Syntheses and crystal structures of new mono- and di-nuclear platinum(II) complexes with dithioether ligands

Article abstract of DOI:10.1016/S0022-2860(01)00912-7

Two new platinum(II) complexes with dithioether ligands, cis-[Pt(L¹)Cl₂] (1) and cis-[Pt(L²)Cl₂]₂ (2), where L¹ = 1,3-bis(phenylthio)propane and L² = 1,5-bis(n-propylthio)pentane

Full text of DOI:10.1016/S0022-2860(01)00912-7

Journal of Molecular Structure 607 ꢀ2002) 175±179
www.elsevier.com/locate/molstruc
Syntheses and crystal structures of new mono- and di-nuclear
platinumꢀII) complexes with dithioether ligands
*
Jian-Rong Li, Miao Du, Ruo-Hua Zhang, Xian-He Bu
Department of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
Received 24 August 2001; revised 10 October 2001; accepted 10 October 2001
Abstract
Two new platinumꢀII) complexes with dithioether ligands, cis-[PtꢀL1)Cl2] ꢀ1) and cis-[PtꢀL2)Cl2]2 ꢀ2), where L1 ˆ 1,3-
bisꢀphenylthio)propane and L2 ˆ 1,5-bisꢀn-propylthio)pentane, have been synthesized and structurally characterized by X-
ray diffraction analyses. In 1, the PtꢀII) center is four-coordinated and forms a six-membered chelated ring with L1, while 2
exhibits a unique di-nuclear structure containing a 16-membered metallomacrocyles with chair-shaped conformation, in which
each PtꢀII) center is coordinated by two chloride anions and two sulfur-donors from two L2 ligands. q 2002 Elsevier Science
B.V. All rights reserved.
Keywords: Synthesis; Crystal structure; Dithioether; PlatinumꢀII) complexes
1. Introduction
2. Experimental
2.1. Materials and general methods
PlatinumꢀII) bonded to some ligands in cis-mode
may produce functional complexes with potential
antineoplastic activity [1]. Special attention and
several efforts have been devoted to the studies of
bisꢀthioether)bidentate ligands and their platinumꢀII)
complexes [2±8]. However, to our knowledge, the X-
ray crystal structures of dithioetherplatinum
complexes are still rare [6±8]. Here, we report the
syntheses and crystal structures of cis-[PtꢀL1)Cl2]
ꢀ1) and cis-[PtꢀL2)Cl2]2 ꢀ2) ꢀL1 ˆ 1,3-bisꢀphenylthio)-
propane and L2 ˆ 1,5-bisꢀn-propylthio)pentane).
Complex 1 is a mono-nuclear platinum complex
with a six-membered chelated ring, whereas 2 is a
novel di-nuclear complex with a 16-membered ring
due to the difference of the ligands.
All reagents for syntheses and analyses were of
analytical grade. FT-IR spectra were taken on a FT-
1
IR 170 SX ꢀNicolet) spectrometer. HNMR spectra
were measured on a Bruker AC-P 200 spectrometer
using TMS as the internal standard. Elemental
analyses were obtained using a Perkin±Elmer 240C
analyzer. 1,3-Bisꢀphenylthio)propane ꢀL1) and 1,5-
bisꢀn-propylthio)pentane ꢀL2) were prepared by the
literature method [3].
2.2. Preparation of [Pt*L1)Cl2] *1) and [Pt*L2)Cl2]2
*2)
Complex 1 was synthesized by mixing 1:1 molar
ratio of PtCl4 and L1 in methanol/chloroform at room
temperature. The mixture was stirred and ®ltered. Pale
red single crystals suitable for X-ray investigation
* Corresponding author. Tel.: 186-22-235-02809; fax: 186-22-
235-30850.
E-mail address: buxh@nankai.edu.cn ꢀX.-H. Bu).
