Preparation and characterisation of CdII, HgII and PbII complexes of a macrodinucleating hexaaza-dithiophenolate ligand

Article abstract of DOI:10.1002/ejic.200400603

The ligating properties of a Robson-type 24-membered macrodinucleating hexaaza-dithiophenolate ligand towards the heavy metal ions Cd^II, Hg^II and Pb^II have been examined. The complexation of H₂L^Me with CdCl₂ or Cd(OAc)₂ in the presence of triethylamine leads to monocationic [(L^Me)Cd ₂(μ-L′)]⁺ complexes bearing additional coligands [L′ = Cl^- (2) or OAc^- (3)]. With Hg(OAc)₂ and Pb(OAc)₂, the respective dicationic complexes [(L ^Me)Hg₂]²⁺ (4) and [(L^Me)Pb ₂]²⁺ (5) were obtained. The latter show no tendency to bind to further co-ligands. The crystal structure determinations of 2-BPh ₄ and 3-BPh₄ revealed the presence of bowl-shaped, calixarene-like [(L^Me)Cd₂(μ-L′)]⁺ cations featuring six-coordinate Cd^II ions with N₃S ₂Cl (2) or N₃S₂O (3) environments. The metal ions in the dications 4 and 5 display highly irregular N₃S coordination environments, presumably as a consequence of the steric constraints imposed by the rigid macrocyclic nature of (L^Me)^2-. All complexes could also be fully characterised by ¹H and ¹³C NMR spectroscopy. These results have thus established the ability of the macrodinucleating polyaza-dithiophenolate ligand to support the formation of stable dinuclear complexes of toxic heavy metals. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejic.200400603

FULL PAPER
Preparation and Characterisation of CdII, HgII and PbII Complexes of a
Macrodinucleating Hexaaza-dithiophenolate Ligand
Vasile Lozan[a] and Berthold Kersting*[a]
Keywords: Macrocyclic ligands / Cadmium / Mercury / Lead / Complexes
The ligating properties of a Robson-type 24-membered mac-
rodinucleating hexaaza-dithiophenolate ligand towards the
heavy metal ions CdII, HgII and PbII have been examined.
The complexation of H2LMe with CdCl2 or Cd(OAc)2 in the
presence of triethylamine leads to monocationic [(LMe)Cd2(µ-
ions with N3S2Cl (2) or N3S2O (3) environments. The metal
ions in the dications 4 and 5 display highly irregular N3S co-
ordination environments, presumably as a consequence of
the steric constraints imposed by the rigid macrocyclic nature
of (L )
Me 2−. All complexes could also be fully characterised
LЈ)]+ complexes bearing additional coligands [LЈ = Cl− (2) or by 1H and 13C NMR spectroscopy. These results have thus
OAc− (3)]. With Hg(OAc)2 and Pb(OAc)2, the respective di-
cationic complexes [(LMe)Hg2]2+ (4) and [(LMe)Pb2]2+ (5) were
obtained. The latter show no tendency to bind to further co-
ligands. The crystal structure determinations of 2·BPh4 and
3·BPh4 revealed the presence of bowl-shaped, calixarene-
like [(LMe)Cd2(µ-LЈ)]+ cations featuring six-coordinate CdII
established the ability of the macrodinucleating polyaza-di-
thiophenolate ligand to support the formation of stable di-
nuclear complexes of toxic heavy metals.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
Introduction
It is well established that macrodinucleating ligands of
the Robson type[1] are ideally suited to the formation of
kinetically and thermodynamically stable complexes of the
3d elements.[2] Since these ligands also bind strongly to a
range of toxic and precious heavy metal ions,[3Ϫ5] they may
serve as complexing or extracting agents for biological, en-
vironmental or recycling purposes.[6Ϫ8] With regards to the
soft characteristics of the heavy metal ions,[9] it could be
advantageous to use macrocyclic ligands with mixed nitro-
gen-sulfur donor sets to improve their metal-ion selectivity.
Consequently, a large number of N,S-based macrocycles
have been reported and their binding properties towards en-
vironmentally important elements have been investi-
gated.[10,11] To the best of our knowledge, the thiophenolate
Scheme 1. Structure of the ligand H2LMe
tadentate N6S2 macrocycle H2LMe. The results of IR and
NMR spectroscopic investigations are also reported.
derivatives[12Ϫ14] of Robson-type macrocycles have not yet Results and Discussion
been tested in this respect. This led us to investigate the
Preparation
ligating properties of the dinucleating hexaaza-thio-
phenolate ligand (LMe 2Ϫ (see Scheme 1)[15,16] towards the
)
The synthesised compounds and their labels are collected
in Scheme 1 with Scheme 2 depicting the synthetic pro-
cedures. The complexation reactions of the free macrocycle
H2LMe·6HCl with CdCl2, Cd(OAc)2, Hg(OAc)2 and
Pb(OAc)2 were all carried out in methanol in the presence
of triethylamine. All reactions proceeded smoothly and pro-
duced clear solutions from which, upon addition of an ex-
cess of LiClO4, the highly crystalline salts [(LMe)Cd2(µ-
Cl)]ClO4 (2·ClO4), [(LMe)Cd2(µ-OAc)]ClO4 (3·ClO4),
[(LMe)Hg2](ClO4)2 (4·ClO4) and [(LMe)Pb2](ClO4)2 (5·ClO4)
precipitated in good to excellent yields. Complex 3 was also
metal ions CdII, HgII and PbII.
Herein we demonstrate that such metal ions can be read-
ily accommodated in the two binding pockets of H2LMe. In
each case we have obtained single crystals suitable for X-
ray structure determinations. It has therefore been possible
to study, in detail, the binding of the metal ions to the oc-
[a]
Institut für Anorganische Chemie, Universität Leipzig
Johannisallee 29, 04103 Leipzig
Fax: (internat.) ϩ 49-341-9736143
E-mail: b.kersting@uni-leipzig.de
504
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200400603
Eur. J. Inorg. Chem. 2005, 504Ϫ512

CdII, HgII and PbII Complexes of a Macrodinucleating Hexaaza-dithiophenolate Ligand
FULL PAPER
accessible from [(LMe)Cd2(µ-Cl)]ClO4 (2·ClO4) and so- stretching modes [νsym(OAcϪ)] of the acetate group, respec-
dium acetate.
tively.[18] These values are very similar to those of the zinc
complex [(LMe)Zn2(µ-OAc)]ϩ (1),[16] indicating that the ace-
tate group in the cadmium complex 3 is also in the µ1,3
-
bridging mode. The IR spectra of complexes 4 and 5 lack
these two bands which is in good agreement with the pres-
ence of unligated [(LMe)M2]2ϩ dications. The IR spectra of
4 and 5 were otherwise not very informative with regards
to the compositions and structures of the complexes.
