Metallosupramolecular complexes derived from bis(benzene-o-dithiol) Ligands

Article abstract of DOI:10.1002/chem.200802560

Contrary to its catechol analogue, the 1,5-naphthalenediamido-bridged bis(benzene-o-dithiol) ligand H₄-3 does not yield [Ti ₄L₆]^8- clusters when reacted with Ti ⁴⁺ starting materials, but instead give

Full text of DOI:10.1002/chem.200802560

FULL PAPER
DOI: 10.1002/chem.200802560
Metallosupramolecular Complexes Derived from Bis(benzene-o-dithiol)
Ligands
Birgit Birkmann,[a] Andreas W. Ehlers,[b] Roland Frçhlich,[c] Koop Lammertsma,*[b] and
F. Ekkehardt Hahn*[a]
Abstract: Contrary to its catechol ana-
logue, the 1,5-naphthalenediamido-
bridged bis(benzene-o-dithiol) ligand
H4-3 does not yield [Ti4L6]8ꢀ clusters
when reacted with Ti4+ starting materi-
als, but instead gives dinuclear, triple-
stranded complexes of type [Ti2L3]4ꢀ.
The molecular structures of such com-
plexes differ depending on the size of
the counterions employed. The forma-
tion of both meso complexes (L,D or
D,L isomers) and of dinuclear triple-
stranded helicates (L,L or D,D iso-
mers) was observed. Molecular-model-
ing calculations show energetically
close minima for the meso complex
and the corresponding helicate. In spite
of the structural differences in the solid
state, proton NMR spectra reveal C3
symmetry for all three complex anions.
Metal–donor interactions mainly dic-
tate the coordination behavior, where-
as the topology of the ligand has less
influence. In addition, the dinuclear
complex [Ti2(8)3]4ꢀ with the unsymmet-
rical bis(benzene-o-dithiol) ligand H4-8
has been prepared. The unsymmetrical
ligand can lead to four different stereo-
isomers when forming dinuclear triple-
stranded complexes of type [Ti2(8)3]4ꢀ,
two of which have been observed in so-
lution.
Keywords: benzene-o-dithiol · co-
ordination compounds · molecular
modeling
·
self-assembly
·
supramolecular chemistry
Introduction
others,[6] have been prepared using metal-controlled self-as-
sembly reactions. Among these, metallohelicates have re-
ceived special interest due to the presence of the helix motif
in nature.
In 1987, Lehn et al. reported the first structurally charac-
terized metallohelicate containing two tris(bipyridine) li-
gands and three CuI ions.[7] Since then, metallosupramolecu-
lar dinuclear double- and triple-stranded helical complexes
containing amine or catecholato[2,8] donor groups have been
studied in detail. Related ligands and complexes derived
from benzene-o-dithiol donor groups[1e] remained rare in
supramolecular chemistry most likely due to the difficulties
encountered during the preparation of the bis- or tris(ben-
zene-o-dithiol) ligands.
In 1995 we reported a method for the ortho functionaliza-
tion of benzene-o-dithiol that allowed the preparation of the
first bis- and tris(benzene-o-dithiol) ligands.[9] By using these
ligands we prepared dinuclear triple-stranded helicates with
bis(benzene-o-dithiolato)[10] and mixed benzene-o-dithiolato/
catecholato ligands.[11]
The tris(benzene-o-dithiolato) complexes are of special
interest due to the possible variation in the coordination ge-
ometry from octahedral to trigonal-prismatic depending on
the formal oxidation state of the metal center. This type of
geometry change has been discussed in detail for tris(ben-
The spontaneous self-assembly of coordination compounds
forming metallosupramolecular architectures has attracted
considerable interest. A number of spectacular molecules
have emerged from research in this area over the last
decade.[1] Several supramolecular structural motifs, such as
helicates,[2] boxes,[3] squares,[4] molecular containers,[5] and
[a] B. Birkmann, Prof. Dr. F. E. Hahn
Institut fꢀr Anorganische und Analytische Chemie
Westfꢁlische Wilhelms-Universitꢁt Mꢀnster
Corrensstraße 30, 48149 Mꢀnster (Germany)
Fax : (+49)251-833-3108
E-mail: fehahn@uni-muenster.de
[b] Dr. A. W. Ehlers, Prof. Dr. K. Lammertsma
Department of Chemistry and Pharmaceutical Sciences
Vrije Universiteit Amsterdam
De Boelelaan 1081 HV Amsterdam (The Netherlands)
Fax : (+31)20-598-7488
E-mail: k.lammertsma@few.vu.nl
[c] Dr. R. Frçhlich
Institut fꢀr Organische Chemie
Westfꢁlische Wilhelms-Universitꢁt Mꢀnster
Corrensstrasse 40, 48149 Mꢀnster (Germany)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200802560.
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4301

zene-o-dithiolato) complexes of type [MACTHNUTRGNEUNG
(bdt)3]nꢀ (M=
Mo,[12] W;[13] bdt=benzene-o-dithiolato dianion).
Up to now only a few ligands have been known to gener-
ate different structural motifs when used in metal-controlled
self-assembly reactions. Enemark and Stack described the
dicatechol ligand H4-A (Scheme 1), which is capable of
Scheme 2. Preparation of the 1,5-diamidonaphthalene-bridged ligand H4-
3 (top) and the unsymmetrically bridged ligand H4-8 (bottom).
Scheme 1. Dicatechol ligands H4-A and H4-B and their double- and
triple-stranded dinuclear complexes.
ing calculations were performed on these complexes to elu-
cidate the reasons for the formation of meso complexes
versus helicates. With the synthesis of the directional ligand
H4-8 we succeeded in the preparation of a new type of bis-
forming a triple-stranded helicate [Fe2(A)3]6ꢀ or a dinuclear
double-stranded complex [Fe2(A)2(OH)2]4ꢀ depending on
the metal/ligand ratio used.[14] The analogous bis(benzene-o-
dithiol) ligand reacts with Ti4+ to yield exclusively the
triple-stranded helicate regardless of the metal/ligand ratio
used.[10a] Albrecht et al. prepared a series of amino acid
bridged dicatechol ligands of type H4-B (Scheme 1) that ex-
clusively form dinuclear double-stranded complexes
[Ti2(B)2(OR)2]2ꢀ (R=H, CH3) with two bridging alkoxy co-
AHCTUNGTREG(NNUN benzene-o-dithiol) ligand by linkage of the two differently
functionalized benzene-o-dithiol groups 1 and 6 (Scheme 2).
Ligand H4-8 reacts with Ti4+ to form dinuclear, triple-
stranded complexes that exhibit either a parallel or an anti-
parallel orientation of the ligand strands.
