Syntheses and structural characterization of new dithiophosphinato cadmium complexes

Article abstract of DOI:10.1007/s12039-015-0930-y

New cadmium complexes of 4-methoxyphenyl dithiophosphinic acids, H₃CO-C₆ H ₄-(R)PS₂H were prepared. The five dithiophosphinato ligands (L) involved were of the general structure H₃CO-C₆ H <

Full text of DOI:10.1007/s12039-015-0930-y

c
J. Chem. Sci. Vol. 127, No. 9, September 2015, pp. 1653–1663. ꢀ Indian Academy of Sciences.
DOI 10.1007/s12039-015-0930-y
Syntheses and structural characterization of new dithiophosphinato
cadmium complexes
a
b,∗
c
˘
˘
˙
˙
ERTUGRUL GAZI SAGLAM , NURCAN ACAR , YASEMIN SÜZEN ,
BERLINE MOUGANG-SOUMÉd and TUNCER HÖKELEKe
aDepartment of Chemistry, Bozok University, 66900, Yozgat, Turkey
bDepartment of Chemistry, Ankara University, 06100 Tandog˘an, Ankara, Turkey
cDepartment of Chemistry, Anadolu University, 26470 Yenibag˘lar, Eskis¸ehir, Turkey
dDepartment of Chemistry, Université de Montréal, Montréal, Québec, Canada
eDepartment of Physics, Hacettepe University, 06800 Beytepe, Ankara, Turkey
e-mail: saglameg@gmail.com; nurcanacar97@gmail.com; ysuzen@gmail.com; djanbe@yahoo.fr;
merzifon@hacettepe.edu.tr
MS received 27 April 2015; revised 27 June 2015; accepted 29 June 2015
Abstract. New cadmium complexes of 4-methoxyphenyl dithiophosphinic acids, H3CO-C6H4-(R)PS2H were
prepared. The five dithiophosphinato ligands (L) involved were of the general structure H3CO-C6H4-(R)PS−
with R= 3-methylbutyl, (L1); n-butyl, (L2); 2-methylpropyl, (L3); 1-methylpropyl, (L4) and 2-propyl, (L52).
To the best of our knowledge, this is the first report on the preparation and characterization of the n-butyl-
derivative. The acid forms of the ligands were obtained by treatment of the Lawesson reagent, (LR) [2,4-bis(4-
methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide] with the corresponding Grignard reagent in dry
diethylether. The acids formed were transformed into easily crystallizable ammonium salts (NH4L) for purifica-
tion. These salts were treated with CdCl2 in ethanol at room temperature to produce the bis-dithiophosphinato
cadmium complexes ([Cd(L)2]2) exclusively. The structures of the complexes were elucidated by elemental
analysis, MS, FTIR and Raman spectroscopy techniques as well as 1H-, 13C- and 31P- NMR. The crystal struc-
tures of [Cd(L1)2]2 and [Cd(L2)2]2 were also studied as examples. X-ray studies confirmed the nonplanar, four-
coordination geometry of the complexes and indicate that electron delocalization prevails in the PS−2 moiety of
the dithiophosphinato groups.
Keywords. Cadmium dithiophosphinato complexes; Thio-Phosphorus Complexes; Dithiophosphinic acid;
Phosphinodithioic acid; X-ray Structure.
1. Introduction
also employed in heavy metal removal from industrial
wastes.8
Dithiophosphoric acids, (OR)2P(S)SH; dithiophospho-
nic acids, (OR)(R)P(S)SH and dithiophosphinic acids,
(R)2P(S)SH, as well as their metal complexes are
in current use in rubber vulcanization,1 lubricating
oils2 and pesticides.3 Tin and antimony complexes of
some dithiophosphinic acids (DTPA) are also of poten-
tially useful as chemotherapy agents in the treatment
of some cancers.4 In addition, some DTPA-99Tc
complexes have been introduced as brain imaging
agents in radiography5 and cephalosporin-type chem-
icals containing DTPA moieties have been suggested
as antibiotics in clinical medicine.6 The commer-
cial sequestering agent CYANEX 301, (bis(2,4,4-tri-
methylpentyl)dithiophosphinic acid) is in current use
for the extraction metals from ores.7 The same agent is
The synthesis of DTPA-type compounds is rela-
tively more tedious compared to the synthesis of other
dithiophosphorus acids.9 Coupled with their disagree-
able odour and the difficulty in obtaining the starting
reagents, these compounds have attracted compara-
tively less attention in the past.10 Various routes have
been developed for the DTPA synthesis,11 the most
general one being the addition reaction of Grignard
reagents with perthiophosphonic acid anhydrides such
as Lawesson reagent, (LR). The DTPAs formed were
further reacted with ammonia to form the easily
crystallizable ammonium salts, facilitating a quick
refinement of the DTPA. The ammonium salt is sta-
ble and can easily be converted to complexes when
desired.12
Depending on the identity of the metal cation, the
coordination number of the DTPA complex changes.
Most of the complexes generally display a four- or
∗For correspondence
1653

1654
Ertug˘rul Gazi Sag˘lam et al.
