Synthesis and characterization of Ni(II), Zn(II), and Cd(II) complexes with dithiophosphonate derivatives

Article abstract of DOI:10.1134/S1070328406060078

Ammonium salts of p-methoxyphenyldithiophosphonic acid O-alkyl esters (H₃CO-C₆H₄-(RO)P(S)S^-NH ₄ ⁺ ; R = C₂H₅,-CH₂CH ₂CH₂CH₂-, and cyclopentyl) and their complexes with Ni²⁺, Cd²⁺, and Zn²⁺ were prepared. 2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide, the so-called Lawesson reagent, was treated with the corresponding alcohol to give the O-alkyl ester of the acid. Dry NH₃ was then purged through the solution of this ester to form the ammonium salt of the O-alkyl dithiophosphonic acids. Nickel complexes of these ligands were formed in acetic acid, while zinc and cadmium complexes were formed in water and an ethanol medium, respectively. The geometry of the coordinated atoms was square planar with Ni²⁺ and tetrahedral with Zn²⁺ and Cd²⁺. Using an alkanediol, two dithiophosphonic acids were bridged, thus forming a ligand with four S atoms for coordination. The zinc and cadmium complexes of these tetradentate ligands were also synthesized. Pleiades publishing, Inc. 2006.

Full text of DOI:10.1134/S1070328406060078

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2006, Vol. 32, No. 6, pp. 437–443. © Pleiades Publishing, Inc., 2006.
Synthesis and Characterization of Ni(II), Zn(II),
and Cd(II) Complexes with Dithiophosphonate Derivatives1
Mehmet Karakusa and H. Yilmazb
a
Department of Chemistry, Faculty of Arts and Sciences, Pamukkale University, 20017 Denizli, Turkey
b
Department of Chemistry, Science Faculty, Ankara University, 06100 Ankara, Turkey
e-mail: Hamza.Yilmaz@science.ankara.edu.tr
Received April 4, 2005
Abstract—Ammonium salts of p-methoxyphenyldithiophosphonic acid O-alkyl esters (H3CO–C6H4–(RO)P(S)S–NH4+;
R = C2H5, –CH2CH2CH2CH2–, and cyclopentyl) and their complexes with Ni2+, Cd2+, and Zn2+ were prepared.
2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane–2,4-disulfide, the so-called Lawesson reagent, was treated
with the corresponding alcohol to give the O-alkyl ester of the acid. Dry NH3 was then purged through the solution
of this ester to form the ammonium salt of the O-alkyl dithiophosphonic acids. Nickel complexes of these ligands
were formed in acetic acid, while zinc and cadmium complexes were formed in water and an ethanol medium,
respectively. The geometry of the coordinated atoms was square planar with Ni2+ and tetrahedral with Zn2+ and
Cd2+. Using an alkanediol, two dithiophosphonic acids were bridged, thus forming a ligand with four S atoms for
coordination. The zinc and cadmium complexes of these tetradentate ligands were also synthesized.
DOI: 10.1134/S1070328406060078
INTRODUCTION
Ni(II) complexes [4–8] and tetrahedral Zn(II) and
Cd(II) complexes [17, 18, 23] have been reported. The
reactions of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiad-
iphosphethane-2,4-disulfide (I) with alkanediols were
also investigated [26, 27].
The coordination compounds formed by the interac-
tion of metal ions with SS type ligands, such as dithio-
phosphonate [R(RO)PS2– ] [1–18], dithiophosphate
[(RO)2PS–2 ] [19–23], and dithiophosphinate (R2PS–2 )
[24, 25], have specific properties and were effectively
In this work, we report the preparation and character-
utilized in industry, medicine, and agriculture. Dithio- ization of some new Ni(II), Zn(II), and Cd(II) complexes
phosphonates are well-known bidentate ligands, and of the dithiophosphonate-type ligands. The sequence of
many of these chelating agents were investigated. In the reactions employed to obtain aryl–dithiophosphonic acid
last decades, some of square-planar and octahedral ester (ammonium salt) can be summarized as follows:
S
P
S
i
ii
MeO
P
S
OMe
S
I
S
P
O CH2CH2CH2CH2
O
OR
SH
MeO
MeO
MeO
P S
SH
S P
OMe
SH
(III)
(II)
iii
iii
O CH2CH2CH2CH2
O
S
P
OR
P S
S P
OMe
MeO
–
+
–
–
+
+
S] NH4
S] NH4
S] NH4
(VI)
R = C2H5 (IV), C5H9 (V)
i: HO–(CH2)4–OH, ii: R = C2H5, C5H9, iii: dry NH3.