A
Results and Discussion
al ligands, a mixture of geometrical and stereoisomers was
obtained but no triple-stranded complexes were observed
with ligands of type B4ꢀ.[15]
Synthesis of ligands H4-3 and H4-8: Scheme 2 (top) depicts
the preparation of the 1,5-diamidonaphthalene-bridged bis-
The formation of triple-stranded, dinuclear helicates or
meso complexes based on catechol-containing ligands is well
documented. Much less is known about ligands with ben-
zene-o-dithiol donor functions. In this study, we describe the
coordination chemistry of bis(benzene-o-dithiol) ligands H4-
3 and H4-8 (Scheme 2). Both ligands form dinuclear triple-
stranded complexes with Ti4+ (Scheme 3). For the symmetri-
cal ligand H4-3, we observe formation of three isomeric di-
nuclear complexes (meso complexes (Ph4As)4[9] and
(Et4N)4[10] and the helicate (Bu4N)4[11]). Molecular-model-
ACHTUNGRTEN(NGNU benzene-o-dithiol) ligand H4-3. The synthesis starts with
2,3-di(isopropylmercapto)benzoic acid chloride (1), which
was prepared as previously described.[9] Reaction of 1 and
1,5-diaminonaphthalene in the presence of NEt3 gave the S-
alkylated ligand precursor 2. The isopropyl protection
groups were removed by treatment of 2 with sodium and
naphthalene in THF[9] to give the air-sensitive ligand H4-3
after hydrolysis with HCl/H2O.[16]
The unsymmetrical ligand H4-8 was obtained from the
acid chloride derivative 1 and benzylamine 6. This latter
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Metallosupramolecular Complexes
FULL PAPER
of alkali metal cation on the composition of the assembled
complex anion. However, none of the complexes M4ACHTUNGTRENNUNG[Ti2(3)3]
(M=Li+, Na+, K+) could be isolated in an analytically pure
form. Therefore, the alkali metal cations were exchanged
for larger organic cations. The use of these cations allowed
the isolation of the salts (Ph4As)4[9], (Et4N)4[10],[16] and
(Bu4N)4[11] (Scheme 3) in an analytically pure form and in
yields of 40–60% after recrystallization from DMF/acetoni-
trile/diethyl ether. The compositions of the salts were con-
firmed by elemental analyses and ESI mass spectroscopy.
The unsymmetrical ligand H4-8 was reacted with [Ti-
AHCTUNGTRENNUNG
CTHUNGTRENNUNG
directionality of the ligand, several different stereoisomers
of the anion [12]4ꢀ can form in this reaction. Figure 1 shows
the possible stereoisomers. Both the parallel and the anti-
parallel orientation of the ligand strands each lead to a pair
of helical enantiomers. Two more pairs of enantiomers
result for the nonhelical complexes with the parallel or the
antiparallel orientation of the ligand strands. Thus a total of
eight stereoisomers exist for anions of type [Ti2(8)3]4ꢀ.
Scheme 3. Formation of dinuclear complexes derived from ligand H4-3
and H4-8.
building block was prepared by a Gabriel synthesis starting
with 2,3-di(isopropylmercapto)benzoyl bromide (4).[9b,c]
Compound 4 reacts with potassium phthalimide to form the
phthalimide derivative 5, which upon reaction with hydro-
chloric acid and after basic workup yields 2,3-di(isopropyl-
mercapto)benzoyl amine (6). One equivalent each of 6 and
1 can be coupled to give the ligand precursor 7, which after
reductive cleavage of the S-iPr bonds yields ligand H4-8.
Since most bis(benzene-o-dithiol) ligands are only soluble in
DMF, ligands H4-3 and H4-8 can be purified by washing the
crude reaction products with water and diethyl ether.
Figure 1. Possible stereoisomers formed with ligand H4-8 and Ti4+
.
X-ray diffraction analyses: We have briefly described the
molecular structures of (Ph4As)4[9]·2Et2O and
Synthesis of dinuclear, triple-stranded complexes: Ligand
H4-3 reacts with Ti4+ ions in methanol in the presence of
(Et4N)4[10]·2DMF·H2O.[16] In an extension of this study and
for comparison we describe here the molecular structure of
the salt (Bu4N)4[11], which also contains the dinuclear
triple-stranded tetraanion [Ti2(3)3]4ꢀ. Although the three di-
nuclear, triple-stranded complex anions [9]4ꢀ–[11]4ꢀ have
identical formulae ([Ti2(3)3]4ꢀ; Scheme 3) they exhibit differ-
ent molecular structures that appear to be caused by the dif-
ferences in the countercations.
Na2CO3 as a base, to form a deep red solution (lmax
540 nm), typical for the {Ti
(bdt)3}2ꢀ chromophore.[17] It is
reasonable to assume that the triple-stranded dinuclear com-
plex Na4A[Ti2(3)3] is formed through a self-assembly reac-
tion.[16] In the presence of Li2CO3 or K2CO3 instead of
Na2CO3, the corresponding complexes Li4A[Ti2(3)3] and K4-
[Ti2(3)3] were obtained, indicating no influence of the type
=
AHCTUNGTRENNUNG
CHTUNGTRENNUNG
CTHUNGTRENNUNG
ACHTUNGTRENNUNG
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K. Lammertsma, F. E. Hahn et al.
Both anions [9]4ꢀ and [10]4ꢀ are meso complexes with op-
posite absolute configurations of the metal centers (L and
D). Complex anion [9]4ꢀ crystallized in the centrosymmetric
space group P21/n with the tetraanion residing on a crystal-
lographic inversion center located at the midpoint of the
ꢀ
C26 C26* bond (Figure 2, left). The titanium atoms are co-
Figure 3. Molecular structure of the complex anion [Et4NꢁTi2(3)3]3ꢀ as
seen from a side view (left) and along the Ti–Ti axis (right). The tetra-
AHCTUNGTRENNUNG
ꢀ
ꢀ
bond lengths [ꢃ] and angles [8]: Ti1 S1A 2.397(3), Ti1 S1B 2.381(3),
ꢀ
ꢀ
ꢀ
ꢀ
Ti1 S1C 2.403(4), Ti1 S2A 2.453(3), Ti1 S2B 2.439(3), Ti1 S2C
ꢀ
ꢀ
ꢀ
ꢀ
2.436(3), Ti2 S3A 2.380(3), Ti2 S3B 2.407(3), Ti2 S3C 2.381(4), Ti2
ꢀ
ꢀ
S4A 2.446(3), Ti2 S4B 2.430(3), Ti2 S4C 2.459(4); S1A-Ti1-S2A
80.70(11), S1B-Ti1-S2B 82.11(10), S1C-Ti1-S2C 81.52(11), S3A-Ti2-S4A
81.12(11), S3B-Ti2-S4B 81.00(11), S3C-Ti2-S4C 80.12(13).
Figure 2. Molecular structure of the complex anion [9]4ꢀ as seen from a
side view (left) and along the Ti–Ti axis (right). Hydrogen atoms, cations,
and solvent molecules have been omitted for clarity. Selected bond
ꢀ
ꢀ
ꢀ
lengths [ꢃ] and angles [8]: Ti S1 2.423(2), Ti S2 2.422(2), Ti S3
ꢀ
ꢀ
ꢀ
2.427(2), Ti S4 2.410(2), Ti S5 2.419(2), Ti S6 2.404(2); S1-Ti-S2
80.87(5), S3-Ti-S4 80.19(5), S5-Ti-S6 97.95(5).
ordinated by six sulfur atoms in a strongly distorted octahe-
dral fashion with a calculated twist angle of f=29.78. The
view along the Ti–Ti axis (Figure 2, right) shows the centro-
symmetric geometry of anion [9]4ꢀ. The naphthalene spacers
of two ligand strands adopt a parallel arrangement. The
third ligand strand proceeds from one metal ion to the
other, crossing the Ti–Ti axis.
Exchange of the Ph4As+ cations in (Ph4As)4[9] for Et4N+
cations gave compound (Et4N)4[10] (Scheme 3). The X-ray
diffraction study revealed formation of the salt (Et4N)3-
A
Figure 4. Molecular structure of the complex anion [11]4ꢀ shown parallel
(left) and perpendicular (right) to the Ti–Ti axis. Hydrogen atoms and
cations have been omitted for clarity. Selected bond lengths [ꢃ] and
one tetraethylammonium cation located between the two
metal atoms. The two titanium atoms in the complex anion
are each coordinated by three benzene-o-dithiolato groups
differing slightly in their coordination geometry and exhibit-
ing opposite chiralities (Ti1: D, f=24.08; Ti2: L, f=30.98).
