Redox-active 17- and 19-membered metallamacrocycles incorporating tetrathiafulvalene

Article abstract of DOI:10.1002/ejic.200600101

Redox-active 17- and 19-membered metallamacrocycles were prepared thanks to the chelating ability of bis[(diphenylphosphane)alkylthio]TTF towards the M(CO)₄ fragment (M = Mo, W). The TTF unit can adopt either a cis or a trans configuration as c

Full text of DOI:10.1002/ejic.200600101

FULL PAPER
DOI: 10.1002/ejic.200600101
Redox-Active 17- and 19-Membered Metallamacrocycles Incorporating
Tetrathiafulvalene
Grégory Gachot,[a] Pascal Pellon,[a] Thierry Roisnel,[a] and Dominique Lorcy*[a]
Keywords: Metallamacrocycle / Tetrathiafulvalene / Diphosphane ligands / Molybdenum / Tungsten
Redox-active 17- and 19-membered metallamacrocycles
were prepared thanks to the chelating ability of bis[(diphen-
ylphosphane)alkylthio]TTF towards the M(CO)4 fragment
(M = Mo, W). The TTF unit can adopt either a cis or a trans
configuration as can the phosphorus atoms coordinated to
the metal center. Moreover, an element of planar chirality is
generated by the trans isomer of the TTF. Thus, the reaction
affords six stereoisomers as evidenced by 31P NMR and X-
ray crystallographic analyses. The electrochemical properties
significant influence of the two redox moieties was detected,
whereas in the 17-membered metallamacrocycles, the oxid-
ized TTF modifies the redox behavior of the metal center.
Two crystalline complexes obtained with tetracyanoquinodi-
methane (TCNQ) and the tungsten 17- and 19-membered
metallamacrocycles are reported. Comparison of the crystal
structures shows that these metallamacrocycles appear to be
rather flexible even with strained structures.
of the title compounds have been investigated by cyclic vol- (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
tammetry. Within the 19-membered metallamacrocycles, no
Germany, 2006)
cal properties of the metallamacrocycles. Comparison of
the effect of the length of the spacer group on the molecular
structure and the redox behavior will then be discussed. An-
other interesting feature that will be presented is the influ-
ence of the complexation with TCNQ on the conformation
of these metallamacrocycles.
Introduction
Various cyclophanes or cage molecules incorporating one
or more electroactive units such as a tetrathiafulvalene core
(TTF) have been studied with the aim of creating, through
intramolecular or intermolecular interactions, nanoelec-
tronic devices.[1] Among the electroactive macrocycles de-
scribed so far, none of them contain a metallic fragment.
Association of the TTFs with one appropriate metal will
lead to a macrocycle with multiple redox sites and the pos-
sibility of interaction between the inorganic and organic
moieties.[2] Various potential applications can be envisioned
for these hybrid molecules, as molecular materials or in
catalytic systems as it is well known that the steric and elec-
tronic properties of the ligand have an enormous effect on
the reactivity of metal complexes.[3] A simple route toward
the formation of large metallamacrocycles involves the co-
ordination of a bidentate α,ω-diphosphane ligand to the
transition metal center.[4] Therefore, we have studied the
ability of bis-substituted [(diphenylphosphanyl)propylthio]-
TTF 1[5] to form metal carbonyl complexes upon chelation
of the Mo(CO)4 and W(CO)4 fragments. Moreover, we also
present the synthesis of the diphosphanyl ligand 2 where the
phosphane moieties are linked to the donor core through a
longer spacer group such as a thiobutyl one and the influ-
ence of this longer chain on the structural and electrochemi-
Results and Discussion
The synthesis of the ligand 2 was accomplished as de-
picted in Scheme 1 according to the chemical pathway used
for the synthesis of bis[(diphenylphosphanyl)propylthio]-
TTF 1 using the preformed TTF derivative 3 as the starting
material.[5] The methodology consists first of the synthesis
of the bis[(boronatodiphenylphosphanyl)butylthio]TTF 5.