1
The text was submitted by the authors in English.
437

438
KARAKUS, YILMAZ
All the compounds were identified on the basis of with diethyl ether, and dried under reduced pressure.
elemental analyses, IR, NMR, and for the complexes,
mass spectroscopic data.
The yield is 0.22 g (91%); m.p. >125°C (decomp.).
Preparation of tris(1,10-phenanthroline)nickel(II)-
bis[O-ethyl-(4-methoxyphenyl)dithiophosphonate]
(IVc). Nickel(II) complex IVa (0.1187 g, 0.21 mmol)
was dissolved in 25 ml of boiling CH2Cl2, and, to this
solution, 1,10-phenanthroline (0.126 g, 0.63 mmol) in
15 ml of hot CH2Cl2 was added. After stirring for a few
min, until the solution became pink, the mixture was
left aside. Pink-colored crystals formed were filtered
off and dried in air. The yield is 0.18 g (78%); mp >
178°C (decomp.).
EXPERIMENTAL
The initial compound I (Lawesson reagent), pyri-
dine, 1,4-butanediol, and 1,10-phenanthroline were
purchased from Aldrich Chem. Co., and nickel(II) ace-
tate and benzene from Merck AG., cyclopentyl alcohol
from Fluka Chem. Co. Technical ethanol was distilled
over and kept with CaO before use. The ligands inves-
tigated were synthesized by a desired method [1, 2].
Ni(II)-bis[O-ethyl-(4-methoxyphenyl)dithiophospho-
nate] (IVa) was prepared by a known method [8]. Melt-
ing points were determined with a Gallenkamp appara-
tus without correction. Elemental analyses for C, H, S,
and N were carried out with a model LECO-CHNS-O
elemental analyzer. IR spectra were recorded on a
model Mattson 1000 FTIR spectrophotometer with
KBr pellets. The NMR spectra (1H, 13C, and 31P) were
recorded at 400 MHz on a Bruker DPX-400 instrument
in CDCl3, DMSO-d6, and D2O.
Preparation of Ni(II)-bis[O-cyclopentyl-(4-meth-
oxyphenyl)dithiophosphonate] (Va). A 0.1 M solution
of nickel(II) acetate (16.5 ml, 1.65 mmol) in glacial
acetic acid was added to a solution of V (1.0 g, 3.28
mmol) in the same solvent (25 ml). After stirring for a
few min without heating, the purple-colored solution
was left aside. Purple crystals were obtained, filtered
off, and recrystallized from CH2Cl2. The yield is 0.8093
g (82.38%); mp 148°C.
Preparation of Ni(II)-bis{pyridine-[O-cyclo-
pentyl-(4-methoxyphenyl)dithiophosphonate]}
(Vb). Nickel(II) complex Va (0.25 g, 0.395 mmol)
was dissolved in 25 ml of boiling CH2Cl2, and excess
pyridine was added dropwise until the solution
became green. The green crystalline product was fil-
tered off, washed with cold diethyl ether, and dried
under reduced pressure. The yield is 0.30 g (97%);
mp >125°C (decomp.).
General procedure for the synthesis of the ligands
Compounds IV, V, andVI were obtained by the reaction
with I and the relevant alcohol. In the case of ligand VI,
1,4-butanediol was added dropwise to a suspension of I
in dry benzene. Crude dithiophosphonic acid obtained
was converted to ammonium salt of dithiophosphonic
acid by purging dry NH3.
Ammonium O-ethyl-(4-methoxyphenyl)dithio-
phosphonate (IV) and ammonium O-cyclopentyl-
(4-methoxypentyl)dithiophosphonate (V). Elemental
Preparation of Ni(II)-bis{3-acetylpyridine-[O-cyclo-
pentyl-(4-methoxyphenyl)dithiophosphonate]} (Vc).
Nickel(II) complex Va (0.10 g, 0.158 mmol) was dis-
solved in 25 ml of boiling CH2Cl2, and excess
3-acetylpyridine was added dropwise until the solution
became green. The green crystalline product was fil-
tered off, washed with cold diethyl ether, and dried
under reduced pressure. The yield is 0.11 g (80%); mp
137–138°C.
31
analysis, P NMR, and physical characterization data
were already reported for compounds IV and V [1], and
our findings confirm these data.