(55%). White colour. M.P. 179–180◦C. NMR spectro-
scopic data and mass data are as follows: 1H NMR (in
D2O): δ = 0.66 (t, 3JHH = 7.29 Hz, 6H, -C9H); 1.14 (m,
2H, -C7H); 1.27 (m, 2H, -C8H); 2.06 (m, 2H, -C6H);
six-coordination.13 The nickel(II) complexes are exclu-
sively mono-nuclear and generally of a square-planar
topology as is the case with other soft ligands; whereas,
DTPA complexes of manganese(II), cobalt(II), Zinc(II)
and cadmium(II) are known to display four coordi-
nated, dimeric structures.14 In the case of the latter com-
plexes, S atoms of the PS−2 group are known to act as
singly-bonded and also as bridging ligands.
X-ray crystallographic studies on the crystal struc-
tures ditihophosphinato complexes of group 12 metals,
namely, zinc (II), cadmium (II) and mercury (II), are
scarce. These dimeric complexes display a chair confor-
mation although some complexes are known to display
a boat conformation.14c,15
3.70 (s, 3H, OCH3); 6.89 (A-part of AA’MM’X, 4JPH
=
ꢁ
2.13 Hz (JAX), N = JAM+ JAM = 8.90 Hz, 2H, m-H);
3
7.80 (M-part of AA’MM’X, JPH = 12.60 Hz (JMX),
N =8.90 Hz, 2H, o-H). 13C-NMR (ppm, in D2O): δ =
2
12.9 (s, -C9); 22.8 (d, JP−C = 17.86 Hz, C7); 25.9
3
(d, JP−C = 4.1 Hz, C8); 43.6 (d, JP−C = 56.1 Hz, P-
C6); 55.4 (s, O-C5H3); 113.5 (d, 3JP−C = 13.3 Hz, Ar-
C
meta); 131.8 (d, JP−C = 80.5 Hz, P-Carom); 131.7 (d,
2JP−C = 13.3 Hz, Ar-Cortho); 163.5 (d, 4JP−C = 3.0 Hz,
CH3O-C). 31P-NMR (in D2O): δ = 63.4. LC/MS MS:
m/z 261.2 ([L2]+, 100%), 227.2 ([(L2-(n-C4H9)+Na]+,
49%), 205.3 ([L2-(n-C4H9]+, 11%). Anal. Calcd. for
C11H20NOPS2 (277.4 g.mol−1): C, 47.6; H, 7.3; N, 5.1;
S, 23.1; found: C, 47.8; H, 7.3; N, 5.2; S, 23.4%.
2. Experimental
2.1 Materials and Methods
Analytical-grade LR, 3-methylbutyl bromide, n-butyl
bromide, 2-methylpropyl bromide, 1-methylpropyl bro-
mide and 2-propyl bromide were purchased from
Merck and used without further purification. Benzene,
chloroform, ethanol, diethyl ether, CdCl2 were pur-
chased from Merck. Benzene and diethyl ether were
distilled and dried before use. NH4L1, NH4L2, NH4L3,
NH4L4 and NH4L5 were prepared according to the
literature.12a,16,17
2.2.2 Preparation of the complexes, [Cd(L)2]2: A
solution of CdCl2, (0.1 g, 0.55 mmol) in ethanol (10
mL) was added to an ethanolic solution (10 mL) of 1.09
mmol ligand (0.32 g, for NH4L1; 0.30 g, for NH4L2;
0.30 g, for NH4L3 and NH4L4; 0.29 g, for NH4L5). The
mixture was stirred overnight at room temperature. The
resulting solution was left to stand overnight. The com-
plexes were of colourless, fine crystallic appearance.
The crystals were filtered off and recrystallized from
chloroform. The numbering scheme for compounds is
given in figure 1. The structural data for the complexes
were as follows.
The LC/MS spectra were recorded with a Waters
Micromass ZQ connected with Waters Alliance HPLC,
using ESI(+) ionization and C-18 column. Melting
points were measured with a Gallenkamp apparatus
1
using a capillary tube. H-, 13C{1H} - and 31P{1H}
Bis-{bis-[4-methoxyphenyl(3-methylbutyl)dithiophosphi-
nato]cadmium(II)}, [Cd(L1)2]2 [Yield: 0.59 g, 73%].
Colourless. M.p. 209–210◦C. 1H NMR (ppm, in
- spectra were recorded with a Varian Mercury (Agi-
lent) 400 MHz FT spectrometer in CDCl3 SiMe4 (1H,
13C) and 85% H3PO4 (31P) were used as standards.
IR spectra were recorded on a Perkin Elmer Spectrum
400 FTIR spectrophotometer (200–4000 cm−1) and are
reported in cm−1 units. All Raman spectra were mea-
sured in the range of 4000–100 cm−1, at room tem-
perature, using a Renishaw in-Via Raman microscope,
equipped with Peltier-cooled CCD detectors (−70◦C).
For Raman microscopy, a 50X objective was usually
used and all the spectra were excited by the 785 line
of a diode laser. Microanalyses were performed using a
LECO CHNS-932 C elemental analyzer.