The use of phosphane–borane substituents in the synthesis
of the target TTFs presents several advantages as they are
very stable compared to phosphane derivatives towards the
[a] UMR 6226 “Sciences Chimiques de Rennes” CNRS-Université
de Rennes 1,
Campus de Beaulieu, Bât 10A, 35042 Rennes cedex, France
Fax: +33-22323-67-38
E-mail: dominique.lorcy@univ-rennes1.fr
2604
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Redox-Active Metallamacrocycles Incorporating Tetrathiafulvalene
FULL PAPER
Scheme 1.
usual oxidizing or electrophilic reagents, and very easy to expected metallamacrocycles 6–9 (Scheme 2) but also poly-
handle and to purify.[6,7] The bis(cyanoethylthioTTF) 3 was meric derivatives resulting respectively from an intramolec-
treated with cesium hydroxide and reacted with the bromo- ular and an intermolecular complexation. The mononuclear
butyldiphenylphosphane–borane leading to TTF 5. Decom- metallamacrocycles formed can be easily isolated after col-
plexation of the phosphane–borane complex was performed umn chromatography upon silica gel in an overall yield of
in the presence of DABCO under an inert atmosphere to 20–33%.
give the bis[(diphenylphosphanyl)butylthio]TTF 2.[8] These
Analysis of the fraction containing the mononuclear
TTFs 1–2 should be kept under an inert atmosphere to complexes by 31P NMR, after the chromatographic separa-
avoid the formation of the corresponding phosphane ox- tion, reveals the presence of four signals for each of the four
ides. Note that all these TTFs 1–5 are obtained as a mixture investigated derivatives 6–9 (Table 1). Indeed, besides the
of the cis and trans isomers and attempts to separate these cis/trans isomerism of the TTF core, the phosphorus atoms
isomers are worthless as TTFs are prone to isomerization can also be either cis or trans coordinated to the metal cen-
in solution upon light exposure or in the presence of traces ter. For the tungsten metallamacrocyles 6 and 8, a small
of acid.[9,10]
doublet due to the coupling of the phosphorus atom with
In order to form metal carbonyl complexes with these the 183W isotope is associated with the four singlets. Thanks
TTF ligands, we used cis-M(CO)4(C5H10NH)2 derivatives to the coupling constant, it is possible to distinguish the cis-
(M = Mo, W) where the two labile piperidine ligands can P–W–P isomers from the trans-P–W–P ones.[13] Indeed, the
be easily replaced by other ligands such as two phospha- phosphorus atoms resonate at high field for 6 and 8 with
nes.[11] As mentioned earlier for monosubstituted phos- 1JPW = 230 Hz characteristic for the cis-P–W–P isomers
phanylTTF derivatives, the metal carbonyl complexation while the two signals observed at low field for 6 and 8 exhi-
can be realized directly from the phosphane–borane TTF bit a 1JPW = 279 Hz characteristic for the trans-P–W–P one.
complexes,[12] in a one-pot procedure by a two-step chemi- For the molybdenum metallamacrocycles, by analogy with
cal synthesis: firstly decomplexation of the phosphane–bo- previous results on monodiphenylphosphanylpropylthio-
rane complex in the presence of DABCO and then addition TTF (P–TTF) cis coordinated to the Mo(CO)4, cis-Mo(CO)4-
of one equivalent of cis-M(CO)4(C5H10NH)2 in the medium (P–TTF)2,[12] where the phosphorus atoms resonated at δ =
where the bis[(diphenylphosphanyl)alkylthio]TTFs were 26.6 ppm, the singlets observed at high field for 7 and 9
formed. The solution was warmed at 80 °C for 2 h. Actu- can be attributed to cis-P–Mo–P isomers while the signals
ally, because of the flexibility of the alkylthio spacer groups, observed at low field for 7 and 9 are assigned to the trans
two types of metal carbonyl complexes were obtained, the isomers.
Scheme 2.
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Table 1. 31P chemical shifts for compounds 6–9 in CDCl3 solution.