NMR Spectroscopy
All of the new complexes were further characterised by
1H and 13C NMR spectroscopy. Table 1 lists selected NMR
spectroscopic data for complexes 2Ϫ5. The data for com-
plex 1 have been reported previously and are included for
Scheme 2. Synthesis of complexes and their labels; the complexes
Ϫ
Ϫ
were either isolated as ClO4 or BPh4 salts
1
The new compounds are colourless to pale-yellow solids
and dissolve readily in polar protic solvents such as meth-
anol or ethanol. With the exception of complex 2, which
fixes carbon dioxide from air to give the methyl carbonate
complex [(LMe)Cd2(µ-O2COMe)]ϩ, all compounds are
stable in air both in solution and in the solid state. All com-
pounds gave satisfactory elemental analyses and were
characterised by spectroscopic methods (IR, 1H and 13C
NMR spectroscopy) and X-ray crystallography.
comparative purposes. As can be seen, the H NMR spec-
troscopic data of the acetato-bridged complexes 1 and 3 are
very similar. Both complexes display only one set of signals,
indicating that both exist as single isomers in solution. Fur-
thermore, the four aromatic protons (ArH), the methyl pro-
tons on the benzylic nitrogens (NBzCH3), the methyl pro-
tons on the central amine nitrogen of the linking diethylene
triamine units (NCH3) and the tert-butyl protons [C(CH3)3]
appear as singlets, indicative of C2v symmetry for the
[(LMe)M2(µ-OAc)]ϩ cations in solution. This is further sup-
ported by the fact that the [(LMe)M2]2ϩ fragments give rise
to only eleven 13C signals (7 for the aliphatic and 4 for the
aromatic carbon atoms). Of note is the appearance of the
Spectroscopic Characterisation
Infrared Spectroscopy
The infrared spectra of all compounds are dominated by 1H NMR signals for the methyl protons of the acetato co-
the absorptions of the [(LMe)M2]2ϩ fragments and the coun- ligands in 1 and 3 at δ ϭ 0.85 and δ ϭ 0.98 ppm, respec-
terions (ClO4 or BPh4Ϫ).[17] The IR spectrum of 3·ClO4 tively. The signals are shifted considerably to high-field
Ϫ
shows two bands at 1577 and 1422 cmϪ1 which can be as- compared with the value recorded for free sodium acetate
signed to the asymmetric [νasym(OAcϪ)] and symmetric in the same solvent (δ ϭ 1.83 ppm). This provides strong
1
Table 1. Selected H and 13C NMR spectroscopic data for complexes 1Ϫ5
1[a][b]
7.13 s
2[a]
7.20 s
3[a]
7.12 s
4[a]
5[a]
ArH
7.36 d, 7.31 d
7.27 d, 7.26 d
2.80 s, 2.57 s
2.42 s, 2.33 s
2.31 s, 2.24 s
1.23 s, 1.19 s
Ϫ
151.3, 149.9
137.5, 137.4
136.9, 136.7
135.3, 134.1
133.9, 133.7
133.6, 132.6
66.8, 64.5, 63.3
62.9, 62.0, 60.0
58.6, 57.3, 55.6
54.9, 52.0, 51.3
49.7, 49.3, 46.4
46.3, 46.2, 44.9
35.2, 35.1
7.69 d
7.45 d
3.33 s
NCH3
2.92 s
2.84 s
2.84 s
NBzCH3
tBu
2.48 s
1.28 s
0.85 s
2.33 s
1.26 s
Ϫ
2.36 s
1.23 s
0.98 s
2.40 s, 2.27 s
1.36 s
OAc
Ϫ
Carom.
145.7
147.1
146.4
151.2
139.9
139.1
138.7
131.4
130.8
64.3, 63.2
60.5, 59.7
57.1, 56.7
142.5
136.8
134.3
141.8
135.8
131.0
141.5
136.1
130.5
CH2
64.2
59.2
57.9
63.8
60.8
58.0
63.0
60.4
57.9
NCH3
49.8
46.7
34.4
31.8
50.1
46.0
34.7
31.6
50.3
46.7
34.7
31.6
48.1, 43.8, 39.9
C(CH3)3
C(CH3)3
35.1
31.8
31.4, 31.3
[a]
All spectra were recorded in CD3CN at ambient temperature. [b] 13C NMR spectroscopic data recorded for the BPh4 salt in CDCl3.
Ϫ
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505

V. Lozan, B. Kersting
FULL PAPER
evidence that the coordinated acetate groups sense the ring-
The lead complex 5 displays only half as many 13C NMR
currents of the two flanking phenyl rings of (LMe 2Ϫ
) . As signals as 4 but the total number of 17 resonances is still
can be seen from Figure 2 (see below), the methyl protons larger than the 11 resonances observed for 3, indicating
of the acetate groups are positioned in the binding cavity symmetry higher than C1 but lower than C2v. The 1H NMR
of the [(LMe)M2]2ϩ fragment slightly above the centre of spectroscopic data suggest that it is C2 symmetry which was
the two phenyl rings in the shielded region. Since the angle observed in the solid state. The higher symmetry of 5 (rela-
between the phenyl rings in the zinc complex 1 (80.0°)[16] is tive to 4) is easily detectable in the identical configurations
much smaller than in the cadmium complex 3 (94.4°), the for the four benzylic amine nitrogen donors in the two op-
distance of the methyl protons to the centre of the phenyl posing diethylene triamine units [e.g. (S)-N(1), (S)-N(3),
rings is smaller in the former and hence the shielding effect (S)-N(4), and (S)-N(6), see Figure 4, below]. In summary,
is more pronounced in this compound. These spectroscopic the NMR spectroscopic investigations have clearly estab-
findings thus clearly show that the coligands in 1 and 3 lished that all complexes exist as discrete and stable species
remain attached to the metal ions in solution with retention in solution.
of their solid-state structures.
The 1H NMR spectroscopic data of the dicadmium com-
plex 2 are very similar to those of 3. Again, the ArH,
NBzCH3, NCH3 and C(CH3)3 protons all appear as well-
resolved singlets. Likewise, there are only eleven signals in
the 13C spectrum. On the basis of these data, one can also
conclude the existence of C2v symmetry in the [(LMe)Cd2(µ-
Cl)]ϩ cation. The most striking feature in the 1H NMR
spectrum of 2·ClO4 is the rare observation of satellites for
the ArCH2N and the NBzCH3 protons that presumably
X-ray Crystallography
Further confirmation regarding the composition and
structures of the complexes was provided by X-ray diffrac-
tion studies. Single crystals of X-ray quality were obtained
for the tetraphenylborate salts of 2Ϫ4 and for the diper-
chlorate salt of 5. The molecular structures of the com-
plexes are displayed in Figures 1Ϫ4 and selected bond
lengths and angles are given in Tables 2 and 3.
arise
from
three-bond
1HϪ111,113Cd
couplings
[3J(111,113CdϪ1H) ϭ 4.6 Hz and 4.0 Hz, respectively].[19]
This reflects kinetic inertness of the complex cation in solu-
tion as well as a degree of covalency in the CdϪligand
bonds. Similar findings have been observed for other cad-
mium complexes of macrocyclic ligands.[10,20]
The 13C NMR spectroscopic data of the mercury com-
plex 4 differ significantly from those of the compounds
above and, as we will show below, this complex exhibits C1
symmetry in the solid state. This symmetry arises because
of different configurations for the two chiral amine donors
in the two opposing diethylene triamine units [e.g. (R)-N(1),
(R)-N(3) vs. (S)-N(4), (R)-N(6), see Figure 3 below]. This
in turn renders all carbon atoms of the present complex
chemically inequivalent and, given that its solid-state struc-
ture is maintained in solution, a total of 34[21] resonances
(12 aromatic C atoms, 4 benzylic C atoms, 8 ethylene C
atoms, 4 tert-butyl C atoms and 6 N-methyl C atoms) are,
in principle, observable. The experiment clearly shows that
this is indeed the case (see Table 1). At 75 MHz, the differ-
ences in the 13C chemical shift values are sufficiently large
for all the expected 34 resonances to be resolved. The 12
aromatic carbon atoms resonate in the region δ ϭ 150Ϫ120
and the 22 aliphatic carbon atoms can be observed between
70 and 30 ppm. The fact that 4 is a C1-symmetric species is
also supported by 1H NMR spectroscopy. In the case of the
benzylic CH2 and the ethylenic CH2 protons the chemical
shift differences are too small for full resolution of all ex-
pected 16 resonances. However, the expected 14 signals for
the four aromatic protons, the four CH3 groups on the
benzylic nitrogen atoms, the two CH3 groups on the central
amine N atoms of the diethylene triamine units and the two
tert-butyl groups are all observable with the correct inten-
sity ratios. It can therefore be concluded that 4 maintains
its solid-state structure in solution.