3
CDCl3): δ = 0.84 (d, JHH = 6.5 Hz, 24H, -C9H);
1.44 (m, 8H, -C8H); 1.54 (m, 8H, -C7H); 2.28 (m,
8H, -C6H); 3.84 (s, 12H, OCH3); 6.88 (A-part of
4
ꢁ
AA’MM’X, JPH = 2.4 Hz (JAX), N = JAM+ JAM
=
8.7 Hz, 8H, m-H); 7.89 (M-part of AA’MM’X, 3JPH
=
13.4 Hz (JMX), N =8.7 Hz, 8H, o-H). 13C-NMR (ppm,
3
in CDCl3): δ = 22.2 (s, -C9); 32.5 (d, JP−C = 4.3
2
Hz, C8); 28.6 (d, JP−C = 17.5 Hz, C7); 41.2 (d,
JP−C = 52.5 Hz, P-C6); 55.3 (s, O-C5H3); 113.7 (d,
3JP−C = 14.1 Hz, Ar-Cmeta); 126.9 (d, JP−C = 80.2
2
Hz, P-C1); 132.6 (d, JP−C = 13.0 Hz, Ar-Cortho);
161.9 (d, JP−C = 3.0 Hz, CH3O-C4). 31P-NMR
4
(ppm, in CDCl3): δ = 71.9. Analysis: Calculated for
2.2 Preparation and structural data
C48H72Cd2O8P4S8 (1318.3 g.mol−1): C, 43.7; H, 5.5; S,
2.2.1 Ammonium n-butyl(4-methoxyphenyl)dithiophos- 19.5. Found: C, 43.8; H, 5.7; S, 19.6%. LC/MS: m/z
phinate, NH4L2: The method of preparation was the 243.0 ([L1-(CH3O-)]+, 100%), 1045.3 ([Cd2(L1)3]+,
same as described in the literature.16: Yield: 1.52 g 14%).

New dithiophosphinato cadmium complexes
1655
O
4
CH
5
3
R
S
S
S
S
3
1
P
Cd
P
2
R
H C
3
O
2
[Cd(L1)2]2
[Cd(L2)2]2
[Cd(L3)2]2
[Cd(L4)2]2
[Cd(L5)2]2
CH
CH
CH
3
CH
2
CH
6
CH
3
3
3
2
9
6
CH
6
HC
7
CH
6
CH
8
HC
6
CH
7
HC
8
CH
7
CH
2
2
2
2
2
R
8
CH
H C
37
CH
8
CH
3
7
CH
9
3
3
3
9
s: singlet; d: doublet; t: triplet; dd: doublet of doublets; m: multiplet.
Figure 1. Numbering scheme for compound.
Bis-{bis-[n-butyl(4-methoxyphenyl)dithiophosphinato]
(ppm, in CDCl3): δ = 70.1. Analysis: Calculated for
cadmium(II)}, [Cd(L2)2]2 [Yield: 0.58 g, 84%]. C44H64Cd2O4P4S8 (1262.2 g mol−1): C,41.9; H, 5.1;
Colourless. M.p. 144–145oC. 1H NMR (ppm, in S, 20.3%. Found: C, 42.0; H, 5.4; S, 20.4%. LC/MS:
3
CDCl3): δ = 0.84 (d, JHH = 7.3 Hz, 12H, -C9H); m/z 325.1 ([((C6H5)PS2)Cd+CH3CN]+, 100%), 413.9
1.32 (m, 8H, -C8H); 1.53 (m, 8H, -C7H); 2.28 (m, ([Cd(L3)+CH3CN]+, 8%).
8H, -C6H); 3.83 (s, 12H, OCH3); 6.93 (A-part of
4
ꢁ
AA’MM’X, JPH = 2.4 Hz (JAX), N= JAM+ JAM
=
=
Bis-{bis-[4-methoxyphenyl(1-methylpropyl)dithiophos-
8.8 Hz, 8H, m-H); 7.89 (M-part of AA’MM’X, 3JPH
phinato]cadmium(II)}, [Cd(L4)2]2 [Yield: 0.56 g,
13.4 Hz (JMX), N =8.8 Hz, 8H, o-H). 13C-NMR (ppm,
in CDCl3): δ = 13.6 (s, -C9); 25.9 (d, 3JP−C = 4.2 Hz,
C8); 23.3 (d, 2JP−C = 18.6 Hz, C7); 42.9 (d, JP−C = 52.3
1
81%] Colourless. M.p. 247-248◦C. H NMR (ppm,
3
in CDCl3): δ = 0.89 (t, JHH = 7.3 Hz, 12H, -C9H);
1.96 (m, 8H, -C8H); 1.16 (m, 3JHH = 6.86 Hz, 2JP−H
=
3
Hz, P-C6); 55.4 (s, O-C5H3); 113.7 (d, JP−C = 14.1
21.94 Hz, 16H, C6-H and C7-H adjacent); 1.16 (m,
16H, C6-H and C7-H adjacent); 3.84 (s, 12H, OCH3);
Hz, Ar-Cmeta); 127.0 (d, JP−C = 80.3 Hz, P-C1); 132.6
2
4
(d, JP−C = 13.0 Hz, Ar-Cortho); 162.0 (d, JP−C = 2.9
Hz, CH3O-C4). 31P-NMR (ppm, in CDCl3): δ = 71.5.
Analysis: Calculated for C44H64Cd2O4P4S8 (1262.2 g
mol−1): C,41.9; H, 5.1; S, 20.3. Found: C, 42.0; H, 5.3;
S, 20.3%. LC/MS: m/z 228.9 ([L2-(CH3O-)]+, 100%),
632.9 ([Cd(L2)2]+, 7%), 1002.9 ([Cd2(L2)3]+, 6%),
1265.4 ([Cd2(L2)4]+, 4 %).
