Pd(II) and Au(I) chloride complexes with tetrakis(butylthiomethyl)calix[4] arene: Synthesis and crystal structures

Article abstract of DOI:10.1134/S1070328408050084

Two novel complexes, (AuCl)₄L³(I) and (PdCl ₂)₂L³(II) (L³ is calix[4]arene-thioether), were synthesized and their structures were determined. In complex I, one thioether group of molecule L³ is coordinated to every Au atom. In complex II, the bidentate coordination of L³ to the Pd atoms is observed; two thioether groups are in the trans-positions in the Pd square surrounding. Both complexes have the layered crystal lattices. In the Au complex, the layers are more stable due to the short contacts Au-Au (3.19-3.23 A).

Full text of DOI:10.1134/S1070328408050084

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2008, Vol. 34, No. 5, pp. 360–366. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © G.A. Kostin, V.I. Mashukov, N.V. Kurat’eva, S.V. Tkachev, V.G. Torgov, A.B. Drapailo, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol. 34,
No. 5, pp. 366–372.
Pd(II) and Au(I) Chloride Complexes
with Tetrakis(butylthiomethyl)calix[4]arene:
Synthesis and Crystal Structures
G. A. Kostina, V. I. Mashukova, N. V. Kurat’evaa, S. V. Tkacheva,
V. G. Torgova, and A. B. Drapailob
aNikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia
bInstitute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
E-mail: kostin@che.nsk.su
Received April 25, 2007
Abstract—Two novel complexes, (AuCl)4L3 (I) and (PdCl2)2L3 (II) (L3 is calix[4]arene-thioether), were synthe-
sized and their structures were determined. In complex I, one thioether group of molecule L3 is coordinated to
every Au atom. In complex II, the bidentate coordination of L3 to the Pd atoms is observed; two thioether groups
are in the trans-positions in the Pd square surrounding. Both complexes have the layered crystal lattices. In the Au
complex, the layers are more stable due to the short contacts Au–Au (3.19–3.23 Å).
DOI: 10.1134/S1070328408050084
Calixarenes are suitable macrocyclic platforms for with combined supramolecular and catalytic properties
[4–6].
The data available in the literature on the structures
of the noble metal (NM) complexes with calixarenes
mainly concern with calix[4]arenes (L) functionalized
by the PR2 groups in the upper (L1) [7–9] or lower (L2)
the target synthesis of the transition metal complexes
due to the easy functionalization by different donor
groups [1–3]. The metal atom coordination changes the
conformation lability, size, and form of the calixarene
internal cavity, while close location of the metal centers
to the cavity makes these complexes potential catalysts [10–13] rims:
Bu
Bu
S
Bu
S
Bu
S
t-Bu
t-Bu
t-Bu
t-Bu
S
PR2
PR2
PR2
PR2
O
O
O O
O
O
O
O
O
O
O
Pr
O
Pr
Pr
Pr
Pr
PR
2 PR
Pr
PR PR
Pr
2
2
2
Pr
L1
L2
L3
In most cases, the stoichiometry of isolated com- of Au(I), (AuCl)2L2, with coordination of two of the
pounds corresponds to a maximum saturation with the four PR2 groups was synthesized for calixarene L2 with
metal atoms: (AuCl)4L [11, 12] for monodentate and the chelate substituent at the P atom [11]. In all com-
(AgCl)2L [10], (PdCl2)2L [9], (PtCl2)2L [7, 9] for biden- pounds in the solid phase, calix[4]arene has the flat-
tate coordination of L to a metal atom. The NMR data tened cone configuration. In the case of the bidentate L
show that solutions contain also the species with a coordination to a metal, this conformation can be
lower number of the metal centers per one L molecule. detected also in solutions. Note that in all monomer
However, their isolation as separate phases is difficult complexes with calixarenes in the solid phase, the Pd
due to the disproportionation [9] and exchange [11] (Pt) atoms are in the cis-surrounding of two chloride
reactions. The sole structurally characterized complex ions and two donor groups. The trans-coordination of
360

Pd(II) AND Au(I) CHLORIDE COMPLEXES
361
3
Fig. 1. Two structurally independent fragments (AuCl) L (the butyl substituents at the S atom are omitted).
