Synthesis and Characterization of Copper Complexes with the N-(2,6-Diisopropylphenyl)-N′-acylthiourea Ligands

Article abstract of DOI:10.1002/ejic.201601451

Three N-(2,6-diisopropylphenyl)-N′-acylthiourea ligands [Ar′NHC(S)NHC(O)Ar; Ar′ = 2,6-iPr₂C₆H₃; Ar = p-tBuC₆H₄ (1, L¹), Mes (2, L²), and 1-Naph (3, L³)] were synthesized and compared with the homologous ligand L⁰ (Ar = Ph) in terms of their resultant complexes with copper halides. The reaction of L¹ with CuCl₂ led to the formation of mononuclear L¹₂CuCl (4), while treatment of L¹ with CuX (X = Cl, Br) resulted in the adamantane cage complexes (L¹CuX)₄ (X = Cl, 5; Br, 6). These findings are similar to the results shown by its parent ligand L⁰. The reaction of L¹ with CuI yielded the iodide-bridged dimeric complex [L¹₂Cu(μ-I)]₂ (7), in contrast to the ligand-bridged dimer supported by L⁰. L² readily afforded the mononuclear Cu^I complexes 8–10 coordinated by two or three ligands. L³ gave monomeric L³₃CuX (X = Cl, 11; Br, 12) and the iodide-bridged dimeric [L³₂Cu(μ-I)]₂ (13). L³ can bind with Cu^I halides in a ratio of 1:1 to give complexes L³CuX(PPh₃)₂ (14–16), when Cu₂X₂(PPh₃)₃ (X = Cl, Br) or CuI(PPh₃)₃ were used as precursors. Treatment of (L¹CuCl)₄ (5), L²₂CuBr (8), and L³₃CuCl (11), respectively, with hot EtOH resulted in the formation of trans-CuLⁿ′₂ (17–19) compounds. All compounds were characterized by single-crystal X-ray diffraction studies.

Full text of DOI:10.1002/ejic.201601451

A Journal of
Accepted Article
Title: Synthesis and Characterization of Copper Complexes with the N-
(2,6-Diisopropylphenyl)-N'-Acylthiourea Ligands
Authors: Herbert W. Roesky, Dan Wang, Sun-Yun Wu, Hai-Pu Li, and
Ying Yang
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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201601451
Link to VoR: http://dx.doi.org/10.1002/ejic.201601451

European Journal of Inorganic Chemistry
10.1002/ejic.201601451
FULL PAPER
DOI: 10.1002/ejic.201((will be filled in by the editorial staff))
Synthesis and Characterization of Copper Complexes with the
N-(2,6-Diisopropylphenyl)-N'-Acylthiourea Ligands
[a]
[a,c]
[a]
[a]
[b]
Dan Wang, Su-Yu Wu, Hai-Pu Li, Ying Yang,* and Herbert W. Roesky*
th
Dedicated to Professor Ionel Haiduc on the occasion of his 80 birthday
Keywords: Acylthiourea / Copper halides / S ligands / Cage compounds
0
2
Abstract: Three N-(2,6-diisopropylphenyl)-N'-acylthiourea ligands ligand-bridged dimer supported by L . L readily afforded the
Ar'NHC(S)NHC(O)Ar, Ar' = 2,6-iPr ; Ar = p-tBuC (1, mononuclear copper(I) complexes (8–10) coordinated by two or
(
2
C
6
H
3
6 3
H
1
2
3
3
3
L ), Mes (2, L ), 1-Naph (3, L )) were synthesized and compared three ligands. L gave monomeric L
with the homologous ligand L (Ar = Ph) in terms of their resultant and iodide-bridged dimeric [L
complexes with copper halides. Reactions of L with CuCl
the formation of mononuclear L1
with CuX (X = Cl, Br) resulted in the adamantane cage complexes used as precursors. Treatment of (L CuCl)
(
2
shown by its parent ligand L . The reaction of L with CuI yielded formation of trans-CuL ' (17–19) compounds. All compounds
the iodide-bridged dimeric complex [L1
3
CuX (X = Cl, 11; Br, 12)
0
3
3
2
Cu(μ-I)]
2
(13). L can bind with
1
3
2
led to Cu(I) halides in a ratio of 1:1 to give complexes L CuX(PPh
3
)
2
1
2
CuCl (4), while treatment of L
2 2 3 3 3 3
(14–16), when Cu X (PPh ) (X = Cl, Br) or CuI(PPh )
were
CuBr (8), and
3
L CuCl (11), respectively, with hot EtOH resulted in the
1
2
4
(5), L
2
1
3
L CuX)
4
(X= Cl, 5; Br, 6). These findings are similar to the results
0
1
n
2
2
Cu(μ-I)] (7), in contrast to were characterized by single crystal X-ray diffraction studies.
