Hypodentate coordination of N,N-di(alkyl/aryl)-N′-acylthiourea derivatives in Cu(I) complexes

Article abstract of DOI:10.1016/j.poly.2011.12.002

New four-coordinated tetrahedral Cu(I) complexes of the general formula [CuCl(HL)(PPh₃)₂] have been synthesized from the reactions between [CuCl₂(PPh₃)₂] and N-(dibenzylcarbamothioyl)benzamide (HL1) o

Full text of DOI:10.1016/j.poly.2011.12.002

Polyhedron 34 (2012) 41–45
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Hypodentate coordination of N,N-di(alkyl/aryl)-N0-acylthiourea derivatives in
Cu(I) complexes
N. Gunasekaran a, S.W. Ng b,c, E.R.T. Tiekink b, R. Karvembu a,
⇑
a Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015, India
b Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
c Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history:
New four-coordinated tetrahedral Cu(I) complexes of the general formula [CuCl(HL)(PPh3)2] have been
synthesized from the reactions between [CuCl2(PPh3)2] and N-(dibenzylcarbamothioyl)benzamide
(HL1) or N-(methylpentylcarbamothioyl)benzamide (HL2) in benzene. The complexes have been charac-
terized by elemental analyses, IR, UV–Vis, 1H, 13C and 31P NMR spectroscopy. The molecular structures of
[CuCl(HL1)(PPh3)2] (1) and [CuCl(HL2)(PPh3)2] (2) were determined by single crystal X-ray crystallogra-
phy. Each complex displays a distorted tetrahedral, ClP2S, coordination geometry with hypodentate coor-
dination of acylthiourea ligands which coordinate the Cu(I) centre through sulfur atom exclusively.
Ó 2011 Elsevier Ltd. All rights reserved.
Received 19 October 2011
Accepted 6 December 2011
Available online 27 December 2011
Keywords:
Copper(I)
N-Dialkyl/aryl-N0-acylthiourea derivatives
Hypodentate coordination
Crystal structure
1. Introduction
bidentate [18] or monobasic bridging ligands [19] are also rare.
These thiourea derivatives exhibit remarkable applications in
Generally, a reaction between a transition metal ion and a mul-
tidentate ligand proceeds with coordination of all suitably disposed
ligand donor atoms to form a metal complex with concomitant for-
mation of chelate ring(s). One reason for this might be the entropy
increase which occurs on replacement of monodentate ligands of
the metal precursor by the donor atoms of a multidentate ligand
to form chelate rings [1]. However, there are some examples in
which multidentate ligands are coordinated through less than max-
imum number of potential donor atoms and avoid the formation of
chelate ring(s) [2]. Constable has introduced the term ‘hypodentate’
to describe this type of coordination [3]. Metal complexes of hypod-
entate ligands have gained importance in the view of design and
syntheses of heteropolymetallic systems [4,5].
analytical and biological sciences [20–22]. The recent increase in
attention paid to these complexes has arisen mainly due to their
coordination versatility and varied applications such as in precious
metal separation and extraction [20], single source precursors for
nanomaterials [21], biological activity [23,24], etc. We have
reported N-[di(alkyl/aryl)carbamothioyl]benzamide complexes of
Ru(II) [25], Ru(III) [26], Cu(I) [27] and Co(III) [28] as catalysts for
oxidation of alcohols to the corresponding carbonyl compounds in
the presence of oxidants such as N-methylmorpholine-N-oxide
(NMO)/hydrogen peroxide/tert-butyl hydroperoxide (TBHP). We
report herein the synthesis, characterization and crystal structures
of new four-coordinated tetrahedral copper(I) complexes contain-
ing hypodentate N-[(dibenzyl/methylpentyl)carbamothioyl]benz-
amide and triphenylphosphine ligands; see Fig. 1 for the chemical
structures of the ligands used in this study.
