Synthesis, molecular structures and ESI-mass studies of copper(I) complexes with ligands incorporating N, S and P donor atoms

Article abstract of DOI:10.1007/s12039-015-0953-4

Equimolar reaction of copper(I) bromide with 2-thiouracil (tucH₂) in acetonitrile-methanol formed a light yellow solid which on subsequent treatment with a mole of triphenyl phosphine (PPh₃) in chloroform has yielded a sulfur-bridged dinuclear complex, [Cu₂Br₂(μ-S-tucH₂)₂(PPh₃)₂] 2CHCl₃ 1. A reaction of copper(I) bromide with two moles of 2,4-dithiouracil (dtucH₂) in acetonitrile-methanol followed by addition of two moles of PPh₃, designed to form [Cu(μ-S,S-dtuc)₂(PPh₃)₄Cu] 2a, instead resulted in the formation of previously reported polymer, {CuBr(μ-S,S-dtucH₂)(PPh₃)}_n 2. Reaction of copper(I) iodide with 2-thiouracil (tucH₂) and PPh₃ in 1:1:2 molar ratio (Cu:H₂tuc:PPh₃) as well as that of copper(I) thiocyanate with pyridine-2-thione (pySH) or pyrimidine-2-thione (pymSH) and PPh₃ in similar ratio, yielded an iodo-bridged unsymmetrical dimer, [(PPh₃)₂(μ-I)₂Cu(PPh₃)] 3 and thiocyanate bridged symmetrical dimer, [(PPh₃)₂Cu(μ-N,S- SCN)₂Cu(PPh₃)₂] 4, respectively. In both the latter reactions, thio-ligands which initially bind to Cu metal center, are de-ligated by PPh₃ ligand. Crystal data: 1, P2₁/c: 173(2) K, monoclinic, a, 13.4900(6); b, 17.1639(5); c, 12.1860(5) ?; β, 111.807(5) ^a; R, 5.10%; 2, Pbca: 296(2) K, orthorhombic, a, 10.859(3); b, 17.718(4); c, 23.713(6) ?; α=β=γ, 90 ^a; R, 4.60%; 3, P2₁: 173(2) K, monoclinic, a, 10.4208(7); b, 20.6402(12); c, 11.7260(7) ?; β, 105.601(7)^a; R, 3.97%; 4, P-1: 173(2) K, triclinic, a, 10.2035(4); b, 13.0192(5); c, 13.3586(6) ?; α, 114.856(4); β, 92.872(4)^a; γ, 100.720(4)^a; R, 3.71%. ESI-mass studies reveal different fragments of complexes.

Full text of DOI:10.1007/s12039-015-0953-4

J. Chem. Sci. Vol. 127, No. 10, October 2015, pp. 1859–1869. ꢀc Indian Academy of Sciences.
DOI 10.1007/s12039-015-0953-4
Synthesis, molecular structures and ESI-mass studies of copper(I)
complexes with ligands incorporating N, S and P donor atoms
a,∗
a
a
a
TARLOK S LOBANA , ARVINDER KAUR , ROHIT SHARMA , MADHU BALA ,
a
b
b
AMANPREET K JASSAL , COURTNEY E DUFF and JERRY P JASINSKI
Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India
Department of Chemistry, Keene State College, Keene NH 03435–2001, USA
a
b
e-mail: tarlokslobana@yahoo.co.in
MS received 11 June 2015; revised 19 August 2015; accepted 24 August 2015
Abstract. Equimolar reaction of copper(I) bromide with 2-thiouracil (tucH2) in acetonitrile-methanol formed
a light yellow solid which on subsequent treatment with a mole of triphenyl phosphine (PPh3) in chloro-
form has yielded a sulfur-bridged dinuclear complex, [Cu2Br2(μ-S-tucH2)2(PPh3)2]·2CHCl3 1. A reaction of
copper(I) bromide with two moles of 2,4-dithiouracil (dtucH2) in acetonitrile-methanol followed by addi-
tion of two moles of PPh3, designed to form [Cu(μ-S,S-dtuc)2(PPh3)4Cu] 2a, instead resulted in the forma-
tion of previously reported polymer, {CuBr(μ-S,S-dtucH2)(PPh3)} n 2. Reaction of copper(I) iodide with 2-
thiouracil (tucH2) and PPh3 in 1:1:2 molar ratio (Cu:H2tuc:PPh3) as well as that of copper(I) thiocyanate with
pyridine-2-thione (pySH) or pyrimidine-2-thione (pymSH) and PPh3 in similar ratio, yielded an iodo-bridged
unsymmetrical dimer, [(PPh3)2(μ-I)2Cu(PPh3)] 3 and thiocyanate bridged symmetrical dimer, [(PPh3)2Cu(μ-
N,S- SCN)2Cu(PPh3)2] 4, respectively. In both the latter reactions, thio-ligands which initially bind to Cu
metal center, are de-ligated by PPh3 ligand. Crystal data: 1, P21/c: 173(2) K, monoclinic, a, 13.4900(6);
◦
b, 17.1639(5); c, 12.1860(5) Å; β, 111.807(5) ; R, 5.10%; 2, Pbca: 296(2) K, orthorhombic, a, 10.859(3);
◦
◦
b, 17.718(4); c, 23.713(6) Å; α = β = γ , 90 ; R, 4.60%; 3, P21: 173(2) K, monoclinic, a, 10.4208(7);
b, 20.6402(12); c, 11.7260(7) Å; β, 105.601(7) ; R, 3.97%; 4, P-1: 173(2) K, triclinic, a, 10.2035(4); b,
◦
◦
1
3.0192(5); c, 13.3586(6) Å; α, 114.856(4); β, 92.872(4) ; γ , 100.720(4) ; R, 3.71%. ESI-mass studies reveal
different fragments of complexes.