0022-2860/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-2860ꢀ01)00912-7

176
J.-R. Li et al. / Journal of Molecular Structure 607 *2002) 175±179
Table 1
Crystal data and structure re®nement summary for 1 and 2
1
2
Empirical formula
Formula weight
Crystal system
Space group
C15H16Cl2S2Pt
526.39
C22H48Cl4S4Pt2
972.82
Monoclinic
P21/c
Monoclinic
P21/n
Ê
Unit cell dimensions ꢀA, 8)
a ˆ 10:198ꢀ3†
b ˆ 10:862ꢀ3†
c ˆ 15:334ꢀ5†
b ˆ 102:660ꢀ5†
1657.3ꢀ8)
a ˆ 10:235ꢀ3†
b ˆ 13:406ꢀ4†
c ˆ 12:284ꢀ4†
b ˆ 95:797ꢀ6†
1677.0ꢀ9)
Ê 3
Volume ꢀA )
Z
4
4
Dcalcd ꢀg/cm3)
2.110
1.927
m ꢀmm21
Fꢀ000)
)
9.028
8.911
1000
936
Range of h, k, l
2 12/12, 212/9, 215/18
6746/2931
0.4655 and 0.2654
2931/0/181
1.029
2 9/12, 214/15, 214/14
6816/2941
0.3483 and 0.1752
2941/0/145
0.871
Re¯ections collected/unique
Max. and min. transmission
Data/restraints/parameters
Goodness-of-®t on F2
R and wR
0.0336 and 0.0589
1.269 and 21.517
0.0392 and 0.0479
0.992 and 20.983
Ê 3
Largest diff. peak and hole ꢀe/A )
were obtained by slow evaporation of the solvent in
35% yield. FT-IR ꢀKBr pellets, cm21): 2961w,
1636m, 1472m, 1438s, 1068w, 1021w, 758s, 691m,
493w. Anal. Calcd for C15H16Cl2S2Pt: C 34.22, H
3.06; found: C 34.10, H3.25. 1HNMR ꢀDMSO): d
1.82 ꢀm, 2H), 3.08 ꢀt, 4H), 7.15±7.35 ꢀm, 10H).
Complex 2 was prepared with a similar method in
40% yield. FT-IR ꢀKBr pellets, cm21): 2964s,
2931m, 2866m, 1459s, 1420s, 1378w, 1285w,
1246s, 1091m, 823m, 741s, 462w. Anal. Calcd for
C22H48Cl4S4Pt2: C 27.16, H4.97; found: C 26.87, H
Table 2
Atomic coordinates ꢀ £ 104) and equivalent isotropic displacement
3
Ê 2
parameters ꢀA £ 10 ) for 1
x
y
z
Ueq
Ptꢀ1)
Clꢀ1)
Clꢀ2)
Sꢀ1)
7507ꢀ1)
9198ꢀ2)
6052ꢀ2)
5721ꢀ2)
9010ꢀ2)
4515ꢀ7)
3175ꢀ7)
2209ꢀ8)
2544ꢀ8)
3858ꢀ8)
4856ꢀ7)
6067ꢀ8)
6962ꢀ9)
8425ꢀ8)
7899ꢀ1)
7536ꢀ2)
6648ꢀ2)
8102ꢀ2)
9200ꢀ2)
9065ꢀ6)
8894ꢀ7)
9645ꢀ8)
1888ꢀ1)
1119ꢀ2)
885ꢀ1)
32ꢀ1)
51ꢀ1)
45ꢀ1)
39ꢀ1)
42ꢀ1)
35ꢀ2)
46ꢀ2)
56ꢀ2)
55ꢀ2)
46ꢀ2)
39ꢀ2)
57ꢀ2)
72ꢀ3)
68ꢀ3)
34ꢀ2)
47ꢀ2)
61ꢀ3)
52ꢀ2)
50ꢀ2)
45ꢀ2)
2538ꢀ1)
2738ꢀ1)
1816ꢀ5)
1861ꢀ5)
1363ꢀ6)
830ꢀ6)
1
Sꢀ2)
5.16. HNMR ꢀDMSO): d 0.93 ꢀt, 12H), 1.02 ꢀm,
12H), 1.49±1.76 ꢀm, 24H).
Cꢀ1)
Cꢀ2)
Cꢀ3)
Cꢀ4)
Cꢀ5)
Cꢀ6)
Cꢀ7)
Cꢀ8)
Cꢀ9)
Cꢀ10)
Cꢀ11)
Cꢀ12)
Cꢀ13)
Cꢀ14)
Cꢀ15)
2.3. X-ray crystallographic studies of complexes 1 and
2
10539ꢀ7)
10681ꢀ7)
9947ꢀ6)
9072ꢀ8)
10185ꢀ8)
9850ꢀ8)
8351ꢀ6)
7095ꢀ7)
6525ꢀ8)
7212ꢀ7)
8458ꢀ8)
9040ꢀ7)
769ꢀ5)
1270ꢀ5)
3523ꢀ5)
3494ꢀ6)
3694ꢀ6)
3356ꢀ5)
3495ꢀ5)
4014ꢀ6)
4403ꢀ6)
4256ꢀ6)
3727ꢀ5)
Single crystal X-ray diffraction measurements were
carried out on a Bruker Smart 1000 diffractometer.
