Charge-transfer salts of octamethylferrocenyl thioethers with organic acceptors (TCNQ and TCNQF4) and trihalides (Br3- and I3-). Synthesis, structure, and physical properties

Article abstract of DOI:10.1021/om9902075

Six charge-transfer (CT) complexes containing three different octamethylferrocene derivatives (Fe(η⁵-C₅Me₄SMe)₂, 1; Fe(η⁵-C₅Me₄S^tBu)₂, 2; Fe(η⁵-C₅Me₄S)₂S, 3) and TCNQ or TCNQF₄, respectively (4-9), have been prepared and fully characterized. X-ray crystal structural studies of 4, 5, 7, and 9 have been carried out. The CT complexes 4 and 5, containing TCNQ, display stacks of acceptor molecules with noncommon donor/acceptor stoichiometries of 3:7 for 4 and 1:3 for 5, whereas the charge-transfer complexes 7 and 9, containing TCNQF₄, display strongly interacting dimers of acceptor anions. The compounds 4-6 behave as semiconductors with room-temperature conductivities up to 3.5 S cm^-1 for 6. Magnetic susceptibility measurements indicate strong antiferromagnetic interaction for the (TCNQF₄)₂^2- dimers in 7-9, the dimers being diamagnetic (S = 0) at room temperature. Antiferromagnetic interactions are also observed for the three compounds 4-6. To obtain more accurate Lande?-g factors for the three possible cations from 1-3, the corresponding trihalogenide salts with Br₃^- (10-12) and I₃^- (13-15) were prepared and fully characterized. Their magnetic properties, only deriving from the cations, were measured, and X-ray crystal structural studies have been carried out for the compounds 11, 12, 14, and 15. For the two compounds containing the tert-butyl substituent (11 and 14), a DADA structural motif was observed, and with the trithiaferrocenophanium, chains (12) and networks (15) of alternating sulfur bridges and trihalogenide anions were observed.

Full text of DOI:10.1021/om9902075

Organometallics 1999, 18, 3679-3689
3679
Ch a r ge-Tr a n sfer Sa lts of Octa m eth ylfer r ocen yl
Th ioeth er s w ith Or ga n ic Accep tor s (TCNQ a n d TCNQF 4)
-
-
a n d Tr ih a lid es (Br 3 a n d I3 ). Syn th esis, Str u ctu r e, a n d
P h ysica l P r op er ties
Stefan Zu¨rcher, J eannine Petrig, Volker Gramlich,† Michael Wo¨rle,†
Christian Mensing,‡ Dieter von Arx,§ and Antonio Togni*
Laboratory of Inorganic Chemistry, ETH Zentrum, Swiss Federal Institute of Technology,
CH-8092 Zu¨rich, Switzerland
Received March 24, 1999
Six charge-transfer (CT) complexes containing three different octamethylferrocene deriva-
tives (Fe(η5-C5Me4SMe)2, 1; Fe(η5-C5Me4StBu)2, 2; Fe(η5-C5Me4S)2S, 3) and TCNQ or TCNQF4,
respectively (4-9), have been prepared and fully characterized. X-ray crystal structural
studies of 4, 5, 7, and 9 have been carried out. The CT complexes 4 and 5, containing TCNQ,
display stacks of acceptor molecules with noncommon donor/acceptor stoichiometries of 3:7
for 4 and 1:3 for 5, whereas the charge-transfer complexes 7 and 9, containing TCNQF4,
display strongly interacting dimers of acceptor anions. The compounds 4-6 behave as
semiconductors with room-temperature conductivities up to 3.5 S cm-1 for 6. Magnetic
2-
susceptibility measurements indicate strong antiferromagnetic interaction for the (TCNQF4)2
dimers in 7-9, the dimers being diamagnetic (S ) 0) at room temperature. Antiferromagnetic
interactions are also observed for the three compounds 4-6. To obtain more accurate Lande´-g
factors for the three possible cations from 1-3, the corresponding trihalogenide salts with
-
-
Br3 (10-12) and I3 (13-15) were prepared and fully characterized. Their magnetic
properties, only deriving from the cations, were measured, and X-ray crystal structural
studies have been carried out for the compounds 11, 12, 14, and 15. For the two compounds
containing the tert-butyl substituent (11 and 14), a DADA structural motif was observed,
and with the trithiaferrocenophanium, chains (12) and networks (15) of alternating sulfur
bridges and trihalogenide anions were observed.
