Reactivity of thiazolidine-2-thione towards CuI/CuII: Synthesis and structures of [3-(2-thiazolin-2-yl)thiazolidine-2-thione]copper(I) bromide and [bis(2,2′-bipyridine)nitratocopper(II)] nitrate

Article abstract of DOI:10.1007/s12039-014-0760-3

Thiazolidine-2-thione (L¹, NC₃H₅S₂) reacted with copper(I) bromide in CH₃CN under aerobic conditions and transformed through C-S bond cleavage into 3-(2-thiazolin-2-yl)thiazolidine-2-thione (L², C₃H₄S₂N-C₃H₄SN). This thio-ligand L² with Cu^I ion yielded a three coordinate complex, [3-(2-Thiazolin-2-yl)thiazolidine-2-thione]copper(I)bromide 1a which crystallized in the triclinic system with the space group P1 as reported earlier. Treatment of 1a with bis(diphenylphosphino)methane (dppm) in dichloromethane also formed [3-(2-thiazolin-2-yl)thiazolidine-2-thione]copper(I) bromide 1b but it crystallized into the triclinic system with a new space group, P-1: 296(2) K, a, 7.3890(19); b, 8.473(2); c, 9.491(2) ?; α, 70.273(5); β, 67.170(5); γ, 84.949(5)°; R, 6.79%. Reactions of copper(II) nitrate with thiazolidine-2-thione followed by the addition of 2,2^′-bipyridine or with 2,2^′-bipyridine first followed by the addition of thiazolidine-2-thione, gave blue crystals in both the cases. The x-ray crystallography revealed stoichiometry of the complex formed as: [Cu(κ ²-N,N^′-bipy)₂(κ ¹-ONO₂)](NO₃)2, which crystallized in monoclinic crystal system with space group, P2₁/n(14). Crystal data: 173(2) K, a, 11.318(1), b, 12.160(1), c, 14.967(1) ?; β = 98.01(1)°, R, 3.99%; 296(2) K, a, 11.340(5), b, 12.249(5), c, 15.065(6) ?; β = 98.04(2)°, R, 4.09%. [Figure not available: see fulltext.]

Full text of DOI:10.1007/s12039-014-0760-3

c
J. Chem. Sci. Vol. 127, No. 1, January 2015, pp. 149–153. ꢀ Indian Academy of Sciences.
DOI 10.1007/s12039-014-0760-3
Reactivity of thiazolidine-2-thione towards CuI/CuII: Synthesis
and structures of [3-(2-thiazolin-2-yl)thiazolidine-2-thione]copper(I)
bromide and [bis(2,2ꢁ-bipyridine)nitratocopper(II)] nitrate
TARLOK S LOBANAa,∗, ANU RANIa, AMANPREET K JASSALa and JERRY P JASINSKIb
aDepartment of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India
bDepartment of Chemistry, Keene State College, Keene, NH 03435–2001, USA
e-mail: tarlokslobana@yahoo.co.in
MS received 16 June 2014; revised 17 July 2014; accepted 28 July 2014
Abstract. Thiazolidine-2-thione (L1,NC3H5S2) reacted with copper(I) bromide in CH3CN under aerobic
conditions and transformed through C–S bond cleavage into 3-(2-thiazolin-2-yl)thiazolidine-2-thione (L2,
C3H4S2N-C3H4SN). This thio-ligand L2 with CuI ion yielded a three coordinate complex, [3-(2-Thiazolin-2-
yl)thiazolidine-2-thione]copper(I)bromide 1a which crystallized in the triclinic system with the space group
P1 as reported earlier. Treatment of 1a with bis(diphenylphosphino)methane (dppm) in dichloromethane also
formed [3-(2-thiazolin-2-yl)thiazolidine-2-thione]copper(I) bromide 1b but it crystallized into the triclinic sys-
tem with a new space group, P-1: 296(2) K, a, 7.3890(19); b, 8.473(2); c, 9.491(2) Å; α, 70.273(5); β,
67.170(5); γ , 84.949(5)◦; R, 6.79%. Reactions of copper(II) nitrate with thiazolidine-2-thione followed by the
addition of 2,2ꢁ-bipyridine or with 2,2ꢁ-bipyridine first followed by the addition of thiazolidine-2-thione, gave
blue crystals in both the cases. The x-ray crystallography revealed stoichiometry of the complex formed as:
[Cu(κ2-N,Nꢁ-bipy)2(κ1-ONO2)](NO3) 2, which crystallized in monoclinic crystal system with space group,
P21/n(14). Crystal data: 173(2) K, a, 11.318(1), b, 12.160(1), c, 14.967(1) Å; β = 98.01(1)◦, R, 3.99%; 296(2)
K, a, 11.340(5), b, 12.249(5), c, 15.065(6) Å; β = 98.04(2)◦, R, 4.09%.
Keywords. Thiazolidine-2-thione; 3-(2-thiazolin-2-yl)thiazolidine-2-thione; 2,2ꢁ-bipyridine; copper(I) bro-
mide; copper(II) nitrate.
of 2,2ꢁ-bipyridine are described. Compound 1b with a
new crystal modification as well as the product 2 are
reported in this paper.
1. Introduction
In literature, it was recently reported that reactions of
heterocyclic thioamides with copper(I) salts in ace-
tonitrile have shown C-S rupture, formation of new
thio-ligands (in situ formed) and their subsequent coor-
dination to CuI or CuII.1–3 Further, it is known that C-S
bond activation, cleavage and transformations using
transition metal compounds have found wide interest
in synthetic chemistry, shown relevance in the biological
reactions,4–6 as well as has found importance in petroleum
industry.7 We investigated that the reactions of thiazoli-
dine-2-thione (L1) with copper(I) chloride/bromide or
with [Cu(NCCH3)4](BF4) under aerobic conditions
generated a new ligand, 3-(2-thiazolin-2-yl)thiazolidine-
2-thione (L2), which in situ coordinated to CuI ions
and gave complexes (1a, 3, 4) as shown in scheme 1.3
In this paper, reactions of thio-ligand L1 with cop-
per(I) bromide under aerobic conditions followed by the
treatment with bis(diphenylphosphino)methane (dppm)
as well as that with copper(II) nitrate in the presence
2. Experimental
2.1 Materials
Copper(I) bromide was prepared by reducing an aque-
ous solution of CuSO4·5H2O using SO2 in the presence
of NaBr in water. Copper(II) nitrate, thiazolidine-2-
thione and 2,2ꢁ-bipyridine were purchased from Sigma–
Aldrich Ltd. Solvents were of Analytical Research grade
and used as such.
2.2 Synthesis of [Cu(κ2 − N, S − C3H4S2N − C3H4
SN)Br] (1b)
Copper(I) bromide (0.025 g, 0.17 mmol) was dissolved
in acetonitrile and to it solid thiazolidine-2-thione
(0.022 g, 0.25 mmol) was added. The reaction mixture
was kept undisturbed. After several days, red violet (or
red brown) crystals along with the light blue crystals
∗For correspondence
149