Figure 1. Molecular structure of the cation 2; thermal ellipsoids
are drawn at the 50% probability level; hydrogen atoms are omitted
for clarity
Figure 2. Molecular structure of the cation 3; thermal ellipsoids
are drawn at the 30% probability level; hydrogen atoms are omitted
for clarity
506
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 504Ϫ512

CdII, HgII and PbII Complexes of a Macrodinucleating Hexaaza-dithiophenolate Ligand
FULL PAPER
ence of the latter for adopting the ‘‘partial cone’’ confor-
mation is presumably due to the smaller ionic radii of these
II
II
II
˚
˚
˚
metal ions (Co : 0.885 A, Ni : 0.83 A, Zn : 0.88 A vs. 1.06
II [23]
˚
A for Cd ) and presumably also due to the rigid nature
of the 24-membered macrocycle.
[(LMe)Cd2(µ-OAc)]BPh4·2MeCN·MeOH
(3·BPh4·2MeCN·MeOH)
The crystal structure determination of the title com-
pound showed the structure of the dinuclear [(LMe)Cd2(µ-
OAc)]ϩ complex to be isostructural with the zinc complex
[(LMe)Zn2(µ-OAc)]ϩ (1).[16] The hexaaza-dithiophenolate li-
gand assumes a bowl-shaped ‘‘calixarene-like’’ confor-
mation which is typical for carboxylato-bridged complexes
of this ligand.[24] The acetate ion bridges the two cadmium
Figure 3. Molecular structure of the dication 4; thermal ellipsoids
are drawn at the 30% probability level; hydrogen atoms are omitted
for clarity
˚
ions in a symmetrical fashion [O(1)ϪC(39) 1.222(4) A,
˚
O(2)ϪC(39) 1.232(4) A] with a Cd···Cd distance of 3.402(2)
˚
A. It is deeply buried in the binding cavity of the
[(LMe)Cd2]2ϩ fragment. As a consequence, its methyl pro-
tons are positioned above the centre of the two phenyl rings
in the shielding region. The angle between the planes
through the two phenyl rings of 94.4° is larger than in 1
(80.0°). This explains why the acetate protons in 1 experi-
ence a larger high-field shift compared with those in 3 (vide
˚
supra). The average CdϪN bond length of 2.439 A is nor-
mal for six-coordinate cadmium complexes with amine do-
nor ligands.[25,26] The same holds for the average CdϪS dis-
˚
tance of 2.669 A and the average CdϪO distance of 2.238
A.[27,28] As expected, the metal-ligand bond lengths in 3 are
˚
˚
larger than those in 1. The mean difference of 0.13 A is
Figure 4. Molecular structure of the dication 5; thermal ellipsoids
are drawn at the 50% probability level; hydrogen atoms are omitted
for clarity
close to the difference between the ionic radii of the two ele-
ments.
[(LMe)Hg2](BPh4)2·MeCN [4·(BPh4)2·MeCN]
Description of the Crystal Structures
[(LMe)Cd2(µ-Cl)]BPh4·1.5MeOH (2·BPh4·1.5MeOH)
The crystal structure determination of 4·(BPh4)2·MeCN
¯
This salt crystallises in the triclinic space group P1. The unambiguously confirmed the identity of the dimercury(ii)
structure revealed the presence of discrete dinuclear complex 4. Its molecular structure is illustrated in Figure 3.
[(LMe)Cd2(µ-Cl)]ϩ cations, tetraphenylborate anions and The [(LMe)Hg2]2ϩ dication bears no additional coligands
methanol solvate molecules. The dicadmium complex exhi- and has an intramolecular Hg···Hg separation of 3.725(1)
bits idealized C2v symmetry as was established by NMR A. The HgII ions are surrounded by three nitrogen and two
˚
spectroscopy. As can be seen in Figure 1, the cadmium(ii) sulfur donor atoms from (LMe 2Ϫ
in highly irregular N3S2
)
ions are coordinated in a distorted octahedral fashion by coordination environments (coordination number of HgII:
three facially oriented nitrogen atoms, two bridging thio- 4 ϩ 1). The intramolecular separations Hg(1)···S(1) of
˚
˚
phenolate sulfur atoms and a bridging halide ion. The mini- 2.897(2) A and Hg(2)···S(2) of 3.313(2) A are much longer
˚
mum and maximum deviations from the ideal 90° and 180° than the other two HgϪS distances of 2.383 and 2.395 A,
bond angles of a perfect octahedron are Ϫ14.8° for indicating that the latter exhibit more covalent character
N(1)ϪCd(1)ϪN(2) and Ϫ10.4° for ClϪCd(2)ϪN(5), while the former are more electrostatic in nature. The dieth-
respectively. The mean cadmiumϪligand bond lengths ylene triamine units are facially coordinated with one large
˚
˚
˚
(CdϪN 2.421 A, CdϪS 2.677 A, CdϪCl 2.703 A) show no and two smaller NϪHgϪN bond angles, this being the
unusual features and compare well with those in 3 (see be- most commonly observed situation in complexes with this
low) and related complexes with mixed N and S lig- tridentate unit.[29] The HgϪN bond lengths (mean value:
ation.[20,22] It is also worth mentioning that the macrocycle 2.413 A) are somewhat longer in comparison with the more
˚
in 2 adopts the ‘‘conical’’ calixarene-like conformation covalent HgϪS bonds but are similar to those in related
which differs from the alternative ‘‘partial cone’’ confor- mercury complexes.[30,31] In [Hg(en)2](ClO4)2 for example
mation seen in the related complexes [(LMe)M2(µ-Cl)]ϩ of (en ϭ ethylene diamine), an average HgϪN distance of 2.32
the lighter 3d elements CoII, NiII and ZnII.[15,24] The prefer- A has been reported.