In tr od u ction
TCNQ or TCNQF4 have also been reported.2,15-44 These
materials turn out to be either insulators (e.g., the 1:1
In continuation of our studies concerning CT com-
plexes with ferrocene donor molecules,1-5 in particular
the recently described 1,1′-bis(alkylthio)octamethyl-
ferrocenes,1 we report herein the synthesis and struc-
tural and physical characterization of CT complexes
corresponding to the six combinations of donors 1-3 and
the acceptors TCNQ and TCNQF4, respectively (see
Scheme 1). In general, depending on the redox potential
and the steric demand of the donor molecules, TCNQ-
containing complexes show different stoichiometries
(donor-to-acceptor ratio), such as 1:1,6 1:2,2,7-9 1:3,10,11
1:4,12,13 and 2:5,14 although other proportions have been
observed. Several organometallic derivatives containing
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‡ Conductivity measurements.
§ Magnetic susceptibility measurements.
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10.1021/om9902075 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 08/05/1999

3680 Organometallics, Vol. 18, No. 18, 1999
Zu¨rcher et al.
ferrocenium cations2,7); alternatively they show metallic
character (e.g., (TTF)(TCNQ)45 or (TSeF)(TCNQ)46), as
reported in excellent review articles concerning conduct-
ing organic compounds.47,48 On the other hand, com-
pounds with interesting magnetic properties (normal
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Sch em e 1
The two 1,1′-bis(alkylthio)octamethylferrocenes 1 and
2 differ only in the steric bulk of the thioalkyl group
and have the same redox potential of -0.28(2) V vs the
Fc/ Fc+ couple, which corresponds also to the potential
of the acceptor TCNQ.4,29 Moreover, the redox potential
of the trithiaferrocenophane 3 is higher (-0.10(2) V vs
the Fc/ Fc+ couple) and the molecule is more compact,
as compared to compounds 1 and 2. Therefore, on the
basis of these properties, different stoichiometries of the
CT complexes were anticipated. Furthermore, for a more
reliable interpretation of the magnetic properties of such
CT complexes and because ferrocenes are known to have
strongly anisotropic Lande´-g factors,50,51 six trihalo-
genide salts (with bromine and iodine) of 1-3, possess-
ing a paramagnetic cation and a diamagnetic anion,
have been prepared. Magnetic susceptibility measure-
ments thereof allowed the calculation of the g -factors
for the three ferrocene donor molecules 1-3.
Resu lts a n d Discu ssion
salts containing ammonium cations) or semiconductors
(e.g., the mixed valent 1:2 or 1:3 complexes with
Syn th esis of Ch a r ge-Tr a n sfer Com p lexes. The
CT complexes 4 and 5 containing the octamethyl-
ferrocene derivatives 1 and 2, respectively, and TCNQ
could be obtained on mixing hot acetonitrile solutions
of the two components, followed by slow cooling to room
temperature. Even when the precursors were mixed in
different ratios, only one stoichiometry of donor and
acceptor was obtained, i.e., [1]3[TCNQ]7 for 4 and [2]-
[TCNQ]3 for 5, as confirmed by elemental analyses on
crystalline materials. Experiments using molar ratios
of the reagents different from the stoichiometric coef-
ficients of the CT salts afforded the products in lower
yields and often contaminated by the neutral starting
materials. A ratio of donor and acceptor of 3:7, as
observed for 4 is unprecedented in the solid-state
chemistry of TCNQ.