150
Tarlok S Lobana et al.
S
S
N
S
N
S
CuI
CuI
Cl
Br
S
N
S
N
S
N
N
S
3
CuI salts (i, ii, iii)
CH3CN
S
1a
S
HN
S
N
S
S
N
S
L1
(BF4)
CuI
L2
N
S
S
N
S
4
Scheme 1. Reactions with products: i. CuCl, ii. CuBr, iii. [Cu(NCCH3)4](BF4)] in CH3CN.
of CuSO4.5H2O were formed. The mother liquor was methods using the program SHELXS- 97, refined by
removed and to the solid left behind was added a full-matrix least-squares techniques against FV using
solution of dppm in dichloromethane. The red violet SHELX-97 and molecular graphics from SHELXL.9
compound rapidly dissolved in dichloromethane solu- The data collected at room temperature was also pro-
tion of dppm leaving behind blue crystals of CuSO4. cessed with Bruker Kapa – Apex(II) CCD and cor-
5H2O. This solution was left at room temperature in a rected for absorption using SADABS.10 The structures
culture tube which gave red brown crystals of [Cu(κ2- were solved by direct methods using SIR-92 software10
N,S-C3H4S2N-C3H4SN)Br] (1b) studied using x-ray and refined by full-matrix least-squares method based
crystallography. Yield 60%.
on FV using the program using SHELX-97.9 Atomic
scattering factors taken from “International Tables for
Crystallography”.11
2.3 Synthesis of [Cu(κ2-N,N’-bipy)2(κ1-ONO2)](NO3)
(2)
3. Results and Discussion
To a blue solution of copper(II) nitrate (0.025 g, 0.10
mmol) in ethanol (2 mL) was added a solution of
thiazolidine-2-thione (0.11g, 0.10 mmol) in ethanol (2
mL). To the mixture was added two drops of dimethyl
formamide. The colour of the solution becomes light
blue and blue precipitates were formed. The contents
were left undisturbed at room temperature (25oC) until
the colour changed to green after 24 h. To this solution,
2,2ꢁ-bipyridine (0.038 g, 0.24 mmol) was added and
allowed the solution undisturbed. This led to the forma-
tion of bluish green crystals. Same product was formed
when order of addition was reversed. The crystals were
studied by using x-ray crystallography at 176(2) K and
296(2) K. Yield: 55%.
3.1 Synthesis and general comments
Reaction of copper(I) bromide with the thio-ligand L1
is reported to form the compound [3-(2-thiazolin-2-yl)
thiazolidine-2-thione]copper(I) bromide 1a, whose x-ray
crystallography suggested that it has triclinic crystal
with the space group P1 as shown in figure 1.3 Com-
pound 1a was reacted with bis(diphenylphosphino)
2.4 X-ray crystallography
A single crystal was mounted on a glass fiber and
used for data collection with a Xcalibur, Eos, Gemini
(2a and 173(2) K) equipped with graphite monochro-
mated Cu-Kα (λ = 1.54184 Å) as well as with
a Bruker Kapa – Apex (II) CCD diffractometer (1b
and 2b; 296(2) K) equipped with graphite monochro-
mated Mo-Kα (λ = 0.71073 Å). The data recorded at
low temperature was processed with CrysAlisPro CCD
(data collection), CrysAlisPro RED (cell refinement,
data reduction).8 The structure was solved by direct
Figure 1. Molecular structure of compound 1a.3