Intensities of re¯ections were measured using
graphite monochromatized Mo Ka radiation ꢀl ˆ
10419ꢀ7)
10404ꢀ7)
11498ꢀ8)
12621ꢀ8)
12647ꢀ8)
11554ꢀ7)
ꢀ
0:71073 A† with v scan mode at 293ꢀ2) K in the
range of 2:05 , u , 25:038 for 1 and 2:25 , u ,
25:028 for 2. Unit cell dimensions were obtained
with least-squares re®nements and semi-empirical

J.-R. Li et al. / Journal of Molecular Structure 607 *2002) 175±179
177
Table 3
Atomic coordinates ꢀ £ 104) and equivalent isotropic displacement
Table 5
Ê
Selected bond lengths ꢀA) and angles ꢀ8) for complex 2
3
Ê 2
parameters ꢀA £ 10 ) for 2
Ptꢀ1)±Sꢀ2)
Ptꢀ1)±Clꢀ1)
Sꢀ1)±Cꢀ3)
Sꢀ2)±Cꢀ9)
2.278ꢀ2) Ptꢀ1)±Sꢀ1)
2.318ꢀ2) Ptꢀ1)±Clꢀ2)
1.809ꢀ7) Sꢀ1)±Cꢀ4)
1.807ꢀ7) Sꢀ2)±Cꢀ10)
2.288ꢀ2)
2.322ꢀ2)
1.821ꢀ7)
1.806ꢀ7)
x
y
z
Ueq
39ꢀ1)
Ptꢀ1)
Clꢀ1)
Clꢀ2)
Sꢀ1)
1392ꢀ1)
1ꢀ2)
7225ꢀ1)
7279ꢀ2)
6306ꢀ2)
8123ꢀ1)
7210ꢀ2)
2146ꢀ1)
3522ꢀ2)
3273ꢀ2)
997ꢀ2)
788ꢀ2)
1701ꢀ7)
1069ꢀ7)
1756ꢀ6)
843ꢀ6)
314ꢀ7)
71ꢀ6)
61ꢀ1)
63ꢀ1)
45ꢀ1)
45ꢀ1)
72ꢀ3)
62ꢀ3)
51ꢀ2)
43ꢀ2)
52ꢀ2)
47ꢀ2)
151ꢀ6)
95ꢀ4)
54ꢀ2)
40ꢀ2)
56ꢀ2)
Sꢀ2)±Ptꢀ1)±Sꢀ1)
Sꢀ1)±Ptꢀ1)±Clꢀ1)
87.73ꢀ8)
91.39ꢀ8)
Sꢀ2)±Ptꢀ1)±Clꢀ1)
178.71ꢀ8)
90.71ꢀ8)
90.18ꢀ8)
106.6ꢀ3)
100.3ꢀ4)
2903ꢀ2)
2 63ꢀ2)
2751ꢀ2)
Sꢀ2)±Ptꢀ1)±Clꢀ2)
Clꢀ1)±Ptꢀ1)±Clꢀ2)
Cꢀ3)±Sꢀ1)±Ptꢀ1)
Cꢀ9)±Sꢀ2)±Cꢀ10)
Sꢀ1)±Ptꢀ1)±Clꢀ2) 178.41ꢀ8)
Cꢀ3)±Sꢀ1)±Cꢀ4) 102.3ꢀ3)
Sꢀ2)
Cꢀ1)
Cꢀ2)
Cꢀ3)
Cꢀ4)
Cꢀ5)
Cꢀ6)
Cꢀ7)
Cꢀ8)
Cꢀ9)
Cꢀ10)
Cꢀ11)
2 1716ꢀ9)
2 1414ꢀ8)
2 512ꢀ8)
2 1588ꢀ6)
2 1317ꢀ7)
2 2524ꢀ8)
5231ꢀ11)
4041ꢀ10)
4264ꢀ7)
10829ꢀ6)
9913ꢀ6)
9205ꢀ5)
7414ꢀ5)
6425ꢀ6)
5776ꢀ5)
9363ꢀ8)
8875ꢀ7)
7788ꢀ6)
5948ꢀ5)
5271ꢀ6)
Cꢀ4)±Sꢀ1)±Ptꢀ1) 106.7ꢀ3)
Cꢀ9)±Sꢀ2)±Ptꢀ1) 106.1ꢀ2)
Cꢀ10)±Sꢀ2)±Ptꢀ1) 108.6ꢀ2)
3. Results and discussion
2057ꢀ12)
1595ꢀ9)
1355ꢀ6)
614ꢀ6)
3.1. Preparations of the complexes
3310ꢀ7)
2197ꢀ8)
Several dithioetherplatinumꢀII) complexes have
been prepared by the reaction of dithioether ligands
with A2PtX4 ꢀA ˆ Na or K and X ˆ Cl2, Br2 or I2) or
platinum perchlorate, generally having the formula of
[PtꢀL)2]ꢀClO4)2 or [PtLX2] [2,3]. In this report, we try
the reaction of dithioether with PtCl4, which also
produces the PtꢀII) complexes. In this case, CH3OH
may act as a sacri®cial reducing agent to afford the
PtꢀII) complex.