(22) Lequan, R. M.; Lequan, M.; Flandrois, S.; Delhaes, P.; Bravic,
G.; Gaultier, J . Synth. Met. 1991, 42, 1663-1666.
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M. Acta Crystallogr. 1992, 48C, 1425-1428.
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Lyding, J . W.; Rauchfuss, T. B.; Wilson, S. R. Organometallics 1986,
5, 2386-2388.
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1991, 2377-2393.
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Commun. 1991, 489-491.
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The third CT complex 6, [3][TCNQ]2, could only be
obtained upon addition of an excess of [Bu4N]BF4 to the
reaction mixture. Black crystals of 6 were thus obtained
in good yields by slow evaporation of solutions at ca. 60
°C during several days. In the absence of [Bu4N]BF4
only the neutral starting materials crystallized.
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Candela, G. A.; Swartzendruber, L. J .; Miller, J . S. J . Am. Chem. Soc.
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Chakraborty, A.; Epstein, A. J . Inorg. Chem. 1989, 28, 2930-2939.
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Organometallics 1991, 10, 688-693.
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Plenum: New York, 1979; Vol. 6, pp 407-414.
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970.

CT Salts of Octamethylferrocenyl Thioethers
Organometallics, Vol. 18, No. 18, 1999 3681
Ta ble 1. Cr ysta llogr a p h ic Da ta for CT Com p lexes 4, 5, 7, a n d 9
4
5
7
9
formula
fw
C
48H39.33N9.33S2Fe
C31H27N6SFe0.5
543.6
C32H30F4N4S2Fe
666.57
C30H24F4N4S3Fe
668.57
866.86
cryst dimens, mm
cryst syst
space group (No.)
a, Å
b, Å
c, Å
0.2 × 0.3 × 0.3
triclinic
P1h (No. 2)
8.860(4)
16.375(8)
23.199(12)
81.56(2)
80.72(2)
84.69(2)
3278(3)
3
0.2 × 0.4 × 0.4
triclinic
P1h (No. 2)
8.834(9)
10.173(9)
17.12(2)
82.36(7)
83.34(8)
68.20(8)
1412(2)
2
0.4 × 0.4 × 0.8
triclinic
P1h (No. 2)
8.780(3)
14.716(4)
24.879(9)
81.98(3)
87.89(3)
79.24(2)
3127(2)
0.36 × 0.22 × 0.2
triclinic
P1h (No.2)
9.6858(15)
11.951(2)
25.199(4)
102.17(3)
91.91(3)
92.02(3)
2847.1(8)
4
R, deg
â, deg
γ , deg
V, Å3
Z
4
F(calcd)r, g cm-3
µ, mm-1
F(000)
1.318
0.486
1352
1.278
0.392
568
1.416
0.668
1376
1.560
0.805
1368
diffractometer
Syntex P21
Syntex P21
Syntex P21
Siemens SMART PLATFORM
with CCD detector
Mo KR, λ ) 0.71073
0.83-26.40
21370
11625
762
0.0947
0.0421
wavelength λ, Å
θ range, deg
Mo KR, λ ) 0.71073
1.64-20.06
6714
6178
818
0.0690
0.0328
0.737
Mo KR, λ ) 0.71073
2.58-20.04
2832
2611
350
0.0965
0.0350
1.091
Mo KR, λ ) 0.71073
1.54-20.04
5878
5878
776
0.1104
0.0455
0.888
no. of measd reflcns
no. of obsd reflcns (n)a
no. of params refined (p)
wR2 [I > 2σ(I)]b
R1 [I > 2σ(I)]c
GOF on F2 d
0.926
(|Fo | > 4.0σ(|F| )). wR2 ) [σ(w(Fo - Fc2)2]/σ[w(Fo2)2]1/2
.
c R1 ) σ||Fo| - |Fc||/σ|Fo|. GOF ) S ) [σ(w(Fo - Fc2)2]/(n - p)]1/2
.