Compound (metal, n) δ = 31P ppm (1JPW [Hz])
6 (W, 3)
7 (Mo, 3)
8 (W, 4)
9 (Mo, 4)
5.9 (230), 6.9 (230), 13.5 (279), 14.6 (279)
24.2, 24.7, 38.4, 39.3
8.0 (230), 8.6 (230), 14.8 (279), 14.9 (279)
25.5, 25.7, 39.0, 39.1
Interestingly, the intensity of the various signals observed
indicates that a majority of the trans isomers on the metal
center are formed in all the cases with an estimated trans
P–M–P/cis P–M–P ratio of 5:2. The obtention of cis/trans
isomers on the metal center, starting from the cis-M(CO)4-
(piperidine)2 derivatives (M = Mo, W), finds its origin in
the temperature used to form these metallamacrocycles.[11]
Indeed, when the reaction was performed at 50 °C, no isom-
erization occurs as previously observed for monosubsti-
tuted TTF but the reaction rate is very low, while at 80 °C
substitution of the two piperidine ligands occurs, especially
for the cis-W(CO)4(piperidine)2 derivative, but also isomer-
ization on the metallic center. The TTF core can also adopt
either a cis or trans configuration. The presence of isomers
on the TTF moiety is not surprising as we started from a
mixture of cis and trans isomers for both TTFs 4 and 5.
Moreover, the trans form of the TTF introduces an element
of planar chirality. Therefore, as depicted in Scheme 3, six
stereoisomers can be envisioned for each metallamacrocy-
cle, 6–9, corresponding to the following isomers: (i) a cis
TTF/trans P–M–P, (ii) b cis TTF/cis P–M–P, (iii) c trans
(R)TTF/cis P–M–P and cЈ trans (S)TTF/cis P–M–P and (iv)
d trans (R)TTF/trans P–M–P, and dЈ trans (S)TTF/trans P–
M–P, hence the four 31P NMR signals since the enantio-
mers c/cЈ and d/dЈ can not be distinguished in this way.
Crystals of the metallamacrocyles 6, 7, and 8 were iso-
lated from a mixture of dichloromethane and methanol.
The crystal structure determinations reveal that in the case
of the macrocycles 6 (n = 3, M = W) and 8 (n = 4, M
= W), the isomers a (cis TTF/trans P–W–P), were isolated
(Figure 1), while for 7 (n = 3, M = Mo) the two enantio-
meric forms 7 c/cЈ [trans (R/S) TTF/cis P–Mo–P] (Figure 2)
were crystallized in the racemic mixture.
Scheme 3.
Figure 1. Molecular structure of (left) 6a and (right) 8a. The hydro-
gen atoms and the phenyl rings are not shown for clarity (thermal
ellipsoids set at 50% probability). Selected bond lengths [Å] and
angles [°]: W(1)–P(1) 2.4636(12), W(1)–P(2) 2.4644(14), P(1)–W(1)–
P(2) 177.36(5) for 6a and: W(1)–P(1) 2.4717(8), W(1)–P(2)
2.4652(8), P(1)–W(1)–P(2) 176.20(2) for 8a.
All the TTF moieties adopt a boat conformation within
these metallacyclophanes where both dithiole rings are usual range. Therefore, constrains brought by the formation
folded along the S···S vector with asymmetric folding of the metallamacrocycle are more effective on the fulvalene
angles, which are more pronounced for the most strained skeleton than on the inorganic part. Analysis of the crystals
17-membered metallamacrocycles 6a (17 and 28°) and 7c/cЈ 6a and 8a, dissolved in CDCl3, by 31P NMR reveals that
(19 and 36°) than for the 19-membered metallamacrocycle the isomers a (cis TTF/trans P–W–P) exhibit only one set
8a (9 and 11°). Comparison of the crystal structure of 6a of signals at δ = 13.5 ppm for 6a and at δ = 14.8 ppm for
(n = 3) with 8a (n = 4), where the difference is only due to 8a. The same CDCl3 solution left under ambient light expo-
the length of the spacer group between the TTF and the sure and analyzed again one day later exhibits this time two
phosphorus atoms, shows that in both cases, the W–P dis- sets of signals caused by the presence of the cis and trans
tances and P–W–P interligand angles are similar and in the TTF isomers.[9]
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Redox-Active Metallamacrocycles Incorporating Tetrathiafulvalene
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described above. Interestingly, comparison can also be
made with TTF cyclophanes where fully covalent bridges
of various lengths link the two dithiole moieties leading to
14-, 18-, and 20-membered rings.[16–18] Indeed, among those
cyclophanes, the most constrained one with the shortest
bisthioalkyl link (–S(CH2)6S–[16] and –SCH2C6H4-
CH2S–[16,17]) were found to exhibit a single irreversible oxi-
dation wave, while by contrast, longer links [–S(CH2)10–12S][18]
or the redox active metallamacrocycles described here
display a first fully reversible oxidation wave. The lack of
reversibility of the redox system on the 14-membered TTF
cyclophanes was attributed to the severe bending of the
TTF core as for instance the cis-substituted TTF with a
bisthiohexyl bridge, [–S(CH2)6S], is folded by 47 and 34°
along the S···S vector.[16b] Although, in 6–9, the metallic
fragment with the CO ligands brings a novel inner con-
straint to the TTF unit, the bridge is long enough to enable
the two typical redox waves of a TTF core.