Ammonium-O,O-(1,4-buthenyl)bis[(4-methoxy-
phenyl)dithiophospho-nate] (VI) Compound
I
(4.16 g, 10 mmol) was mixed with 5–10 ml of benzene
in a flask (100 ml), and to this mixture, 1,4-butanediol
(0.90 ml, 10 mmol) was added dropwise. The tempera-
ture was maintained between 60–70°C until the com-
plete dissolution of all solids (~30 min). The crude
bis-dithiophosphonic acid obtained was filtered, the fil-
trate was cooled to 5–10°C, and the acid was converted
to VI by purging dry NH3. The precipitated compound
VI was filtered off, washed with cold benzene, and
dried in air. The product was recrystallized from meth-
anol. The resulting colorless crystalline solid was fil-
tered off and dried in air. The yield is 4.96 g (94%);
mp 196°C.
Preparation of Zn(II)-[O,O-(1,4-buthenyl)-(4-
methoxyphenyl)dithiophosphonate] (VIa). A solu-
tion of ZnSO4 · 7H2O (0.362 g, 1.259 mmol) in water
(10 ml) was added dropwise to an aqueous solution of
compound VI (0.665 g, 1.259 mmol, 20 ml). A white
precipitate formed immediately. It was recrystallized
from a mixture of DMSO–ethanol (1 : 3). The yield is
0.58 g (83%); mp >172°C (decomp.).
Preparation of Cd(II)-[O,O-(1,4-buthenyl)-(4-
methoxyphenyl) dithiophosphonate] (VIb). A solu-
Preparation of Ni(II)-bis{pyridine-[O-ethyl-(4- tion of Cd(CH3COO)2 · 2H2O (0.412 g, 1.54 mmol) in
methoxyphenyl)
dithiophosphonate]}
(IVb).
ethanol (10 ml) was added dropwise to a solution of
compound VI (0.817 g, 1.54 mmol, 20 ml) in ethanol.
A white precipitate was obtained. It was recrystallized
Nickel(II) complex IVa (0.1886 g, 0.34 mmol) was dis-
solved in 25 ml of boiling CH2Cl2, and excess pyridine
was added dropwise until the solution became green. from a mixture of DMSO–ethanol (1 : 3). The yield is
The green crystalline product was filtered off, washed 0.85 g (91%); mp >189°C (decomp.).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 6 2006

SYNTHESIS AND CHARACTERIZATION OF Ni(II)
439
Preparation of Ni(II)-bis[O-propyln-(4-methoxy-
phenyl)dithiophosphonate] (VII). Synthesis and physi-
cal characterization data were already reported for this
compound VII, and our findings confirm these data [5].
OR
S
S
S
S
MeO
P
OR
Ni
P
OMe
R = C2H5 (IVa), C5H9 (cyclopentyl) (VIa), C3Hn7–(VII).
Scheme of square-planar Ni(II) complexes is the
following:
Scheme of octahedral Ni(II) complexes is the fol-
lowing:
R'
[Ni(1,10-phen)3]X2
N
1,10-phen:
OR
S
S
S
S
N
N
MeO
P
OR
Ni
N
P
OMe
S–
S
X:
MeO
P
OC2H5
R'
R = C2H5, R; = H (IVb);
R = C5H9 (cyclopentyl), R' = H (Vb);
R = C5H9 (cyclopentyl), R' = 3-acetyl (Vc) and (IVc) for [Ni(1,10-phen)3]X2.
RESULTS AND DISCUSSION
assigned to ν(PSsym) and ν(PSasym) vibrations, respec-
tively [12]. The bands at about 560–670 cm–1 for com-
pounds IV, V, andVI shift slightly to lower values in the
spectra of the complexes. This is not surprising at all,
because the formation of a coordination bond with the
cation would be expected to reduce the strength of the
PS bond and, thereby, to decrease the vibration fre-
quency.
Elemental analysis data of all studied compounds
and their IR spectra are summarized in Tables 1 and 2,
respectively. The IR spectra of IV, V, and VI show char-
acteristic N–H stretching vibration at about 3400 cm–1,
and this band disappears in the spectra of all the com-
plexes as expected. The bands at about 1015–1039 cm−1
can be assigned to the ν[P–O–C] vibrations [11]. The
IR spectra of all the complexes display two bands in
Scheme of proposed tetrahedral complexes of Zn(II)
ranges of 537–556 and 641–662 cm–1, and they are and Cd(II) is the following:
O CH2CH2CH2CH2
O
CH3O
P S
S
S P
S
OCH3
M2+/2
M2+/2
M = Zn (VIa) and Cd (VIb).