Keywords. 2-Thiouracil; 2,4-dithiouracil; pyridine-2-thione; pyrimidine-2-thione; copper(I) bromide; cop-
per(I) thiocyanate.
2
1
1
. Introduction
it has yielded mononuclear [CuBr(κ -P,P-dppbz)(κ -
S-dtucH )]{dppbz = 1,2-bis(diphenylphosphan-yl)ben-
2
The coordination chemistry of heterocyclic thioamide
ligands, namely, pyridine-2-thiones, 2-thiouracils, 2,4-
dithiouracils, imidazolidine-2-thiones and thiazolidine-
32
1
1
zene}, dinuclear [Cu (μ-X)(κ -S,κ -S-dtucH)(PPh ) ]
2
3 4
33
(
X = Cl, Br), and polynuclear complexes [Cu(μ-S,
34
S-dtucH )(PPh )X] (X = Cl, Br, I), and with other
2
3
n
2
-thiones with transition/main-group metals has been
metals, namely, silver(I), cobalt(III), titanium(III) and
the focus of many investigators describing synthesis
and structures of compounds as well as their biochem-
19,35–37
ruthenium(II),
complexes.
it has formed only mononuclear
1
–42
ical applications.
Among applications, copper com-
Further, the coordination chemistry of copper(I)
plexes have shown antitumor, anti-inflammatory and
1–3,10–13,17,18
halides is well documented,
however, there
antimicrobial activities.2
,14–16
Chart 1 shows the ligands
are only a few mononuclear complexes of heterocyclic
thioamides with copper(I) thiocyanate or mercury(II)
under study. It is known that 2-thiouracil (tucH ) with
2
copper(I) has formed only mono-nuclear trigonal pla-
thiocyanate, namely, [Cu(NCS)L ] (L = 1,3-imidazol-
2
1
17
1
nar, [CuCl(κ -S-tucH ) ], and tetrahedral, [CuCl(κ -
38,39
2
2
idine-2-thione),
[Cu(NCS)L(PPh ) ] (L = 4,6-
3
2
18
S-tucH ) (PPh ) ] complexes. Further, 2-thiouracils
40
2
2
3 2
dimethyl-pyrimidine-2-thione), Hg(SCN) L ] (L =
2 2
4
1
have yielded mononuclear complexes with several
tetrahydropyrimidine-2-thione), and one polymer,
1
9
20–22
other metals, namely, ruthenium(II), cobalt(III),
{
Cu (μ-S-L) (μ-SCN) } (L = 1,3-imidazolidine-2-
2
2
2 n
23–27
28,29
30
31
42
gold(I),
zinc(II),
mercury(II) and thallium(III).
thione). In the present investigation, some reactions
of 2-thiouracil, 2,4-dithiouracil, pyridine-2-thione and
pyrimidine-2-thione with copper(I) halides/pseudo
halides in presence of triphenylphosphine have been
As regards dithiouracil (dtucH ), with copper(I) halides
2
∗
For correspondence
1859

1860
Tarlok S Lobana et al.
+
O
S
(PPh ) ] ; (D) m/z 991.04(obsvd.), 991.72 (calcd.),
3 2
formula, C H Br Cu N O PS , species, [Cu Br (H uc)
30
27
2
3
6
3
3
3
2
2
3
+
N
NH
NH
(
PPh ) ] .
3 2
N
H
S
N
H
S
N
H
S
N
H
S
2.3 Synthesis of {CuBr(μ-S,S-dtucH
)(PPh
)}
(2)
2
3
n
I
II
III
IV
To a colorless solution of copper(I) bromide (0.025 g,
.17 mmol) in acetonitrile (5 mL) was added a solution
of 2, 4-dithiouracil (0.050 g, 0.35 mmol) in methanol
5 mL) and the resulting solution was stirred for about
4 h at room temperature. To the green precipitate
0
Chart 1. Molecular structures of thioligands under study.
(
2
carried out and the results of the study are reported in
this paper.
formed was added solid PPh (0.091 g, 0.35 mmol) and
3
the contents stirred until a clear solution was obtained.