4
the donor groups was found only in the dimeric com-
Synthesis of (PdCl2)2L3 (II). A mixture of 5 ml of
plexes [9, 13], when the PdCl2 fragment acts as a bridge 10–1 M K2PdCl4 solution in 3 M HCl and 5 ml of 0.05 M
between two calixarene molecules.
solution of L3 in CH2Cl2 was stirred for 2 h. Upon the
addition of 20 ml of diethyl ether to the separated
organic phase, complex II was formed as a viscous yel-
low precipitate. The yield was 272.5 mg (81.1%). The
single crystal suitable for X-ray diffraction analysis
was obtained by a slow diffusion of diethyl ether to a
solution of II in dichloromethane.
The thioether calixarene derivatives are of great
interest for extraction and separation of the noble met-
als [14, 15]; however, the noble metal complexes with
the above calixarenes have not been reported in the lit-
erature so far.
The aim of this work was to synthesize and study
two novel complexes of Au(I) and Pd(I) with
5,11,17,23-tetrakis(butylthiomethyl)-25,26,27,28-tetra-
propoxycalix[4]arene (L3).
For C60H88S4O4Cl4Pd2
anal. calcd (%):
Found (%):
C, 53.10;
C, 52.84;
H, 9.48;
H, 9.76;
Cl, 10.47.
Cl, 10.85.
EXPERIMENTAL
The 13C NMR spectra were recorded on a Bruker-
MSL300 spectrometer with TMS as the internal stan-
dard. The signal assignment in the 13C NMR L3 spectra
(the ëDCl3–CCl4 mixture (1 : 1)) was performed as
described in [17].
X-ray diffraction analysis was performed on an
automated Bruker Nonius X8Apex CCD diffractometer
at 100K (MoKα radiation, graphite monochromator,
ϕ,ω scan mode). The absorption correction was applied
with SADABS program package [18]. The structures of
The metallic gold and palladium (99.99%) were
used; the other reagents were of the chemically pure
grade at least. Chloro(dimethylsulfide)gold(I) was pre-
pared by dissolving powdered gold in a mixture
DMSO−HClconc on heating as described in [16]. Potas-
sium tetrachloropalladate was obtained by dissolving
palladium in a mixtureHNO3–HCl (1 : 3) with subse-
quent denitration and precipitation with a potassium
salt. Tetrakis(butylthiomethyl)calix[4]arene (L3) was
prepared by a known procedure [15].
Synthesis of (AuCl)4L3 (I). The reagents L3 I, II were solved by the direct method and refined by
(100 mg, 10–4 mol) and (CH3)2SAuCl (118 mg, 4 × the full-matrix least-squares method (SHELXTL) [18].
10−4 mol) were dissolved in 5 ml of a mixture benzene– The hydrogen atoms were located geometrically and
acetone (1 : 1) in the dark, at room temperature for 12 h. refined in isotropic approximation. The crystallograph-
When 20 ml of diethyl ether was added, complex I pre- ical data are listed in Table 1.
cipitated from the reaction mixture as crystal solvate
with benzene. The yield was 138.2 mg (71.2%). The
single crystal suitable for X-ray diffraction analysis
RESULTS AND DISCUSSION
was obtained by a slow evaporation of the reaction mix-
ture for 7 days.
The crystal lattice of complex I is formed by the
(AuCl)4L3 molecular fragments, where each Au atom is
coordinated to one thioether group of the L3 ligand and
to the chloride ion. The average lengths of the bonds
Au–S (2.263 Å) and Au–Cl (2.276 Å) in I are close to
the analogous bonds in complexes with the monoden-
tate thioethers [16, 19]. A slight deviation from linear-
For C60H88S4O4Cl4Au4
anal. calcd (%): C, 37.31;
Found (%): C, 36.94;
H, 4.56;
H, 4.25;
Cl, 7.36.
Cl, 7.00.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 5 2008

362
KOSTIN et al.