a
2
2
b
2
d
2
Ta ble 2. Cr ysta llogr a p h ic Da ta for Com p ou n d s 11, 12, 14, a n d 15
11
12
14
15
formula
fw
C
26H42FeBr3S2
C18H24FeBr3S3
632.13
C26H42FeI3S2
855.27
C18H24FeI3S3
733.13
740.30
cryst dimens, mm
cryst syst
space group (No.)
a, Å
b, Å
c, Å
1.2 × 0.2 × 0.1
monoclinic
P21/n (No. 14)
10.572(3)
10.928(4)
13.533(5)
90
0.2 × 0.15 × 0.12
triclinic
P1h (No. 2)
9.194(5)
11.104(6)
12.092(6)
76.64(2)
79.310(10)
69.64(2)
1118.5(10)
2
0.3 × 0.1 × 0.1
orthorhombic
Pnnm (No. 58)
10.878(6)
11.003(7)
13.533(7)
90
90
90
1620(2)
2
1.754
0.3 × 0.3 × 0.1
orthorhombic
Pbca (No. 61)
15.189(9)
12.610(7)
25.080(15)
90
90
90
4804
8
R, deg
â, deg
94
90
γ , deg
V, Å3
1559.3(9)
2
1.521
4.474
722
Z
F(calcd)r, g cm-3
1.877
14.294
622
2.138
4.746
2920
µ, mm-1
3.466
830
F(000)
diffractometer
wavelength λ, Å
θ, range, deg
no. of measd reflcns
no. of obsd reflcns (n)a
no. of params refined (p)
wR2 [I > 2σ(I)]b
R1 [I > 2σ(I)]c
GOF on F2 d
Syntex P21
Mo KR, λ ) 0.71073
2.36-20.04
1461
1461
156
0.0871
0.0390
0.750
Syntex P21
Mo KR, λ ) 0.71073
1.89-25.00
2287
2287
227
0.1274
0.0491
1.092
Syntex P21
Mo KR, λ ) 0.71073
2.39-22.55
1126
1126
92
0.0601
0.0265
0.727
Syntex P21
Mo KR, λ ) 0.71073
1.62-22.55
3166
3166
227
0.1485
0.0579
0.838
a
2
2
b
2
d
2
(|Fo | > 4.0σ(|F| )). wR2 ) [σ(w(Fo - Fc2)2]/σ[w(Fo2)2]1/2
.
c R1 ) σ||Fo| - |Fc||/σ|Fo|. GOF ) S ) [σ(w(Fo - Fc2)2]/(n - p)]1/2
.
The three corresponding CT salts containing TCNQF4,
7-9, were obtained by a similar procedure as applied
for 4 and 5. However, only the 1:1 stoichiometry was
observed, even when an excess of TCNQF4 was used.
Finally, the six trihalogenide salts 10-15, [Donor][X3]
(see Scheme 1), could be obtained by simply adding a
slight excess of halogen to the corresponding ferrocene
in 1,2-dichloroethane. Slow diffusion of tert-butylmethyl
ether into these solutions afforded the crystalline prod-
ucts in yields up to 88%.
properties (vide infra), it was important to elucidate the
factors so drastically influencing the composition of the
crystalline materials. Single crystals suitable for X-ray
diffraction studies were obtained for compounds 4, 5,
7, 9, 11, 12, 14, and 15. Tables 1 and 2 gives the relevant
crystal and data collection parameters. Bond distances
and angles of each asymmetric unit were found to fall
in the expected ranges and will not be discussed here
(they are provided as Supporting Information, along
with ORTEP representations of the respective asym-
metric unit). Figures 1-7 illustrate the relative ar-
rangement of the molecular components in tridimen-
sional space.