N-Alkyl/aryl-N0-acylthiourea or N,N-di(alkyl/aryl)-N0-acylthiou-
rea are known to form stable complexes with a large number of tran-
sition metal ions [6–8]. Due to the presence of O, N, N0 and S donor
atoms, these versatile ligands coordinate in four different modes
to the metal ions. In the majority of their structurally characterized
complexes, they act as chelating bidentate O,S-monoanionic ligands
[9,10]. Hypodentate coordination only through sulfur as neutral,
monodentate ligand is rare and seen in some Au(I) [11], Ag(I) [12],
Hg(II) [13], Pt(II) [14,15] and Cu(I) [16,17] complexes. Examples of
transition metal complexes with acylthiourea ligands as neutral
⇑
Corresponding author. Tel.: +91 431 2503636; fax: +91 431 2500133.
E-mail address: kar@nitt.edu (R. Karvembu).
Fig. 1. Chemical structures of ligands investigated herein.
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.12.002

42
N. Gunasekaran et al. / Polyhedron 34 (2012) 41–45
13C NMR in CDCl3, d ppm: 172.96 (C@S), 157.80 (C@O), 122.22,
2. Experimental
123.47, 125.66, 125.77, 127.53, 127.67 (aromatic), 49.95, 35.25,
22.22, 19.31 (CH2), 15.94, 7.66 (CH3). 31P NMR in CDCl3, d ppm:
29.38 (s).
2.1. Materials and reagents
All the chemicals were obtained from commercial sources and
used as received. The solvents were purified and dried in accordance
with the standard literature methods. The precursor [CuCl2(PPh3)2]
was prepared by the literature procedure [29]. N-(Benzylcarbamo-
thioyl)benzamide (HL1) and N-(methylpentylcarbamothioyl)benz
amide (HL2) were prepared from benzoyl chloride, potassium
thiocyanate and dibenzyl amine or n-methylpentyl amine in dry
acetone [30].
2.4. X-ray crystallography
Intensity data were measured at 100 K on an Agilent Technolo-
gies SuperNova Dual CCD with an Atlas detector fitted with Mo K
a
radiation with hmax = 27.5°. The data processing and absorption
correction were accomplished with CRYSALIS PRO [31]. The structures
were solved by direct-methods with SHELXS-97 [32] and refinement
(anisotropic displacement parameters, hydrogen atoms in the rid-
ing model approximation and a weighting scheme of the form
2.2. Physical measurements
w = 1/[r
2(Fo2) + (aP)2 + bP] for P = (Fo2 + 2Fc2)/3) was on F2 by
means of SHELXL-97 [32]. The crystallographic data and the final
refinement details are given in Table 1. Figs. 2 and 3 were drawn
with ORTEP [33] at the 50% probability level and the remaining crys-
tallographic figures were drawn with DIAMOND using arbitrary
Microanalyses were carried out with a Vario EL AMX-400 ele-
mental analyzer. Melting points were recorded with a Veego
VMP-D melting point apparatus and were uncorrected. FT-IR spec-
tra were recorded as KBr pellets with a PerkinElmer Spectrum RX1
FT-IR spectrophotometer in the range 4000–400 cmꢀ1. Electronic
spectra of the complexes were recorded in ethanol solutions using
a PG Instruments Ltd T90+ spectrophotometer in the 800–200 nm
range. Magnetic susceptibility measurements were made with a
Sherwood Scientific auto magnetic susceptibility balance. 1H, 13C
and 31P NMR spectra were recorded in Bruker Avance 400 MHz
instrument in CDCl3. TMS was used as an internal standard for
1H and 13C NMR spectra. H3PO4 was used as an internal standard
for 31P NMR spectra.
Table 1
Crystal data for 1 and 2.
Crystal data
1
2
Empirical formula
Formula weight
Crystal colour
Crystal dimensions (mm)
Crystal system
Space group
a (Å)
C
58H50ClCuN2OP2S
C50H50ClCuN2OP2S
887.91
colourless
983.99
light-yellow
0.20 ꢁ 0.25 ꢁ 0.30
monoclinic
C2/c
35.2407(11)
11.4936(3)
27.3488(9)
90
118.896(4)
90
9698.3(5)
8
0.20 ꢁ 0.30 ꢁ 0.40
triclinic
ꢀ
P1
12.8918(4)
13.3376(5)
14.0061(5)
100.287(3)
103.483(3)
104.271(3)
2197.29(13)
2
b (Å)
c (Å)
2.3. Synthesis of Cu(I) complexes
a
(°)
b (°)
Both the complexes were prepared using the following general
procedure. Ligand (HL) (0.1980–0.2703 g, 0.75 mmol) dissolved in
benzene (15 mL) was added to [CuCl2(PPh3)2] (0.5 g, 0.75 mmol)
in benzene (25 mL). The mixture was stirred for 36 h at 27 °C. This
was concentrated to 3 mL and an ethyl acetate/n-hexane mixture
(25 mL; 1:9) was added. The resultant orange oily precipitate
was stirred, filtered, recrystallized from dichloromethane/n-hex-
ane and dried in vacuo.