This leads again to the formation of the meso complex. The
tetraethylammonium cation located between two ligand
strands forces the three ligands to adopt slightly different
orientations (Figure 3).
ꢀ
ꢀ
ꢀ
angles [8]: Ti1 S11A 2.412(2), Ti1 S11B 2.426(3), Ti1 S11C 2.411(2),
ꢀ
ꢀ
ꢀ
ꢀ
Ti1 S12A 2.399(3), Ti1 S12B 2.406(3), Ti1 S12C 2.395(2), Ti2 S37A
ꢀ
ꢀ
ꢀ
ꢀ
2.397(2), Ti2 S37B 2.407(2), Ti2 S37C 2.365(2), Ti2 S38A 2.426(2), Ti2
S38B 2.426(2), Ti2 S38C 2.441(2); S11A-Ti1-S12A 81.07(8), S11B-Ti1-
S12B 81.29(9), S11C-Ti1-S12C 81.21(8), S37A-Ti2-S38A 80.62(8), S37B-
Ti2-S38B 81.32(8), S37C-Ti2-S38C 81.17(8).
ꢀ
Related bond parameters in the [Et4NꢁTi2(3)3]3ꢀ anion
are similar to those found for the [Ti2(3)3]4ꢀ anion. Long and
variable N···S separations (ranging from 2.981 to 4.132 ꢃ)
the molecular structure of the complex anion both parallel
(left) and perpendicular to the Ti–Ti axis (right). Each tita-
nium atom is surrounded by six sulfur atoms in a strongly
distorted octahedral fashion with calculated twist angles of
40.0 (Ti1) and 35.28 (Ti2). Surprisingly in this case, both tita-
nium atoms possess the same absolute configuration, L, and
therefore tetraanion [11]4ꢀ is a dinuclear, triple-stranded
rule out the presence of N H···S hydrogen bonds. The
TiS2C4H4 fragments in both [Ti2(3)3]4ꢀ and [Et4NꢁTi2(3)3]3ꢀ
are bent about the S···S vector in accord with previous ob-
servations.[10–11,17–18]
helicate with
a calculated helix angle of 58.28. Since
compound (Bu4N)
4ACHTUNGTRENNUNG[Ti2(3)3] ((Bu4N)4[11]). Figure 4 shows
(Bu4N)4[11] crystallized in the centrosymmetric space group
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Metallosupramolecular Complexes
FULL PAPER
C2/c both the L,L and the D,D enantiomers are present in
the same crystal. Complex anion [11]4ꢀ shows nonbonding
N···S separations in the range of 2.904–3.017 ꢃ, indicative of
ꢀ
the presence of only weak intramolecular N H···S hydrogen
bonds. The assumption of only weak hydrogen bonds is cor-
ꢀ
roborated by the observation of Ti Sortho bonds that are not
ꢀ
significantly longer than the Ti Smeta bonds. A significant dif-
ꢀ
ference in the Ti S bond lengths would have been expected
ꢀ
in the case of the formation of strong N H···Sortho hydrogen
bonds.[11] A comparison of the molecular structure of the
helical (Bu4N)4[11] to both meso complexes (Ph4As)4[9] and
ꢀ
(Et4N)4[10] revealed similar Ti S bond lengths and S-Ti-S
bite angles. Since only the size of the counterions varies in
the three compounds, this is most likely responsible for the
structural differences, with the encapsulated tetraethyl am-
monium cation accounting for the structural differences be-
tween the two meso complexes [9]4ꢀ and [10]4ꢀ.
The influence of the counterions on the coordination ge-
ometry of mononuclear tungsten and molybdenum com-
Figure 5. 1H NMR spectrum of complex (Et4N)4[10] at ambient tempera-
ture in [D7]DMF.
plexes of type [MACHTUNGTRENNUNG
(bdt)3]nꢀ has been studied by Sugimoto
and co-workers.[19] They observed a dependence of the coor-
dination geometry around the metal center from the coun-
terion employed in the reaction.
all four tetraethylammonium cations. We therefore assume
that the tetraethylammonium exchange is fast compared to
the NMR spectroscopy timescale. The resonance for the
amide protons in complexes (Ph4As)4[9] and (Et4N)4[10] is
shifted downfield relative to the free ligand H4-3 (Dd=0.75
and 0.62 ppm in [9]4ꢀ and [10]4ꢀ, respectively). We have pre-
viously noted a similar downfield shift for related dinuclear,
triple-stranded complexes with bis(benzene-o-dithiolato) li-
gands and assign this shift to the formation of intramolecu-
The factors that govern the preferred formation of either
the meso complex or the helicate have been discussed by
Albrecht and co-workers.[20] Experimental studies performed
on complexes with alkyl-bridged dicatecholato ligands re-
vealed the formation of helicates with an even number of
methylene groups in the alkyl spacer and meso complexes
with an odd number of methylene groups in the spacer. Al-
brecht also described a spontaneous self-assembly process in
which the formation of a dinuclear triple-stranded tetra-
lar N H···S hydrogen bonds in solution.[10,11] These hydrogen
ꢀ
bonds, however, have not been detected in the solid-state
molecular structures of the complex anions [9]4ꢀ and [10]4ꢀ.
Even at low temperature (213 K) the 1H NMR spectrosco-
py resonances for the protons of the tetraethylammonium
cations in (Et4N)4[10] were only recorded as broad signals.
Since the molecular-structure determination of (Et4N)4[10]
revealed one encapsulated tetraethylammonium cation in
the solid state (Figure 3), two sets of resonances in a ratio of
3:1 for the free and the encapsulated tetraethyl ammonium
cations were expected at low temperature where the ex-
change between free and encapsulated tetraethyl ammoni-
um cations should be slowed down. Figure S1 (see the Sup-
porting Information) shows, however, that only one set of
resonances at dꢂ1.2 and 3.2 ppm was detected over a wide
temperature range including the lowest data-collection tem-
perature (213 K). We assume that at ambient temperature a
fast exchange of the encapsulated tetraethylammonium
cation with nonencapsulated cations occurs, whereas at low
temperature all tetraethylammonium cations remain outside
of the complex and no interaction with the anion [10]4ꢀ
takes place at all.
ACHTUNGTRENNUNGanionic meso complex with dicatecholato ligands is influ-
enced by the counterion present.[20b] In general, however,
there are very few examples of ligands forming different iso-
mers in metal-directed self-assembly reactions as observed
for the anions [9]4ꢀ–[11]4ꢀ.[2b]
NMR spectroscopy studies: The observed differences in the
molecular structures of the dinuclear anions [9]4ꢀ–[11]4ꢀ in
the solid state have also been studied in solution by NMR
spectroscopy. The anions in (Ph4As)4[9] and (Et4N)4[10] ex-
1
hibit quite simple H NMR spectra with only one set of sig-
nals for the protons of all three ligand strands indicative of
C3 symmetry of the complex anions in solution. The simple
NMR spectra are also an indication of the formation of only
one pair of enantiomers, either meso complexes or helicates
in solution (Figure 1).