[32]
˚
Eur. J. Inorg. Chem. 2005, 504Ϫ512
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507

V. Lozan, B. Kersting
Table 2. Selected bond lengths [A] and angles [°] in the cations [(LMe)Zn2(OAc)]ϩ (1), [(LMe)Cd2(Cl)]ϩ (2), [(LMe)Cd2(OAc)]ϩ (3)
FULL PAPER
˚
1
2
3
M ϭ Zn, X ϭ Y ϭ O
M ϭ Cd, X ϭ Y ϭ Cl
M ϭ Cd, X ϭ Y ϭ O
M(1)ϪX
2.026(2)
2.379(2)
2.202(2)
2.316(2)
2.551(1)
2.515(1)
2.027(2)
2.314(2)
2.219(2)
2.388(2)
2.572(1)
2.508(1)
2.303
2.682(1)
2.453(3)
2.424(3)
2.410(4)
2.653(1)
2.699(2)
2.723(1)
2.441(3)
2.388(3)
2.409(3)
2.696(1)
2.659(1)
2.421
2.245(2)
2.474(3)
2.436(3)
2.408(3)
2.654(1)
2.677(1)
2.230(2)
2.467(3)
2.411(3)
2.442(3)
2.698(1)
2.645(1)
2.439
M(1)ϪN(1)
M(1)ϪN(2)
M(1)ϪN(3)
M(1)ϪS(1)
M(1)ϪS(2)
M(2)ϪY
M(2)ϪN(4)
M(2)ϪN(5)
M(2)ϪN(6)
M(2)ϪS(1)
M(2)ϪS(2)
MϪN[a]
MϪX[a]
2.027
2.536
2.703
2.677
2.238
2.669
MϪS[a]
M(1)ϪS(1)ϪM(2)
M(1)ϪS(2)ϪM(2)
M(1)ϪµClϪM(2)
N(1)ϪM(1)ϪN(2)
N(1)ϪM(1)ϪN(3)
N(2)ϪM(1)ϪN(3)
N(4)ϪM(2)ϪN(5)
N(4)ϪM(2)ϪN(6)
N(5)ϪM(2)ϪN(6)
C(4)···C(20)
Ph/Ph[b]
84.00(4)
86.05(3)
Ϫ
78.92(8)
98.84(7)
80.98(9)
80.23(7)
99.00(7)
79.05(7)
9.404
77.78(4)
77.63(4)
76.83(4)
75.17(11)
99.40(12)
76.48(12)
75.97(12)
99.77(12)
76.83(12)
9.824
78.92(4)
79.46(4)
Ϫ
75.22(9)
101.87(9)
75.99(9)
75.84(10)
103.53(10)
76.31(9)
10.247
80.0
3.427(1)
83.7
3.358(1)
94.4
3.402(2)
M···M
[a]
[b]
Average values. Angle between the normals of the planes of the two aryl rings.
Table 3. Selected bond lengths [A] and angles [°] in [(LMe)Hg2]2ϩ
(4) and [(LMe)Pb2]2ϩ (5)
˚
interactions [i.e. Hg(2)···S(2), Hg(2)···S(1)] are, at least in
part, a consequence of these different N configurations.
They are also responsible for the C1 symmetry of the
[(LMe)Hg2]2ϩ dication.
4
5
Hg(1)···S(1)
Hg(1)ϪS(2)
Hg(1)ϪN(1)
Hg(1)ϪN(2)
Hg(1)ϪN(3)
Hg(2)ϪS(1)
Hg(2)···S(2)
Hg(2)ϪN(4)
Hg(2)ϪN(5)
Hg(2)ϪN(6)
Hg(1)···Hg(2)
HgϪN[a]
2.897(2) Pb(1)···S(1)
2.383(2) Pb(1)ϪS(2)
2.276(5) Pb(1)ϪN(1)
2.566(5) Pb(1)ϪN(2)
2.449(5) Pb(1)ϪN(3)
2.395(2) Pb(2)ϪS(1)
3.313(2) Pb(2)···S(2)
2.269(5) Pb(2)ϪN(4)
2.401(5) Pb(2)ϪN(5)
2.517(5) Pb(2)ϪN(6)
3.725(1) Pb(1)···Pb(2)
3.465(3)
2.640(3)
2.584(10)
2.427(9)
2.552(10)
2.554(3)
3.824(3)
2.591(10)
2.403(8)
2.600(9)
3.4192(8)
2.526
[(LMe)Pb2](ClO4)2·MeCN [5·(ClO4)2·MeCN]
This structure contains discrete [(LMe)Pb2]2ϩ cations, per-
chlorate anions and acetonitrile solvate molecules. Figure 4
shows the structure of the cation 5 together with the atomic
numbering scheme. Similar to 4, the dication is not bound
to any further coligands. Complex 5 exhibits no crystallo-
graphically imposed symmetry but has idealized C2 sym-
metry. The coordination environment of each lead(ii) ion
consists of three tertiary amine donors and one thio-
phenolate sulfur atom. The coordination geometry is best
considered as distorted square pyramidal, with the lead ion
2.413
2.389
PbϪN[a]
HgϪS[a]
PbϪS[a]
2.597
71.0(3)
N(1)ϪHg(1)ϪN(2)
N(1)ϪHg(1)ϪN(3) 108.91(19) N(1)ϪPb(1)ϪN(3) 137.0(3)
N(2)ϪHg(1)ϪN(3)
N(4)ϪHg(2)ϪN(5)
N(4)ϪHg(2)ϪN(6) 108.81(18) N(4)ϪPb(2)ϪN(6) 139.3(3)
76.17(18) N(1)ϪPb(1)ϪN(2)
˚
73.24(17) N(2)ϪPb(1)ϪN(3)
78.36(18) N(4)ϪPb(2)ϪN(5)
74.1(3)
73.8(3)
sitting ca 1.3 A above the plane formed from the four donor
atoms [mean deviation from the planes N(1)N(2)N(3)S(2):
˚
˚
0.32 A, N(4)N(5)N(6)S(1): 0.31 A]. The empty space above
the lead(ii) ion on the apex of the pyramid is indicative of
a stereochemically active lone pair as in PbO (yellow modi-
fication).[33] In contrast to the dimercury complex 4, the
N(5)ϪHg(2)ϪN(6)
73.83(18) N(5)ϪPb(2)ϪN(6)
74.5(3)
[a]
Average values.
It should be noted that the configurations of the benzylic diethylene triamine units bind in a meridional fashion
nitrogen atoms in the opposing diethylene triamine are dif- which results in larger N(1)ϪPb(1)ϪN(3) [137.0(3)°] and
ferent. Thus, the configurations are (R)-N(1) and (R)-N(3) N(4)ϪPb(2)ϪN(6) [139.3(3)°] angles. This has also been
for one diethylene linker, whereas they are (S)-N(4) and (R)- observed in lead complexes of macrodinucleating polyaza-
N(6) for the other. The differences in the secondary Hg···S phenolate ligands.[34] The average PbϪN bond length of
508
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 504Ϫ512

CdII, HgII and PbII Complexes of a Macrodinucleating Hexaaza-dithiophenolate Ligand
[35,36]
FULL PAPER
˚
(all CH2), 50.1, 46.0 (all NCH3), 34.7 [C(CH3)3], 31.6 [C(CH3)3]
ppm. C38H64Cd2Cl2N6O4S2 (1028.81): calcd. C 44.36, H 6.27, N
8.17, S 6.23; found C 43.92, H 6.12, N 8.00, S 5.77. The tetraphe-
nylborate salt, [(LMe)Cd2(µ-Cl)]BPh4 (2·BPh4), was prepared by ad-
ding a solution of NaBPh4 (198 mg, 0.580 mmol) in methanol
(3 mL) to an argon-purged solution of 1·ClO4 (103 mg,
0.100 mmol) in methanol (50 mL). The resultant colourless precipi-
tate was isolated by filtration, washed with 5 mL of cold methanol
and dried in air. Yield 112 mg (90%). M.p. 293Ϫ294 °C (decomp.).
IR (KBr pellet): ν˜ ϭ 3053 m, 3032 w, 2996 w, 2964 s, 2925 w, 2900
w, 2862 m, 2835 w, 2807 w, 1477 m, 1457 s, 1425 m, 1394 m, 1365
m, 1352 w, 1313 m, 1290 m, 1267 m, 1232 m, 1203 w, 1181 w, 1170
w, 1157 m, 1131 w, 1114 w, 1083 s, 1044 s, 1011 w, 1000 w, 981 w,
927 w, 910 m, 887 m, 844 m, 815 m, 802 m, 734 s, 705 s [ν(BPh4Ϫ)],
625 m, 612 m, 555 w, 475 w cmϪ1. The tetraphenylborate salt was
additionally characterised by X-ray crystallography.
2.526 A is normal for lead(ii) complexes.
The same is
true for the PbϪS distances.