Figure 2. Molecular structure of 7c. The hydrogen atoms and the
phenyl rings are not shown for clarity (thermal ellipsoids set at
50% probability). Selected bond lengths [Å] and angles [°]: Mo(1)–
P(1) 2.5386(13), Mo(1)–P(2) 2.5666(12), P(1)–Mo(1)–P(2) 99.85(4).
Table 2. Oxidation potentials V vs. SCE, Pt-working electrode with
nBu4NPF6 (0.1 ⁾ in CH2Cl2, scanning rate 0.1 V/s.
2
2
Compound (metal, n)
E1
Epa / Epc
W(CO)4(PPh3)2
Mo(CO)4(PPh3)2
6 (W, 3)
0.87[a]
0.85/0.76
0.45
0.47
0.41
0.41
0.46
0.39
0.93/.0.82
0.91/.0.82
0.88/0.77
0.85/0.76
0.86/0.80
0.82[a]
7 (Mo, 3)
8 (W, 4)
9 (Mo, 4)
1 (n = 3)
2 (n = 4)[14]
The redox properties of the metallacyclophanes 6–9 were
studied by cyclic voltammetry and peak potentials of the
various complexes are collected in Table 2 together with the
data for the starting ligands TTF 1 and 2. In order to ob-
tain an insight into the effect of the ligand environment on
the redox potentials of the metal center, we also added to
Table 2 the data for complexes Mo(CO)4(PPh3)2 and
W(CO)4(PPh3)2. It is worth noting that cis-M(CO)4-
(PPh3)2 and trans-M(CO)4(PPh3)2 (M = Mo, W) present
almost identical E° values [15] and exhibit cyclic voltammog-
[a] Irreversible process.
Considering the second redox process, the comparison of
2
rams which are partially reversible for the molybdenum the anodic peak potential Epa in the complexes 6–9 with
complex and irreversible for the tungsten one because of the value of the noncyclic Mo(CO)4(PPh3)2 and W(CO)4-
2
the loss of carbon monoxide on the metallic center upon (PPh3)2 shows a significant positive shift of Epa in the 17-
oxidation.[15] Concerning the various metallamacrocycles, membered cyclic compounds 6 and 7 (+60 mV for Mo, W)
2
two oxidation waves are observed. The first reversible oxi- while the Epa potentials are almost identical in the less-
dation step corresponds to the oxidation of the TTF in its constrained 8 and 9 molecules. This indicates that through-
radical cation while the second oxidation process is due to space interactions occur between the two−organic and
the concomitant oxidation of the TTF radical cation into organometallic−redox moieties in the smallest metallamac-
the dication and the oxidation of the metallic center. How- rocycles. This effect on Epa2 is most probably due to electro-
ever, this process is not fully reversible due to the loss of static repulsion and the close proximity of the TTF dication
the carbonyl ligand upon oxidation (Figure 3). This con- to the bound metal. Note that by contrast, when the phos-
comitant oxidation of the organic and inorganic moieties phane is directly linked to the TTF core, as in [P2][M(CO)4]
was also observed on phosphane TTF linked to a metal via (M = Mo, W), oxidation of the coordinated metallic center
a nonconjugated spacer group, such as cis-Mo(CO)4- occurs at a more positive potential than the TTF+/TTF2+
(P–TTF)2.[12] Within the metallamacrocycles of the same redox system because of even stronger electrostatic interac-
size, the nature of the metal center, Mo or W, does not tions.[19] In this case the donating ability of the TTF core
modify the redox potentials. Moreover, comparison of the within the complexes was also significantly decreased as a
first redox potentials of the complexes with those of the positive shift of about 200 mV was observed, while in our
starting ligands (1 and 2) shows that there is no significant metallamacrocycle 6–9 the redox properties of the donor
influence of the cyclization despite the strained structures are conserved.