The slow evaporation of the solution at room tem-
perature formed red crystals which were characterized
using X-ray crystallography. The formation of the prod-
uct [Cu(μ-S,S-dtuc) (PPh ) Cu] was expected, how-
2
. Experimental
2.1 Materials
2
3 4
ever, X-ray crystallography supported the formation of
Copper(I) bromide/iodide/thiocyanate were prepared
{
CuBr(μ-S,S-dtucH )(PPh )} 2. Yield: 0.068 g; 72%;
by reducing an aqueous solution of CuSO ·5H O using
2
3
n
4
2
◦
M.p. 288-290 C. Lack of solubility prevented recording
of ESI-mass spectrum.
SO in the presence of NaX (X = Br, I, SCN) in
2
water. The thio-ligands pyridine-2-thione, pyrimidine-2-
thione, 2-thiouracil and 2,4-dithiouracil were procured
from Sigma–Aldrich Ltd. Solvents were of Analytical
Research grade and used as such. The IR spectrum was
recorded using KBr pellets on Varian 660 FT IR in
2
.4 Synthesis of [(PPh ) Cu(μ − I) Cu(PPh )] (3)
3 2
2
3
To a colorless solution of copper(I) iodide (0.015 g,
0.08 mmol) in acetonitrile (5 mL) was added a solution
of 2-thiouracil (0.011 g, 0.08 mmol) in methanol (5 mL)
and the resulting solution was stirred for about 24 h
at room temperature. To it was added triphenylphos-
phine (0.041 g, 0.16 mmol), stirred for 30 min and it
formed a clear solution. Slow evaporation of this solu-
tion yielded colorless crystals which were character-
ized using X-ray crystallography. The formation of
−1
the 4000-200 cm range. The ESI-mass spectra were
recorded in DMSO using Bruker Daltonik LS-MS high
resolution microTOF-Q II 10356.
2
.2 Synthesis of [Cu Br (μ-S-tucH ) (PPh ) ]·
2
2
2 2
3 2
2CHCl (1)
3
1
To a colorless solution of copper(I) bromide (0.025 g,
.17 mmol) in acetonitrile (5 mL) was added a solution
product, [CuI(κ -S-tucH )(PPh ) ] was expected, how-
2
3 2
0
ever, X-ray crystallography supported the formation
of 2-thiouracil (0.022 g, 0.17 mmol) in methanol (5 mL)
and the resulting solution was stirred for about 24 h at
room temperature. The mother liquor was removed and
the light yellow solid left was placed in chloroform.
To it was added triphenylphosphine (0.045g, 0.17mmol)
and stirred for 30 min and it formed a clear solution.
Slow evaporation of this solution yielded light yellow
crystals, which were characterized using X-ray crystal-
of unsymmetrical dinuclear complex, [(PPh ) (μ-I)
3
2
2
◦
Cu(PPh )] 3. Yield: 0.062 g; 67%; M.p. 184–185 C.
3
ESI-mass data: (A) m/z 587.07(obsvd.), 587.11 (calcd.),
+
formula, C H CuP , species, [Cu(PPh ) ] ; (B) m/z
36
30
2
3 2
6
03.06(obsvd.), 603.10 (calcd.), formula, C H CuP O,
36 30 2
+
species, [Cu(OPPh )(PPh )] ; (C) m/z 849.13(obsvd.),
3
3
8
49.20(calcd.), formula, C H CuP , species, [Cu
54 45 3
+
(
PPh ) ] ; (D) m/z 992.97(obsvd.), 993.11 (calcd.), for-
3 3
◦
+
lography. Yield: 0.059 g; 64%; M.p. 178–180 C. Main
mula, C H CuIOP , species, [CuI(PPh ) (OPPh )] .
54
45
3
3 2
3
−1
IR peaks (KBr, cm ): ν (O-H), 3435w; ν (N-H), 3150m;
ν (C-H), 3075m, 3015w, 2965w; ν (C-N) + δ (C-H)
2
.5 Synthesis of [(PPh ) Cu(μ-N,S-SCN) Cu(PPh ) ]
3 2 2 3 2
1
1
580m, 1475s; 1430s, 1319m, ν (C-S) 1150m; ν (P-C),
090(s); 1025m, 989m, 920w, 848m, 740m, 690s, 518m.