Conclusion
The main findings of the present work can be summar-
ised as follows: a) The 24-membered hexaaza-dithio-
phenolate macrocycle H2LMe supports the formation of di-
nuclear complexes of CdII, HgII and PbII. b) The complexes
dissolve in organic solvents without decomposition. c) The
dicadmium complexes [(LMe)M2(µ-LЈ)] differ from the Hg
and Pb complexes in that they bind additional coligands.
This offers the opportunity to selectively recognise or separ-
ate Cd from a mixture of the three elements. d) The struc-
tures of [(LMe)Hg2]2ϩ and [(LMe)Pb2]2ϩ have clarified the
binding preferences of the two toxic heavy metal ions
towards the donors of H2LMe. This can now be used as a
guide for fine-tuning the ligand to achieve high metal-ion
selectivity. Current studies in this laboratory are focusing
on the determination of the complex stability constants and
on methods of metal-ion extraction.
[(LMe)Cd2(µ-OAc)]ClO4 (3·ClO4): To a solution of 2·ClO4 (103 mg,
0.100 mmol) in methanol (50 mL) was added a solution of sodium
acetate (12.3 mg, 0.150 mmol) in methanol (5 mL). After the reac-
tion mixture had been stirred for 3 h, a solution of LiClO4·3H2O
(802 mg, 5.00 mmol) in methanol (2 mL) was added. The resultant
colourless microcrystalline solid was isolated by filtration, washed
with methanol and dried in air. Yield 91 mg (86%). M.p. 352Ϫ353
°C (decomp.). IR (KBr, pellet): ν˜ ϭ 2960 s, 2900 m, 2865 s, 2837
sh, 2806 m, 1577 s [νas(OAcϪ)], 1456 s, 1422 s [νs(OAcϪ)], 1396 w,
1365 m, 1314 w, 1293 m, 1267 m, 1230 m, 1203 m, 1170 w, 1155
w, 1093 vs. [ν(ClO4Ϫ)], 1044 s, 1012 w, 1000 w, 981 w, 925 w, 911
m, 884 m, 816 s, 802 m, 744 m, 684 w, 654 m, 624 s, 596 w, 555 w,
Experimental Section
General: Unless otherwise noted, the preparations of the metal
complexes were carried out under argon using standard Schlenk
techniques. The compound H2LMe·6HCl was prepared as described
in the literature.[15,37] All other compounds and reagents were pur-
chased. Melting points were determined in capillaries and are un-
1
535 w cmϪ1. H NMR (200 MHz, [D3]CH3CN, 25 °C, TMS): δ ϭ
2
7.12 (s, 4 H, ArH), 4.54 (d, J ϭ 11.5 Hz, 4 H, ArCH2), 3.40 (m,
4 H, CH2), 3.18 (m, 4 H, CH2), 2.84 (s, 6 H, NCH3), 2.82 (m, 4
H, CH2), 2.74 (d, 4 H, ArCH2), 2.48 (m, 4 H, CH2), 2.36 (s, 12 H,
NCH3), 1.23 (s, 18 H, CH3), 0.98 (s, 3 H, O2CCH3) ppm. 13C NMR
(75.42 MHz, [D3]CH3CN, 25 °C, TMS): δ ϭ 176.3 (OAc), 146.4,
141.5, 136.1, 130.5, 63.0 (CH2), 60.4 (CH2), 57.9 (CH2), 50.3
(NCH3), 46.7 (NCH3), 34.7 (C), 31.6 [C(CH3)3], 23.2 (OAc) ppm.
The tetraphenylborate salt, [(LMe)Cd2(µ-OAc)]BPh4 (3·BPh4), was
prepared by adding NaBPh4 (342 mg, 1.00 mmol) to a solution of
3·ClO4 (103 mg, 0.100 mmol) in methanol (50 mL). The resultant
colourless solid was recrystallised from a mixed acetonitrile/meth-
anol (1:1) solvent system. Yield 116 mg (91%). M.p. 304Ϫ305 °C
(decomp.). IR (KBr pellet): ν˜ ϭ 3055 m, 3034 m, 2908 sh, 2963 s,
2924 m, 2899 m, 2866 m, 2836 m, 2804 w, 1576 s [νasym(OAcϪ)],
1476 w, 1455 s, 1425 s [νsym(OAcϪ)], 1395 w, 1364 w, 1353 w, 1313
w, 1291 w, 1267 w, 1230 w, 1203 w, 1181 w, 1170 w, 1155 m, 1133
w, 1116 w, 1082 s, 1045 s, 1012 w, 996 w, 981 w, 924 m, 911 m, 886
m, 842w, 815 s, 800 m, 744 m, 734 s, 704 s [ν(BPh4Ϫ)], 653 w, 625
m, 612 m, 594 w, 556 w cmϪ1. C64H87BCd2N6O2S2 (1272.18): calcd.
C 60.42, H 6.89, N 6.61, S 5.04; found C 60.24, H 6.72, N 6.47, S
4.94. This salt was additionally characterised by X-ray crystallogra-
phy.
1
corrected. H and 13C NMR spectra were recorded with a Bruker
AVANCE DPX-200 or a Varian 300 unity spectrometer. Elemental
analyses were performed with a Vario EL analyser (Elementarana-
lysensysteme GmbH). IR spectra were recorded with a Bruker
VECTOR 22 FT-IR spectrometer as KBr pellets.
Safety Note: Caution; perchlorate salts of transition metal complexes
are hazardous and may explode; only small quantities should be pre-
pared and great care should be taken!