the
Introduction1
or trans isomer is related to the balance of the flank substituents in
size to tune the geometric difference between the cis complex and
its trans isomer. In most of the cases, this complexation can even
be carried out by oxidizing the Cu(I) halide precursor. Interestingly,
HL also was found to be able to act as a neutral, monodentate
The formation of complexes with transition metal cations is
favored in the presence of soft donor atoms such as nitrogen, sulfur
or phosphorus containing ligands.[1] Acylthiourea, simultaneously
[
7]
ligand to bind CuCl through the sulfur site on its own or with the
bearing O, N, N' and S donor atoms within the C(O)N(H)C(S)N
[
2]
[3, 8]
skeleton, leads to a huge structural diversity in binding modes of
their metal complexes.[3] Especially their copper products have
found extensive application in analytical, environmental, and
3
support of PPh as an auxiliary donor.
In contrast, H
deprotonation in a monodentate or bridging mode in its complexes
with Cu(I) salts. Moreover, it was observed that H L can even
reduce the Cu(II) halide in solution. However, under some
circumstances, the CuCl adduct can also be obtained during the
Due to the less protective environment of the
sulfur site and the highly labile and easily distorted feature of the
2
L mostly behaves as a neutral sulfur donor without
[
4]
medicinal chemistry.
2
[
9]
According to the type of the substituents on the N-site, the
acyclic acylthioureas can be generally divided into two main
classes: N,N-di-substituted acylthiourea (HL) and N-alkyl/aryl-N'-
2
[
10]
redox process.
2
acylthiourea (H L).
1
0
d
Cu(I), the geometry formed during the crystallization of
complexes with H L and Cu(I) halide is significantly affected by
the hydrogen-bonding, the steric hindrance of the substituents,
and the halide type. As such, the H L ligands tend to support Cu(I)
When HL is treated with copper halides, it is readily
deprotonated to the monoanionic ligand to yield the O,S-bis-chelate
Cu(II) complexes, which are elusively formed in the cis or trans
2
[
11]
2
[
5]
[6]
halide in a 2:1 stoichiometry in a monomeric or dimeric
configuration or in a 3:1 composition. The 2:1 complexes exhibit a
conformation. In our recent report, the trend of formation of cis
[
10, 12]
butterfly-like structure as the most favorite mode.
The two
[
a]
School of Chemistry and Chemical Engineering, Centre for
Environment and Water Resource, Central South University,
Lushannan Road 932, 410083 Changsha, P.R. China
Fax: +86-731-88879616
ligands adopt a cis arrangement relative to the geometry of the
halide atom directed by the intramolecular hydrogen bonds N–
H···X. Interestingly, the 4:2 dimeric complexes are often bridged
[
10, 13]
E-mail: yangy@csu.edu.cn
through sulfur atoms,
while only on a few occasions, the
[
[
b] Institut für Anorganische Chemie, Universität Göttingen,
Tammannstrasse 4, 37077 Göttingen, Germany
Fax: +49-551-39-33373
chloride bridged isomers were found to coexist in the same unit
cell of the crystal. Similar to the 2:1 complexes, the structure of
[14]
mononuclear 3:1 complexes exhibit intramolecular N–H···Cl
E-mail: hroesky@gwdg.de
[
15]
hydrogen bonds and show a three-legged piano stool geometry.
c]
Department of Materials and Chemical Engineering, Hunan Institute
of Technology, Henghua Road 18, 421002 Hengyang, P.R. China
Supporting information for this article is available on the WWW
under http://www.eurjic.org/ or from the author.