For both anions [9]4ꢀ and [10]4ꢀ, the signals for the aro-
matic protons of the benzene-o-dithiolato groups appear as
two doublet of doublets and a triplet, typical for an AMX
spin system. The molecular-structure analysis of (Et4N)4[10]
revealed the presence of an encapsulated tetraethyl ammo-
nium cation located in between the titanium atoms in a
The proton NMR spectrum of compound (Bu4N)4ACHTUNGTRENNUNG[Ti2(3)3]
((Bu4N)4[11]; Figure 6) shows the presence of two isomers
in solution. Presumably these are a helical and a meso com-
plex, while only one set of resonances was observed for the
tetrabutylammonium cations. For the helical anion, the reso-
1
triple-stranded meso complex (Figure 3). The H NMR spec-
trum of the complex recorded at ambient temperature
(Figure 5), however, showed only one set of resonances for
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4305

K. Lammertsma, F. E. Hahn et al.
Figure 6. 1H NMR spectrum of complex (Bu4N)4[11] at ambient tempera-
^
.
ture in [D7]DMF. Resonances for the helical isomer are marked with
Figure 7. 1H NMR spectrum of complex (Ph4As)4[12] (resonances for
both isomers [12a]4ꢀ and [12b]4ꢀ are detectable) at ambient temperature
and 370 K in [D7]DMF.
nance for the amide protons (d=11.40 ppm) is shifted
downfield relative to the resonance for the free ligand H4-3
ꢀ
(Dd=0.77 ppm), which is indicative of N H···S hydrogen
bonds in solution. Contrary to this situation, two resonances
for the amide protons were detected for the meso complex
at d=10.29 and 10.94 ppm, respectively, in a ratio of 2:1,
shifted upfield and downfield relative to the resonance for
the free ligand. Figure 6 illustrates that two types of ligand
strands exist in a meso complex that accounts for the two
observed amide resonances in a ratio of 2:1.
measured at ambient temperature and at 370 K in [D7]DMF.
At ambient temperature the spectrum reveals only two
sharp signals for the amide protons in a ratio of 3:2 at d=
10.17 and 10.10 ppm, respectively. A third very broad signal
was detected at d=9.81 ppm. These resonances can be as-
signed to a complex anion with three ligand strands in a par-
allel orientation (d=10.17 ppm) and a complex anion with
an antiparallel orientation of the ligand stands (d=10.10
und 9.81 ppm) occurring in about equal amounts in solution.
At higher temperature (370 K) the spectrum shows three
sharp amide-H resonances in a ratio of 3:2:4 and more sig-
nals for the aromatic protons. This would indicate an excess
of the complex anion [12b]4ꢀ with the antiparallel orienta-
tion of the ligand strands at elevated temperature.
The 1H NMR spectrum of (Bu4N)4[11] also displays the
typical signals for the aromatic protons of an AMX spin
system for both isomeric complexes. One set of signals was
detected for the three ligand strands of the helical anion
(these are marked with in Figure 6). The meso stereoiso-
mer, however, leads to two sets of Ar H resonances in a
ratio of 2:1. Although some of the resonances for the meso
complex are obscured by additional resonances in Figure 6,
the full set of resonances was identified by 2D NMR spec-
troscopy experiments that verified the presence of the two
isomers in solution. Since both isomeric species are present
in solution at ambient temperature, we expect a small
energy difference between them. However, up to a measur-
ing temperature of 390 K the spectra do not simplify, which
suggests a high barrier and consequently a low rate for inter-
conversion.
^
ꢀ
For both isomers [12a]4ꢀ and [12b]4ꢀ the signals for the
amide protons are shifted downfield relative to the free
ꢀ
ligand, indicative of the formation of N H···S hydrogen
bonds in solution. In addition, the H NMR spectrum dis-
1
plays two signals for the diastereotopic hydrogen atoms of
the methylene groups at d=4.67 and 3.90 ppm. We consider
the observation of three signals for the amide protons as in-
dication for the formation of two stereoisomers in solution,
one with a parallel and the other one with an antiparallel
orientation of the ligand strands. Supplementary 2D NMR
spectroscopy experiments support this assumption. The
question as to whether the isomer with the parallel orienta-
tion is a meso complex or a helicate must remain unan-
swered at this time.
1
The H NMR spectrum of ligand H4-8 showed, as expect-
ed, two doublet of doublets and one triplet for the protons
of each of the two aromatic rings. A doublet was detected at
d=4.67 ppm for the methylene protons coupled to the
amide proton at d=9.07 ppm (triplet). The broad signal at
d=5.49 ppm for the resonances of the sulfur protons disap-
pears upon deprotonation and reaction with Ti4+
Figure 7 displays the H NMR spectrum of the mixture of
.
Molecular-modeling calculations: In the reaction of ligand
H4-3 with Ti4+ we observed formation of three complex
anions with differing structural properties. Both meso-com-
1
complexes (Ph4As)
4ACHUTNGTREN[GUN 12a] and (Ph4As)4ACHTUNGTRENN[GUN 12b] (Scheme 3)
4306
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ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 4301 – 4311

Metallosupramolecular Complexes
FULL PAPER
plex anions ([9]4ꢀ and [10]4ꢀ) as well as helicate [11]4ꢀ have
been characterized by X-ray diffraction studies in the solid
state. Both metal centers in the helical anion [11]4ꢀ possess
the same absolute configuration (L,L or D,D), whereas the
metal centers in the meso complex anions exhibit opposite
absolute configurations. Based on the observation of com-
plex anions with different absolute configurations generated
from the same metal ion/ligand combination we became in-
terested in the magnitude of the barrier for interconversion
of these isomers and addressed this question with DFT cal-
culations.
isomers (6.6 kcalmolꢀ1), as compared with that for the cate-
cholato analogue (10.2 kcalmolꢀ1).
The origin of the difference in transition structures must
be sought in the different nature of the donor groups. Titani-
um–oxygen bonds are usually short and the M–catecholato
rings in such complexes are likely to be planar, which is the
case for [TiACTHNUTRGNEUNG
(cat)3]2ꢀ. Their interconversion proceeds via the
Bailar transition state[23b] as expected for pseudo-octahedral
complexes with three chelating ligands. This behavior is dif-
ferent in the case of bdt2ꢀ ligands due to the longer Ti S
ꢀ
bond lengths caused by the softer nature of the sulfur
Since transition-state searches with complexes consisting
of about 140 atoms are beyond our means, we reduced the
system to a smaller representative unit, the mononuclear ti-
donor. In the C3h transition structure of complex [TiACHTUNGTRENNUNG
(bdt)3]2ꢀ,
the repulsion between the sulfur lone pairs is minimized by
the bent arrangement of the ligands.[10–11,17–18]
tanium tris(benzene-o-dithiolato) complex [Ti
N
Next, based on the X-ray molecular structure of [9]4ꢀ, we
optimized its geometry at B3LYP/SDD, and the results for
the optimized structure [9a]4ꢀ are depicted in Figure 9
([9a]4ꢀ, left) with selected bond lengths and angles summar-
ized in Table 2. The slightly longer bond lengths for the cal-
culated structure may be due to the absence of the counter-
ions and solvent molecules in the geometry optimization.
ometry optimization of this complex with DFT using the
B3LYP functional[21] and the SDD basis set[22] gave the ex-
pected distorted octahedral species as a global minimum.
The octahedral form is energetically favored over the D3h
and C3h symmetrical trigonal-prismatic ones (Figure 8). Ray-
mond and co-workers demonstrated earlier for mononuclear
catecholato complexes [TiACHTNUGRTNEUNG
(cat)3]2ꢀ (cat=catecholato di-
ACHTUNGTRENNUNGanion) that the D3h form is the transition structure for inter-
conversion of a L isomer to its D enantiomer.[23a]
Figure 8. B3LYP/SDD-optimized geometries for the pseudo-Oh (left), C3h
(bdt)3]2ꢀ
(middle), and D3h configurations (right) of [TiCAHTUNGTERNUNGN .
Figure 9. B3LYP/SDD-optimized structures for the meso complex anion
[9a]4ꢀ (left) and the corresponding helicate [9b]4ꢀ (right).