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in the unit cell, one TCNQ located on an inversion center,
one acetonitrile disordered on an inversion center, and one
acetonitrile in a general position. Complex (8)2(TCNQ)·
¯
(CH3CN)2 crystallizes in a triclinic system, space group P1,
with molecule 8 in a general position in the unit cell, TCNQ
located on an inversion center with only one acetonitrile in
a general position. In the solid state, the TCNQ molecule
is, in each case, sandwiched by two TTF cores of the metall-
amacrocycles in a ···DAD··· (D = 6 or 8 and A = TCNQ)
motif. The TCNQ ring overlaps the central C=C bond of
the TTF core and the interplanar separations between the
donor and the acceptor are 3.48 and 3.53 Å for (6)2(TCNQ)·
(CH3CN)3 and (8)2(TCNQ)·(CH3CN)2, respectively (Fig-
ure 4). Using the empirical formula of Kistenmacher, which
correlates the bond lengths to the formal charge of the
TCNQ in various charge transfer salts,[22] we found that in
both complexes the TCNQ is neutral. This is supported by
the EPR analyses carried out on the crystals and no EPR
signal was observed from room to liquid helium tempera-
ture. This is also confirmed by the diamagnetic behavior
found in the whole temperature range by SQUID suscep-
tibility measurements. Therefore, both complexes, (6)2-
(TCNQ)·(CH3CN)3 and (8)2(TCNQ)·(CH3CN)2, are neu-
tral donor/acceptor complexes. Concerning (8)2(TCNQ)·
(CH3CN)2, the DAD motifs form stacks with a lateral slip
between two neighboring TTF cores with S···S distances at
4.499(9) Å, while for (6)2(TCNQ)·(CH3CN)3 the DAD mo-
tifs are isolated from each other by the inorganic moieties
of the macrocycles (Figure 5).
Figure 3. Cyclic voltammogram of 9, nBu4NPF6 (0.1 ⁾ in CH2Cl2,
scanning rate 0.1 V/s.
Formation of charge transfer salts with TCNQ depends
on the relative redox potentials of the donor (ED1) and
1
TCNQ (EA = 0.18 V vs. SCE). These metallamacrocycles
with their first redox potentials above 0.40 V are a rather
borderline case as precursors of such charge transfer salts
1
since ED1-EA Ͼ 0.22 V. Indeed, it is known that a partial
1
or full charge transfer is only possible when ED1-EA
Ͻ
0.25 V.[20–21] Mixing a dichloromethane solution of the
metallamacrocycles 6 or 8 with an acetonitrile solution of
TCNQ afforded deep purple shiny single crystals after slow
evaporation. X-ray crystal structure determinations reveal
a stoichiometry of two metallamacrocycles for one TCNQ
in each case with inclusion of acetonitrile, that is (6)2-
(TCNQ)·(CH3CN)3 and (8)2(TCNQ)·(CH3CN)2. The for-
mer complex with 6 (n = 3) crystallizes in the triclinic sys-
Figure 4. TTF/TCNQ overlap in (6a)2(TCNQ)·(CH3CN)3 (left) and
¯
tem, space group P1, with molecule 6 in a general position (8a)2(TCNQ)·(CH3CN)2 (right).
Figure 5. Stacking arrangement of (6a)2(TCNQ)·(CH3CN)3 (top) and (8a)2(TCNQ)·(CH3CN)2 (bottom).