(4)
ESI-mass data: (A) m/z 403.03(obsvd.), 403.94 (calcd.), To a colorless solution of copper(I) thiocyanate
+
formula, C H BrCuP, species, [CuBr(PPh )] ; (B) m/z (0.015 g, 0.12 mmol) in acetonitrile (10 mL) was added
18
15
3
5
87.11(obsvd.), 587.11 (calcd.), formula, C H CuP , solid pyridine-2-thione (0.014 g, 0.12 mmol) and the
36 30 2
+
2
+
species, [Cu(PPh ) ] ;)] ; (C) m/z 728.95(obsvd.), 728.96 resulting solution was stirred for about 24 h at room
3
(
calcd.), formula, C H BrCu P , species, [Cu Br temperature. It led to the formation of red precipitate
36 30 2 2 2

Copper(I) complexes with N,S and P donor ligands
1861
and addition of triphenylphosphine (0.065g, 0.24mmol) the identical product 4 was formed. Yield: 0.125 g;
◦
in chloroform (5mL) formed a clear solution. Slow evap- 78%; M.p. 182–184 C. ESI-mass data: (A) m/z 587.17
oration of this solution yielded yellow crystals which (obsvd.), 587.11 (calcd.), formula, C H CuP , species,
3
6
30
2
+
were characterized using x-ray crystallography. It was [Cu(PPh ) ] ; (B) m/z 603.16 (obsvd.), 603.11 (calcd.),
designed to obtain [Cu(SCN)(κ -S-pySH)(PPh ) ], how- formula, C H CuP O, species, [Cu(OPPh )(PPh )] ;
3
2
1
+
3
2
36 30
2
3
3
ever, X-ray crystallography supported the formation of (C) m/z 849.28 (obsvd.), 849.20 (calcd.), formula,
+
[
(PPh ) Cu(μ-N,S-SCN) Cu(PPh ) ] 4. Similarly, with C H CuP , species, [Cu(PPh ) ] ; (D) m/z 970.19
3
2
2
3 2
54 45
3
3 3
pyrimidine-2-thione, the expected product [Cu(SCN) (obsvd.), 970.10 (calcd.), formula, C H Cu NP S,
55
45
2
3
1
+
(
κ -S-pymSH)(PPh ) ] could not be obtained, rather species, [(PPh )Cu(SCN)Cu(PPh ) ] .
3 2
3 3 2
Figure 1. Molecular structure of [Cu2Br2(μ-S-tucH2)2(PPh3)2]·2CHCl3 1.
6
1
N
L =
5
S- 2 N3
PPh3
Cu
HN
N
4
S
H
PPh3
Ph P
S
3
N
H
O
N
H
S
N
H
S
Cu
Cu
L
H
3a
4a
4b
PPh3 Ph P
Ph P
N
3
X
3
S
S
N
3
a,4a,4b
X = I, 3a; NCS, 4a; NCS, 4b
2a
Chart 2. A view of bonding pattern of expected complexes from the reactions 2 to 4.

1862
Tarlok S Lobana et al.
2.6 X-ray crystallography
suspended in chloroform and addition of triphenyl-
phosphine (equimolar reaction, Cu:tucH :PPh :: 1:1:1)
2
3
A single crystal was mounted on a glass fiber and used formed a clear solution which on slow evaporation gave
for data collection with a Xcalibur, Eos, Gemini (1, 3-4, crystals whose single crystal X-ray crystallographic
1
73(2) K) or with a Bruker Kapa – Apex (II) CCD study supported the formation of dinuclear complex
diffractometer (2; 296(2) K) both equipped with gra- [Cu Br (μ-S-tucH ) (PPh ) ]·2CHCl 1 (figure 1). The
2
2
2 2
3 2
3
phite monochromated Mo-Kα (λ = 0.71073 Å). The reaction of copper(I) iodide with tucH and PPh in
2
3
data recorded at low temperature was processed with 1:1:1 molar ratio in CH CN-MeOH mixture (1:1 v/v)
3
CrysAlisPro CCD (data collection), CrysAlisPro RED did not give a crystalline product similar to 1 and thus
(
cell refinement, data reduction).43 The structure was reaction in presence of two moles of PPh was carried
3
solved by direct methods using the program SHEXS- out in same CH CN-MeOH mixture. From this reaction,
3
1
9
7, refined by full-matrix least-squares techniques it was expected to obtain the product, [CuI(κ -S-tucH )
against F using SHELX-97 and molecular graphics from (PPh ) ] 3a (chart 2). However, X-ray crystallogra-
SHELXL. The data collected at room temperature phy supported the formation of a dinuclear complex,
2
2
3
2
44
was also processed with Bruker Kapa – Apex(II) CCD [(PPh ) (μ-I) Cu(PPh )] 3 (figure 3). Here in this reac-
3
2
2
3
10
and corrected for absorption using SADABS. The tion, the thio-ligand initially clearly binds to the metal
structures were solved by direct methods using SIR-92 center (yellow precipitate), but the addition of PPh3
4
5
software and refined by full-matrix least-squares meth- replaced tucH yielding the colorless dimer 3. Reaction
2
2
44
od based on F using the program using SHELX-97.
of copper(I) thiocyanate with pySH (or pymSH) and
Atomic scattering factors were taken from “Interna- PPh (1:1:2 molar ratio) in acetonitrile-chloroform was
3
tional Tables for Crystallography”.46
designed to obtain mononuclear complexes, [Cu(SCN)
1
(
κ -S-L)(PPh ) ] (chart 2, L = pySH, 4a; pymSH, 4b),
3
2
however, X-ray crystallography supported the forma-
3
. Results and Discussion
tion of dinuclear complex [(PPh ) Cu(μ-N,S-SCN)
3
2
2
Cu(PPh ) ] 4 in each case (figure 4). Here, in these
reactions also, the thio-ligands pySH (or pymSH) gave
3
2
3.1 Synthesis and general comments
The addition of solution of tucH in methanol to cop- red precipitate with copper(I) thiocyanate suggesting
2
per(I) bromide solution in acetonitrile followed by stir- binding to metal center, but the addition of PPh
de-
3
ring gave light yellow precipitate. The precipitate was ligated the thio-ligands yielding dinuclear complex 4
Figure 2. Structure of polymer {CuBr(μ-S,S-dtucH2)(PPh3)}n 2.