Contrary to the situation found for the [Ti
the present study on [Ti
(bdt)3]2ꢀ we found the D3h symmetri-
(cat)3]2ꢀ case, in
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Table 2. Characteristic bond lengths [ꢃ] and angles [8] for [9]4ꢀ obtained
from the X-ray diffraction study and those obtained at B3LYP/SDD for
the meso complex ([9a]4ꢀ) and helicate ([9b]4ꢀ) complex anions.
cal structure to have a higher-order saddle point with two
(degenerate) imaginary frequencies. Instead, the C3h sym-
metrical structure represents the transition state for the L!
D
interconversion with
a
single imaginary frequency
Bond lengths
and angles
[9]4ꢀ
(X-ray data)
G
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
(Figure 8). The relative energies given in Table 1 together
with the two for [Ti
(cat)3]2ꢀ show indeed a smaller activa-
tion energy for the L!D interconversion of the [Ti
(bdt)3]2ꢀ
ꢀ
Ti Sortho
2.403–2.422
2.419–2.427
3.026–3.043
174.13
2.438–2.490
2.420–2.470
3.090–3.170
175.37
2.420–2.480
2.420–2.470
3.050–3.190
176.26
AHCTUNGTRENNUNG
ꢀ
Ti Smeta
AHCTUNGTRENNUNG
N···S
H-N-C-O[a]
[b]
So-Ti-Sm
80.33
81.28
81.43
Table 1. Relative energies (in kcalmolꢀ1) for the B3LYP/SDD-optimized
structures of mononuclear tris(benzene-o-dithiolato) and tricatecholato
titanium complexes.
[a] Average dihedral angle. [b] Average bite angle.
Complex
D3
D3h
C3h
6.6 [a]
In the next step we changed the absolute configurations
of the titanium centers from L,D in the meso complex
[9a]4ꢀ (Figure 9, left) to L,L in the helicate [9b]4ꢀ (Figure 9,
right). More specifically, the D (“bottom”) titanium unit in
[9a]4ꢀ was changed manually to the L configuration and the
[b]
[a]
[Ti
[Ti
U
0
0
15.1
10.2
[c]
E
–
[a] One and [b] two (degenerate) imaginary frequencies. [c] Optimization
of the C3h-symmetric tris(catecholato) resulted in all cases in the D3h-sym-
metric isomer.
Chem. Eur. J. 2009, 15, 4301 – 4311
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4307

K. Lammertsma, F. E. Hahn et al.
tra were recorded at 298 K with Bruker AC 200 (200 MHz), Bruker
AMX 400 (400 MHz), or Varian Inova (600 MHz) spectrometers and are
reported relative to TMS as an internal standard or to the solvent signal.
IR spectra were measured with a Bruker Vector 22 IR spectrometer.
Mass spectra were obtained with Varian MAT 212 (EI), Micromass Quat-
tro LC-Z (ESI), or Bruker Reflex IV (MALDI) spectrometers. Elemen-
tal analyses were performed with a Vario EL III CHNS analyzer. Com-
resulting structure was optimized. Interestingly, the energy
difference between the two isomers amounts to only
0.68 kcalmolꢀ1. Hence, this small energy difference together
with the discussed low barrier for L,D interconversion, ex-
plains the observed formation of both the meso complexes
and helicate with ligand H4-3.
mercially available [TiACHTNURTGEN(UNG OPr)4] (Aldrich) was used without further purifi-
cation. 2,3-Di(isopropylmercapto)benzoic acid chloride (1)[9a,c] and 2,3-
di(isopropylmercapto)benzoyl bromide (4)[9b,c] were prepared as de-
scribed previously.
Conclusion
1,5-BisACTHNUGRTENUNG[2,3-di(isopropylmercapto)benzamido]naphthalene (2): Freshly
We have presented a detailed investigation of the coordina-
tion chemistry of the naphthalene-bridged bis(benzene-o-di-
thiol) ligand H4-3. The interaction of the hard titanium
cation with the soft sulfur donors of the noninnocent bdt2ꢀ
ligand leads to new structural motifs compared with the
analogous catecholato ligand. Ligand H4-3 is the first bis-
prepared 2,3-di(isopropylmercapto)benzoic acid chloride (1; 653 mg,
2.26 mmol) was dissolved in THF (20 mL) and this solution was added to
a solution of 1,5-diaminonaphthalene (179 mg, 1.13 mmol) and NEt3
(1.7 mmol) in THF (40 mL). The reaction mixture was stirred for 12 h at
ambient temperature. Subsequently, insoluble material was removed by
filtration and the solvent was removed from the filtrate under vacuum.
The solid residue was purified by column chromatography (silica gel,
CH2Cl2/n-hexane 1:1, v/v). Yield: 710 mg (1.07 mmol, 95%); 1H NMR
ACHTUNGTRENNUNG(benzene-o-dithiolato) derivative that has been shown to be
capable of forming isomeric complexes (meso complexes
(400 MHz, [D7]DMF): d=10.39 (s, 2H; N-H), 8.23 (d, 3J
2H; naphthalene-H), 7.70 (d, 3J
(H,H)=8.4 Hz, 2H; naphthalene-H),
7.58 (t, 3J(H,H)=8.4 Hz, 2H; naphthalene-H), 7.48 (t, 3J
(H,H)=6.7 Hz,
2H; Ar-H), 7.37 (dd, J (H,H)=2.4 Hz, 2H; Ar-H), 7.19
(dd, 3J(H,H)=6.7 Hz, 4J
(H,H)=2.4 Hz, 2H; Ar-H), 3.60 (m, 4H; CH-
(CH3)2), 1.36 (d, 6H; CH3), 1.19 ppm (d, 6H; CH3); 13C NMR (100 MHz,
ACHTUNGTREN(NUNG H,H)=8.4 Hz,
AHCTUNGTRENNUNG
and helicate) in metal-directed self-assembly reactions with
A
ACHTUNGTRENNUNG
Ti4+. Both a helicate and a meso complex with the composi-
3
4
ACHUTNGREN(NUG H,H)=6.7 Hz, JACHTNUGTRENNUNG
1
A
ACHTUNGTRENNUNG
tion (Bu4N)
N
AHCTUNGTRENNUNG
spectroscopy, whereas only the helicate could be crystallized
from such solutions. Only one meso complex anion was de-
tected in the solid state by using X-ray diffraction and in so-
lution by 1H NMR spectroscopy for the compounds
[D7]DMF): d=167.7 (C(O)NH), 144.8, 142.5 (C-S), 133.7, 129.6, 125.1,
122.9, 121.7 (naphthalene-C), 129.1, 127.2, 126.7, 123.0 (Ar-C), 45.7, 34.8
(CHACHTNUGTRNEUNG(CH3)2), 25.0, 23.0, 22.7, 22.4 ppm (CH3); elemental analysis calcd
(%) for C36H42N2O2S4: C 65.22, H 6.39, N 4.23, S 19.34; found: C 65.28,
H 6.29, N 4.01, S 18.18.