295ꢀ7)
absorption corrections were applied using sadabs
program. All the structures were solved by direct
method [9,10]. The PtꢀII) atoms were located from
E-maps and the other non-hydrogen atoms were
obtained in successive difference Fourier syntheses.
The ®nal re®nement was performed by full-matrix
least-squares methods on F2 by shelxl-97 program
package [9,10]. Hydrogen atoms were included in
calculated positions and re®ned with ®xed thermal
parameters riding on the parent atoms. Crystallo-
graphic data and experimental details for structural
analyses are summarized in Table 1. Positional para-
meters and atomic coordinates are given in Tables 2
and 3, whereas selected bond lengths and angles are
presented in Tables 4 and 5, respectively.
3.2. Description of the crystal structures
The crystal structure of 1 consists of neutral
PtCl2[PhSꢀCH2)3SPh] molecule which exhibits the
expected cis-square planar coordination sphere
around the PtꢀII) atom, and form a six-membered
chelate ring as shown in Fig. 1. The central PtꢀII)
atom in 1 is four-coordinated with two S-donors of
L1 and two terminal Cl anions. The two Pt±Cl bond
lengths are approximately equivalent with the mean
Table 4
Ê
Selected bond lengths ꢀA) and angles ꢀ8) for complex 1
Ê
value of 2.325ꢀ10) A, being in the normal range of
Ê
the terminal PtꢀII)±Cl distances ꢀ2.26±2.45 A) [6].
Ptꢀ1)±Sꢀ1)
Ptꢀ1)±Clꢀ1)
Sꢀ1)±Cꢀ1)
Sꢀ2)±Cꢀ10)
2.271ꢀ2) Ptꢀ1)±Sꢀ2)
2.326ꢀ2) Ptꢀ1)±Clꢀ2)
1.799ꢀ7) Sꢀ1)±Cꢀ7)
1.794ꢀ7) Sꢀ2)±Cꢀ9)
2.274ꢀ2)
2.325ꢀ2)
1.811ꢀ8)
1.840ꢀ9)
Ê
The Pt±S distances of 2.271ꢀ2) and 2.2742ꢀ19) A
Ê
differ slightly and the PtꢀII) center lies 0.0286 A
from the Sꢀ1)±Sꢀ2)±Clꢀ1)±Clꢀ2) basal plane. The
six-membered
Ptꢀ1)±Sꢀ1)±Sꢀ2)±Cꢀ7)±Cꢀ8)±Cꢀ9)
Sꢀ1)±Ptꢀ1)±Sꢀ2)
Sꢀ2)±Ptꢀ1)±Clꢀ1)
101.09ꢀ7)
85.07ꢀ8)
Sꢀ1)±Ptꢀ1)±Clꢀ1) 173.84ꢀ7)
chelated ring adopts a distorted chair conformation.