Recently, we have reported on the synthesis and structural
characterization
of
the
acylthiourea
ligand
N-(2,6-
1
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European Journal of Inorganic Chemistry
10.1002/ejic.201601451
FULL PAPER
0
[9, 16]
parameters,[19] it was sufficient to characterize 4 as the 2:1
diisopropylphenyl)-N'-benzoyl-thiourea (L )
and its reaction
The 2,6-diisopropylphenyl substituted
ligand L provided unique examples of Cu(I) halide complexes
[
9, 17]
1
with copper halides.
mononuclear L
principally the same as that of the reaction of the parent ligand L
2
CuCl complex (Figure S4). This result is
0
0
0
[9]
with diversified structures, including the mononuclear L
2
CuCl, the
(X= Br, I) and the rare
4
. Herein, we describe the synthesis of
with CuCl
2 2
·2H O.
0
0
dimeric binuclear [L XCu(μ-L )]
2
0
The 1:1 reaction of L1 (1) with CuCl resulted in product 5
adamantane cage (L CuBr)
three new ligands N-(2,6-diisopropoylphenyl)-N'-acylthiourea (L
1
–
1
1
2
(Scheme 2) with a similar H NMR spectrum to that of L CuCl (4),
3
)
and their reactions with copper halides, with the aim of studying
in view of the chemical shifts of NH protons (12.53 and 11.08 ppm
their coordination modes and structural features.
for 5 vs. 12.39 and 11.25 ppm for 4). Elemental analysis of 5
suggests a 1:1 stoichiometric composition of acylthiourea ligand L
1
with CuCl. Single crystal X-ray structural analysis shows the
Results and Discussion
1
formation of an adamantane cage complex (L CuCl)
4
(5),
crystallizing in the orthorhombic space group Pbcn. The molecular
structure of 5 is illustrated in Figure 1 with selected bond lengths
and angles in the caption.
Three N-(2,6-diisopropylphenyl)-N'-acylthiourea ligands (L1–3
,
Scheme 1) were synthesized using the in situ prepared 4-(tert-
butyl)benzoyl chloride, or the commercial available 2,4,6-
trimethylbenzoyl chloride and 1-naphthoyl chloride, respectively.
We followed a similar procedure as that reported for N-(2,6-
0
[9]
diisopropylphenyl)-N'-benzoylthiourea
dimethylphenyl)-N'-benzoyl thiourea.[18]
(L )
and
N-(2,6-
1–3
Scheme 1 Three new acylthioureas L
1
–3
The melting points of the products L were found in the range
of 202–211°C. The further characterization of L1–3 ligands is given
in the Supporting Material.
1
Figure 1. Molecular structure of (L CuCl)
4
(5). Other hydrogen atoms are
omitted for clarity. Selected bond lengths /Å and angles /°: Cu(1)–S(1)
2.3041(9), Cu(1)–Cl(2) 2.3553(9), Cu(1)–S(2) 2.3626(8), Cu(1)–Cl(1)
2.3636(7), Cu(2)···Cu(2A) 2.6896(9); Cu(1A)–Cl(1)–Cu(1) 115.25(5),
The equimolar reaction of L1 (1) in THF with the ethanol
O led to the formation of L1
solution of CuCl
2
·2H
2
2
CuCl (4,
Cu(2)–Cl(3)–Cu(2A) 72.07(4).
Scheme 2), where the acylthiourea ligand acts as reducing reagent
towards Cu(II) chloride. The melting point of 4 (243°C ) is much
1
higher than that of its ligand L (211°C ).
From the above results, it can be suggested that the use of CuCl
or CuCl as a reactant may afford different Cu(I) products.
2
1
The similar 1:1 reaction of L (1) with CuBr also produced the
1
4
adamantane cage complex (L CuBr) (6, Scheme 2) as disclosed
by the X-ray structural analysis (Figure S5).
It can be noticed in the cage structure of both 5 and 6 that all
halide atoms act as bridging ligands to link the Cu(I) atoms into a
puckered eight-membered ring Cu (μ-X) , while two acylthiourea
4 4
ligands coordinate the Cu(I) anions in a monodentate mode and the
other two in a bridging arrangement. The first adamantane cage
2 4 4
complex that contains the unprecedented S Cu Br core was
0
[9]
furnished by L . It is obvious that the introduction of the p-tBu
0
substituents at the L ligand created additional chances to produce
more 1:1 acylthiourea Cu(I) complexes with an even higher
symmetric geometry of the unit cell.