(Ph4As)4ACHTUNGTRENNUNG[Ti2(3)3] and (Et4N)4ACHUTNTGREN[NNGU Ti2(3)3]. The formation of iso-
meric complex anions [Ti2(3)3]4ꢀ is most likely caused by the
different cations present during their synthesis. Analysis
with density functional theory showed different mechanisms
for the L!D interconversion of tris(catecholato) and tris-
Ligand H4-3: Dry, freshly distilled THF (60 mL) was added to a mixture
of compound 2 (710 mg, 1.07 mmol), sodium (247 mg, 10.7 mmol), and
naphthalene (697 mg, 5.35 mmol). The reaction mixture was stirred for
12 h. Subsequently methanol (10 mL) was added to remove unreacted
sodium. All solvents were then removed under vacuum and the solid resi-
due was dissolved in degassed water and washed three times with de-
gassed diethyl ether (20 mL each). Insoluble material was removed by fil-
tration. The clear aqueous solution was treated dropwise with HCl
(37%) until a white precipitate formed. The precipitate was isolated by
filtration and washed with water and diethyl ether. The solid residue was
dried under vacuum. Yield: 450 mg (0.91 mmol, 85%); 1H NMR
(400 MHz, [D7]DMF): d=10.63 (s, 2H; N-H), 8.26 (m, 2H; naphthalene-
H), 7.93 (m, 2H; Ar-H), 7.70 (m, 2H; naphthalene-H), 7.62 (m, 2H; Ar-
H), 7.49 (t, 2H; Ar-H), 7.25 (t, 2H; naphthalene-H), 3.95 ppm (brs, 4H;
S-H). 13C NMR data could not be obtained due to the instability of the
ligand in solution over longer periods of time.[16]
A
conversion of the mononuclear [Ti
ceeds via a C3h-symmetric transition structure, whereas a D3h
transition state was previously found for the [Ti
(cat)3]4ꢀ
(bdt)3]2ꢀ complex pro-
ACHTUNGTRENNUNG
complex anion. The DFT calculations also revealed a small
activation energy for the L!D interconversion, which
would transform a meso complex anion of type [Ti2(3)]4ꢀ
into the helicate.
Finally, we described the synthesis and coordination
chemistry of the unsymmetrical bis(benzene-o-dithiol)
ligand H4-8. The topology of the ligand provides two elec-
tronically different donor units, one being more electron
rich than the other. The self-assembly reactions of ligand
H4-8 with Ti4+ lead to a mixture of dinuclear triple-stranded
complexes exhibiting either a parallel or an antiparallel ori-
entation of the ligand stands.
2,3-Di(isopropylmercapto)benzoyl phthalimide (5): 2,3-Di(isopropylmer-
capto)benzoyl bromide (4; 1.36 g, 4.26 mmol) and potassium phthalimide
(1.18 g, 6.37 mmol) were dissolved in acetone (50 mL). The reaction mix-
ture was heated under reflux for 12 h. Solids were isolated by filtration
and suspended in water (40 mL). The aqueous suspension was heated
under reflux for two more hours. The reaction mixture was then filtered
and the solid residue was washed with water, recrystallized from ethanol,
and dried under vacuum. Compound 5 was isolated as a white crystalline
solid (1.36 g, 3.53 mmol, 83%). 1H NMR (400 MHz, [D7]DMF): d=7.88
(d, 2H; phthalimide-H), 7.74 (d, 2H; phthalimide-H), 7.17 (t, 1H; Ar-
H), 7.16 (d, 1H; Ar-H), 6.81 (d, 1H; Ar-H), 5.21 (d, 2H; CH2), 3.56
Experimental Section
(sept, 1H; CHACTHNUGTRENN(UG CH3)2), 3.48 (sept, 1H; CHCAHTUNGTNERN(UGN CH3)2), 1.38 (d, 6H; CH3),
1.32 ppm (d, 6H; CH3); 13C NMR (100 MHz, [D7]DMF): d=168.1
(C(O)N), 145.8, 130.7 (C-S), 141.5, 134.1, 132.2, 129.0, 125.5, 123.4, 122.3
(Ar-C), 41.0 (CH2), 39.4, 35.9 (CH), 23.2, 22.7 ppm (CH3); MS (70 eV):
m/z (%): 386 (88) [MꢀH]+; elemental analysis calcd (%) for
C21H23NO2S2: C 65.42, H 6.01, N 3.63, S 16.63; found: C 65.85, H 5.94, N
3.38, S 16.12.
Computational methods: All density functional theory calculations
(B3LYP)[21] were performed with the Gaussian 03 suite of programs,[24]
using the SDD basis set and pseudopotentials for titanium[22] and the
D95V[25] basis set for all other atoms. The nature of the transition-state
structures was confirmed by frequency calculations.
2,3-Di(isopropylmercapto)benzoyl amine (6): A solution of 5 (1.40 g,
3.63 mmol) in ethanol (40 mL) was treated with hydrazine monohydrate
(309 mg, 6.17 mmol). The reaction mixture was heated under reflux for
Syntheses and analyses: All operations were carried out under an atmos-
phere of dry argon using Schlenk and vacuum techniques. Solvents were
dried by standard methods and freshly distilled prior to use. NMR spec-
4308
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Chem. Eur. J. 2009, 15, 4301 – 4311

Metallosupramolecular Complexes
FULL PAPER
2 h. Then an excess of hydrochloric acid was added. The reaction mixture
was filtered and the remaining solids were washed with water. The major-
ity of the ethanol was removed under vacuum and sodium hydroxide was
added to the remaining solution until a basic pH was reached. The mix-
ture was extracted three times with diethyl ether (30 mL each) and the
combined ether phases were dried over Na2SO4. After removal of the sol-
vent under vacuum compound 6 was obtained as a yellow oil (640 mg,
2.51 mmol, 69%). 1H NMR (400 MHz, [D7]DMF): d=7.23 (t, 1H; Ar-
H), 7.13 (d, 1H; Ar-H), 7.12 (d, 1H; Ar-H), 4.03 (s, 2H; CH2), 3.47
6H; naphthalene-H), 7.95 (m, 16H; Ph-H), 7.86 (m, 32H; Ph-H), 7.84
(m, 32H; Ph-H), 7.66 (d, 3J
ACHTUNGTRENNUNG
(dd, 3J
G
E
ACHTUNGTRENNUNG
4
3
7.7 Hz, J
thalene-H), 6.83 ppm (t, 3J
AHCTUNGTRENNUNG
(100 MHz, [D7]DMF): d=167.8 (C(O)NH), 156.4, 151.6 (C-S), 135.1,
134.2, 131.7, 122.1 (Ph-C), 133.6, 129.4, 125.2, 121.9 (Ar-C), 135.5, 129.5,
126.2, 121.3, 121.1 ppm (naphthalene-C); MS (ESI, negative ions): m/z:
784.3 [Ti2(3)3+2H]2ꢀ, 523.1 [Ti2(3)3+H]3ꢀ, 392.1 [Ti2(3)3]4ꢀ
.
(sept, 1H; CHACHTUNGTRENNUNG(CH3)2), 3.46 (sept, 1H; CHAHCUTNGTRENN(GUN CH3)2), 1.96 (brs, 2H; NH2),
Preparation of (Et4N)
pared as described for (Ph4As) CTHUGNTRENNNUG
[Ti2(3)3] ((Et4N)4[10]): The compound was pre-
4A[Ti2(3)3] with the exception that Et4NBr
1.36 (d, 6H; CH3), 1.20 ppm (d, 6H; CH3); 13C NMR (100 MHz,
[D7]DMF): d=148.3, 145.4, 130.9, 129.1, 125.3, 124.7 (Ar-C), 45.9 (CH2),
39.0, 35.8 (CH), 23.1, 22.7 ppm (CH3); elemental analysis calcd (%) for
C13H21NS2: C 61.13, H 8.29, N 5.48, S 25.10; found: C 60.48, H 8.03, N
4.83, S 25.89.