The displacement of the Ptꢀ1) and Cꢀ8) atoms from
the least-squares plane drawn through the Sꢀ1)±Cꢀ7)±
Ê
Sꢀ2)±Cꢀ9) atoms are 0.1205 and 0.7806 A, and that of
Ê
Cꢀ1) and Cꢀ10) atoms are 1.6703 and 1.5418 A,
Sꢀ1)±Ptꢀ1)±Clꢀ2)
Clꢀ1)±Ptꢀ1)±Clꢀ2)
Cꢀ1)±Sꢀ1)±Ptꢀ1)
Cꢀ10)±Sꢀ2)±Cꢀ9)
Cꢀ9)±Sꢀ2)±Ptꢀ1)
83.72ꢀ7)
90.15ꢀ8)
107.0ꢀ3)
98.0ꢀ4)
Sꢀ2)±Ptꢀ1)±Clꢀ2) 173.77ꢀ8)
Cꢀ1)±Sꢀ1)±Cꢀ7)
Cꢀ7)±Sꢀ1)±Ptꢀ1)
89.0ꢀ4)
113.2ꢀ3)
Cꢀ10)±Sꢀ2)±Ptꢀ1) 110.2ꢀ2)
113.6ꢀ3)

178
J.-R. Li et al. / Journal of Molecular Structure 607 *2002) 175±179
Fig. 1. ORTEP view of 1 with 50% thermal ellipsoids probability.
respectively. The phenyl group substituents of the
sulfur atoms are in anti-mode with respect to the
chelate ring. In other bisꢀthioether) chelate complexes
of platinumꢀII), the terminal substituents of the group
VIA donor atoms give the syn-con®guration [11,12],
which may be a consequence of the constrained
geometry of the ligand. The angles between the two
phenyl rings and the square-plane of Ptꢀ1) are 86.1
and 104.98, respectively, and the dihedral angle
formed by the two phenyl rings is 42.98.
The perspective view of the binuclear entity in 2
with atomic labeling is given in Fig. 2. Each PtꢀII)
atom is four-coordinated by two S-donors from two
ligands and two Cl2 forming a square-planar
geometry, and related by a crystallographic center of
symmetry. The mean bond lengths of Pt±Cl and Pt±S
Ê
are 2.320ꢀ10) and 2.284ꢀ10) A, respectively. Both
PtꢀII) centers are equivalently bridged by two L2
ligands forming a 16-membered metallomacrocyles.
The 16-membered ring has a symmetric chair
Fig. 2. ORTEP view of 2 with 50% thermal ellipsoids probability.

J.-R. Li et al. / Journal of Molecular Structure 607 *2002) 175±179
179
conformation with sides formed by the extended S±
ꢀCH2)5±S linkages and the bulky PrnS groups occu-
the distance between the two S donors in the different
ligands.
Ê
pying the four corners ꢀthe Pt´´´Pt distance is 8.276 A
Ê
and that of Cꢀ6)´´´Cꢀ6A) is 5.590 A). Each PtꢀII) deri-
Ê
vates from the basal plane by ca. only 0.006 A and a
Acknowledgement
pair of PtCl2 groups lies up and down the plane of the
16-membered ring forming the chair con®guration.
This is different with the structure of the 16-
membered ring dithioether palladiumꢀII) complex,
trans-[Pd2Cl4{ButSꢀCH2)5SBut}2], having a barge
conformation [4]. This conformation is preferred
because it allows all the Cl±Pd±S±But torsion angles
to be ca. 908, which minimizes the Cl´´´But steric
interaction. However in 2, the torsion angles are rela-
tively smaller ꢀin the range of 48.3±58.88).
In both complexes, each PtꢀII) atom is four-coordi-
nated by two S atoms of the ligand and two Cl2 anions
forming the square-planar geometry. The S±Pt±S
angle of 1 is larger than that of 2 due to the molecular
tensile force when it forms a six-membered chelated
This work was supported by NSFC ꢀNo. 29971019)
of China.
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Ê
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Ê
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Ê
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Ê
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2
ization of ionic radii of Pt21 ꢀ0.850 A) and Cl
Ê
Ê
ꢀ1.810 A) [14], may be due to the result of the form
of covalent bond of Cl2 with Pt21 that adopts dsp2
hybrid orbital.
[12] B.E. Mann, P.M. Bailey, P.M. Maitlis, J. Am. Chem. Soc. 97
ꢀ1975) 1275.
In summary, complex 1 is a mono-nuclear complex
with a chelate ligand, while 2 is a di-nuclear
compound with two bridged ligands to connect two
PtꢀII) atoms forming a 16-membered metallomacro-
cyles, which is mainly attributable to the difference of
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[14] CRC Handbook of Chemistry and Physics 70th B-2 B-3,
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