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Redox-Active Metallamacrocycles Incorporating Tetrathiafulvalene
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Also noticeable, among the six possible stereoisomers for altered and for 6a it amounts to 169.16(3)° instead of
each metallamacrocycle 6 and 8 present in the starting solu- 177.36(5)° and for 8a 176.20(2)° instead of 172.58(4)°, ac-
tion for the elaboration of the TCNQ complexes, the iso- counting for the consequences of the complexation with
mers that crystallized within these complexes are the iso- TCNQ (Table 3). Therefore, even with a constrained struc-
mers a (cis TTF/trans P–W–P), which were independently ture such as 6a these metallamacrocyles remain flexible and
crystallographically characterized and described above. The the planarization of the TTF core, within the TCNQ com-
complexation with TCNQ has a significant influence on the plexes, induces a transfer of the constraints onto the met-
conformation of the metallamacrocycles 6a and 8a as de- allic fragment.
picted in Figure 6. Comparison of the molecular structures
shows that the TTF core for the 17-membered metallamac-
Table 3. Significant bond lengths [Å] and angles [°].
Compound
d W–P
d C=C Angle P–W–P Folding angles
along S···S vector
rocycle 6a is more planar within the complex as the folding
angles along the S···S vector for the dithiole rings are
smaller (11 and 15° instead of 17 and 28°). The planariz-
ation of the TTF core in (6a)2(TCNQ)·(CH3CN)3 brings
the metal closer to the TTF core with a distance of about
5.85 vs. 6.25 Å in the starting complex. Contrariwise, for
the 19-membered metallamacrocycle 8a, the folding angles
are in the same range (10 and 10° instead of 11 and 9°).
Actually, the difference brought by the complexation on 8a
lies in the location of the metal in relation to the TTF core.
Indeed, within the complex (8a)2(TCNQ)·(CH3CN)2 the
side chain with the metallic moiety is located in a plane
perpendicular to the plane of the TTF core, while before
complexation the chain with the metallic fragment was lo-
cated more on the side of the TTF (Figure 6).
6a
2.4636(12) 1.310(9) 177.36(5)
2.4644(14)
2.4655(10) 1.340(6) 169.16(3)
2.4697(9)
17
28
11
15
9
11
10
10
(6a)2(TCNQ)
8a
2.4652(8)
2.4717(8)
1.312(6) 176.20(2)
(8a)2(TCNQ)
2.4550(12) 1.340(9) 172.58(4)
2.4606(12)
Conclusions
In this study, redox active 17- and 19-membered metalla-
macrocycles incorporating one TTF unit have been syn-
thesized through the coordination of the bidentate [(di-
phenylphosphanyl)alkylthio]TTFs to the Mo(CO)4 and
W(CO)4 fragments. As a consequence of the possible
cis/trans isomerization of the TTF core and the metallic
fragment six stereoisomers were formed. As evidenced by
the X-ray diffraction studies, the central TTF unit in these
metallamacrocycles is not planar, however it is significantly
less folded in the 19-membered ring than in the 17-mem-
bered ring. Nevertheless, the bending of the TTF is not suf-
ficient to negate the electron-donating ability of this redox
unit. Furthermore, in the 17-membered metallamacrocycles,
the close proximity of the metallic fragment to the TTF
produces electrostatic interactions as evidenced by the shift
of the oxidation peak potentials of the metallic fragment to
more positive potentials. Two TCNQ complexes with the
17- and 19-membered metallamacrocycles (M = W) have
been obtained and crystallographically analyzed. Although
no charge transfer was observed, comparison of the crystal
structures provide valuable information on the relative flexi-
bility of these strained structures. An attractive feature of
these metallamacrocycles lies in the modification of the
TTF core upon oxidation which should modify the molecu-
lar organization in the neighborhood of the metal fragment
and attempts at isolating cation radical salts are currently
under way.
Figure 6. Side view of the metallamacrocycles, (a) 6a, (b) (6a)2-
(TCNQ)·(CH3CN)3, (c) 8a, (d) (8a)2(TCNQ)·(CH3CN)2.
Analysis of the bond lengths of the metallamacrocycles
within the TCNQ complexes shows that in both cases the
bond lengths of the TTF core are in the usual range for
neutral TTF moieties with the central C=C bond length-
ened by 1.340 Å, but still within the range for the neutral
TTF core. Similarly, the W–P distances are not significantly
Experimental Section
1H NMR and 31P NMR spectra were recorded with a Bruker AC
300P spectrometer. Chemical shifts are reported in ppm referenced
to TMS for 1H NMR and to H3PO4 for 31P NMR spectroscopy.