Scheme 2. Preparation of Cu(I) complexes 4–13
1
Treatment of L with equivalent amounts of CuBr
2
gave the
1
The H NMR spectrum of 4 exhibits two distinct NH protons
same cage complex 6, instead of the expected 2:1 complex
1
1
1
resonances at 12.39 and 11.25 ppm, showing a downfield shift
when compared to those of the ligand L (11.83, 9.17 ppm). These
changes are highly related to the complex formation.
composition of L
2 2 2
L CuBr like L CuCl (4) by L with CuCl . Interestingly, the 1:1
1
1
reaction of L with CuI provided an iodide-bridged dimeric
[
12d]
1
The
[L Cu(μ-I)] (7, Scheme 2). The molecular structure of 7 is
2
2
1
2
CuCl (4) was further confirmed by elemental-
depicted in Figure 2.
analysis. Although the quality of a single crystal of 4 was not
adequate enough to accurately determine the molecular geometric
2
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European Journal of Inorganic Chemistry
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FULL PAPER
Previous studies of complexes with Cu(I) and two acylthiourea
The X-ray structure of 9 reveals a mononuclear Cu(I) iodide
complex where the copper is coordinated by two S atoms of each
acylthiourea ligand and one iodide ligand (Figure 3). The two
ligands of 9 adopt a cis arrangement relative to the iodide anion.
The Cu–I and Cu–S bond lengths are each found in the expected
range and the sum of the bond angles around the copper is exactly
360° exhibiting a trigonal planar geometry.
[
10, 12]
ligands crystallize either as monomers in a cis arrangement
or
as dimers bridged by sulfur atoms.[10, 13] So far, only two bridging
chloride species with terminal acylthiourea ligands were observed
but they coexisted with the ligand-bridged isomers in the crystal
[
14]
1
structure. [L
2 2
Cu(μ-I)] (7) represents the first of this type to be
isolated and structurally characterized. Some complexes of Cu(I)
with thiourea ligands contain halide bridges only when PPh
used as an auxiliary ligand.[20]
3
was
2
Figure 3. Molecular structure of L
2
CuI (9), showing intramolecular
hydrogen bonds as dotted lines. Thermal ellipsoids are drawn at 30% level.
Other hydrogen atoms are omitted for clarity. Selected bond lengths /Å and
angles /°: Cu(1)–S(1) 2.2335(19), Cu(1)–S(2) 2.2373(17), Cu(1)–I(1)
2
.4783(9); S(1)–Cu(1)–S(2) 104.19(7).
1
Figure 2. Molecular structure of [L
2
Cu(μ-I)]
2
(7). Thermal ellipsoids are
drawn at 30% level. Other hydrogen atoms are omitted for clarity. Selected
bond lengths /Å and angles /°: Cu(1)–S(1) 2.2990(9), Cu(1)–S(2)
0
0
[9]
A comparison of the dimeric products [L ICu(μ-L )]
2
and
L1
Cu(μ-I)] (7) with the monomeric L CuI (9) leads to an
2 2 2
2
2
.3450(10), Cu(1)–I(1) 2.5940(4), Cu(1)–I(1A) 2.6851(4), Cu(1)···Cu(1A)
.8781(8); S(1)–Cu(1)–S(2) 103.13(4), Cu(1)–I(1)–Cu(1A) 66.050(15).
2
[
unexpected result. Therefore, a reference reaction in a 2:1 ratio of
ligand L with CuI was carried out, aiming at the isolation of a
. The resultant product is a bright yellow solid,
while its H NMR spectrum is almost the same as that of
CuI (9). The X-ray structural analysis confirmed a
CuI (10, Scheme 2). Complex 10
crystallizes in the monoclinic space group P2(1)/n (Figure 4).
2
2
The dimeric complex [L1
triclinic space group P-1, comprising a [Cu(μ-I)]
dimeric (L
2
CuI)
2
2
Cu(μ-I)]
2
(7) crystallizes in the
four-membered
1
2
2
monomeric L
2
ring in a crystallographic center of symmetry. The Cu–I bond
lengths (2.5940(4) and 2.6853(4) Å), I–Cu–I bond angles
3
:1 composition of L2
3
(
113.953(15)°), and Cu(1)–Cu(1A) separation (2.8781(8) Å) fall in
[
20-21]
the expected range.