4
6.92 (A-part of AA’MM’X, JPH = 2.4 Hz (JAX),
ꢁ
N= JAM+ JAM = 8.9 Hz, 8H, m-H); 7.87 (M-part of
3
AA’MM’X, JPH = 12.7 Hz (JMX), N =8.9 Hz, 8H,
o-H). 13C-NMR (ppm, in CDCl3): δ = 12.3 (s, -C9);
2
23.2 (s, C8); 12.3 (d, JP−C = 16.8 Hz, C7); 45.3 (d,
JP−C = 50.3 Hz, P-C6); 55.3 (s, O-C5H3); 113.4 (d,
3JP−C = 13.7 Hz, Ar-Cmeta); 126.6 (d, JP−C = 77.3
2
Hz, P-C1); 133.4 (d, JP−C = 13.7 Hz, Ar-Cortho);
4
161.9 (d, JP−C = 2.9 Hz, CH3O-C4). 31P-NMR
Bis-{bis-[4-methoxyphenyl(2-methylpropyl)dithiophos-
(ppm, in CDCl3): δ = 82.5. Analysis: Calculated for
C44H64Cd2O4P4S8 (1262.2 g mol−1): C,41.9; H, 5.1;
S, 20.3%. Found: C, 42.1; H, 5.2; S, 20.5%. LC/MS:
m/z 391.1 ([Cd2P2S2+CH3CN]+, 100 %), 413.1
([Cd2P2S4+H]+, 77%), 1001.0 ([Cd2(L4)3]+, 4%),
1265.3 ([Cd2(L4)4]+, 11%).
phinato]cadmium(II)}, [Cd(L3)2]2 [Yield: 0.55 g,
1
79%] Colourless. M.p. 199–200◦C. H NMR (ppm,
3
in CDCl3): δ = 0.88 (d, JHH = 6.7 Hz, 24H, -C8H);
3
2.11 (m, 4H, -C7H); 2.28 (dd, JHH
= 6.1 Hz,
2JP−H = 11.9 Hz, 8H, -C6H); 3.84 (s, 12H, OCH3);
4
6.92 (A-part of AA’MM’X, JPH = 2.5 Hz (JAX),
ꢁ
3
N = JAM+ JAM = 8.8 Hz, 8H, m-H); 7.91 (M-part
of AA’MM’X, JPH = 13.4 Hz (JMX), N =8.8 Hz, Bis-{bis[iso-propyl(4-methoxyphenyl)dithiophosphi-
8H, o-H). 13C-NMR (ppm, in CDCl3): δ = 25.5 (d, nato]cadmium(II)} [Cd(L5)2]2 [Yield: 0.62 g, 94%]
3JP−C = 3.9 Hz, C8); 24.3 (d, JP−C = 10.0 Hz, C7); Colourless. M.p. 129–130◦C. 1H NMR (ppm, in
2
3
42.9 (d, JP−C = 51.4 Hz, P-C6); 55.4 (s, O-C5H3); CDCl3): δ = 1.12 (t, JPH = 21.2 Hz, 24H, -C7H);
113.7 (d, 3JP−C = 14.1 Hz, Ar-Cmeta); 127.8 (d, JP−C
=
2.25 (m, 4H, -C7H); 3.84 (s, 12H, OCH3); 6.92 (A-
80.3 Hz, P-C1); 132.6 (d, 2JP−C = 13.1 Hz, Ar-Cortho); part of AA’MM’X, JPH = 2.4 Hz (JAX), N = JAM
+
4
161.9 (d, JP−C = 2.9 Hz, CH3O-C4). 31P-NMR JAM = 8.9 Hz, 8H, m-H); 7.9 (M-part of AA’MM’X,
4
ꢁ

1656
Ertug˘rul Gazi Sag˘lam et al.
3JPH = 12.8 Hz (JMX), N =8.8 Hz, 8H, o-H). 13C- and refined by full-matrix least squares against F2 using
2
NMR (ppm, in CDCl3): δ = 16.7 (d, JP−C = 1.2 all data.18 All non-H atoms were refined anisotropically.
Hz, C7); 38.8 (d, JP−C = 51.3 Hz, P-C6); 55.4 (s, H atoms were positioned geometrically at distances of
O-C5H3); 113.4 (d, 3JP−C = 13.7 Hz, Ar-Cmeta); 125.4 0.93 Å (aromatic CH), 0.97 Å (CH2) and 0.96 Å (CH3)
(d, JP−C = 77.6 Hz, P-C1); 133.4 (d, 2JP−C = 12.3 Hz, (for [Cd(L1)2]2) and 0.95 Å (aromatic CH), 0.99 Å
4
Ar-Cortho); 161.9 (d, JP−C = 3.0 Hz, CH3O-C4). 31P- (CH2) and 0.98 Å (CH3) (for [Cd(L2)2]2) from the par-
NMR (ppm, in CDCl3): δ = 83.6. Analysis: Calculated ent C atoms; a riding model was used during the refine-
for C40H56Cd2O4P4S8 (1206,1 g mol−1): C, 39.83; H, ment proceses and the Uiso (H) values were constrained
4.68; S, 21.52%. Found: C, 39.61; H, 4.53; S, 21.52 to be xUeq (carrier atom), where x = 1.2 for CH and
%. LC/MS: m/z 391.2 ([(L5)2CdS]+, 100%); 602.1 CH2, and x = 1.5 for CH3. Experimental data are given
([Cd(L5)2+Na]+, 12%); 959.8 ([Cd2(L5)3]+, 16%); in table 1.
1205.6 ([Cd2(L5)4]+, 4%).
