, the Hirshfeld surface analysis was conducted and their 2D fingerprint plots were
established using CrystalExplorer17 software [22]. All the Hirshfeld surfaces were generated for all
the structure of the phosphanecopper(I) complexes CT1-CT7. There were four different Hirshfeld
surfaces obtained, namely; dnorm, shape index, curvedness and electrostatic potential. Since the
complex CT1-CT7 are all closely related structures (where they only differ by a few atoms or a small
18

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group of atoms), their Hirshfeld surface analysis results in a somewhat analogous but still differ
considerably. All the Hirshfeld surfaces were elucidated as transparent to permit visualization of the
molecular structure and the positioning of each of the complexes was set individually in accordance
with the specific and significant orientation of interest. Such information is crucial to fully understand
and appreciate the interaction based on the crystal packing of the entire molecule [15].
3.5.1 The Hirshfeld Surface Maps
Figure 4: Relevant complementary patches and the neighboring molecule on the shape index
surface of CT5
The Hirshfeld surface mapped with shape index function illustrated the consistent pattern of
adjacent blue and red triangles for complexes CT5 as in Figure 4 respectively. They showed a planar
stacking arrangement of the molecules, a typical characteristic for a planar geometry aromatic
hydrocarbon rings arranged in such a way. This is obvious when associated to the de and di range,
which is within the van der Waals radii separation (clearly seen as the large white region in the dnorm
mapping surrounding the planar surface of the ligand) [13]. The alternating red and blue region
represented the concave and convex structure correspondingly, indicating that the neighboring
molecule participated in a πꢀꢀꢀπ stacking interaction in these crystal structures [43]. Complex CT6
exhibits similar properties whereas, there is no such existence of participation in complexes CT1,
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CT2, CT3, CT4 and CT7.
Figure 5: Curvedness mapping of CT6
This is further proven by the evidence observed on the of the Hirshfeld surface. This gives
insight into the different acylthiourea surface geometry resulting in different crystal packing.
Complexes CT5 and CT6 (Figure5) showed relatively large green plane at the region of the
acylthiourea ligand and CT5 was observed to be more planar than CT6. This deduction is based on
the fine blue lines on the CT6 surface around the acylthiourea ligand. This is due to the presence of
the tetrahedral methyl group on the acylthiourea ligand. Instead, obvious sharp edges were observed
on the surface surrounding the acylthiourea in CT5 because the chlorine atom is planar to the
aromatic ring. The curvedness mapping provided a convincing suggestion of the planarity of CT5 and
CT6 and that give rise to the πꢀꢀꢀπ stacking interaction between the crystal molecules resulting in a
triclinic crystal packing [44]. Whereas all the complexes CT1, CT2, CT3, CT4, and CT7 showed
many sharp edge faces and no such flat surfaces on the aromatic rings of the acylthiourea ligand. The
differences between these phosphanecopper(I) complexes were due to their distinctive conformations
affected by the small different substituent groups [13].
The molecular electrostatic potentials mapped on Hirshfeld surfaces is over the range of -0.09
to 0.04 au for all the molecules. In specific, the blue (electropositive) and red (electronegative)
mapping provided a very strong indication of the theory of electrostatic complementarity. The
20