c
(°)
V (Å3)
Z
Dcalc (g cmꢀ3
F(000)
)
1.348
4096
0.658
1.342
928
0.718
l
(Mo K
a
) (mmꢀ1
)
Reflections collected
Rint
24116
0.031
17607
0.030
Unique reflections
Observed reflections [I > 2
R [observed reflections]
a, b, in weighting scheme
wR (all data)
10824
8906
0.037
0.043, 9.326
0.098
9718
8218
0.037
0.032, 1.047
0.088
r(I)]
[CuCl(HL1)(PPh3)2] (1) was prepared from N-(dibenzylcarbamo
thioyl)benzamide (HL1) (0.2703 g, 0.75 mmol) and [CuCl2(PPh3)2]
(0.5 g, 0.75 mmol). Single crystals suitable for X-ray diffraction
were grown at room temperature from ethyl acetate. Yield: 88%,
decomposition point 172 °C. Anal. Calc. for C58H50ClCuN2OP2S
(formula weight 984.04): C, 70.79; H, 5.12; N, 2.85; S, 3.26. Found:
C, 70.76; H, 5.07; N, 2.78; S, 3.21%.
(N–H), 1689 (C@O), 1255 (C@S), 1435, 1095, 744 (PPh3). UV [etha-
nol, d in nm (
in dm3 molꢀ1 cmꢀ1)]: 209 (68,142), 277 (20,828). 1H
leff = 0. FT-IR (KBr) m
cmꢀ1: 3329
e
NMR in CDCl3, d ppm: 7.15–8.26 (m, 45H, aromatic), 11.80 (s, 1H,
N–H), 4.68 (2H, CH2), 5.13 (2H, CH2). 13C NMR in CDCl3, d ppm:
175.50 (C@S), 158.45 (C@O), 121.96, 122.05, 123.19, 127.32,
127.47 (aromatic). 31P NMR in CDCl3, d ppm: 28.10 (s).
[CuCl(HL2)(PPh3)2] (2) was prepared from N-(methylpentyl
carbamothioyl)benzamide (HL2) (0.1980 g, 0.75 mmol) and
[CuCl2(PPh3)2] (0.5 g, 0.75 mmol). Single crystals suitable for
X-ray diffraction were grown at room temperature from dichloro-
methane solution by the diffusion of diethyl ether vapour. Yield:
85%, decomposition point 165 °C. Anal. Calc. for C50H50ClCuN2OP2S
(formula weight 887.95): C, 67.63; H, 5.68; N, 3.15; S, 3.61. Found:
C, 67.60; H, 5.63; N, 3.10; S, 3.58%.
(N–H), 1690 (C@O), 1178 (C@S), 1435, 1094, 744 (PPh3). UV [etha-
nol, k in nm (
in dm3 molꢀ1 cmꢀ1)]: 209 (64,285), 270 (11,228). 1H
leff = 0. FT-IR (KBr) m
cmꢀ1: 3181
e
NMR in CDCl3, d ppm: 7.27–8.19 (m, 35H, aromatic), 11.35 (s, 1H,
N–H), 3.50 (t, 2H, CH2), 3.18 (s, 3H, CH3), 1.98–2.16 (m, 2H, CH2),
1.69–1.78 (m, 2H, CH2), 1.22–1.43 (m, 2H, CH2), 0.92 (t, 3H, CH3).
Fig. 2. Molecular structure of 1 showing atomic labelling schemes. The H atoms
have been omitted for reasons of clarity.

N. Gunasekaran et al. / Polyhedron 34 (2012) 41–45
43
Table 2
Selected bond lengths (Å) and bond angles (°) for 1 and 2.