3. Results and Discussion
2.3 X-ray crystallography
3.1 Synthesis and characterization
Single-crystal X-ray diffraction analyses of [Cd(L1)2]2
and [Cd(L2)2]2 were performed on a Bruker Kappa In this work, five novel cadmium-DTPA complexes
APEXII CCD area-detector diffractometer using Mo and one new dithiophosphinato ligand (NH4L2) were
Kα (λ = 0.71073 Å) (for [Cd(L1)2]2) and Cu Kα (λ = synthesized. LR was reacted with five different Grig-
1.5418 Å) (for [Cd(L2)2]2) radiations at a temperature nard reagents to obtain dithiophosphinic acids. As the
of 100 K. Structures were solved by direct methods18 dithiophosphinic acids are viscous liquids and difficult
Table 1. Experimental details for [Cd(L1)2]2 and [Cd(L2)2]2.
Compound
[Cd(L1)2]2
[Cd(L2)2]2
Empirical Formula
Colour/shape
Formula weight
Temperature (K)
Radiation, graphite monochr.
Crystal system
Space group
C48H72Cd2O4P4S8
green/block
1318.24
100(2)
C44H64Cd2O4P4S8
green/block
1262.11
100(2)
Mo Kα (λ = 0.71073)
Cu Kα (λ = 1.54178)
triclinic
triclinic
P -1
P -1
a, b, c (Å),
11.3887(4),12.2986(4),12.5052(4)
91.902(1), 107.177(1), 116.112(1)
1475.19(8)
1
1.151
1.484
9.8249(1),11.6464(1),13.6449(1)
68.440(1), 83.434(1), 69.380(1)
1358.85(2)
1
10.560
1.542
α, β, γ (◦)
Volume (Å3)
Z
Abs. coefficients (mm−1
)
Dcalc (mg m−3
)
Max. crystal dim. (mm)
0.04X0.06X0.08
29.19
0.04X0.06X0.08
71.08
ꢀ(max) (◦)
Reflections measured
Range of h, k, l
Diffractometer/scan
7876
5076
-15< h< 14, -16< k< 16, -17< l<17
-12< h< 12, -14< k< 14, -15< l< 16
Bruker Kappa APEX II / phi and w
No. of reflections with I>2 σ(I)
Corrections applied
Computer programs
Source of scatter. Factors
Structure solution
Treatment of hydrogen atoms
No. of parameters varied
GOF
7298
4902
Lorentz polarization
SHELXS-9718, SHELXL-9718, ORTEP-319
International Table for X-Ray Crystallography20
Direct methods
Geometric calculation
298
284
1.024
0.0194
0.0489
0.499
−0.318
1.045
0.0222
0.0589
0.709
−0.396
R = IIFoI – IFcII / IFoI
Rw
( ρ)max (e Å−3
)
( ρ)min (e Å−3
)

New dithiophosphinato cadmium complexes
1657
to purify, they are converted to their ammonium salts
(scheme 1).
In the IR spectra of NH4L2, the characteristic νN−H
band is observed at 3183 cm−1; this band is absent in
The [Cd(L)2]2 complexes were prepared by the reac- the spectra of the [Cd(L2)2]2 complex, confirming the
tion of NH4L with cadmium(II) cation (scheme 2).
exclusion of the NH+4 ion.
The frequencies of the corresponding signals in the
IR and the Raman spectra of the complexes are quite
comparable as expected. All these values are in agree-
ment with the literature.14c,21 The prominent peaks are
given in table 2.
3.2 Spectroscopic Studies
3.2.1 IR and Raman Spectra: In the IR spectra, the
asymmetric and symmetric (PS) stretching signals
(νasym and νsym) of the compounds appear in the regions
of 650–616 cm−1 and 552–524 cm−1, respectively. In 3.2.2 Mass Spectra: The mass spectra of the com-
the Raman spectra, similar signals appear in the regions plexes [Cd(L2)2]2, [Cd(L4)2]2 and [Cd(L5)2]2 display
of 654–632 cm−1 and 555–523 cm−1, respectively. The molecular ion peaks corresponding to the proposed din-
metal-sulphur stretching give rise to the signals between uclear structures. The Mass spectra of all the complexes
200 cm−1 and 400 cm−1 (272–312 cm−1 for IR; 273– except [Cd(L3)2]2, display peaks indicating removal
310 cm−1 for Raman).
of a ligand leaving back a species of the formula
S
NH4L
R
R
S
S
S
H C
3
+
P
+ H /H O
2
CH
CH
3
O
2
P
P
S
O
2
RMgX
+
3
2
NH4L1
SH
CH
CH
HC
- 2MgXOH
2
2
CH
3
H C
3
CH
O
2
NH4L2
NH4L3
Lawesson reagent
LH
CH
CH
2
CH
3
CH
3
CH
HC
2
CH
3
S
S
S
R
R
CH
2
3
P
P
NH
4
NH4L4
NH4L5
NH
+
CH
CH
3 (Dry)
SH
H C
3
H C
H C
3
3
CH
O
O
3
HC
NH4L
LH
CH
3
Scheme 1. Synthesis reaction of NH4L.
CH
3
O
S
S
O
CH
R
3
R
P
P
P
NH
4
2+
4
2
S
Cd
S
S
S
S
R
+
- 4 NH
4
P
Cd
Cd
P
H C
3
R
S
S
S
O
H C
3
R
O
O
H C
NH4L
3
[Cd(L)2]2
Scheme 2. Synthesis of complexes.

1658
Ertug˘rul Gazi Sag˘lam et al.
Table 2. Selected FTIR and Raman (R) data (cm−1) assignment of significant bands.