Copper(I) complexes with N,S and P donor ligands
1863
in each case. Finally, reaction of copper(I) bro-
The molecular structure of dinuclear complex
mide with 2, 4-dithiouracil and PPh in acetonitrile- [Cu Br (μ-S-tucH ) (PPh ) ]·2CHCl 1 is shown in
3
2
2
2 2
3 2
3
methanol in 1:2:2 molar ratio was designed to obtain figure 1. Compound 1 crystallized in monoclinic crys-
Cu(μ-S,S-dtuc) (PPh ) Cu] 2a (chart 2), however, X- tal system in P2 /c space group (table 1). Each Cu
[
2
3 4
1
ray crystallography supported the formation of poly- metal atom is bonded to two bridging sulfur atoms at
mer, {CuBr(μ-S,S-dtucH )(PPh )} 2 (figure 2).
Cu-S bond distances of 2.3004(8), 2.5969((9) Å, to one
P donor atom at Cu-P bond distance of 2.2325(8) Å
and to one halogen atom at Cu-Br bond distance of
2
3
n
2
.4137(5) Å (table 2). The central core Cu S of the din-
3
.2 IR spectra and molecular structure of [Cu Br (μ-
2 2
2
2
uclear complex comprises a parallelogram with unequal
Cu-S bond distances as noted above. The Cu-S-Cu and
S-tucH ) (PPh ) ]·2CHCl 1
2
2
3 2
3
◦
The IR spectral data support the presence of both S-Cu-S bond angles of 77.79(3) and 102.21(3) , respec-
thio-ligand triphenylphosphine in complex 1. The tively are typical of Cu
S
cores in different dinuclear
2
2
47
ν(N-H) and ν(O-H) bands appeared at 3150(m) and complexes. The angles around each Cu metal center
−1
◦
3
435(w) cm , respectively, suggesting that thio-ligand vary in the range, 99 to 117 suggesting distorted tetra-
tucH is coordinating to the metal center as neutral lig- hedral geometry. The C-S bond distance of 1.696(3) Å
2
and. Similarly, the diagnostic ν(C-S) band occurred at is in between the C=S double-bond length of 1.62 Å
4
8,49
−
1
and the C–S single-bond length of 1.81 Å.
This
1
150(m) cm which is at low energy relative to the free
−1
shows weakening of C–S bond on coordination but
there is considerable double-bond character in it.
ligand. The ν(P-C ) band at 1090(s) cm showed the
presence of PPh in complex 1.
Ph
3
Table 1. Crystal data for compounds 1-4.
1
2
3
4
Empirical
formula
T(K)
C44H38Br2Cu2N4
-2P2S2·2(CHCl3)
173(2)
C22H19BrCuN2PS2
C54H45Cu2I2P3
C74H60Cu2N2P4S2
296(2)
549.95
0.71073
173(2)
1167.69
0.71073
Monoclinic
P21
173(2)
1292.32
0.71073
Triclinic
P-1
M
1306.48
λ (Å)
Crystal system
Space group
0.71073
Monoclinic
P21/c
Orthorhombic
Pbca
Unit cell dimensions
a(Å)
b(Å)
c(Å)
13.4900(6)
17.1639(5)
12.1860(5)
90
10.859(3)
17.718(4)
23.713(6)
90
10.4208(7)
20.6402(12)
11.7260(7)
90
10.2035(4)
13.0192(5)
13.3586(6)
114.856(4)
92.872(4)
100.720(4)
1565.63(13)
1
◦
α( )
◦
β( )
111.807(5)
90
90
105.601(7)
90
◦
γ ( )
90
3
V(Å )
2619.64(19)
4562(2)
2429.2(3)
Z
2
8
2
Dcalcd(g cm 3)
−
1.656
1.601
1.596
2.281
1156
1.371
−1
μ(mm
F(000)
Flack parameter
Reflections collected
Unique reflections
)
2.826
2.974
0.894
1304
2208
668
–
–
−0.037(14)
–
19801
23140
5652,
18423
19647
8706,
12271,
10396,
Rint = 0.0446
Rint = 0.0741
Rint = 0.0385
Rint = 0.0293
Data/restraints/
parameters
8706/ 12/303
5652 / 2 / 268
12271/ 1/551
10396/0/379
Goodness- of- fit
Reflns.with [I > 2σ(I)]
R Indices
1.033
6392
1.001
3432
1.027
1.041
8428
10749
R
1
0.0510
0.1115
0.0460
0.1036
0.0397
0.0794
0.0371
0.0827
wR2
R indices(alldata)
R
0.0805
0.1288
1.649 e.Å
−1.260 e.Å
0.0950
0.0497
0.0518
1
wR2
0.1240
0.0856
0.0912
−
3
−3
−3
−3
Largest diff.