[(LMe)Cd2(µ-Cl)]ClO4 (2·ClO4): To a suspension of H2LMe·6HCl
(890 mg, 1.00 mmol) in methanol (40 mL) was added solid
CdCl2·H2O (403 mg, 2.00 mmol). A solution of triethylamine
(808 mg, 8.00 mmol) in methanol (2 mL) was then added to give a
colourless solution. After stirring at room temperature for 3 h, solid
LiClO4·3H2O (2.50 g, 15.6 mmol) was added to give the perchlorate
salt 2·ClO4 as a white microcrystalline solid. This material was fil-
tered, washed with cold ethanol (5 mL) and diethyl ether (5 mL),
and dried in vacuo. Yield 876 mg (85%). M.p. 302Ϫ303 °C (decom-
poses without melting). IR (KBr pellet): ν˜ ϭ 3446 s br, 2958 s, 2865
s, 1630 m, 1457 s, 1394 w, 1365 m, 1314 m, 1291 m, 1267 m, 1234 [(LMe)Hg2](ClO4)2 [4·(ClO4)2]: To a suspension of H2LMe·6HCl
m, 1203 w, 1168 w, 1158 w, 1100 vs. [ν(ClO4)], 1046 s, 1012 w, 1000
(890 mg, 1.00 mmol) in methanol (40 mL) was added a solution
of Hg(CH3COO)2 (637 mg, 2.00 mmol) in methanol (10 mL). A
w, 978 m, 928 m, 910 m, 887 m, 815 s, 802 m, 746 m, 686 w, 664
w, 624 s, 593 w, 555 w, 484 w cmϪ1. 1H NMR (300 MHz, CD3CN, solution of triethylamine (808 mg, 8.00 mmol) in methanol (5 mL)
25 °C, TMS): δ ϭ 7.20 (s, 4 H, ArH), 4.70 [d, 2J ϭ 11.5,
was then added to give a colourless solution. The reaction mixture
3J(111,113Cd-1H) ϭ 4.6 Hz, 4 H, ArCH2], 3.42 (m, 4 H, NCH2), 3.24 was stirred for 12 h after which time a solution of LiClO4·3H2O
(m, 4 H, NCH2), 2.88Ϫ2.78 (m, 4 H ϩ4 H, NCH2ϩArCH2), 2.84 (802 mg, 5.00 mmol) in methanol (2 mL) was added. The resultant
3
(s, 6 H, NCH3), 2.50 (m, 4 H, NCH2), 2.33 [s, J(111,113Cd-1H) ϭ
colourless microcrystalline solid was isolated by filtration, washed
4.6 Hz, 12 H, BzNCH3], 1.26 [s, 18 H, C(CH3)3] ppm. 13C{1H} with methanol and dried in air. Yield 901 mg (71%). M.p. 246Ϫ247
NMR (75.42 MHz, [D3]CH3CN, 25 °C, TMS): δ ϭ 147.1, 141.8,
135.8 (CH), 131.0 (CH) (aromatic carbon atoms), 63.8, 60.8, 58.0
°C (decomp). IR (KBr pellet): ν˜ ϭ 2958 s, 2902 w, 2864 s, 1463 m,
1394 w, 1366 m, 1307 w, 1290 w, 1266 w, 1231 m, 1202 w, 1183 w,
Eur. J. Inorg. Chem. 2005, 504Ϫ512
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
509

V. Lozan, B. Kersting
FULL PAPER
1143 m, 1119 s, 1107 s, 1088 s [ν(ClO4Ϫ)], 1045 w, 1022 w, 1010 w,
was then added to give a pale yellow solution. After stirring for
991 w, 960 w, 948 w, 927 w, 910 m, 901 m, 889 m, 810 m, 796 m, 12 h, a solution of LiClO4·3H2O (802 mg, 5.00 mmol) in methanol
782 w, 753 w, 742 w, 685 w, 630 m, 624 s. 1H NMR (300 MHz, (5 mL) was added. The resultant pale-yellow precipitate was iso-
4
[D3]CH3CN, 25 °C, TMS): δ ϭ 7.36 (d, J ϭ 2.3 Hz, 1 H, ArH), lated by filtration, washed with methanol and dried in air. Yield
4
4
7.31 (d, J ϭ 2.3 Hz, 1 H, ArH), 7.27 (d, J ϭ 2.3 Hz, 1 H, ArH), 1.03 g (80%). M.p. 346Ϫ347 °C (decomp.). IR (KBr pellet): ν˜ ϭ
7.26 (d, 4J ϭ 2.3 Hz, 1 H, ArH), 4.91 (d, 2J ϭ 12.0 Hz, 1 H,
ArCH2), 4.74 (d, 2J ϭ 12.0 Hz, 1 H, ArCH2), 4.26 (d, 2J ϭ 12.0 Hz, 1296 w, 1259 w, 1228 w, 1203 w, 1175 w, 1144 m, 1107 sh, 1091 vs
2955 s, 2901 m, 2862 s, 2810 m, 1459 m, 1396 w, 1364 m, 1304 w,
2
2
1 H, ArCH2), 4.20 (d, J ϭ 12.0 Hz, 1 H, ArCH2), 3.71 (d, J ϭ [ν(ClO4Ϫ)], 1045 w, 1000 w, 958 w, 927 w, 918 w, 888 w, 811 m, 797
2
1
12.0 Hz, 1 H, ArCH2), 3.44 (d, J ϭ 12.0 Hz, 1 H, ArCH2), 3.38
m, 759 m, 625 s, 460 w cmϪ1. H NMR (300 MHz, [D3]CH3CN,
(d, 2J ϭ 12.0 Hz, 1 H, ArCH2), 3.25Ϫ2.50 (m, 1 H ϩ16 H, ArCH2 25 °C, TMS): δ ϭ 7.69 (d, J ϭ 2.2 Hz, 2 H, ArH), 7.45 (d, J ϭ
4
4
2
ϩ NCH2CH2N), 2.80 (s, 3 H, NCH3), 2.57 (s, 3 H, NCH3), 2.42 2.2 Hz, 2 H, ArH), 4.92 (d, J ϭ 13.2 Hz, 2 H, ArCH2), 4.59 (d,
2
(s, 3 H, NCH3) 2.33 (s, 3 H, NCH3) 2.31 (s, 3 H, NCH3) 2.24 (s, 3
2J ϭ 11.7 Hz, 2 H, ArCH2), 4.29 (d, J ϭ 13.2 Hz, 2 H, ArCH2),
H, NCH3), 1.23 (s, 9 H, CH3), 1.19 (s, 9 H, CH3) ppm. 13C{1H} 3.88 (d, J ϭ 11.6 Hz, 2 H, ArCH2), 3.86Ϫ2.92 (m, 16 H, NCH2),
2
NMR (75.42 MHz, [D3]CH3CN, 25 °C, TMS): δ ϭ 151.3, 149.9, 3.33 (s, 6 H, NCH3), 2.40 (s, 6 H, NCH3), 2.27 (s, 6 H, NCH3),
137.5, 137.4, 136.9, 136.7, 135.3, 134.1, 133.9, 133.7, 133.6, 132.6
(aromatic carbon atoms), 66.8, 64.5, 63.3, 62.9, 62.0, 60.0, 58.6,
1.36 [s, 18 H, C(CH3)3] ppm. 13C{1H} NMR (75.42 MHz,
[D3]CH3CN, 25 °C, TMS): δ ϭ 151.2, 139.9, 139.1, 138.7, 131.4,
57.3, 55.6, 54.9, 52.0, 51.3 (all CH2), 49.7, 49.3, 46.4, 46.3, 46.2, 130.8 (aromatic carbon atoms), 64.3, 63.2, 60.5, 59.7, 57.1, 56.7 (all
44.9 (all NCH3), 35.2, 35.1 [C(CH3)3], 31.4, 31.3 [C(CH3)3] ppm. CH2), 48.1, 43.8, 39.9 (all NCH3), 35.1 [C(CH3)3], 31.8 [C(CH3)3]
The tetraphenylborate salt, [(LMe)Hg2](BPh4)2 [4·(BPh4)2], was pre-
ppm. C38H64Cl2N6O8Pb2S2 (1282.39): calcd. C 35.59, H 5.03, N
pared by adding a solution of NaBPh4 (342 mg, 1.00 mmol) in 6.55, S 5.00; found C 35.49, H 5.21, N 6.33, S 4.69.
methanol (3 mL) to a solution of [(LMe)Hg2](ClO4)2 (127 mg,
0.100 mmol) in methanol (50 mL). The resultant colourless solid
was isolated by filtration, washed with 5 mL of cold methanol, and
Crystal Structure Determinations: Single-crystals suitable for X-ray
structural analyses were grown by recrystallisation from
methanol (2·BPh4·1.5MeOH), acetonitrile [4·(BPh4)2·MeCN,
5
dried in air. Yield 150 mg (88%). M.p. 170Ϫ171 °C (decomp.). IR
(KBr pellet): ν˜ ϭ 3054 s, 3034 s, 2997 m, 2982 m, 2961 s, 2927 w,
2903 w, 2864 m, 2808 w, 1579 w, 1559 w, 1476 m, 1460 s, 1439 sh,
1425 m, 1396 m, 1375 w, 1364 m, 1351 w, 1307 w, 1285 w, 1265 m,
1229 m, 1202 w, 1183 w, 1157 m, 1133 m, 1111 w, 1087 m, 1063
m, 1042 m, 1032 m, 1009 vw, 992 w, 961 vw, 951 vw, 911 m, 890
m, 845 m, 810 m, 797 w, 784 w, 749 sh, 735 s, 706 s [ν(BPh4)], 625
(ClO4)2·MeCN] or a mixed acetonitrile/methanol solvent system (3
BPh4·2MeCN·MeOH). The crystals were mounted on glass fibres
using perfluoropolyether oil. Intensity data were collected at 210(2)
K using a Bruker SMART CCD diffractometer. Graphite-mono-
˚
chromated Mo-Kα radiation (λ ϭ 0.71073 A) was used throughout.