Compound
ν(M−S)
ν(sym) (PS)
ν(asym) (PS)
ν(N−H)
IR
R
IR
R
IR
R
IR
R
[Cd(L1)2]2
[Cd(L2)2]2
[Cd(L3)2]2
[Cd(L4)2]2
[Cd(L5)2]2
NH4L2
290
312
280
272
274
-
289
310
282
273
273
-
527
529; 519
526
552; 532
548; 524
545; 534
535; 524
542; 523
542; 525
555; 537
549;528
549;528
638
647; 635
643
650; 639
649;640
646;616
631; 632
647; 633
652; 632
653; 633
654;635
637;636
-
-
-
-
-
-
-
-
-
-
-
3180
[Cd2(L)3]. The complexes [Cd(L2)2]2 and [Cd(L5)2]2 of metal- as well as phosphorus and sulphur iso-
display Mass-peaks corresponding to the mono-nuclear topes are observable in the structures of the molec-
[Cd(L2)2] and [Cd(L5)2] moieties. The natural abundance ular ion signals. Reminiscent signal structures are
Table 3. Selected bond lengths (Å) and angles (◦) for [Cd(L1)2]2 and
[Cd(L2)2]2.
[Cd(L1)2]2
[Cd(L2)2]2
Cd1-S1
Cd1-S2
Cd1-S3
Cd1-S4
P1-S1
P1-S2
P1-C1
P1-C8
2.5325(3)
2.6671(3)
2.5354(3)
2.5703(3)
2.0252(5)
2.0107(5)
Cd1-S1
Cd1-S2
Cd1-S3ii
Cd1-S4
P1-S1
P1-S2
P1-C1
P1-C8
P2-S3
2.5460(5)
2.6542(4)
2.5442(5)
2.5726(4)
2.0253(6)
2.0128(6)
1.8043(19)
1.820(2)
2.0349(6)
2.0099(6)
1.7955(19)
1.8166(19)
79.897(14)
134.434(15)
122.969(16)
107.797(14)
99.957(14)
100.388(15)
84.86(2)
1.8014(13)
1.8161(14)
2.0364(4)
2.0093(5)
1.7929(13)
1.8181(14)
79.709(11)
136.923(11)
117.464(12)
108.310(11)
103.918(11)
101.913(11)
85.347(15)
82.104(15)
105.342(16)
93.481(15)
111.38(2)
110.23(5)
112.15(5)
103.87(6)
109.12(5)
109.80(5)
113.81(2)
110.62(5)
111.17(5)
104.48(6)
105.87(5)
110.35(5)
P2-S3
P2-S4i
P2-S4
P2-C13
P2-C20
P2-C12
P2-C19
S1-Cd1-S2
S1-Cd1-S2
S1-Cd1-S3
S1-Cd1-S4
S2-Cd1-S3
S2-Cd1-S4
S3-Cd1-S4
P1-S1-Cd1
P1-S2-Cd1
P2-S3-Cd1
P2-S4-Cd1i
S2-P1-S1
C1-P1-S1
C1-P1-S2
C1-P1-C8
C8-P1-S1
C8-P1-S2
S4-P2-S3i
C13-P2-S3
C13-P2-S4i
C13-P2-C20
C20-P2-S3
C20-P2-S4i
S1-Cd1-S3ii
S1-Cd1-S4
S2-Cd1-S3ii
S2-Cd1-S4
S3-Cd1-S4ii
P1-S1-Cd1
P1-S2-Cd1
P2-S3-Cd1ii
P2-S4-Cd1
S1-P1-S2
82.274(19)
103.67(2)
92.97(2)
111.62(3)
111.49(6)
109.54(7)
110.68(7)
109.52(7)
103.69(9)
113.12(3)
110.44(6)
106.92(7)
111.35(6)
109.20(7)
105.41(9)
S1-P1-C1
S1-P1-C8
S2-P1-C1
S2-P1-C8
C1-P1-C8
S3-P2-S4
S3-P2-C12
S3-P2-C19
S4-P2-C12
S4-P2-C19
C12-P2-C19
Symmetry codes: (i) – x, – y, – z, (ii) 1 – x, – y, 2 – z.

New dithiophosphinato cadmium complexes
1659
reported for similar compounds.22 The patterns of
disintegration are compatible with those reported for
similar structures.23
JP−C couplings lie in the range of 77.3–80.3 Hz for the
aromatic carbons and 50.3-52.5 Hz for the aliphatic
carbons. Similar trends were reported for structurally
related compounds.25 The two-bond 31P-13C coupling
for the aromatic carbon atoms ortho- to the phosphorus
are observed to be in the narrow range of 12.2–13.1 Hz
in the anisol groups. Interestingly, the three-bond 31P-
13C coupling constants of the aromatic carbons are com-
3.2.3 NMR Studies
1
3.2.3a H–NMR Spectra: 1H-NMR spectral data of
2
paratively higher (in the range of 13.7-14.1 Hz). JP−C
NH4L2 are given in the Experimental section. The aro-
matic protons, together with the phosphorus atom con-
stitute an AA’MM’X spin system. The AA’MM’ parts
(proton signals) display essentially an AMX pattern;
values for the aliphatic carbons appear to change in a
wide range. A similar trend is valid for the phosphorus-
coupling constants of the aliphatic carbons. For exam-
2
ple, in the compound [Cd(L2)2]2, JP−C = 18.2 Hz
ꢁ
ꢁ
because JAM and JA M are close to zero. So the chemical
shift assignments of the aromatic protons can be made
on the basis of the magnitudes of the coupling constants
to phosphorus. Namely, in the compounds, [Cd(L1)2]2,
[Cd(L2)2]2, [Cd(L3)2]2, [Cd(L4)2]2, [Cd(L5)2]2 and L2,
the protons in ortho- position to phosphorus display a
2
whereas in the compound [Cd(L4)2]2 JP−C = 0.0 Hz.