ACCEPTED MANUSCRIPT
complexes presented a rather dramatic fashion and clear distinction can be observed between them.
This proved how small substituent groups on the acylthiourea affected the electrostatic potential of the
complexes. The intermolecular hydrogen bonding of N—HꢀꢀꢀO=C interaction that was observed in
CT3, CT4 and CT7 is signified based on the electrostatic environment on the surface that resulted in
the dipole moments of the molecule. For instance, Figure 6 illustrated the electrostatic potential
mapping of complex CT4. The presence of a hydroxy group (dominated with a blue surface) on the
acylthiourea ligand consequently involved in electrostatic complementary interaction with the iodine
(enveloped with a red surface) of the adjacent molecule. Thus, forming a polymeric crystal chain
interaction. Observing at the electrostatic potential mapping of complexes CT1 and CT2, it indicates
similar electrostatic potential distribution. This is where the area enveloping the triphenylphosphine
group appeared to be blue and the region for the acylthiourea ligand is overall red. Therefore, in the
complexes (CT1-CT2) crystal packing, they arranged themselves accordingly by obeying the
electrostatic complementarity.
Figure 6: Electrostatic potential mapping and the polymeric neighboring molecules of CT4
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The dnorm (-0.5 to 1.5) Å mapping of the Hirshfeld surface revealed several red spots with
different sizes and intensity. The red spots proved that the intramolecular distance to be notably
shorter than the sum of the van der Waals radii. Larger and more intensify red spots noticed on
complex CT3 (Figure 7) and CT7, corresponding to a close and strong intermolecular hydrogen
bonding and they are consistent with the crystal structures. They showed the dominant interactions at
the thiourea backbone between the hydrogen of the amine and its adjacent oxygen of the carbonyl
atoms (N—HꢀꢀꢀO=C), forming a dimeric arrangement in the crystal packing. Thus, it built the stability
of the unit cell packing. For complex CT4, apart from the N—HꢀꢀꢀO=C interaction, there is also
additional intense red spot representing the intermolecular hydrogen bonding due to the presence of
hydrogen of the hydroxy group and the iodine atom (O—HꢀꢀꢀI—Cu). In the case of CT1, CT2, CT5
and CT6, they were only dotted with smaller and paler red spots representing weaker close contacts
[7].
Figure 7: Neighboring molecules associated with intermolecular hydrogen bonding on a dnorm of
CT3.
3.5.2 2D Fingerprint Plot
The full colored, 2D fingerprint plots of the Hirshfeld surface was plotted over the range 0.4-
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2.8 Å in each of di and de. Each fingerprint plot was decomposed into specific pairs of atom-types
contributions to highlight all their interactions (including H⋅⋅⋅H, H⋅⋅⋅C, H⋅⋅⋅O, H⋅⋅⋅I, H⋅⋅⋅S, H⋅⋅⋅N,
C⋅⋅⋅C and other), allowing the relationship and their contributions towards the different intermolecular
interaction types within the crystal packing [16]. For each plot, the outline of the original fingerprint
plots is represented as a grey shadow and the reciprocal contacts were included.
Each Hirshfeld surface of the complexes does not generate the same 2D plotting and there are
distinguishable likenesses and differences that could be discussed. For all the complexes (CT1-CT7),
they showed a large number and a great spread of points (de and di) displayed as tailed structures; as
seen at the top right of the plots where they nearly filled up all the available plotting area (Figure8).
These regions also described that de is generally greater than di, indicating that voids exist around the
molecule in the crystal packing are very small. This type of points distribution was observed and
reported in other benzene and phenyl-containing compounds, showing both de and di points covering
much greater ranges in the fingerprint plots [15, 45, 46]. This also supported the large blue areas
surrounding the aromatic rings in the dnorm mapping, corresponding to the longer contact distances
contributed by the bulky phosphine group.
Figure 8: 2D fingerprint plots of CT1 (Full), CT3 (H···H contacts) and CT2 (H···C contacts)
The intermolecular HꢀꢀꢀH contacts (Figure 8) is in accordance with the Hirshfeld surface
analysis for all the molecules, containing from 52.6 to 67.3 % of the total number of contacts. They
are major contributors to the crystal packing. The characteristic spikes representing the shortest HꢀꢀꢀH
contacts are converging along the diagonal line in the fingerprint plots at de + di ≈ 2.2-2.4 Å.
23