Table 1. Crystallographic characteristics and summary of data collection and refinement of structures I · 0.75C6H6, II
Value
Parameter
I · 0.75C6H6
II
Empirical formula
C60H88S4O4Cl4Au4 · 0.75C6H6
1989.88
C60H88S4O4Cl4Pd2
1356.23
M
Space group
P1
P1
15.2174(10)
15.2889(9)
32.7567(22)
95.278(1)
a, Å
14.5883(7)
15.3535(7)
29.7001(14)
76.478(2)
b, Å
c, Å
α, deg
β, deg
94.304(1)
81.952(2)
γ, deg
90.010(1)
89.332(2)
V, Å3
7567.18 (8)
4
6402.6(5)
Z
4
Temperature, K
Crystal size, mm
Number of reflections
Number of independent reflections
R (I < 2σ(I))
150
150
0.9 × 0.35 × 0.32
38406
0.32 × 0.3 × 0.24
37650
29554
23769
R = 0.0633, wR = 0.1712
R = 0.0981, wR = 0.1833
1.071
R = 0.0984, wR = 0.2302
R = 0.2218, wR = 0.2689
0.955
R (for all reflections)
GOOF
ity (169.810(5)°–176.692(5)°) of the SAuCl angles is zene rings B and D are almost perpendicular (the angle
between them being 88.694°) and make the angles with
the plane [C4] equal to 44.423° and 44.271°, respec-
tively. The average distances S···S in the upper rim are
4.538 Å (S(2)···S(3), S(4)···S(1), S(7)···S(8), S(5)···S(6))
and 7.072 Å (S(1)···S(2), S(3)···S(4), S(6)···S(7),
S(5)···S(8)), while the shortest distances between the
S atoms of the opposite arene fragments (S(1)···S(3),
S(6)···S(8)) lie in the range 6.5523(3)−6.5620(3) Å. Two
structurally independent fragments (AuCl)4L3 differ in
the direction of SAuCl rotation about the ë2 axis pass-
ing though the center of calixarene plane (right- and
left-hand twisted).
due to the intermolecular Au···Au contacts. In complex I,
calix[4]arene has the flattened cone conformation with
insignificant deviation form the symmetry C2ν (Fig. 1).
The angles between the planes of benzene rings A, C
and the plane [C4} passing through the C atoms of the
bridging groups Ar–CH2–Ar are equal to 77.433° and
76.541°, respectively; both benzene rings are directed
into the molecular cavity (Table 2). The planes of ben-
Table 2. The average distance (Å) between the centers of
molecules in complexes I, II
The structural units of crystal II are the (PdCl2)2L3
molecules with the S atoms of two thioether groups and
two chloride ions trans-coordinated to each Pd atom
(Fig. 2). According to the quantum-chemical calcula-
tions of the [(Pd(NO2)2]2L [14], the above coordination
is more favorable than the cis-position of the ligands,
despite substantial distortion of a macrocycle. Never-
theless, such coordination of Pd has not been encoun-
tered in the monomer complexes with calixarenes. The
Distance
I
II
In a layer
10.64 1.0 10.78 0.01
16.79 0.4 18.17 0.01
Interlayer distance “upper
rim”–“upper rim”
Interlayer distance “lower
rim”–“lower rim"
14.01 0.2 14.81 0.01
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Pd(II) AND Au(I) CHLORIDE COMPLEXES
363
3
Fig. 2. Two structurally independent fragments (PdCl ) L (the butyl substituents at the S atom are omitted).
2 2
Pd–S and Pd–Cl distances in II are close (2.297 and length of substituents (CH2SBu and OPr, respectively).
2.315 Å, respectively) and differ insignificantly from
those in complexes with the monodentate thioethers
[20, 21]. The Pd atoms are located almost in the centers
of squares formed by the donor atoms and deviate from
their planes by 0.04 Å at maximum. The SPdCl angles
lie within 87.201(7)°–93.285(7)°. The internal calix-
arene cavity is inaccessible for the “guest” molecules
due to the chlorine atoms. The distances S(4)···Cl(1)
(3.6515(2) Å) and S(8)···Cl°(5) (3.6559(2) Å) (Fig. 2)
are close to the sum of van der Waals radii of the S and
Cl atoms. The repulsion of two PdCl2S2 fragments leads
to reduction of the calixarene symmetry as compared to
that in (AuCl)4L3. The planes of benzene rings B and D
deviate from the plane [C4] by 44.229° and 41.679°, the
angles between the plane [C4} and the planes of ben-
zene rings A and C are equal to 89.430° and 75.641°,
respectively. The coordination of the Pd atoms makes
the S atoms of the opposite arene fragments closer, i.e.,
the distances S(2)···S(4), S(6)···S(8) are equal to
4.8012(2) and 4.9292(2) Å, respectively. As in the case
of complex I, in complex II, the structurally indepen-
dent units are stereoisomeric, except for the radicals in
the upper and lower rims.