2 2
A closely related [S Cu(μ-I)] core
stabilized by non-chelating sulfur ligands was found in the
heterocyclic 2-thione CuI complex.[22] However, it contains longer
Cu–I bond lengths (2.713(5) and 2.757(5) Å), narrower I–Cu–I
bond angle (98.59(2)°), and a longer Cu(1)–Cu(1A) distance
(3.567 Å).
1
It can be seen that the p-tBu substituted L exhibited more Cu(I)
0
[9]
halide complexes of interest than its parent ligand L . This
finding initiated the preparation of Cu(I) products with the Mes and
2
3
1
-Naph substituted ligands L and L .
Several attempts to isolate pure products from the reaction of L2
with CuCl or CuCl
2
following the previous procedure failed.
Treatment of L with CuBr readily gave a 2:1 monomeric
CuBr (8, Scheme 2), as confirmed by X-ray structural analysis
2
2
2
L
2
[
19]
2
(Figure S6).
Moreover, when CuBr was reacted with L , the
same product 8 was obtained instead of the cage complex.
2
Figure 4. Molecular structure of L
3
CuI (10), showing intramolecular
2
However, the complexation reaction of the L with CuI in a 1:1
hydrogen bonds as dotted lines. Thermal ellipsoids are drawn at 30% level.
Other hydrogen atoms are omitted for clarity. Selected bond lengths /Å and
angles /°: Cu(1)–S(1) 2.3076(13), Cu(1)–S(2) 2.3084(13), Cu(1)–S(3)
.3391(13), Cu(1)–I(1) 2.6483(7); S(1)–Cu(1)–S(2) 105.15(5), S(1)–Cu(1)–
S(3) 101.93(5), S(2)–Cu(1)–S(3) 101.00(5).
ratio afforded the monomeric L2
CuI (9, Scheme 2), which is a
colorless solid and crystallizes in the monoclinic space group
2
2
P2(1)/n (Figure 3).
3
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European Journal of Inorganic Chemistry
10.1002/ejic.201601451
FULL PAPER
Similar to the structural feature in L2
bonds were found in L2
CuI (10), which align the ligands in the
CuI (9), N–H···I hydrogen
The 31P NMR spectra recorded in CDCl
solution confirm the
3
presence of triphenylphosphine with a single resonance in the Cu(I)
2
3
same direction. The Cu–I bond length (2.6486(7) Å) in 10 is
evidently longer than that in 9 (2.4783(9) Å), while the Cu–S bond
lengths share the same trend (av 2.3179 vs 2.2355 Å). Cu(I) halide
complexes bearing three acylthiourea molecules coordinated
through the sulfur atom and a halide atom in the fourth position are
known in literature.[15] However, the acylthiourea ligands that can
support the CuX core in both 3:1 and 2:1 composition are hardly
documented. The potential of this finding needs further research.
complexes (-4.59 ppm, 14; -5.23 ppm, 15; -5.97 ppm, 16). X-ray
single crystal structural analysis further evidenced the composition
3
and structures of complexes 14–16. L CuCl(PPh
crystallizes in the triclinic space group P-1 (Figure 5).
3
)
2
(14)
In the molecule of 14, the Cu(I) center is tetra-coordinate by one
chlorine, one sulfur, and two phosphorus atoms. The structure of
14 is basically homologous to that of its analogue supported by the
[
8]
N,N-diphenyl-N'-benzoylthiourea ligand. In both cases, the O(1)–
C(2)–N(1)–C(1) linkage is almost co-planar with the torsion angle
3
When the 1-Naph substituted acylthiourea L was employed, the
3
[8]
reaction of L with CuX
2
(X = Cl, Br) afforded the monomeric
of -1.56° for 14 and of -8.01° for that in literature. One striking
3
adduct L
3
CuX (X = Cl, 11; Br, 12) of 3:1 stoichiometry (Scheme
difference is the deviation of the S atom away from the C(2)–N(1)–
[
8]
2
). The complexes 11 (Figure S7) and 12 (Figure S8) are
C(1) plane by 0.119 Å for 14 and by 1.692 Å for the latter. It is
suggested that the formation of the intramolecular hydrogen
bonding N(2)–H(2A)···O(1) in 14 keeps the C=O and C=S vectors
co-planar in a restricted conformation. The molecular structure of
isomorphous; therefore, the molecular conformation of them is
3
very similar to each other. In contrast, treatment of L with CuCl
3
failed to give the expected product, while the reaction of L with
CuBr produced L3
1
CuBr (12). The X-ray structural investigation of
2 shows that there is additional π···π interaction between the 1-
L CuBr(PPh
3
)
(15) is shown in Figure S10,
[19]
and of
3
3
2
3
L CuI(PPh
3
)
2
(16) in Figure S11. They share highly similarity in
Naph rings of neighbor molecules within the packing mode.