Reactivity of thiazolidine-2-thione towards copper
151
methane (dppm) for preparing a P-coordinated mono- crystal x-ray crystallography has shown the product as,
nuclear or P,P-coordinated dinuclear complex. However, [Cu(κ2-N,Nꢁ-bipy)2(κ1-ONO2)](NO3) 2 (scheme 3). It
x-ray crystallography of red brown crystals showed means there is no C-S rupture under the experimental
that the new compound formed is [3-(2-thiazolin-2-yl) conditions and the product of type A is not formed in
thiazolidine-2-thione]copper(I) bromide 1b which is the presence of 2,2ꢁ-bipyridine. Likewise, the product
shown in figure 2. Scheme 2 depicts transformation B is also not formed and the only preferred product
of 1a into 1b. Compound 1a is insoluble in dichloro- was compound 2. Due to the strong coordinating ability
methane, but addition of dppm assisted the compound of 2,2ꢁ-bipyridine neither C-S rupture nor coordination
1a to become soluble and then it de-ligated during crys- of thiazolidine-2-thione to copper are observed under
tallization giving rise to the formation of compound 1b. experimental conditions.
In the reactions of copper(II) nitrate with thiazo-
lidine-2-thione and 2,2ꢁ-bipyridine, it was believed that
the C-S rupture similar to that shown by CuCl/CuBr
3.2 Molecular structures (1b, 2)
(scheme 1) might occur and product of the type A as
shown in scheme 3 was expected. However, the single
The x-ray crystal data are given in table 1 and the
bond parameters for compounds 1b and 2 are placed
in table 2. The in situ generated thio-ligand, 3-(2-
thiazolin-2-yl)thiazolidine-2-thione L2 chelates to CuI
of complex 1b through its N, S donor atoms {Cu–S,
2.190(4); Cu–N, 1.970(11) Å} with N-Cu-S bite angle
of 99.3(4)◦. The third position is occupied by bromide
ion {Cu-Br, 2.287(2)} giving rise to a three coordinate
complex. The angles, N-Cu-Br and S-Cu-Br {127.1(3)
and 133.55(13)◦ respectively} and the N-Cu-S bite
angle suggest a distorted trigonal planar geometry
(figure 2). The bond distances/angles are comparable
to those in compound 1a3. Compound 2 crystallized in
monoclinic crystal system with P21/n(14) space group.
The x-ray data at low temperature is labelled as 2a,
and that at room temperature is labelled as 2b. Low
temperature data was obtained to check if more than
one oxygen atom of NO3− is coordinating to CuII which
Figure 2. Molecular structure of compound 1b.
it was not. The quality of data at low temperature is
better with low R factor of 3.99%. Copper(II) is bonded
Ph2P-CH2-PPh2
1b
1a
to two bipy ligands through its nitrogen donor atoms
at Cu-N distances in the range 1.9776(18)–2.1215(18)
Å (figure 3). The fifth site is occupied by one O atom
of one nitrate group at Cu-O distance of 2.0828(18) Å.
CH2Cl2
(Figure 2)
(Figure 1)
Scheme 2. Change of 1a into 1b.
S
S
N
N
N
CuI
O
i,ii
S
N
N
N
N
CuII
O
NO2
S
HN
(NO3)
N
A
i,ii
S
NO2
N
N
CuII
(NO3)2
N
N
2
S
S
NH
Scheme 3. Synthetic products expected: (i) Cu(NO3)2, (ii) bipy.