As compared to II, the interlayer distances in structure I
are 0.8–1.5 Å longer (Table 2). The cavities thus formed
are filled with disordered benzene molecules.
The coordination of the donor groups of L3 to the
metal atoms in solutions of complexes I, II is attended
by the down-field shift (by 5–7 ppm) of the signals from
the carbon atoms neighboring to the sulfur atoms (ë6, ë7)
and by their broadening, which is more pronounced in
the Pd complex spectrum (Table 3, Fig. 5). As com-
Table 3. The signals (δ, ppm) in the 13C NMR spectra of so-
lutions of L3 calixarene and complexes I, II
Number
of atom
C*
L3
I
II
C1
156.00
135.22
132.04
129.06
157.12
136.77
130.31
127.80
Broad diffused
lines
C2
C3
C4
In crystals, the molecules of I and II form the layers
parallel to the plane [001] (Fig. 3). The average distance
between the centers of calixarene fragments in a layer is
equal to 10.78 (10.771(5)−10.798(5)) Å for complex I
and 10.64 (9.696(5)−11.679(55)) Å for complex II. The
layered structure I is stabilized by the intermolecular
contacts Au···Au (3.1965(2)–3.2306(2) Å); Every
(AuCl)4L3 molecule in the two-dimensional networks
formed is linked with four neighboring molecules
(Fig. 4). In each layer of I and II, the (AuCl)4L3 and
C5
77.19 (overlaps with the signal from CDCl3)
C6
36.57
31.90
31.50
31.45
23.75
22.58
14.34
10.91
42.42
38.86
32.00
31.25
23.80
22.40
14.22
10.88
41.63
C7
38.68
C8
31.63
C9
31.23, 30.51
23.53, 24.07
22.46, 22.71
14.21
C10
C11
C12
C13
(PdCl2)2L3 molecules have the same direction, while the
direction of the layers alternate (Fig. 4). In both struc-
tures, the interlayer distances “upper rim”–“upper rim”
(Table 2) are 3–4 Å longer than the distances “lower
rim”–“lower rim”, which agrees with an increase in the
10.55, 11.37
* The numbering of the C atoms corresponds to that in Fig. 5.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 5 2008

364
KOSTIN et al.
3
Fig. 3. The projection of the (AuCl) L cell onto the plane [010] (the disordered benzene molecules are not shown).
4
pared to the spectrum of L3, the signals due to the ali- plex II is peculiar in nonequivalence of the signals from
the corresponding C atoms of the aliphatic radicals and
in disappearance of the signals due to the aromatic C
atoms. The greatest distinction is observed for the propyl
C atoms in the lower rim (ë10, ë13 Δ = 0.5–0.8 ppm),
whereas for the butyl C atoms in the upper rim, only the
splitting for ë11 (Δ = 0.25 ppm) can be indicated with
confidence. The Pd bidentate coordination is likely to
increase the activation energy of the conformational
transition [22], which leads to the appearance of two
signals form the atoms of the aliphatic radicals and dis-
appearance of the signals from the aromatic atoms due
to the slow exchange. The slowing down of the confor-
mational exchange was previously detected for the sil-
ver ion inclusion to the calixarene cavity [23]. Two sig-
nals from the bridging carbon atoms ë9 (Δ = 0.4 ppm)
phatic radical atoms in the spectrum of I are shifted
insignificantly (by 0.2–0.4 ppm). At the same time, the
signals from the aromatic protons ë1–ë4 are shifted up
to 1.7 ppm, the signals due to the atoms ë1, ë2 close to
the lower rim are shifted downfield, while the signals of
ë3, ë4 are shifted upfield (Table 3). This is likely to be
due to an increase in the angle between the planes of
benzene rings as a result of the Au coordination. In this
case, the atoms ë1, ë2 in the complex are shielded to a
higher extent by the whole aromatic π-system of calix-
arene, as compared to a ligand.
The high rate of the conformational exchange flat-
tened cone–cone–flattened cone [22] in calix[4]arene
solutions makes all four arene fragments in the NMR
spectra of L3 and I equivalent. The spectrum of com- appear not due to the conformational transitions but as
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Pd(II) AND Au(I) CHLORIDE COMPLEXES
365
3
Fig. 4. The projection of the (AuCl) L cell onto the plane [001] (the intermolecular Au···Au contacts are shown by dotted lines;
4
the disordered benzene molecules are not shown).