Elemental analyses were obtained from the Laboratoire Central de
modified (Table 3). On the contrary, the P–W–P angles are Microanalyse du CNRS, Lyon. Mass spectra were recorded with
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1
a ZABSpec TOF instrument by the Centre Régional de Mesures
Physiques de l’Ouest, Rennes. CH2Cl2 was distilled from P2O5. Tol-
uene was dried with sodium wire. Chromatography was performed
using silica gel Merck 60 (70–260 mesh). Mo(CO)6 and 1,4-diazabi-
cyclo[2.2.2]octane (DABCO) were purchased from ACROS Or-
ganics, W(CO)6 was purchased from Aldrich. M(CO)4(NHC5H10)2
was prepared from M(CO)6 according to published procedures.[11]
Cyclic voltammetry was carried out in dichloromethane, containing
0.1  nBu4NPF6 as the supporting electrolyte. Voltammograms
were recorded at 0.1 Vs–1 on a platinum disk electrode (A =
1 mm2). The potentials were measured vs. a saturated calomel elec-
trode. TTF 2 was prepared following known procedures.[5]
Complex 8: Yield 120 mg (22%). H NMR (CDCl3): δ = 1.18–1.80
(4 m, 8 H), 2.00, 2.02, 2.10, 2.12 (4 s, 6 H), 2.41–2.62 (4 m, 8 H),
7.15–7.50 (m, 20 H) ppm. 31P NMR (CDCl3): δ = 8.0 (1JWP
=
230 Hz), 8.6 (1JWP = 230 Hz), 14.8 (1JWP = 279 Hz), 14.9 (1JWP
= 279 Hz) ppm. C44H42O4P2S6W: HRMS calcd. 1072.0392; found
1072.0395.
1
Complex 9: Yield 100 mg (20%). H NMR (CDCl3): δ = 1.18–1.40
(4 m, 4 H), 1.40–1.55 (4 m, 4 H), 1.92–2.09 (4 s, 6 H), 2.38–2.62
(4 m, 8 H), 7.12–7.49 (m, 20 H) ppm. 31P NMR (CDCl3): δ = 25.5,
25.7, 39.0, 39.1 ppm. C44H42MoO4P2S6: HRMS calcd. 985.9940;
found 985.9946.
Crystallization of the derivatives 6, 7, and 8 from CH2Cl2/MeOH
afforded prisms of complexes 6a, 7c/cЈ, and 8a that were suitable
for X-ray crystal structure analyses.
General Procedure for the Synthesis of Complexes 6–9: To a solution
of the TTF 4 or 5 (0.5 mmol) in dried, degassed toluene (30 mL)
DABCO (112 mg, 1 mmol) was added under argon. The mixture
was stirred for 4 h at 50 °C after which M(CO)4(NHC5H10)2
(0.5 mmol) in degassed CHCl3 (10 mL) was added. The resulting
solution was stirred at 80 °C for 2 h and then the solvent was re-
moved under reduced pressure. The solid residue was dissolved in
CH2Cl2, washed with water, and dried with Na2SO4. The solvent
was removed and chromatography of the residue over silica gel (3:1
CH2Cl2/PE) afforded the complexes 6–9 as a mixture of isomers.
Single-Crystal Structure Determination: A single crystal of each
compound was carefully selected under a polarizing microscope
and glued to a thin fiber glass. Single crystal data collection was
performed at room temperature with a Nonius KappaCCD dif-
fractometer (Centre de Diffractométrie, Université de Rennes,
France), with Mo-Kα radiation (λ = 0.71073 Å). A crystal-to-detec-
tor distance of 25.0 mm was used for all the crystals and the data
collection strategy (determination and optimization of the goniom-
eter positions) was performed with the help of the COLLECT pro-
gram.[23] Experimental details of the data collection are summa-
rized in Table 4.