Parameter
1
2
Cu–Cl1
Cu–S1
Cu–P1
Cu–P2
2.3322(5)
2.3873(6)
2.2718(5)
2.2738(5)
1.688(2)
1.218(2)
1.325(3)
1.408(2)
106.434(19)
107.71(2)
108.54(2)
110.95(2)
96.71(2)
2.3430(5)
2.3902(5)
2.2745(5)
2.2670(5)
1.6920(19)
1.221(2)a
1.318(3)
S1–C37
O1–C52
N1–C37
N2–C37
Cl1–Cu–S1
Cl1–Cu–P1
Cl1–Cu–P2
S1–Cu–P1
S1–Cu–P2
P1–Cu–P2
1.406(2)
104.841(18)
102.056(19)
107.62(2)
116.52(2)
101.636(19)
122.76(2)
124.91(2)
a
Distance is for O1–C44.
C@S group [30]. In the spectra of complexes 1 and 2, this band was
observed in the lower frequency region, i.e. 1178–1255 cmꢀ1, con-
sistentwithreducedelectrondensityinthisbondandtherefore,sug-
gesting the coordination of the sulfur atom to copper ion [37]. The
free ligands exhibited a strong band corresponding to the C@O group
in the region 1651–1693 cmꢀ1 and to the N–H group in the region
3329–3181 cmꢀ1 [38,39]. These bands also appeared in the same re-
gions in the complexes, which indicate that, the C@O and N–H
groups are in similar environments to those found in the uncoordi-
nated ligands. In addition, the complexes showed new bands around
1435, 1100 and 750 cmꢀ1, which are due to triphenylphosphine li-
gand [37].
Fig. 3. Molecular structure of 2 showing atomic labelling schemes. The H atoms
have been omitted for reasons of clarity.
spheres [34]. The data manipulation and the interpretation were
done with WINGX [35] and PLATON [36].
3. Results and discussion
The new copper complexes 1 and 2 were diamagnetic (leff = 0),
indicating the presence of copper in the +1 oxidation state. In the
3.1. Synthesis
UV–Vis spectra of complexes in ethanol solution, bands observed
e
= 11,228–68,142 molꢀ1 cmꢀ1 dm3)
The Cu(I) complexes [CuCl(HL1)(PPh3)2] (1) and [CuCl(HL2)
(PPh3)2] (2) reported here have been synthesized by reacting
[CuCl2(PPh3)2] with N-(dibenzylcarbamothioyl)benzamide (HL1)
or N-(methylpentylcarbamothioyl)benzamide (HL2), respectively,
in benzene (Scheme 1), indicating that Cu(II) is reduced to Cu(I)
during the course of reaction. Analytical, spectral and single crystal
X-ray diffraction studies reveal that complexes 1 and 2 contain one
molecule of HL1 and HL2, respectively, in addition to two mole-
cules of PPh3. The HL1 and HL2 ligands exhibit neutral monoden-
tate (hypodentate) coordination through the sulfur atom to Cu(I).
The complexes obtained are orange, air-stable, non-hygroscopic
in nature, soluble in acetone, acetonitrile, benzene, dichlorometh-
ane, chloroform, DMSO and DMF, and insoluble in n-hexane and
water. The analytical data obtained are in good agreement with
the proposed molecular formulae.
in the region 209–277 nm (
have been assigned to metal to ligand charge transfer (MLCT) or li-
gand centred
p⁄ transitions [40].
p
–
The 1H, 13C and 31P NMR spectra of 1 and 2 have been recorded
in CDCl3 solution. The 1H NMR spectra showed a complex multiplet
around 7.15–8.26 ppm, which has been attributed to the aromatic
protons present in the triphenylphosphine and N-[(dibenzyl/meth-
ylpentyl)carbamothioyl]benzamide ligands. The characteristic
N–H signal in the region 11.35–11.80 ppm in the ligands was
present in the 1H NMR spectra of both the complexes indicating
the non-participation of the N–H group in coordination. Complex
1 showed two singlets at 4.68 and 5.13 ppm, which are assigned
to the methylene protons of the N-(dibenzylcarbamothioyl)benz-
amide ligand. In complex 1, the amidic (O)C–NH and thioamidic
NH–C(S), and (S)C–N(R/R) bonds of the coordinated ligand are
shorter than the actual C–N single bond. Because of this partial
double bond character of the (S)C–N(R/R) bond, the rotation
around this bond is restricted in solution on the NMR time scale.