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Accordingly, it showed obvious short head-to-head HꢀꢀꢀH contacts [15]. The structures of all
molecules are also dominated by HꢀꢀꢀC contacts, including from 20.4 to 34.5 % of the total Hirshfeld
surface areas. The presence of ‘wings’ at the bottom right and top left of each plot in the fingerprint
plots are a typical representation of a C⋅⋅⋅H contact (Figure 8). In all the complexes, the shortest de +
di ≈ 2.6–2.7 Å are documented as characteristic of a C—Hꢀꢀꢀπ interaction. The wing at the top left
representing di < de relates to points on the surface around the C—H donor. While the bottom right
plotting where de < di corresponds to the surface throughout the π acceptor [15]. All plots contain one
or more C—Hꢀꢀꢀπ interactions because of the presence of the multiple aromatic rings [46].
Figure 9: 2D fingerprint plots of CT7 (H···O contacts), CT4 (H···I contacts) and CT5 (C···C
contacts)
The spikes of HꢀꢀꢀO and HꢀꢀꢀI contacts corresponded to the presence of interactions in all of
the complexes. However, throughout the series, only CT3, CT4 and CT7 showed a higher
contribution of HꢀꢀꢀO contacts which is above 4 %. The sharpest point featured a closer contact of de +
di ≈ 2.2–2.4 Å which is in the range that is in agreeable to the intermolecular hydrogen bonding
between N—H donor and O=C acceptor (N—HꢀꢀꢀO=C) [16] as in Figure 9. All the complexes showed
a trend for the HꢀꢀꢀI contact in the range of 3-4 % of the surface area. CT4 (Figure 9) showed the
shortest contact of de + di ≈ 2.8–3.0 Å that allowed intermolecular hydrogen bonding. This is expected
for interaction engaged between strong hydrogen bond donor O—H and a strong hydrogen bond
acceptor I—Cu (O—HꢀꢀꢀI—Cu) [47].
A particular observation worth discussing from the fingerprint plots is the interests in the
24

ACCEPTED MANUSCRIPT
relative areas associated with CꢀꢀꢀC contacts and correlated with the presence of planar stacking
arrangement of aromatic πꢀꢀꢀπ interaction [15]. This is observed in complexes CT5 (Figure 9) and
CT6 with the contribution of 3.7 % and 2.9 % respectively but there is a negligible amount of
contribution, with less than 1 % in the rest of the series. The structures are further presented by a
smaller insignificant proportion of HꢀꢀꢀS and HꢀꢀꢀN interactions, contributes a very small percentage of
the molecular surfaces, that is less than 1.4 %. Thus, their contacts are almost insignificant throughout
the whole series. Figure 10 illustrated the selected percentage of contributions of the Hirshfeld surface
area. They represented the summarization of the quantitative information of intermolecular
interactions contained in the molecular crystals (CT1-CT7). They all show almost similar pattern
except for CT5 show a larger percentage of other contacts, this is majorly contributed by the HꢀꢀꢀCl
contacts.
H⋯H
H⋯C
H⋯O
H⋯I
H⋯S
H⋯N
C⋯C
Other
CT1
CT2
CT3
CT4
CT5
CT6
CT7
0%
10%
20%
30%
40%
50%
PERCENTAGE, %
60%
70%
80%
90%
100%
Figure 10: Percentage contributions of the Hirshfeld surface area for phosphanecopper(I)
complexes (CT1-CT7).
Acknowledgements
This work was funded by the University of Malaya, under grant BKP086-2016. The authors
also thanked Research Centre for Crystalline Materials, Sunway University for permitting the usage
of the single crystal X-ray diffractometer.
25

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Table 1: Physical data of the phosphanecopper(I) complexes (CT1-CT7).
C (%)
H (%)
N (%)
Compound
Chemical Formula
R
Molecular Weight (g/mol)
Yield (%)
Melting Point ( )
Calc
61.82
62.16
61.25
60.84
59.71
62.16
61.25
Found Calc Found Calc Found
CT1
CT2
CT3
CT4
CT5
CT6
CT7
C50H42CuIN2OP2S
C51H44CuIN2OP2S
C51H44CuIN2O2P2S
C50H42CuIN2O2P2S
C50H41ClCuIN2OP2S
C51H44CuIN2OP2S
C51H44CuIN2O2P2S
H
971.36
985.38
1000.09
987.08
1005.80
985.38
1000.09
81
79
82
85
89
75
80
154-156
155-158
152-154
156-158
166-168
172-174
171-173
61.53
61.96
61.38
60.93
59.91
62.30
61.11
4.36
4.50
4.43
4.29
4.11
4.50
4.43
4.37
4.37
4.29
4.02
4.01
4.48
4.37
2.88
2.84
2.8
2.87
2.66
2.71
2.73
2.79
2.65
2.69
3-Me
3-OMe
3-OH
3-Cl
2.84
2.79
2.84
2.80
2-Me
2-OMe