(28 mg, 0.134 mmol) was added for precipitation. Yield: 66 mg
(0.026 mmol, 78%; 60% after recrystallization); 1H NMR (400 MHz,
[D7]DMF): d=11.25 (s, 6H; N-H), 8.29 (d, 3J
ACHTUNGTRENNUNG
thalene-H), 7.77 (d, 3J
ACHTUNGTRENNUNG
Ligand precursor 7: Freshly prepared 2,3-di(isopropylmercapto)benzoic
acid (317 mg, 1.17 mmol) was converted into the acid chloride 1 by using
oxalyl chloride in benzene. After removal of the solvent the formed 1 (a
98% conversion was assumed) was dissolved in THF (20 mL). This solu-
tion was added to a solution made up from 4 (300 mg, 1.17 mmol) and
NEt3 (178 mg, 1.76 mmol) dissolved in THF (40 mL). The reaction mix-
ture was stirred for 12 h at ambient temperature. It was then filtered and
the solvent was removed under vacuum. The residue was purified by
column chromatography (silica gel, CH2Cl2/n-hexane 1:1, v/v) to give 7 as
a white solid (590 mg, 1.16 mmol, 99%). 1H NMR (400 MHz, [D7]DMF):
(H,H)=7.7 Hz, 4J(H,H)=1.3 Hz, 6H; Ar-H), 7.25 (t, 3J
ACHTUNGTRNEUNGN ACHTNUGTRENNUNG ACTUHNGTRENNUGN
6H; naphthalene-H), 7.20 (dd, 3J
A
N
3
3
Ar-H), 6.84 (t, J
N
CH2), 1.18 ppm (t, 3J
ACHTUNGTRENNUNG
[D7]DMF): d=168.3 (C(O)NH), 156.5, 151.2 (C-S), 133.6, 129.2, 124.6,
121.8 (Ar-C), 135.7, 129.5, 126.3, 121.4, 121.2 (naphthalene-C), 52.5
(CH2), 7.5 ppm (CH3); MS (ESI, negative ions): m/z: 914.4
[Ti2(3)3+2Et4N]2ꢀ
[Ti2(3)3+H]3ꢀ, 392.1 [Ti2(3)3]4ꢀ
Preparation of (Bu4N)4A[Ti2(3)3] ((Bu4N)4[11]): The compound was pre-
pared as described for (Ph4As)4A[Ti2(3)3] with the exception that Bu4NCl
, , , 523.1
784.3 [Ti2(3)3+2H]2ꢀ 566.1 [Ti2(3)3+Et4N]3ꢀ
.
CTHUNGTRENNUNG
d=7.41 (dd, 3J
(H,H)=7.8 Hz, 4J
1H; Ar-H); 7.27 (d, 3J
7.8 Hz, 1H; Ar-H); 7.19 (dd, J
H); 7.13 (t, 3J(H,H)=6.2 Hz, 1H; N-H); 4.89 (d, 3J
CH2); 3.49, 3.48, 3.46, 3.32 (4ꢄsept, 3J
(H,H)=6.7 Hz, 1H; CH
1.38, 1.36, 1.24, 1.09 ppm (4ꢄd, 3J(H,H)=6.7 Hz, 6H; CH3); 13C NMR
A
ACHTUNGTRENNUNG
CTHUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
(40 mg, 0.134 mmol) was added for precipitation. Yield: 53 mg
(0.021 mmol, 63%; 42% after recrystallization); 1H NMR (400 MHz,
A
ACHTUNGTRENNUNG
3
4
ACHUTNGREN(NUG H,H)=7.8 Hz, JACHTNUGTRENNUNG
^
[D7]DMF; signals given for both isomeric species: marks signals of the
A
ACHTUNGTRENNUNG
^
helical complex anion): d=11.40 (s, 6H; N-H, ), 10.94 (s, 2H; N-H),
10.29 (s, 4H; N-H), 8.95 (d, 3J
ACTHUNTGRENNG(U H,H)=8.4 Hz, 2H; naphthalene-H), 8.29
A
ACHTUNGTRENNUNG
(d, 3J(H,H)=8.4 Hz, 6H; naphthalene-H, ), 7.70 (d, 3J
ACTHNUGTRENNUGN ACHTUNGTRENNNUG
AHCTUNGTRENNUNG
^
6H; naphthalene-H, ), 7.62 (dd, 3J(H,H)=7.5 Hz, 4J
ACTHNUTRGENNUG CAHTUNGTRENNUNG
(100 MHz, [D7]DMF): d=168.3 C(O)NH), 145.6, 145.5, 143.7, 142.8,
131.5, 129.2, 129.1, 128.8, 127.9, 126.1, 125.9, 125.5 (Ar-C), 43.5 (CH2),
40.6, 39.3, 36.1, 35.9 (CH), 23.2, 22.8, 22.7, 22.7 ppm (CH3); elemental
analysis calcd (%) for C26H37NOS4: C 61.49, H 7.34, N 2.76, S 25.26;
found: C 62.12, H 7.44, N 2.52, S 25.88.
^
6H; Ar-H, ), 7.53 (d, 3J
A
U
^
7.4 Hz, 2H; naphthalene-H), 7.52 (d, 3J
(d, 3J
ACHTUNGTRENNUNG
T
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
^
Ligand H4-8: Dry, freshly distilled THF (60 mL) was added to a mixture
of compound 7 (500 mg, 0.98 mmol), sodium (227 mg, 9.87 mmol), and
naphthalene (631 mg, 4.85 mmol). The reaction mixture was stirred for
12 h at ambient temperature. Subsequently methanol (10 mL) was added
to remove unreacted sodium. The solvents were then removed under
vacuum. The solid residue was dissolved in degassed water and the re-
sulting solution was washed three times with degassed diethyl ether
(20 mL each). The aqueous solution was filtered and HCl (37%) was
added dropwise until a white precipitate formed. This precipitate was iso-
lated by filtration and washed with water and diethyl ether. The solid res-
idue was dried under vacuum to give ligand H4-8 as a beige powder
(310 mg, 0.91 mmol, 93%). 1H NMR (400 MHz, [D7]DMF): d=9.07 (t,
N
ACHTUNGTRENNUNG
3
E
ACHTUNGTNER(NUNG H,H)=7.3 Hz, 6H; naphthalene-
^
E
ACHTUNGTRENNUNG
3J
H), 6.87 (t, 3J
(m, 32H; N-CH2-CH2-CH2), 1.34 (sext, J
CH3), 0.91 ppm (t, 3J(H,H)=7.4 Hz, 48H; CH3); 13C NMR (100 MHz,
[D7]DMF): d=167.8 (C(O)NH, ), 167.1, 166.9 (C(O)NH), 156.4 (C-S,
R
ACHTUNGTNER(NUNG H,H)=7.7 Hz, 4H; naphthalene-
3
^
AHCTUNGTRENNUNG
3
AHCTUNGTREN(GUNN H,H)=7.4 Hz, 32H; CH2-CH2-
AHCTUNGTRENNUNG
^
^
^
), 155.2, 154.3, 152.5, 152.2 (C-S), 151.6 (C-S, ), 136.7 (Ar-C) 133.7
(Ar-C, ), 133.4 (Ar-C), 129.6 (Ar-C, ), 129.6, 128.6 (Ar-C), 125.2 (Ar-
C, ), 124.7, 123.8, 123.1, 122.7 (Ar-C), 121.9 (Ar-C, ), 135.6 (naphtha-
lene-C, ), 134.0, 133.9 (naphthalene-C), 129.6 (naphthalene-C, ), 129.0
^
^
^
^
3J
1H; Ar-H), 7.50 (dd, J
(dd, 3J(H,H)=7.9 Hz, 4J
7.7 Hz, 4J(H,H)=1.3 Hz, 1H; Ar-H), 7.13 (t, 3J
H), 7.13 (t, 3J
(H,H)=7.9 Hz, 1H; Ar-H), 5.49 (brs, 4H; S-H), 4.67 ppm
(d, 3J(H,H)=5.7 Hz, 2H; CH2); 13C NMR (100 MHz, [D7]DMF): d=
N
N
N
3
4
^
^
3
4
^
(naphthalene-C), 126.3 (naphthalene-C, ), 125.2, 125.1, 124.7, 122.3
^
^
G
(naphthalene-C), 121.3 (naphthalene-C, ), 121.2 (naphthalene-C, ),
120.2, 119.2, 116.5 (naphthalene-C), 58.8 (N-CH2), 24.2 (CH2-CH2-CH2),
20.1 (CH2-CH2-CH3), 13.8 ppm (CH3); MS (ESI, negative ions): m/z:
ACHTUNGTRENNUNG
T
.