3JP−C values aliphatic carbons are in the range 1.2-4.3
Hz.
3.2.3c 31P–NMR Spectra The proton-decoupled 31P–
NMR spectra of [Cd(L1)2]2, [Cd(L2)2]2, [Cd(L3)2]2,
[Cd(L4)2]2 and [Cd(L5)2]2 show singlets at 71.9, 71.5,
70.1, 82.5 and 83,6 ppm, respectively. All these sig-
nals appear at 5-8 ppm lower fields compared to those
related to the corresponding ligands.12a,16
4
3JPH of ∼13 Hz and those meta- to phosphorus a JPH
of ∼2.4 Hz.
The diastreotropic -CH2- protons at the C8 position
of [Cd(L4)2]2 are partly superimposed but still distin-
guishable. Similarly the azo-methin proton at the C6
position of the same compound is partly shielded by the
intense -CH3 signal at the C7 position. Similar phenom-
ena are reported for related structures.16 The splitting
patterns of the signals due to the apical -CH3 groups
of the alkyls are all as expected. Similar findings are
reported for analogous compounds.24
3.2.4 Descriptions of the crystal structures: The X-ray
structural determinations of [Cd(L1)2]2 and [Cd(L2)2]2
confirm the assignments of their structures from spec-
troscopic data. Selected bond lengths and angles are
given in table 3. The molecular structures along with
the atom-numbering schemes are depicted in figures 2
3.2.3b 13C-NMR Data 13C-NMR data of NH4L2 are and 3, while the packing diagrams are given in figures 3
as given in the Experimental section. Single bond and 4, respectively.
Figure 2. An ORTEP-319 view of [Cd(L1)2]2. The thermal ellipsoids are drawn at the 50% probability level.

1660
Ertug˘rul Gazi Sag˘lam et al.
Figure 3. An ORTEP-319 view of [Cd(L2)2]2. The thermal ellipsoids are drawn at the 50% probability level.
Figure 4. A partial packing diagram of [Cd(L1)2]2. Hydrogen bonds are
shown as dashed lines. Hydrogen atoms not involved in hydrogen bonding have
been omitted for clarity.
2.5792(5) Å, 2.0207(6) Å, 1.8091(19) Å and 112.37(3)◦
and 104.55(9)◦ (for [Cd(L2)2]2), while S-Cd-S and S-
P-C bond angles are in the ranges of 79.709(11)◦-
136.923(11)◦, 105.87(5)◦-112.15(5)◦ (for [Cd(L1)2]2)
and 79.897(14)◦-134.434(15)◦, 106.92(7)◦- 111.49(6)◦
(for [Cd(L2)2]2), respectively (table 3). The atoms on
the PS2 group of the ligand and the central Cd constitute
In the centrosymmetric molecules of [Cd(L1)2]2 and
[Cd(L2)2]2, the Cd atoms are coordinated by four S
atoms, while the P atoms are coordinated by two S
atoms and two C atoms (figures 2 and 3). The average
Cd-S, P-S and P-C bond lengths and S-P-S and C-P-C
bond angles are 2.5763(3) Å, 2.0204(5) Å, 1.8071(14)
Å and 112.59(2)◦ and 104.17(6)◦ (for [Cd(L1)2]2) and

New dithiophosphinato cadmium complexes
1661
Figure 5. A partial packing diagram of [Cd(L2)2]2. Hydrogen atoms have been omitted for clarity.
centrosymmetric dimers through R22(16) ring motifs26
(for [Cd(L1)2]2) (figure 4), while the molecules are
elongated along the c-axis and stacked along the a-axis
(for [Cd(L2)2]2) (figure 5).
a nearly planar geometry. As an indication, the torsion
angle S1-Cd1-S2-P1 is -7.886(14)◦ in [Cd(L1)2]2 and
-7.585(19)◦ in [Cd(L2)2]2. In the both compounds, the
Cd atoms have a highly distorted tetrahedral coordina-
tion spheres (figures 2 and 3, table 3). This is reflected
on S-Cd-S angles. The angle S1-Cd1-S2 is 79.709(11)◦
in [Cd(L1)2]2 and 79.897(12)◦ in [Cd(L2)2]2; whereas
the angle S3-Cd1-S4 is 101.913(11)◦ and 100.388(15)◦
respectively.