The data were processed with SAINT and corrected for absorption
using SADABS[38] (transmission factors: 1.00Ϫ0.95 for 2·BPh4,
1.00Ϫ0.85 for 3·BPh4, 1.00Ϫ0.64 for 4·(BPh4)2 and 1.00Ϫ0.70 for
5·(ClO4)2]. The structures were solved by direct methods using the
program SHELXS-86[39] and refined by full-matrix least-squares
techniques against F2 using SHELXL-97.[40] The SHELXTL ver-
sion 5.10 program package was used for the structure solutions and
m, 613 s cmϪ1
.
[(LMe)Pb2](ClO4)2 [5·(ClO4)2]: To a suspension of H2LMe 6HCl
(890 mg, 1.00 mmol) in methanol (40 mL) was added a solution of
Pb(CH3COO)2·3H2O (759 mg, 2.00 mmol) in methanol (20 mL). A
solution of triethylamine (808 mg, 8.00 mmol) in methanol (5 mL)
Table 4. Crystallographic data for 2·BPh4·1.5MeOH, 3·BPh4·2MeCN·MeOH, 4(BPh4)2MeCN, 5(ClO4)2MeCN
2
3
4
5
Empirical formula
Mr (gmolϪ1
C63.50H90BCd2ClN6O1.50S2
1296.60
P1
C69H97BCd2N8O3S2
1386.28
P1
14.661(3)
16.726(3)
17.348(3)
112.80(3)
110.47(3)
95.46(3)
C88H107B2Hg2N7S2
1749.73
P21/n
15.857(2)
27.246(4)
19.388(3)
90
97.944(3)
90
C40H67Cl2N7O8Pb2S2
1323.41
P21/n
16.333(3)
14.428(3)
22.556(5)
90
94.32(3)
90
)
¯
¯
Space group
˚
a [A]
13.717(3)
16.016(3)
16.650(3)
110.49(3)
91.15(3)
108.21(3)
3220.2(11)
2
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°9
3
˚
V [A ]
3540.6(11)
2
1.300
8296(2)
4
1.401
5300(2)
4
1.658
Z
dcalcd. [gcmϪ3
]
1.337
Crystal size [mm]
0.25 ϫ 0.25 ϫ 0.25
0.811
2.64Ϫ56.64
29690
0.30 ϫ 0.20 ϫ 0.20
0.708
2.74Ϫ57.68
32216
0.20 ϫ 0.20 ϫ 0.20
3.794
2.60Ϫ57.84
51765
0.20 ϫ 0.20 ϫ 0.20
6.575
2.89Ϫ59.66
48229
µ(Mo-Kα) [mmϪ1
2θ limits [°]
]
Measured refl.
Independent refl.
Observed refl.[a]
No. of parameters
R1[b] (R1 all data)
15205
7769
721
0.0400 (0.1021)
0.0760 (0.0913)
0.703, Ϫ0.611
16591
11397
754
0.0364 (0.0645)
0.0915 (0.1039)
0.776, Ϫ0.670
19837
11519
920
0.0460 (0.0916)
0.1126 (0.1251)
5.333; Ϫ1.498
13351
6018
549
0.0537 (0.1628)
0.1263 (0.1628)
1.623; Ϫ1.951
wR2[c](wR2 all data)
-3
˚
Max, min peaks (eA )
[a]
[b]
[c]
2
2 2
2 2
Observation criterion: I Ͼ 2σ(I). R1 ϭ Σ||Fo| Ϫ |Fc||/Σ|Fo|. wR2 ϭ {Σ[w(Fo ϪFc ) ]/Σ[w(Fo ) ]}1/2
.
510
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 504Ϫ512

CdII, HgII and PbII Complexes of a Macrodinucleating Hexaaza-dithiophenolate Ligand
FULL PAPER
[5]
refinements.[41] PLATON was used to search for higher sym-
metry.[42] ORTEP3 was used for generating the ORTEP dia-
grams.[43] Unless otherwise noted, the anisotropic thermal param-
eters of all nonhydrogen atoms were refined. Hydrogen atoms were
included in calculated positions with their bond lengths and ther-
mal parameters 1.2 times (1.5 times for CH3 groups) the thermal
parameter of the atoms to which they are attached. Selected details
of the data collection and refinements are given in Table 4. In the
crystal structure of 2·BPh4·1.5MeOH one tert-butyl group was
found to be disordered over two positions. A split atom model was
applied for the disordered tBu groups. The site occupancies of the
two orientations were refined as 0.67(1)/0.33(1) [for C(36a/c),
C(37a/c), C(38a/c)]. In the crystal structure of 3·BPh4·2MeCN·
MeOH the methanol solvent molecule of crystallisation was found
to be disordered over two positions. The site occupancies of the
two orientations were fixed at half occupancy. The C and O atoms
of this molecule were refined isotropically. In the crystal structure
of 4·(BPh4)2·MeCN, the tert-butyl groups were found to be dis-
ordered over two positions. A split atom model was applied for
these alkyl groups. The site occupancies of the two orientations
were refined as 0.66(3)/0.34(3) [for C(32a/c), C(33a/c), C(34a/c)]
and 0.56(2)/0.44(2) [for C(36a/c), C(37a/c), C(38a/c)]. The non-hy-
drogen atoms of the disordered tBu groups and the acetonitrile
solvate molecule were refined isotropically. No hydrogen atoms
were calculated for these two residues. In the crystal structure of
5·(ClO4)2, the acetonitrile molecule of solvation and one of the two
perchlorate anions were found to be disordered over two positions.
The site occupancy factors of the two orientations of the aceto-
nitrile molecule were fixed at 0.50 and its C and N atoms were
refined isotropically. No hydrogen atoms were calculated for the
MeCN molecule. The site occupancy factors of the two orien-
tations of the perchlorate anion were refined as 0.68(2) and 0.32(2)
for O(5)O(6a)O(7a)O(8a) and O(5)O(6b)O(7b)O(8b). These atoms
could not be refined anisotropically and, for this reason, were
treated as isotropic scatterers. CCDC-243454 (2), -243455 (3),
-243456 (4) and -243457 (5) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; Fax: (internat.) ϩ 44-1223-336-033; E-mail:
deposit@ccdc.cam.ac.uk].
Q. Zeng, M. Qian, S. Gou, H.-K. Fun, C. Duan, X. You, Inorg.
Chim. Acta 1999, 294, 1Ϫ7.
C. G. Rampley, K. L. Ogden, Environ. Sci. Technol. 1998, 32,
987Ϫ993.
K. Abu-Dari, F. E. Hahn, K. N. Raymond, J. Am. Chem. Soc.
1990, 112, 1519Ϫ1524.
M. Di Vaira, F. Mani, P. Stoppioni, Eur. J. Inorg. Chem.
1999, 833Ϫ837.
G. Henkel, B. Krebs, Chem. Rev. 2004, 104, 801Ϫ824.
A. Bashall, M. McPartlin, B. P. Murphy, H. R. Powell, S. Wai-
kar, J. Chem. Soc., Dalton Trans. 1994, 1383Ϫ1390.
E. C. Constable, C. Sacht, G. Palo, D. A. Tocher, M. Truter, J.
Chem. Soc., Dalton Trans. 1993, 1307Ϫ1312.