The NMR data relating to all studied compounds are tra of the corresponding Ni2+, Zn2+, and Cd2+ com-
1
summarized in Tables 3 and 4. The H NMR peaks in plexes; however, since the solvents used for the ligands
the spectra of paramagnetic complexes IVb, IVc, Vb, (D2O) and for the complexes (CDCl3 and DMSO-d6)
and Vc at room temperature are partly collapsed and were different, the shift is not considered to be due to a
scattered over a wide range, so as to make it extremely structural or constitutional change.
The 13C{1H} NMR spectra display chemical shift
values within the expected range, and the data are listed
in Table 4. The 31P–13C splittings for the carbons num-
bered 2, 3, 6, 7, and 8 are unexpectedly complex for the
square-planar complexes (Va, VII) (see the formula
under Table 3). Some signals are triplet, and some are
quintets, etc. The coupling constants for these carbons
are not given in Table 4.
difficult to gather structural information.
1
The H NMR spectra of the ammonium salts of
ligands IV, V, andVI are almost the same, except for the
signals assigned to the ester groups. Aromatic protons
in the p-methoxyphenyl group are coupled to each
other to give a splitting of 8.8 Hz. For these protons,
couplings to the 31P nucleus are 13.6 Hz from the three-
bond and 2.5 Hz from the four-bond distances. The
OCH3 protons give rise to a singlet as expected. All
31
The P nucleus gives rise to a singlet as expected.
these signals appear at slightly higher fields in the spec- No multiplicity reflecting the isotopic abundances of
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 6 2006

440
KARAKUS, YILMAZ
Table 1. Data of elemental analysis and physical details of all studied compounds
Content (found/calcd), %
Compound Empirical formula Color
Mass
C
H
N
S
VI
C18H30N2O4P2S4 Colorless
C28H34N2O4P2S4Ni Green
C28H34N6O4P2S4Ni Pink
41.19/40.90 5.62/5.68 5.21/5.30 23.94/24.24
47.01/47.26 4.55/4.78 3.84/3.93 17.90/18.01
58.88/59.30 4.35/4.39 7.38/7.68 11.42/11.42
IVb
IVc
Va
Vb
Vc
552, 554, 556 [M−Py]+ (EI)
C24H32O4P2S4Ni
Purple
632, 634, 636 (EI)
45.98/45.52 5.06/5.05
19.77/20.23
C34H42N2O4P2S4Ni Green
C38H46N2O6P2S4Ni Green
632, 634, 636 [M−Py]+ (EI)
51.42/51.38 4.96/5.31 3.67/3.54 15.81/16.18
632, 634, 636 [M–3-acetyl-Py]+ 52.20/52.10 5.02/5.29 3.17/3.19 15.00/14.64
(EI)
VIa
VIb
VII
C18H22O4P2S4Zn Colorless 1116 (ESI) [M]+
C18H22O4P2S4Cd Colorless 1210 (ESI) [M]+
38.75/38.75 3.59/3.94
35.90/35.73 3.69/3.66
41.80/41.32 4.55/4.82
22.64/22.96
20.85/21.20
22.17/22.04
C20H28O4P2S4Ni
Purple
Table 2. IR bands (cm–1) of all studied compounds
Compond
ν(N–H)
ν(C–H)aliph
ν(P–O–C)
ν(PS)asym
ν(PS)sym
VI
3369
2941, 2835
2964, 2834
2967, 2863
2974, 2835
2958, 2834
2935, 2864
2956, 2868
2954, 2836
2950, 2837
1039
1029
1028
1024
1027
1031
1030
1026
1026
668
641
644
645
662
659
658
662
660
563
546
546
541
547
553
539
545
545
IVa
IVb
IVc
Va
Vb
Vc
VIa
VIb
the isotopes of the metals were observed. Chemical VII. Since the solvents differ, it is inappropriate to infer
any general trend.
shifts with respect to 85% H3PO4 vary in a range of
105.14–107.08 ppm for ligands IV, V, and VI and
99.0−104.45 ppm for the complexes Va, VIa, VIb, and ion peaks are observed at m/z 1116 and 1210, respec-
In the ESI mass spectra of VIa and VIb, molecular
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SYNTHESIS AND CHARACTERIZATION OF Ni(II)
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SYNTHESIS AND CHARACTERIZATION OF Ni(II)
443
12. Haiduc, I., David, L., Cozar, O., et al., J. Mol. Struct.,
1999, vols. 482−483, p. 153.
tively, and the ESI mass spectra show that both of them
are dimeric.