1
Complex 6: Yield 170 mg (33%). H NMR (CDCl3): δ = 1.20–1.40
(4 m, 4 H), 1.99, 2.01, 2.09, 2.14 (4 s, 6 H), 2.25–2.64 (4 m, 4 H),
2.70–3.0 (4 m, 4 H), 7.19–7.70 (m, 20 H) ppm. 31P NMR (CDCl3):
δ = 5.9 (1JPW = 230 Hz), 6.9 (1JPW = 230 Hz), 13.5 (1JPW = 279 Hz),
14.6 (1JPW
= 279 Hz) ppm. C42H38O4P2S6W: HRMS calcd.
The integration process and data reduction was carried out using
the DENZO-SCALEPACK[24] program. Numerical absorption
corrections were performed using the multiscan procedure[25a] im-
1044.0075; found 1044.0075. C42H38O4P2S6W·CH3OH: calcd. C
47.95, H 3.90, S 17.84; found C 47.58, H 3.80, S 17.53.
Complex 7: Yield 100 mg (20%). H NMR (CDCl3): δ = 1.20–1.40 plemented in the WinGX program suite.[25b] Structure determi-
1
(4 m, 4 H), 1.98, 2.02, 2.14, 2.16 (4 s, 6 H), 2.25–2.64 (4 m, 4 H),
nation was performed with the direct methods solving program
2.70–3.0 (4 m, 4 H), 7.19–7.70 (m, 20 H) ppm. 31P NMR (CDCl3): SIR97,[26] which revealed all the non-hydrogen atoms. SHELXL
δ = 24.2, 24.7, 38.4, 39.3 ppm. C42H38MoO4P2S6: HRMS calcd.
957.9626; found 957.9626.
97[27] was used to refine the structure. Finally, hydrogen atoms were
placed geometrically and held in the riding mode in the least-square
Table 4. Crystallographic data.
Structure parameter
6a
7c/cЈ
8a
(6a)2(TCNQ)·(CH3CN)3 (8a)2(TCNQ)·(CH3CN)2
Empirical formula
Molecular weight
Color
Cryst. system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C42H38O4P2S6W1 C42H38MoO4P2S6 C44H42O4P2S6W1 C51H44.5N3.5O4P2S6W
C52H47N3O4P2S6W
1216.05
purple
1044.87
orange
triclinic
956.96
yellow
monoclinic
P21/c
1072.93
orange
triclinic
1208.55
purple
triclinic
triclinic
¯
¯
¯
¯
P1
P1
P1
P1
10.4523(2)
12.1755(2)
18.1465(4)
79.438(1)
78.558(1)
80.787(1)
2206.69(7)
2
13.0628(2)
17.6849(4)
19.7180(4)
90
105.2488(10)
90
10.4360(1)
12.5218(1)
18.1813(3)
79.8321(5)
84.1490(5)
85.6027(5)
2322.21(5)
2
12.31580(10)
15.0526(2)
16.5610(3)
68.7400(10)
69.4250(10)
85.3210(10)
2675.01(6)
2
12.1689(3)
12.9499(4)
18.5932(5)
101.823(2)
92.619(2)
109.5750(10)
2681.27(13)
2
γ [°]
V [Å3]
4394.77(15)
4
Z
F(000)
1044
1.573
3.014
42143
10104
0.0611
1960
1.446
0.696
44160
9658
0.0985
1076
1.535
2.867
46842
13458
0.0829
1214
1.501
2.499
52690
11779
0.082
1224
1.506
2.493
41261
11380
0.0836
Dcalcd. [g/cm3]
M [mm–1]
Data collected
Independent data
Rint
Observed data
[I Ͼ 2σ(I)]
Parameters refined
R(F)
8380
497
0.0426
0.1137
1.044
5587
497
0.0532
0.1578
1.02
11327
515
0.0386
0.1005
1.052
9492
625
0.0383
0.0799
1.05
9154
615
0.0459
0.1058
1.085
wR(F2)
GoF
Residual d [e·Å–3]
1.305/–1.198
0.676/–0.589
1.408/–1.501
0.921/–0.882
1.717/–1.46
2610
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 2604–2611

Redox-Active Metallamacrocycles Incorporating Tetrathiafulvalene
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Published Online: May 2, 2006
Eur. J. Inorg. Chem. 2006, 2604–2611
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2611