[6]
[7]
[8]
[9]
[10]
[11]
[12] [12a]
[12b]
S. Brooker, Coord. Chem. Rev. 2001, 222, 33Ϫ56.
S.
Brooker, P. D. Croucher, T. C. Davidson, G. S. Dunbar, C. U.
Beck, S. Subramanian, Eur. J. Inorg. Chem. 2000, 169Ϫ179.
A. J. Atkins, D. Black, A. J. Blake, A. Marin-Becerra, S. Par-
sons, L. Ruiz-Ramirez, M. Schröder, Chem. Commun. 1996,
457Ϫ464.
[13]
[14]
[15]
[16]
B. Kersting, Z. Anorg. Allg. Chem. 2004, 630, 765Ϫ780.
B. Kersting, G. Steinfeld, Chem. Commun. 2001, 1376Ϫ1377.
B. Kersting, Angew. Chem. 2001, 113, 4109Ϫ4112; Angew.
Chem. Int. Ed. 2001, 40, 3987Ϫ3990.
For a complete list of the IR absorptions, see Exp. Sect.
K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 5th ed., VCH-Wiley, New York,
1997.
Similar cadmium satellites are intimated for the ArCH2,
NBzCH3 and NCH3 signals in 3·ClO4, but are not resolved pre-
sumably due to smaller 3J(111,113Cd-1H) couplings. The zinc
complex 1 shows neither satellites nor broadening of these sig-
nals.
M. G. B. Drew, O. W. Howarth, G. G. Morgan, J. Nelson, J.
Chem. Soc., Dalton Trans. 1994, 3149Ϫ3158.
The six tert-butyl methyl carbon atoms give only two signals.
S. S. Tandon, S. Chander, L. K. Thompson, J. N. Bridson, V.
McKee, Inorg. Chim. Acta 1994, 219, 55Ϫ65.
J. E. Huheey, E. A. Keiter, R. L. Keiter, Anorganische Chemie,
2. Aufl., de Gruyter, Berlin, 1995, p. 134.
J. Hausmann, M. H. Klingele, V. Lozan, G. Steinfeld, D.
Siebert, Y. Journaux, J. J. Girerd, B. Kersting, Chem. Eur. J.
2004, 10, 1716Ϫ1728.
Chem. 2002, 41, 1140Ϫ1150.
O. Schlager, K. Wieghardt, H. Grondey, A. Rufinska, B.
Nuber, Inorg. Chem. 1995, 34, 6440Ϫ6448.
P. V. Bernhardt, P. Comba, T. W. Hambley, G. A. Lawrance,
K. Varnagy, J. Chem. Soc., Dalton Trans. 1992, 355Ϫ359.
H. Strasdeit, A. K. Duhme, M. Weber, S. Pohl, Acta Crys-
tallogr., Sect. B 1992, 48, 437Ϫ440.
[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24] [24a]
[24b]
B. Kersting, G. Steinfeld, Inorg.
[25]
[26]
[27]
[28]
[29]
Acknowledgments
B. Krebs, G. Henkel, Angew. Chem. 1991, 103, 785Ϫ804, An-
gew. Chem. Int. Ed. Engl. 1991, 30, 769Ϫ788.
D. A. House, Comprehensive Coordination Chemistry (Eds.: G.
Wilkinson, R. D. Gillard, J. A. McCleverty), Pergamon Press,
Oxford, 1996, vol. 2, p. 23Ϫ72.
We are particularly grateful to Prof. Dr. H. Vahrenkamp for provid-
ing facilities for NMR spectroscopic and X-ray crystallographic
measurements. Financial support of this work from the Deutsche
Forschungsgemeinschaft (Priority programme ‘‘Sekundäre
Wechselwirkungen‘‘, KE 585/3-1,2) and the Wissenschaftliche
Gesellschaft in Freiburg is gratefully acknowledged.
[30]
T. C. W. Mak, Y.-K. Wu, Inorg. Chim. Acta 1985, 104,
149Ϫ153.
[31]
[32]
A. J. Carty, N. J. Taylor, Inorg. Chem. 1977, 16, 177Ϫ181.
T. J. Duplanicic, D. Grdenic, B. Kamenar, P. Matkovic, M.
Sikirica, J. Chem. Soc., Dalton Trans. 1976, 887Ϫ890.
N. N. Greenwood, A. Earnshaw, Chemistry of the Elements,
VCH, Weinheim, 1988.
[33]
[1]
N. H. Pilkington, R. Robson, Aust. J. Chem. 1970, 23,
2225Ϫ2236.
[34] [34a] J. Nishio, H. Okawa, S. Ohtsuka, M. Tomono, Inorg. Chim.
[2] [2a]
P. A. Vigato, S. Tamburini, D. Fenton, Coord. Chem. Rev.
[34b]
[2b]
Acta 1994, 218, 27Ϫ32.
Yonemura, M. Ohba, N. Matsumoto, H. Okawa, Chem. Lett.
1996, 979Ϫ980.
1997, 36, 3911Ϫ3918.
J. Shimoda, H. Furutachi, M.
1990, 106, 25Ϫ170.
159Ϫ168.
D. Fenton, Chem. Soc., Rev. 1999, 28,
[34c]
[3]
H. Furutachi, H. Okawa, Inorg. Chem.
M. Yamami, H. Furutachi, T. Yokoyama, H. Okawa, Inorg.
Chem. 1998, 37, 6832Ϫ6838.
[4] [4a]
[35] [35a]
H. Okawa, H. Furutachi, D. E. Fenton, Coord. Chem. Rev.
M. Di Vaira, F. Mani, P. Stoppioni, J. Chem. Soc., Dalton
1998, 174, 51Ϫ75. [4b] M. Shinoura, S. Kita, M. Ohba, H. Ok-
awa, H. Furutachi, M. Suzuki, Inorg. Chem. 2000, 39,
4520Ϫ4526.
Trans. 1998, 3209Ϫ3213.
Mani, P. Stoppioni, J. Chem. Soc., Dalton Trans. 1996,
1173Ϫ1179.
M. Di Vaira, M. Guerra, F.
[35b]
Eur. J. Inorg. Chem. 2005, 504Ϫ512
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
511

V. Lozan, B. Kersting
FULL PAPER
[36]
[40]
K. Wieghardt, M. Kleine-Boymann, B. Nuber, J. Weiss, L.
Zsolnai, G. Huttner, Inorg. Chem. 1986, 25, 1647Ϫ1650.
G. M. Sheldrick, SHELXL-97, Computer program for crystal
structure refinement, University of Göttingen, Göttingen, Ger-
many, 1997.
SHELXTL, version 5.10, Bruker AXS, Madison, WI, 1998.
A. L. Spek, PLATON Ϫ A Multipurpose Crystallographic Tool,
Utrecht University, Utrecht, The Netherlands, 2000.
L. J. Farrugia, J. Appl. Crystallogr. 1997, 30, 565Ϫ568.
Received July 13, 2004
[37] [37a]
M. H. Klingele, G. Steinfeld, B. Kersting, Z. Naturforsch.,
[41]
[42]
Teil B 2001, 56, 901Ϫ907. [37b] G. Siedle, B. Kersting, Z. Anorg.
Allg. Chem. 2003, 629, 2083Ϫ2090.
[38]
SADABS, An empirical absorption correction program, part of
[43]
the SAINTPlus NT version 5.10 package, BRUKER AXS,
Madison, WI, 1998.
Early View Article
Published Online December 2, 2004
[39]
G. M. Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467Ϫ473.
512
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 504Ϫ512