structure and conformation.
3
Interestingly, the reaction of L with CuI led to the formation of
another iodide-bridged dimer [L3
2 2
Cu(μ-I)] (13, Scheme 2). The
molecular structure of 13 is depicted in Figure S9, where the
Cu···Cu distance (3.076 Å) is found much longer than that in
1
[
L
2
Cu(μ-I)]
2
(7) (2.8781(8) Å). This increase in bond length may
be attributed to the ligand effect caused by the bulky 1-Naph
substituents.
As shown in Scheme 2, it can be noticed that the substitution at
the acylthiourea ligands has a great effect on the results of the
0
n
complexation with CuX. The ligands L to L (n = 1, 2, 3) exhibit
different properties. The composition and conformation of the
resultant products are largely affected by the substituents, the
stoichiometry of the precursors, the valency of the copper educt,
the kind of halides, the hydrogen bonding, and finally the
intermolecular interaction. It is suggested that the p-tBu substituted
1
0
L shared the highest similarity with the parent L and therefore
has the best chance to form the adamantane cage complexes (5 and
6
3
3 2
Figure 5. Molecular structure of L CuCl(PPh ) (14). Thermal ellipsoids
2
3
are drawn at 30% level. Other hydrogen atoms are omitted for clarity.
), while L and L are prone to give mononuclear or binuclear
Selected bond lengths /Å and angles /°: Cu(1)–P(1) 2.2769(6), Cu(1)–P(2)
complexes. In addition, it was realized that the iodide atom is rare
to act as bridging ligand (7 and 13) in these systems, and is even
harder to be involved in cage complexes.
2
1
.2905(5), Cu(1)–Cl(1) 2.3309(6), Cu(1)–S(1) 2.3731(6); P(1)–Cu(1)–P(2)
21.58(2), P(1)–Cu(1)–Cl(1) 103.44(2), P(2)–Cu(1)–Cl(1) 115.16(2),
Cl(1)–Cu(1)–S(1) 105.86(2).
The bulky P donors function selectively in the formation of CuX
complexes with S ligands.[20,
23]
Especially N,N-di-substituted
Complexes 4–13 are found to be air and moisture stable, while
the solids of 14–16 showed a slow color change from clear to
opaque when exposed in open air. Even so, complexes 4–13 have
shown a facile reactivity towards EtOH. For example, during the
recrystallization of complexes 5, 8 and 11 from hot EtOH, dark
acylthiourea ligands have been studied,[3, 8] while the N-alkyl/aryl-
N'-acylthiourea ligands are less explored. Reactions of L with
3
Cu
formation of the mononuclear L CuX(PPh
4; Br, 15; I, 16) (Scheme 3).
2 2 3 3 3 3
X (PPh ) (X = Cl, Br) or CuI(PPh ) , respectively, led to the
3
3
)
2
complexes (X = Cl,
1
colored products of O,N-bis-chelate Cu(II) compounds of trans-
n
CuL '
2
(17–19) were formed, with the release of H
2
S and H
2
through redox reactions (Scheme 4).
3
Scheme 3. Preparation of complexes L CuX(PPh
)
3 2
(14–16).
n
2
Scheme 4. Formation of compounds trans-CuL ' (17–19).