13
3
Fig. 5. The C NMR spectra in a range of 0–50 ppm for solutions of (a) L and complexes (b) I, (c) II in a mixture CDCl –CCl
3
4
(1 : 1).
a result of inclusion of two of the four methylene
groups into 12-membered metal ring. The positions of
the signals from the bridging atoms C9 coincide with
the data reported previously for the palladium extrac-
tion from hydrochloric acid solutions by solutions of L
[24].
ACKNOWLEDGMENTS
This work was supported by the Integration Project
of the Siberian Division of the Russian Academy of
Sciences and the National Academy of Sciences of
Ukraine (project no. 4.12).
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KOSTIN et al.
13. Loeber, C., Matt, D., Briard, P., and Grandjean, D., J.
REFERENCES
Chem. Soc., Dalton Trans., 1995, p. 513.
1. Wieser, C., Dielman, C.B., and Matt, D., Coord. Chem.
Rev., 1997, vol. 165, p. 93.
2. Redshaw, C., Coord. Chem. Rev., 2003, vol. 244, p. 45.
3. Caselli, A., Solari, E., Floriani, C., et al., J. Am. Chem.
Soc., 2002, vol. 122, p. 3652.
14. Torgov, V., Korda, T., Kostin, G., et al., Solvent. Extr. Ion
Exc., 2005, vol. 23, no. 6, p. 781.
15. Torgov, V., Kostin, G., Mashukov, V., et al., Solvent. Extr.
Ion Exc., 2005, vol. 23, no. 2, p. 171.
16. Nifontova, G.A., Krasochka, O.N., Lavrent’ev, I.P.,
et al., Izv. Akad. Nauk SSSR, Ser. Khim., 1988, no. 2,
p. 450.
4. Harvey, P.D., J. Inorg. Organomet. Polym., 2004,
vol. 14, no. 4, p. 211.
17. Yordanov, A.T., Falana, O.M., Koch, H.F., and Roun-
5. Frank, M., Mass, G., and Schatz, J., Eur. J. Org. Chem.,
dhill, D.M., Inorg. Chem., 1997, vol. 36, p. 6486.
2004, p. 607.
18. APEX2 (Version 1.08), SAINT (Version 7.03), SADABS
(Version 2.11) and SHELXTL (Version 6.12). Bruker
Advanced X-ray Solutions, Madison (WI, USA), 2004.
6. Shimizu, S., Shirakawa, S., Sasaki, Y., and Hirai, C.,
Angew. Chem., Int. Ed. Engl., 2000, vol. 39, no. 7,
p. 2862.
19. Takahashi, K. and Tanino, H., Chem. Lett., 1988, no. 4,
7. Lejeune, M., Jeunesse, C., Matt, D., et al., Dalton Trans.,
p. 641.
2002, p. 1642.
20. Byers, P.K., Canty,A.J., Engelhardt, L.M., andWhite,A.H.,
8. Plourde, F., Gilbert, K., Gagnon, J., and Harvey, P.D.,
J. Chem. Soc., Dalton Trans., 1986, p. 1731.
Organometallics, 2003, vol. 22, p. 2862.
21. Shirshova, L.V., Ponomarev, V.I., Korableva, L.G., and
Lavrent’ev, I.P., Koord. Khim., 1990, vol. 16, no. 8,
p. 1118.
9. Takehaka, K., Obora,Y., Jiang, L.H., and Tsuji,Y., Orga-
nometallics, 2002, vol. 21, p. 1158.
10. Stolmar, M., Floriani, C., Chiesi-Villa, A., and Rizzoli, C.,
22. Lhotak, P., Himl, M., Stibor, J., et al., Tetrahedron, 2003,
Inorg. Chem., 1997, vol. 36, p. 1694.
vol. 59, p. 7581.
11. Dieleman, C., Matt, D., Neda, I., et al., Dalton Trans.,
23. Ikeda, F. and Shinkai, S., Chem. Rev., 1997, vol. 97,
1998, p. 2115.
p. 1713.
12. Dieleman, C., Marsol, C., Matt, D., et al., Dalton Trans., 24. Kostin, G.A, Mashukov. V.I., Korda, T.M., et al., Zh.
1999, p. 4139.
Neorg. Khim., 2007, vol. 52, no. 11, p. 1806.
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