Hence separated two singlets were observed for the two methy-
lene groups of the (S)C–N(CH2)2– moiety in complex 1 [6]. The
3.2. Spectroscopy
A medium intensity band was observed around 1239–1314 cmꢀ1
in the FT-IR spectra of the free ligands which is characteristic of the
Scheme 1. Synthesis of Cu(I) complexes 1 and 2.

44
N. Gunasekaran et al. / Polyhedron 34 (2012) 41–45
Fig. 4. Supramolecular chain in the crystal structure of 1. The C–H. . .O and C–H. . .Cl interactions are shown as orange and blue dashed lines, respectively. (For interpretation
of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 5. Supramolecular chain in the crystal structure of 2. The C–H. . .O and C–H. . .Cl interactions are shown as orange and blue dashed lines, respectively. (For interpretation
of the references to colour in this figure legend, the reader is referred to the web version of this article.)
same trend was also noted in the 1H NMR spectrum of ligand HL1.
A triplet appeared at 3.50 ppm in complex 2 due to the methylene
protons proximate to nitrogen. Complex 2 also exhibited three
multiplets at 1.98–2.16, 1.69–1.78 and 1.22–1.43 ppm which were
attributed to remaining methylene protons of aliphatic carbon
chain. A triplet at 0.92 ppm and a singlet at 3.18 ppm in complex
2 have been assigned to the terminal methyl protons of N-(meth-
ylpentylcarbamothioyl)benzamide ligand. The signals observed in
the range 121.96–127.67 ppm in 13C NMR spectra of 1 and 2 are
attributed to the aromatic carbons present in the triphenylphos-
phine and N-[(dibenzyl/methylpentyl)carbamothioyl]benzamide
ligands. The 13C NMR spectra of both complexes showed signals
in the region 172.96–175.50 and 157.80–158.45 ppm, which are
assigned to the C@S and C@O carbons, respectively. Both the
complexes exhibited resonances due to aliphatic carbons in the
expected regions. Complexes 1 and 2 showed only one signal at
28.10 and 29.38 ppm, respectively in their 31P NMR spectra.
from the Cu(I) centre and the amine-H participates in an intramo-
lecular N–H. . .Cl hydrogen bond to close a S(6) {. . .HNCSCuCl} ring.1
Moreover, a comparison of the S–C and N–C parameters in the unco-
ordinated ligand, HL1 [38], with those in 1 confirm little change in the
electronic structures. For example, the C@S bond in 1 of 1.688(2) Å is
equal within experimental error compared to the equivalent bond in
HL1 of 1.676(3) and 1.678(3) Å for the two independent molecules
comprising the asymmetric unit [38].
The molecular structure of 2 closely resembles that of 1 with
the comparable bond distances for the complexes being equal or
approximately equal. The main difference between 1 and 2 is the
narrower range of tetrahedral angles in 2, Table 2. There is a com-
parable disposition of the potential donor atoms of the HL2 mole-
cule in 2, as for HL1 in 1, and the intramolecular N–H. . .Cl
hydrogen bond persists.1 Finally, the experimental equivalence be-
tween the key geometric parameters involving the potential donor
atoms in 2 with those in the structure of the uncoordinated ligand,
HL2 [39] is noted.
There is only one crystal structure in the literature where
N-[di(alkyl/aryl)carbamothioyl]benzamide molecules coordinate
in a monodentate fashion to Cu(I), namely, in the structure of
[Cu(HL)3Cl], [HL = Et2NC(@S)N(H)C(@O)C6H4F-p], where three HL
molecules each coordinate the Cu(I) atom via the sulfur atom only
[41].