13. Kinnear, A.M.. and Perren, E.A., J. Chem. Soc., 1952,
p. 3437.
ACKNOWLEDGMENTS
14. Martin, S.F., Wagman, S.A., Zipp, G.G., and
Gratchev, M.K., J. Org. Chem., 1994, vol. 59, no. 26,
p. 7957.
This work was supported by the State Planning
Organization, DPT (grant nos. 97-K-120550 and
2002-K-120130-5).
15. Mikolajczyk, M. and Omelanczuk, J., Tetrahedron,
1971, vol. 27, no. 22, p. 5587.
16. Murray, H.H., Garzon, G., Raptis, R.G., et al., Inorg.
Chem., 1988, vol. 27, no. 5, p. 836.
17. Karakus, M., Yilmaz, H., Ozcan, Y., and Ide, S., Appl.
Organomet. Chem., 2004, vol. 18, no. 3, p. 141.
REFERENCES
1. Van Zyl, W.E. and Fackler, J.P., Jr., Phosphorous Sulfur
and Silicon and Related Elements, 2000, vol. 167,
p. 117.
18. Karakus, M., Yilmaz, H., Bulak, E., and Lonnecke, P.,
2. Newallis, P.E., Chupp, J.P., and Groenweghe, L.C.D.,
Appl. Organomet. Chem., 2005, vol. 19, no. 3, p. 396.
J. Org. Chem., 1962, vol. 27, no. 11, p. 3829.
19. Harrison, P.G., Begley, M.J., and Kikabhai, T.J.,
3. Chupp, J.P. and Newallis, P.E., J. Org. Chem., 1962,
J. Chem. Soc., Dalton Trans., 1986, no. 5, p. 925.
vol. 27, no. 11, p. 3832.
20. Harrison, P.G., Begley, M.J., and Kikabhai, T.J.,
4. Albano, V.G., Argoni, M.C., Arca, M., et al., Chem.
Commun., 2002, no. 11, p. 1170.
5. Ozcan, Y., Ide, S., Karakus, M., and Yilmaz, H., Anal.
Sci., 2002, vol. 18, no. 11, p. 1285.
6. Aragoni, M.C., Arca, M., Devillanova, F.A., et al., Can.
J. Chem., 2001, vol. 79, no. 10, p. 1483.
7. Aragoni, M.C., Arca, M., Demartin, F., et al., J. Chem.
Soc., Dalton Trans., 2001, no. 18, p. 2671.
J. Chem. Soc., Dalton Trans., 1986, no. 5, p. 929.
21. Harrison, P.G. and Kikabhai, T.J., J. Chem. Soc., Dalton
Trans., 1987, no. 4, p. 807.
22. Foreman, R.S.J., Slawin, A.M.Z., and Woollins, J.D.,
J. Chem. Soc., Dalton Trans., 1996, no. 18, p. 3653.
23. Lawton, S.L. and Kokotailo, G.T., Inorg. Chem., 1969,
vol. 8, no. 11, p. 2411.
24. Malik, M.A., Byrom, C., O’Brien, P., and Motevalli, M.,
8. Arca, M., Cornia, A., Devillanova, F.A., et al., Inorg.
Chim. Acta., 1997, vol. 262, no. 1, p. 81.
Inorg. Chim. Acta, 2002, vol. 338, p. 245.
25. Garcia-Montalvo, V., Toscano, R.A., Badillo-Delgado, A.,
9. Van Zyl, W.E., Staples, R.J., and Fackle, J.P., Jr., Inorg
Chem. Commun., 1998, vol. 1, no. 1, p. 51.
et al., Polyhedron, 2001, vol. 20, nos. 3–4, p. 203.
26. Shabana, R., Osman, F.H., andAtrees, S.S., Tetrahedron,
10. Grecu, R., Contantinescu, R., Silaghi-Dumitrescu, I.,
1993, vol. 49, no. 6, p. 1271.
et al., J. Mol. Struct., 1990, vol. 218, p. 111.
11. Santana, M.D., Garcia, G., Navarro, C.M., et al., Polyhe- 27. Karakus, M., Yilmaz, H.E., and Bulak, E., Rus.J. Coord.
dron, 2002, vol. 21, no. 19, p. 1935. Chem., 2005, vol. 31, no. 5, p. 316.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 6 2006