152
Tarlok S Lobana et al.
Table 1. Crystal data for compounds 1b and 2.
T(K)
1b, 296(2) K
T(K)
2a, 173(2) K,
2b, 296(2) K
Empirical formula
M
C6 H8 BrCuN2S3
347.80
Empirical formula
M
C20H16Cu N5O3·N O3
499.93;
499.94
λ(Å)
Crystal system
Space group
0.71069
Triclinic
P-1
λ(Å)
Crystal system
Space group
1.54184;
Monoclinic
P21/n(14);
0.71073
Monoclinic
P21/n(14);
Unit cell dimensions
Unit cell dimensions
a(Å)
b(Å)
c(Å)
α(◦◦)
β(◦)
γ ( )
V(Å3)
Z
7.3890(19)
8.473(2)
9.491(2)
70.273(5)
67.170(5)
84.949(5)
514.9(2)
2
a(Å)
b(Å)
c(Å)
α(◦◦)
β(◦)
γ ( )
V(Å3)
Z
11.31848(19);
12.1599(2);
14.9672(3);
-
98.0053(16);
-
2039.88(6);
4;
1.628;
11.340(5)
12.249(5)
15.065(6)
-
98.043(16)
-
2072.0(15)
4
1.603
D
calcd(g cm−3
)
2.243
6.560
Dcalcd(g cm−3
)
μ(mm−1
)
μ(mm−1
)
1.988;
1.107
F(000)
Reflections collected
Unique reflections
340
6655
1888
F(000)
Reflections collected
Unique reflections
1020;
13344;
3912
1020
15176
4114
(Rint = 0.0395)
(Rint = 0.041);
(Rint = 0.061)
Data/restraints/
parameters
Reflns. with [I>2σ(I)]
R Indices
1888/0/118
Data/restraints/
parameters
Reflns. with [I>2σ(I)]
R Indices
3912/0/299;
4114/0/298
1742
3577;
2408
R1
wR2
0.0679
0.2195
R1
wR2
0.0399;
0.1088;
0.0409
0.0785
R indices (all data)
R1
wR2
Largest diff.
Peak and hole
R indices (all data)
R1
wR2
Largest diff. Peak
and hole
0.0709
0.2204
0.0428;
0.1116;
0.0912
0.0939
1.954 e. Å−3
,
0.48 e. Å−3
,
0.355 e. Å−3
−0.268 e. Å−3
−1.217 e. Å−3
−0.44 e. Å−3
,
The coordination of nitrate lengthens O1-N5 distance
{1.280(3) Å} vis-à-vis uncoordinated O2-N5 {1.199(3)
Å} and O3-N5{1.241(3) Å} bond distances. The angles
around copper metal centre vary in the wide range,
Table 2. Bond lengths (Å) and angles (◦) of compounds
1b and 2a∗.
1b
Cu1 – Br1
Cu1 – N2
Cu1 – S1
C1– S1
2.287(2) C1– S2
1.970(11) N2 – Cu1 –S1
2.190(4) N2 – Cu1 – Br1 127.1(3)
1.665(15) S1 – Cu1 – Br1 133.55(13)
2a
1.749(14)
99.3(4)
2a
Cu1- O1
Cu1- N1
Cu1 - N2
N1- Cu1- N2 79.93(7)
N1 - Cu1- O1 101.10(7)
N1 - Cu1- N3 103.30(7)
N1 - Cu1- N4 108.36(7)
N2 - Cu1- N3 176.46(7)
2.0828(18) Cu1 – N3
2.1215(18) Cu1 – N4
1.9875(17)
1.9776(18)
2.0228(17)
N2 - Cu1- O1
N2 - Cu1- N4
N3 - Cu1- O1
N3 - Cu1- N4
87.61(7)
99.05(7)
90.31(7)
81.40(7)
N4 - Cu1- O1 150.49(7)
Figure 3. Molecular structure of [Cu(κ2-N,Nꢁ-bipy)2(κ1-
ONO2)](NO3) 2a.
*See supplementary for more details

Reactivity of thiazolidine-2-thione towards copper
153
80–177◦, the shortest being the bite angles (ca. 80◦) of
bipy ligands. The τ parameter of 0.43 suggests signifi-
cant deviation from a square pyramid and the structure
is in between a trigonal bipyramid-square pyramid.
The nitrate has shown a variety of coordination trends
(see supplementary data).12–22
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Supplementary Information
Crystallographic data (excluding structure factors) for
the structures in this paper have been deposited with
the Cambridge Crystallographic Data Centre, CCDC,
12 Union Road, Cambridge CB21EZ, UK. Copies of
the data can be obtained free of charge on quoting the
depository numbers CCDC 1006272 for 1b, 988896
for 2a and 988897 for 2b (Fax: +44-1223-336-033; E-
Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.
ac.uk). (See Tables S1 and S2 for more details about
nitrate coordination, complete bond lengths/angles for
2 as well as for bonding trends of nitrate in presence of
2,2ꢁ-bipyridines).
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