Peak and hole
,
0.630 e.Å
,
1.209 e.Å
,
0.445e.Å
,
−
3
−3
−3
−3
−0.456 e.Å
−0.717 e.Å
−0.383 e.Å

1864
Tarlok S Lobana et al.
◦
Table 2. Bond lengths (Å) and angles ( ) of compounds 1-4.
1
2
Cu1- S1
Cu1 - S1
Cu1- P1
Cu1- Br1
2.3004(8)
2.5969(9)
2.2325(8)
2.4137(5)
1.696(3)
114.33(2)
99.47(2)
102.21(3)
116.39(3)
110.87(3)
111.82(3)
77.79(3)
Cu1-S1
Cu1-S2
Cu1- P1
2.2887(12)
2.4052(13)
2.2418(12)
2.5010(7)
Cu1 - Br1
S1 - C4
S1-C19, S2-C22
P1-Cu1- S1
P1-Cu1- S1
P1- Cu1- S2
S1- Cu1- S2
P1- Cu1- Br1
S1- Cu1-Br1
S2- Cu1- Br1
1.659(4), 1.674(4)
119.65(5)
S1- Cu1- Br1
Br1- Cu1- S1
S1- Cu1- S1
P1- Cu1- Br1
P1- Cu1- S1
P1 -Cu1- S1
Cu1- S1- Cu1
119.65(5)
105.79(5)
102.18(5)
109.06(4)
112.34(4)
106.61(4)
3
4
Cu1-I1, Cu2-I1
Cu1-I2, Cu2-I2
Cu1- P1
Cu2- P2
Cu2- P3
2.5078(7), 2.8019(7)
2.5660(7), 2.7079(7)
2.2199(16)
2.2673(13)
2.2592(15)
3.0249(9)
Cu1- S1
Cu1- P1
Cu1- P2
Cu1- N1
S1- C37
2.3951(4)
2.2813(5)
2.3094(4)
2.0328(13)
1.6522(16)
Cu1- Cu2
Cu1-I1-Cu2,
Cu1-I2- Cu2
I1- Cu1- I2,
I2-Cu2- I1
P1- Cu1- I1
P1- Cu1- I2
P2- Cu2- I1,
P2- Cu2- I2
P3- Cu2- I1,
P3-Cu2- I2
P3 -Cu2- P2
69.20(2),
69.94(2)
116.39(3),
102.99(2)
131.15(5),
112.43(5)
100.08(4),
107.63(4)
110.69(4),
108.81(4)
P1 -Cu1- S1
P1- Cu1- P2
P2- Cu1- S1
N1- Cu1- S1
N1- Cu1- P1
N1- Cu1- P2
111.158(17)
121.716(16)
104.877(17)
98.24(4)
112.85(4)
124.44(6)
105.19(4)
ligands (after loss of –NH proton). As neutral ligands
the coordination to metal center occurs through thione
sulfur either in monocoordination or in μ-S bridging as
for example observed in complex 1, which is concluded
from X-ray crystallography. As anionic ligand thiol
form loses –NH proton and the anion coordinates to the
metal center through S or N,S-donor atoms through a
S
SH
N
N
H
thione
thiol
Chart 3. Thione-thiol tautomerism.
1–3,11
variety of coordination possibilities.
It may be noted that 2-thiouracil has three types 3.3 Molecular structures of complexes 2-4
of donor atoms: N, S and O. However, it has bonded
I
to Cu only through sulfur in a bridging mode (HSAB Compound 2 crystallized in orthorhombic crystal sys-
principle) and the ligand remains neutral. This coordi- tem in Pbca space group (table 1). The thio-ligand 2,4-
nation property is similar to that of pyridine-2-thione dithiouracil acts as a bridging ligand with each sulfur
(
pySH), pyrimidine-2-thione (pymSH) which display atom bonding to different metal centers. Each Cu metal
sulfur bridging in dinuclear complexes, [Cu (μ-S-pySH)
center is binding to one S donor atom of 2,4-dtucH2,
2
2
50
51
(
(
PPh ) Br ], [Cu (μ-S-pySH) (m-tolyl P) Br ], [Cu
one Br atom and one PPh atom generating three coor-
3
2
2
2
2
3
2
2
2
3
4
7
μ-S-pySH) (p-tolyl P) Br ], [Cu (μ-S-pySH) (p- dinate moiety, CuBr(μ-S,S-dtucH )(PPh ). This moiety
2
2
3
2
2
2
2
2
3
5
53
tolyl P) I ], and [Cu (μ-S-pymSH) (p-tolyl P) Cl ],
combines with another similar moiety leading to
3
2 2
2
2
3
2
2
(
m-tolyl P/p-tolyl P are tri-m-tolylphosphine/tri-p-tol- the formation of the polymer, {CuBr(μ-S,S-dtucH2)
3 3
ylphosphine, respectively).