4. Conclusions
The ligand cavities may play important roles in
the complexations and metal-ion selectivities. The
intramolecular Cd1...Cd1i [4.1444(2) Å], S3...S3i
[3.8105(5) Å], S4 . . . S4i [6.3172(6) Å], P2...P2i
[5.6551(5) Å] [symmetry code (i) : – x, – y, –
z] (for [Cd(L1)2]2) and Cd1...Cd1i [3.8875(2) Å],
S3...S3i [4.0290(7) Å], S4...S4i [6.1198(7) Å], P2...P2i
[5.7787(7) Å] [symmetry code (i) : 1 – x, – y, 2 – z] (for
[Cd(L2)2]2) distances may indicate the hole sizes of the
rings. In the four-membered rings A (Cd1/S1/S2/P1),
the angles between the (Cd1/S1/S2) and (S1/S2/P1)
planes are 166.10(2)◦ (for [Cd(L1)2]2) and 166.59(2)◦
(for [Cd(L2)2]2). Thus, A rings may be called to have
twisted-chair conformations. The phenyl rings B (C1-
C6), C (C13-C18) (for [Cd(L1)2]2) and B (C1-C6),
C (C12-C17) (for [Cd(L2)2]2) are oriented at dihedral
angles of 31.73(5)◦ and 24.95(6)◦, respectively. In the
crystal structures, intermolecular C17-H17...S1ii inter-
actions (C17-H17 = 0.93 Å, H17...S1ii = 2.87 Å,
C17...S1ii = 3.80Å and C17-H17...S1ii = 177◦; sym-
metry code: (ii) 1− x, − y, − z) link the molecules into
The five new dithiophosphinato cadmium(II) com-
plexes and one ligand were prepared. The six novel
compounds characterized by, MS, FTIR and RAMAN
spectral and elemental analyses. The molecular and
crystal structures of the two complexes namely,
[Cd(L1)2]2 and [Cd(L2)2]2 were also elucidated by X-
ray crystallography. The structure of the compounds
were analysed by NMR (1H, 13C, 31P). For aromatic car-
bons, the 3JP−C coupling constants are a few Hz higher
than the 2JP−C values. 31P chemical shifts the complexes
were found to be 5-8 Hz downfield compared to those
of the related dithiophosphonato ligands. X-ray analy-
ses show that the P-S bonds in the complexes are indeed
of the same order; in other words, electron delocal-
ization prevails. In the centrosymmetric molecules of
[Cd(L1)2]2 and [Cd(L2)2]2, the Cd atoms are coordi-
nated by four S atoms, while the P atoms are coordi-
nated by two S atoms and two C atoms. The ligand
cavities may play important roles in the complexations
and metal-ion selectivities. In the crystal structure of
[Cd(L1)2]2, intermolecular C-H...S interactions link the

1662
Ertug˘rul Gazi Sag˘lam et al.
molecules into centrosymmetric dimers through R22(16)
ring motifs.
5. Bellande E, Comazzi V, Laine J, Lecayon M, Pasqualini
R, Duatti A and Hoffschir D 1995 Nucl. Med. and Biol.
22 3 315
6. Durckheimer W, Bormann D, Ehlers E, Schrinner E and
Heymes R 1988 U.S. Patent 4758556
Supplementary Information
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Nikiforova L K and Pleshkov M A 2010 Hydromet-
allurgy 105 82; (b) Xihong H, Guoxin T, Jing C
and Linfeng R 2014 Dalton Trans. 43 17352; (c)
Wieszczycka K and Zembrzuska J 2014 J. Radioanal.
Nucl. Chem. 299 709
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Prog. Nucl. Energ. 54 46; (b) Ghoreishi S M, Ansari K
and Ghaziaskar H S 2012 J. Supercrit. Fluids 72 288
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A T, Almaz R N, Ilnar D N and Rafael A C 2014
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10. Wagner J, Ciesielski M, Fleckenstein C A, Denecke H,
Garlichs F, Ball A and Doering M 2013 Org. Process
Res. Dev. 17 47
All additional information relating to the characteri-
zation of the complexes, namely, ESI-MS (figure S1),
IR spectra (figure S2), Raman spectra (figure S3),
NMR (1H, 13C and 31P) spectra (figures S4, S5 and
S6) are available at www.ias.ac.in/chemsci. Crystallo-
graphic data (excluding structure factors) have been
deposited with the Cambridge Crystallographic Data
Centre as the supplementary publication no. 1060403
(for [Cd(L1)2]2, and CCDC 1060404 (for [Cd(L2)2]2).
Copies of the data can be obtained, free of charge,
on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK (fax: +44-1223-336033; E-mail:
deposit@ccdc.cam.ac.uk).
11. (a) Diemert K and Kuchen W 1977 Phosphorus, Sulfur
Silicon Relat. Elem. 3 131; (b) Rauhut M M, Currier
H A and Wystrach V P 1961 J. Org. Chem. 26 5133
Acknowledgements
˙
12. (a) Sag˘lam E G, Çelik Ö, Yılmaz H and Ide S 2010 Tran-
sition Met. Chem. 35 399; (b) Yordanov N D, Gochev
G, Angelova O and Macicek J 1990 Polyhedron 9 2597;
(c) Kuchen W, Metten J and Judat A 1964 Chem. Ber. 97
2306; (d) Cavell R G, Byers W, Day E D and Watkins P
M 1972 Inorg. Chem. 11 1598; (e) Daly S R, Keith J M,
Batista E R, Boland K S, Kozimor S A, Martin R L and
Scott B L 2012 Inorg. Chem. 51 7551
We gratefully acknowledge the financial assistance
of Technical Research Council of Turkey (grant
nos. TBAG 114Z091, TUBITAK) and Research and
Application Centers of Bozok University (BAP2015
FEF/A153). Our thanks also go to the tutors of the
Zurich School of Crystallography, for assistance and
guidance with the data collection and structure deter-
mination of compound [Cd(L1)2]2 and Prof. Davit
Zargarian, Chemistry Department of the Université de
Montréal for their support with the X-ray facility for
[Cd(L2)2]2.
13. (a) Porta P, Sgamellotti A and Vinciguerra N 1971 Inorg.
Chem. 10 541; (b) Pinkerton A A, Ahlers F P, Greiwing
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