3.3. Crystallography
The molecular structures of 1 and 2 are illustrated in Figs. 2 and
3, respectively, and selected geometric parameters are collected in
Table 2. In 1, the Cu(I) atom is coordinated by two phosphorus
atoms of the phosphine ligands, a chloride atom and the sulfur atom
derived from the N-(dibenzylcarbamothioyl)benzamide ligand
(HL1). The coordination geometry is based on a tetrahedral geome-
try with the range of tetrahedral angles being a narrow 96.71(2)° for
S1–Cu–P2 to a wide 124.91(2)° for P1–Cu–P2, i.e. as expected for
the presence of two bulky phosphine ligands in the coordination
sphere. Of particular interest is the monodentate mode of coordina-
tion for the HL1 ligand. The carbonyl-O1 atom is directed away
In the crystal structure of 1, the most prominent intermolecular
interactions are of the type C–HꢂꢂꢂO whereby the carbonyl-O1 atom
1
Intramolecular N2–H. . .Cl1 interaction operating in the crystal structures of 1 and
2. [CuCl(HL1)(PPh3)2] (1): N2–H2. . .Cl1 = 2.35 Å, N2. . .Cl1 = 3.1362(18) Å, and angle at
H2 = 150°. [CuCl(HL2)(PPh3)2] (2): N2–H2. . .Cl1 = 2.31 Å, N2. . .Cl1 = 3.1080(19) Å, and
angle at H2 = 152°.

N. Gunasekaran et al. / Polyhedron 34 (2012) 41–45
45
is bifurcated.2 These interactions assemble molecules into supramo-
lecular chains along [101], Fig. 4. Molecules are consolidated in the
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three-dimensional crystal structure by C–Hꢂꢂꢂ
p A
interactions.2
supramolecular chain is also featured in the crystal structure of 2.
Here, centrosymmetrically related molecules are connected via
C–HꢂꢂꢂO contacts and these are linked into a chain along [001] via
C–HꢂꢂꢂCl contacts [41], Fig. 5. Again, as for 1, C–Hꢂꢂꢂ
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The present study shows synthesis and full characterization of
new four-coordinated tetrahedral copper(I) complexes containing
N-[(dibenzyl/methylpentyl)carbamothioyl]benzamide and triphen
ylphosphine ligands. N-[(Dibenzyl/methylpentyl)carbamothioyl]
benzamide exhibit rare examples of neutral monodentate (hypod-
entate) coordination through sulfur to copper.
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N.G. thanks NITT and the Ministry of Human Resource Develop-
ment, Government of India, for a fellowship. The Ministry of Higher
Education (Malaysia) is thanked for funding this research through
the High-Impact Research scheme (UM.C/HIR/MOHE/SC/03).
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Appendix A. Supplementary data
CCDC 845840 and 845841 contain the supplementary crystallo-
graphic data for compounds 1 and 2, respectively. These data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk.
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References
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[41] Y.-M. Zhang, H.-X. Pang, C. Cao, T.-B. Wei, J. Coord. Chem. 61 (2008) 1663.
2
Intermolecular interactions operating in the crystal structures of
1 and 2.
[CuCl(HL1)(PPh3)2] (1): C47–H47. . .O1i = 2.38 Å, C47. . .O1i = 3.300(3) Å, and angle at
H47 = 162° for symmetry operation (i): 3/2 ꢀ x, 1/2 ꢀ y, 1 ꢀ z. C10–
H10. . .O1ii = 2.59 Å, C10. . .O1ii = 3.506(3) Å, and angle at H10 = 163° for symmetry
operation (ii): 1 ꢀ x, y, 1/2 ꢀ z. Shortest C–H. . .
p interaction: C41–H41...Cg(C53–
C58)i = 2.77 Å, C41. . .Cg(C53–C58)i = 3.513(3) Å, and angle at H2a = 136°.
[CuCl(HL2)(PPh3)2] (2): C28–H28. . .O1i = 2.44 Å, C28. . .O1i = 3.249(3) Å, and angle at
H28 = 142° for symmetry operation (i): 1 ꢀ x, ꢀy, 1 ꢀ z. C38–H38b. . .Cl1ii = 2.44 Å,
C38. . .Cl1ii = 3.249(3) Å, and angle at H38b = 123° for symmetry operation (ii): 1 ꢀ x,
ꢀy, ꢀz. Shortest C–H. . .
p
interaction: C10–H10. . .Cg(C19–C24)iii = 2.68 Å,
C10. . .Cg(C19–C24)iii = 3.596(2) Å, and angle at H10 = 163° for symmetry operation
(iii): 1 ꢀ x, 1 ꢀ y, ꢀz.