(PPh )} 2 (figure 2). The geometry around each metal
3
n
Heterocyclic thioamide ligands are believed to dis- center is distorted tetrahedron. It is noted here that the
play thione-thiol tautomerism in liquid state (chart 3). crystal data and bond parameters of this complex are
In their complexes, they coordinate as neutral or anioinc similar to the previously reported polymeric structure

Copper(I) complexes with N,S and P donor ligands
1865
reported from the same laboratory by direct reaction in figure 3. Both iodides bridge two Cu metal centers.
33
of copper(I) bromide with 2,4-dtucH and PPh . Com- One copper atom is bonded to two P donor atoms
2
3
pound [(PPh ) (μ-I) Cu(PPh )] 3 has the structure shown and two bridging iodides with distorted tetrahedral
3
2
2
3
Figure 3. Molecular structure of [(PPh3)2(μ-I)2Cu(PPh3)] 3.
Figure 4. Molecular structure of [(PPh3)2Cu(μ-N,S- SCN)2Cu(PPh3)2] 4.

1866
Tarlok S Lobana et al.
geometry, while second copper atom is bonded to NCS bridged dimer 4. The bond parameters are sim-
two bridging iodides and one P donor atom with dis- ilar to previously reported parameters in literature.55
torted trigonal planar geometry. The crystal data/bond It is added here that complex 3 has been reported
parameters are similar to previously reported struc- in literature from direct reaction of copper(I) iodide
54
54
ture.
Finally, compound [(PPh ) Cu(μ-N,S-SCN)
with triphenylphosphine. Likewise, the reaction of
3
2
2
Cu(PPh ) ] 4 has the structure shown in figure 4. The CuCl(PPh ) with (SCN) is also reported to yield
3
2
3 3
2
55
SCN moiety acts as a bridge connecting two metal complex 4.
centers. Each copper metal atom is bonded to two P
donor atoms, one N and one S donor atoms from NCS 3.4 ESI-mass data of complexes 1-4
group forming distorted tetrahedral geometry around
each metal center. As commented in section 3.1, in both The ESI-mass of 1 has shown four most signifi-
+
+
reactions leading to the formation of 3 and 4, the cant species, namely, [CuBr(PPh
)] [Cu(PPh
)
] ,
3
3
2
+
+
thio-ligands were de-ligated suggesting strong tendency [Cu
Br(PPh
)
]
and [Cu
Br
(tucH
)
(PPh
)
] . The
2
3
2
3
2
2
3
3
2
to generate unsymmetrical dinuclear complex 3 and most intense signal and its isotopic pattern due to
Intens.
x10
+MS, 0.0-0.2min #2-12
5
1+
1
1
0
0
.5
587.1113
.0
1
+
1
+
589.1101
88.1139
5
.5
.0
1
+
5
90.1113
1
+
5
91.1137
582
584
586
588
590
592
594
596
598
m/z
2
2
1
1
500
000
500
000
CuP C36H30, M, 587.1113
2
1
+
5
87.1113
1
+
5
89.1107
1
+
5
88.1147
1
+
5
00
590.1133
1
+
5
91.1162
0
582
584
586
588
590
592
594
596
598
m/z
+
Figure 5. ESI-mass species [Cu(PPh3)2] of complex 1.
Intens.
+MS, 0.0-0.0min #1-2
993.0380
6
4
2
000
000
000
0
9
95.0390
994.0413
9
91.0399
992.0426
996.0416
97.0373
9
9
88
990
992
994
996
998
1000
1002
1004
1006
1008
m/z
Cu Br PC30H O N S , M-nH, 991.7215
2
2
1
1
500
000
500
000
3
2
27
3
6 3
1
+
9
95.7178
1
+
1+
997.7160
9
93.7196
1+
1+
996.7203
1+
1+
9
94.7223
999.7143
5
00
991.7215 1+
92.7243
1+
9
1000.7162
0
9
90.0
992.5
995.0
997.5
1000.0
1002.5
1005.0
1007.5
m/z
+
Figure 6. ESI-mass species [Cu3Br2(tucH2)3(PPh3)2] of complex 1.

Copper(I) complexes with N,S and P donor ligands
1867
Intens.
00
+MS, 0.0-0.2min #2-13
9
92.9713
1
80
60
40
20
0
9
94
996
998
1000
1002
1004
1006
m/z
CuIC34H45P O, M+nH, 993.1097
2
2
1
1
500
000
500
000
3
1
+
9
93.1097
1
+
1+
94.1131
9
95.1102
9
1
+
9
96.1122
5
00
1+
97.1151
9
0
9
94
996
998
1000
1002
1004
1006
1008m/z
+
Figure 7. ESI-mass species [CuI(PPh3)2(OPPh3)] of complex 3.
Intens.
+MS, 0.0-0.2min #2-13
972.1956
3
2
1
000
000
000
0
970.1954
971.2002
973.1980
9
74.1944
9
75.1991
9
76.2003
9
68
970
972
974
976
978
m/z
2
2
1
1
500
000
500
000
Cu SC55NH45P , M, 970.1072
2
3
1
+
1
+
972.1067
9
70.1072
1
+
1+
973.1091
9
71.1105
1
+
9
74.1070
1
+
5
00
0
9
75.1081
1+
76.1089
9
9
68
970
972
974
976
978
980 m/z
+
Figure 8. ESI-mass species [(PPh3)Cu(SCN)Cu(PPh3)2] of complex 4.