4
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European Journal of Inorganic Chemistry
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FULL PAPER
Single crystals of trans-CuL1'
(17) of X-ray quality are dark
oxidation of 1-phenylethanol. It was found that at room
2
purple. 17 crystallizes in the triclinic space group P-1, and its
molecular structure is shown in Figure 6 with selected bond lengths
and angles in the caption. The Cu(II) center is located in a nearly
temperature Cu(I) complexes (4–13) exhibited a conversion of 1-
n
phenylethanol to acetophenone by 17%–46%, and L Cu(PPh
3
)
2
(14–16) gave a conversion of 15%–31%, which were much lower
than those catalyzed by N,N-di-substituted acylthiourea copper
1
perfect square environment and chelated by two anionic ligands L '
[
3]
in trans conformation through O and N sites. The molecular
complexes (90%–98%).
When kept at 70 °C, the above
2
3
structures of trans-CuL '
2
(18) and trans-CuL '
2
(19) are depicted
conversions were found to be increased marginally, up to 67% and
63%, respectively. Among them, the iodide complexes gave higher
conversion than chloride or bromide ones. This low conversion
may be due to the substrate dependence, and further optimizations
are the next steps in our future studies.
in Figures S12 and S13.
1
By comparison with the structure of the neutral ligand L (1), the
1
O(1)–C(2) bond length in the complex trans-CuL '
2
(17)
1.9026(13) Å) is significantly longer than that in the ligand
1.216(4) Å), while the N–C bond distances in this complex are
(
(
In summary, we have synthesized and characterized three new
evidently shorter. This observation essentially reflects the electron
delocalization over the chelate ring. In each case of 17–19, the
geometry around the Cu atom is a heavily distorted square with the
dihedral angle between two OCuN planes ranging from 32.3 to
N-(2,6-diisopropylphenyl)-N'-acylthiourea ligands (Ar'NHC(S)
1
NHC(O)Ar, Ar' = 2,6-iPr
L ), 1-Naph (3, L )) and explored their complexation with Cu(I)
2
C
6
H
3
; Ar = p-tBuC
6
H
3
(1, L ), Mes (2,
2
3
0
halides (4–13). Combined with the previous results of L (Ar =
[
9]
3
2.8°. This distortion may be due to the repulsive interaction
Ph), it was found that the adducts of these substituted L and CuX
tend to form monomeric adduct L CuX or L CuX, dimeric ligand-
bridged [LXCu(μ-L)] halogen bridged [L Cu(μ-X)] or
adamantane cage (LCuX) complexes, respectively. Although the
adamantane cage structure bearing the S Cu Br core was for the
among the bulky Ar substituents.
2
3
2
,
2
2
,
It is known that thiourea derivatives are reactive to undergo
desulfurization by hydrolysis, amination, and alkoxylation to give
4
2
4
4
[
2b, 24]
[25]
0 [9]
the corresponding acylurea,
acylguanidine,
and isoureas
first time known recently in L , it can be already seen as a
[
26]
respectively. The methoxylation or ethoxylation of acylthiourea
common structural type for these complexes. In addition, the new
n
Cu(II) intermediates has been documented to give O,N-bis-chelate
L ligands have created a possibility to isolate the iodide-bridged
[
27]
n
Cu(II) compounds. The current preparation of trans-CuL '
2
(17–
dimeric complexes [L
2
Cu(μ-I)]
2
.
The composition and
1
9) further proved that the ethoxylation can occur onto the
conformation of the resultant products depend on the substituents,
the precursor stoichiometry, the copper valency, the type of
halogen, and the short intramolecular distances, respectively. In
acylthiourea Cu(I) halides under mild conditions.
n
addition, it was realized that the prepared L ligands can be seen as
2
the typical N-alkyl/aryl-N'-acylthiourea (H L) to play a role as
neutral sulfur donor in its complexation with Cu(I) halides, or even
by reducing the Cu(II) halides, without giving O,S-bis-chelate
Cu(II) complexes. The introduction of PPh
3
donors to the
3
complexation of L with CuX led to the formation of mononuclear
3
L CuX(PPh
3 2
) (14–16). Complexes 4–13 have shown a facile
reactivity towards hot EtOH to give dark colored products of O,N-
n
bis-chelate Cu(II) compounds of trans-CuL '
prepared Cu(I) complexes showed moderate catalytic activity for
the oxidation of 1-phenylethanol in the presence of H
2
(17–19). The
2
2
O .