169.8 (C(O)N), 139.4, 135.2, 134.2, 132.1, 129.3, 129.0, 126.9, 126.2, 126.2,
125.5 (Ar-C, only 10 signals were observed for the 12 aromatic carbon
atoms), 43.4 ppm (CH2); elemental analysis calcd (%) for C14H13NOS4: C
49.53, H 3.86, N 4.13, S 37.77; found: C 49.34, H 3.90, N 3.96, S 36.88.
[Ti2(8)3] ((Ph4As)4[12]): A sample of [Ti
ACHTUNGTRENNUNG(OPr)4]
a
solution of H4-8 (50 mg,
0.147 mmol) and Na2CO3 (10.4 mg, 0.098 mmol) in degassed methanol
(20 mL). The solution was stirred under argon at ambient temperature
for 12 h and then filtered. Addition of Ph4AsCl (86 mg, 0.197 mmol) to
the filtrate yielded a dark red precipitate, which was isolated by filtration,
washed with methanol (2ꢄ10 mL), and dried under vacuum. Yield:
102 mg (0.036 mmol, 73%); 1H NMR (400 MHz, [D7]DMF, 300 K): d=
10.17 (t, 3H; N-H), 10.10 (t, 1H; N-H), 9.81 (m, 2H; N-H), 7.93 (m,
16H; Ph-H), 7.83 (m, 32H; Ph-H), 7.78 (m, 32; Ph-H), 7.63, 7.54, 6.92,
6.91, 6.69, 6.68, 6.64, 6.58, 6.45, 6.41, 6.29, 6.28 (Ar-H), 4.67, 3.90 ppm
(CH2); 13C NMR (100 MHz, [D7]DMF, 300 K): d=167.8, 167.4 (CO),
156.6, 156.5, 154.3, 154.3, 154.2, 154.0, 152.0, 151.5 (C-S), 135.2, 134.0,
Preparation of (Ph4As)
N
ACHTUNGERTN(NUNG OPr)4]
(19.0 mg, 0.067 mmol) was added to
a
solution of H4-3 (50 mg,
0.10 mmol) and Na2CO3 (7.0 mg, 0.067 mmol) in degassed methanol
(20 mL). The solution was stirred under argon at ambient temperature
for 12 h and filtered. Addition of Ph4AsCl (58 mg, 0.134 mmol) to the fil-
trate yielded a dark red precipitate, which was isolated by filtration,
washed with methanol (2ꢄ10 mL), and dried under vacuum. Yield:
92 mg (0.028 mmol, 83%; 66% after recrystallization); 1H NMR
(400 MHz, [D7]DMF): d=11.38 (s, 6H; N-H), 8.25 (d, 3J
ACTHNUGRTENUNG(H,H)=8.2 Hz,
Chem. Eur. J. 2009, 15, 4301 – 4311
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4309

K. Lammertsma, F. E. Hahn et al.
131.8, 121.8 (Ph-C), 135.1, 134.9, 132.0, 131.9, 128.9, 128.7, 126.9, 126.3,
126.1, 125.5, 124.7, 124.1, 120.9, 120.7, 120.7, 120.6 (Ar-C), 44.8, 44.6 ppm
(CH2); three sets of resonances were expected: one for the ligand strands
in the anion with a parallel ligand orientation and two more for the
anion with the antiparallel orientation; however, not all signals could be
resolved with the exception of the N-H resonances in the 1H NMR spec-
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[Ti2(2)3+K]3ꢀ
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, 380.1
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(Et4N)4[10]·2DMF·H2O) or on an Enraf-Nonius Kappa CCD
((Bu4N)4[11]) both equipped with a rotating anode and with CuKa radia-
tion (l=1.54178 ꢃ). Empirical absorption corrections using the program
SADABS[26] were applied to the raw data for (AsPh4)2[9]·2Et2O (0.28ꢃ
Tꢃ0.83) and (Et4N)4[10]·2DMF·H2O (0.34ꢃTꢃ0.81). Program
SORTAV[27] was used for absorption corrections to the raw data of
(NBu4)4[11] (0.77ꢃTꢃ0.55). Structure solutions were found with
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SHELXL[29] using anisotropic thermal parameters for all non-hydrogen
atoms. Hydrogen atoms were added to the structure models on calculated
positions and were refined as riding atoms.
Crystal data for (Ph4As)4ACHTUNGRTEN[UGN Ti2(3)3]·2Et2O: C176H142N6As4O8S12Ti2; Mr =
3249.16; crystal size 0.43ꢄ0.17ꢄ0.05 mm3; monoclinic; space group
P21/n; a=19.4830(8), b=13.8938(6), c=28.3429(11) ꢃ; b=104.625(2)8;
V=7423.6(5) ꢃ3;
Z=2;
2qmax =130.08;
l=1.54178 ꢃ;
m(Cu)=
3.987 mmꢀ1; T=153(2) K; 40787 measured reflections; 12508 independ-
ent reflections used in refinement against jF2 j ; R=0.0589, wR=0.1593
(for 7902 reflections Iꢄ2s(I)).
Crystal data for (Et4N)3ACHTUNGRTEN[NUG Ti2(3)3]·2DMF·H2O: C110H138N12O9S12Ti2; Mr =
2552.86; crystal size 0.37ꢄ0.10ꢄ0.06 mm3; monoclinic; space group
P21/c; a=18.4943(9), b=37.426(2), c=16.5461(9) ꢃ; b=93.488(3)8; V=
11431.6(10) ꢃ3; Z=4; 2qmax =135.08; l=1.54178 ꢃ; m(Cu)=3.717 mmꢀ1
;
T=153(2) K; 65493 measured reflections; 20313 independent reflections
used in refinement against jF2 j ; R=0.1136, wR=0.2964 (for 6711 reflec-
tions Iꢄ2s(I)).
Crystal data for (Bu4N)4ACHTUNGTRENNUNG[Ti2(3)3]: C136H186N10O6S12Ti2; Mr =2537.47; crys-
tal size 0.25ꢄ0.10ꢄ0.10 mm3; monoclinic; space group C2/c; a=
55.5199(13), b=17.1842(5), c=33.4814(9) ꢃ; b=94.500(1)8; V=
31845.0(15) ꢃ3; Z=8; m(Cu)=26.97 cmꢀ1; l=1.54178 ꢃ; T=223(2) K;
119766 measured reflections; 22460 independent reflections used in re-
finement against jF2 j ; R=0.0964, wR=0.2591 (for 11307 reflections Iꢄ
2s(I)).
CCDC-674837
((AsPh4)2[9]·2Et2O),
CCDC-674838
((Et4N)4[10])·2DMF·H2O), and CCDC-712005 ((Bu4N)4[11]) contain the
supplementary crystallographic data for this paper. These data can be ob-
tained free of charge from the Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements
This work was supported by the Deutsche Forschungsgemeinschaft
(IRTG 1444) and the Fonds der Chemischen Industrie. We thank Dr.
Alexander Hepp and Dr. Klaus Bergander for measuring the NMR spec-
tra and Dr. Heinrich Luftmann for measuring the mass spectra.
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Metallosupramolecular Complexes
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Received: December 6, 2008
Published online: March 6, 2009
Chem. Eur. J. 2009, 15, 4301 – 4311
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4311