+
[
Cu(PPh ) ] is shown in figure 5. Interestingly, the 4. Conclusions
3 2
+
3 2
rearranged species [Cu Br (tucH ) (PPh ) ] reveals
3
2
2 3
the presence of both the thio-ligand and PPh ligands Sulfur-bridged dimer [Cu Br (μ-S-tucH ) (PPh ) ]·
3
2
2
2 2
3 2
coordinated to copper(I) metal centre (figure 6). 2CHCl 1 is the first example of a dinuclear complex
3
Complex 3 has shown 4 most significant species, of 2-thiouracil/ 2,4-dithiouracil class of ligands. With
+
+
+
3 3
[
[
Cu(PPh ) ] , [Cu(OPPh )(PPh )] , [Cu(PPh ) ] and 2-thiouracil, only mononuclear complexes are reported
3
2
3
3
+
CuI(PPh ) (OPPh )] . Interestingly, ESI-mass has as highlighted in Introduction. The 2,4-dithiouracil has
3
2
3
shown the formation of OPPh i.e., oxidation of PPh . strong tendency to form polynuclear complex 2 as noted
3
3
+
Figure 7 depicts the species [CuI(PPh ) (OPPh )] of with copper(I) bromide. Formation of 3 demonstrates
3
2
3
complex 3 with its isotopic pattern. Finally, ESI-mass strong tendency of 2-thiouracil to yield unsymmetri-
spectrum of complex 4 has shown mass species, cal iodide bridged dimer. Finally, due to ambidentate
+
+
+
3 3
namely, [Cu(PPh ) ] , [Cu(OPPh )(PPh )] , [Cu(PPh ) ]
nature of NCS moiety, copper(I) thiocyanate complex
with pyridine-2-thione/pyrimidine-2-thione underwent
3
2
3
+
3
and [(PPh )Cu(SCN)Cu(PPh ) ] (see figure 8).
3
3 2

1868
Tarlok S Lobana et al.
de-ligation of thio-ligand in presence of PPh ligand 14. Kela U and Vijayavargiya R 1981 Biochem. J. 193 799
3
1
1
5. Dubler E and Gyr E 1988 Inorg. Chem. 27 1466
6. Masoud M S, Soayed A A and El-Husseiny A F 2012
Spectrochim. Acta Part A 99 365
yielding NCS bridged dinuclear complex 4. ESI-mass
studies have shown the formation of several significant
species.
1
1
1
2
2
7. Hunt G W, Griffith E A H and Amma E L 1976 Inorg.
Chem. 15 2993
8. Lobana T S, Sandhu A K, Sultana R, Butcher R J,
Castineiras A and Jasinski J P 2014 RSC Adv. 4 30511
9. Yamanari K, Nozaki T, Fuyuhiro A, Kushi Y and
Kaizaki S 1996 J. Chem. Soc., Dalton Trans. 2851
0. Yamanari K, Okusako K, Kushi Y and Kaizaki S 1992
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1. Yamanari K, Kida M, Yamamoto M, Fujihara T,
Fuyuhiro A and Kaizaki S 1995 J. Chem. Soc., Dalton
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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 quot-
ing the depository numbers CCDC 1405753 for 1,
2
2
2
2
2
2. Yamanari K, Kida M, Yamamoto M, Fujihara T,
Fuyuhiro A and Kaizaki S 1993 Chem. Lett. 1865
3. Hoskins B F, Zhenrong L and Tiekink E R T 1989 Inorg.
Chim. Acta 158 7
4. Harker C S W, Tiekink E R T and Whitehouse M W
1991 Inorg. Chim. Acta 181 23
1405754 for 2, 1405755 for 3 and 1405756 for 4 (Fax:
+
44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk,
http://www.ccdc.cam.ac.uk). ESI mass data area in
Supplementary Information is available at www.ias.ac.
in/chemsci.
5. Cookson P D and Tiekink E R T 1993 J. Cryst. Spectr.
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6. Cookson P D and Tiekink E R T 1994 Z. Kristallogr.
Acknowledgements
Financial assistance in the form of Emeritus Scientist
209 749
Grant [21(0904)/12-EMR-II] to T.S. Lobana, from the 27. Cookson P D and Tiekink E R T 1994 J. Chem. Cryst.
Council of Scientific and Industrial Research (CSIR),
New Delhi, and grant from the Department of Sci-
ence and Technology (DST) for X-ray diffractome-
ter to Department of Chemistry, GNDU, Amritsar are
gratefully acknowledged. JPJ acknowledges the NSF-
MRI program (Grant No. CHE-1039027) for funds to
purchase the X-ray diffractometer.
24 805
2
2
3
8. Romero M A, Sanchez M P, Quiros M, Sanchez F, Salas
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