X-ray Crystallography: Data were collected on a Bruker SMART APEX
II CCD diffractometer. The diffraction data were obtained by using graphite
monochromated Mo-Kα radiation with a ω-2θ scan technique at room
temperature. The structure was solved by direct methods with SHELX-
1
Figure 6. Molecular structure of trans-CuL '
2
(17). Thermal ellipsoids are
drawn at 30% level. Other hydrogen atoms are omitted for clarity. Selected
bond lengths /Å and angles /°: Cu(1)–O(1) 1.9026(13), Cu(1)–N(2)
.9673(14), N(1)–C(2) 1.312(2), N(1)–C(1) 1.342(2), N(2)–C(1) 1.311(2);
O(1A)–Cu(1)–O(1) 180.00(10), O(1A)–Cu(1)–N(2) 89.60(6), O(1)–Cu(1)–
[28]
2
9
7. A full-matrix least-squares refinement on F was carried out by using
1
[
28]
SHELXL-97.
N(2) 90.40(6).
Compounds 5, 6, 12, 14, 16 and 18 crystallize with severely disordered
solvent molecules in the unit cell. No acceptable connectivity could be
established for the embedded solvent molecules. The disordered electron
densities were excluded using the SQUEEZE function of the PLATON
In a comparative manner, the 2,6-diisopropylphenyl group was
replaced by the imidazole group to prepare N(Him)-N'-(2,4,6-
[
29]
program.
CCDC 1450698 (1), 1450699 (2), 1450700 (3), 1450701 (9), 1450702 (10),
4
trimethylbenzoyl)thiourea (L , 20) (Him = 1H-imidazole, Scheme
4
S1). L was found to be readily transformed into di-(2,4,6-
1
1
1
450703 (11), 1450704 (12), 1450705 (5), 1450706 (6), 1450707 (7),
450708 (13), 1450709 (14), 1450710 (16), 1450711 (17), 1450712 (18),
450713 (19), 1450714 (21), and 1450715 (22) contain the supplementary
trimethylphenyl)carboxamido disulfide (21, Scheme S2) during
recrystallization in EtOH. In addition, the reaction of L with CuBr
gave the Cu(II) adduct trans-(Him)
the facile decomposition of L by liberating free imidazole.
4
2
CuBr
2
(22, Scheme S3), due to
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
4
The Cu(I)/H
2
O
2
catalytic system using N,N-di-substituted
acylthiourea copper complexes for the oxidation of alcohols to
carbonyl compounds has been known.[3] Therefore, the herein
prepared Cu(I) complexes were tentatively tried to catalyze the
Supporting Information Experimental Section. Molecular structures in
Figures S1–S15. Spectroscopic data for 20–22. Structural data in Tables S1.
5
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European Journal of Inorganic Chemistry
10.1002/ejic.201601451
FULL PAPER
Hu, H.-X. Pang, T.-B. Wei, Chin. J. Inorg. Chem. 2009, 25, 1243-
1
247; c) Y.-M. Zhang, H.-X. Pang, C. Cao, T.-B. Wei, J. Coord.
Acknowledgement
Chem. 2008, 61, 1663-1670.
This work was supported by the Research Fund for Teachers of Central
South University (2013JSJJ007). The authors gratefully acknowledge the
NMR measurements from the Modern Analysis and Testing Centre of CSU.
Support of the Deutsche Forschungsgemeinschaft is gratefully
acknowledged.
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2
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1
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_
___________
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6
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European Journal of Inorganic Chemistry
10.1002/ejic.201601451
FULL PAPER
Entry for the Table of Contents
Layout 1:
Copper Complexes
Three
acylthiourea
N-(2,6-diisopropylphenyl)-N'-
n
ligands
(L )
were
Dan Wang, Su-Yun Wu, Hai-Pu Li,
Ying Yang,* and Herbert W.
Roesky* …….. Page No. – Page No.
synthesized and reacted with copper
halides to give the corresponding
mono-, bi-, and tetranuclear Cu(I)
complexes, respectively. The ligand
substitution allows the isolation of
Synthesis and Characterization of Copper
Complexes with the N-(2,6-Diisopropoyl
phenyl)-N'-Acylthiourea Ligands
adamantane cage (LCuX)
4
complexes
(X = Cl, Br) with high crystallographic
symmetry and unique formation of
iodide-bridged dimer of composition
Keywords: Acylthiourea / Copper
[
L
2
Cu(μ-I)]
2
.
halides / S ligands / Cage compounds
7
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