Solid -Sta te Str u ctu r e of Ch a r ge-Tr a n sfer Com -
p lexes. In view of the different stoichiometries observed
for CT complexes containing structurally related donors
and acceptors, and in order to understand their physical
Crystals of 4, 5, 7, and 9 are triclinic and belong to

3682 Organometallics, Vol. 18, No. 18, 1999
Zu¨rcher et al.
F igu r e 2. Side view of two ferrocenium columns with one
TCNQ stack shifted to the front of them in 5. The steric
demand of one cation along the stack is very similar to the
length of a group of three TCNQ molecules.
is expected for van der Waals stacking of aromatic rings
and what is observed also for other CT complexes with
TCNQ.18,19,27,52 The molecular planes are almost paral-
lel, with interplanar angles of 0.3° for BC and 3.30° for
AB. There are two crystallographically independent
ferrocenium cations, X and Y, the iron atom of the latter
being placed on a symmetry center. Thus, the iron
centers of the three cations XYX form a perfect straight
line. The distance FeX-FeY is 8.43 Å, the corresponding
distance between neighboring molecules (FeX-FeX) is
9.49 Å, and the angle FeXFeXFeY is 164.4°. The shortest
Fe-Fe distance between two columns is 8.86 Å, corre-
sponding to the cell dimension a. The pseudo-cen-
trosymmetric cation X has two parallel Cp rings (inter-
planar angle 0.7°), which are rotated against each other
by 178°.
[Fe(η5-C5Me4StBu)2](TCNQ)3 (5) is characterized by
alternating layers of TCNQ stacks and ferrocenium
columns, and the general features of its structure are
very similar to those of [Fe(η5-C5Me4SMe)2]3(TCNQ)7 (4).
The difference is found in the stoichiometry of 1:3 for 5
instead of 3:7 for 4. A TCNQ stack between two
ferrocenium columns is shown in Figure 2.
F igu r e 1. Side view of two TCNQ stacks flanking one
column of ferrocenium cations in 4. The steric demand of
the three cations XYX along the stack is very similar to
the length of a group of seven TCNQ molecules.
space group P1h. [Fe(η5-C5Me4SMe)2]3(TCNQ)7 (4) shows
alternating layers of TCNQ stacks and ferrocenium
columns. The TCNQ molecules form regular stacks, each
interrupted after seven units by a sharp bend. A side
view of two stacks of TCNQ and a ferrocenium column
is shown in Figure 1.
There are two crystallographically independent TCNQ
units A and B, with B on a symmetry center. Always
three molecules form a group with the respective centers
of gravity on a straight line and a distance between the
centers of 3.97 Å. The two acceptors A and B are shifted
by 2.20 Å and the two neighboring molecules A by 1.32
Å in the direction of the longer molecular axes. The
angle between the centers of the molecules AAB is 131°
and the associated distance between two neighboring
units A is 3.68 Å. The interplanar distance of the TCNQ
units is 3.30 Å between AB and 3.44 Å between AA.
The interplanar angle of A and B is 2°. The ferrocenium
cations are placed on the symmetry centers in the edges
of the elementary cell. The Fe-Fe distance in the
stacking direction corresponds to the diagonal of the ab
plane (10.71 Å), and the shortest Fe-Fe distance
corresponds to the cell axis a (8.83 Å).
There are four crystallographically independent ac-
ceptor molecules A-D arranged in the order ABCD-
BCA in a row of seven units, whereby D lies on a
symmetry center. Within each group of seven TCNQ’s
the centers of gravity of the seven molecules lie on a
straight line. This is illustrated by the angles of 179°
between the centers of the acceptors ABC and BCD,
respectively. The plane defined by any of the seven
TCNQ molecules forms an angle of 58° with this axis.
The distance between the centers of the TCNQ’s lies
between 3.87 and 3.89 Å. The bend of the TCNQ stacks
is characterized by an angle of 142° between the axes
of two groups of seven molecules. The distance between
the centers of two neighboring molecules A is 3.53 Å.
Thus, the two A molecules are shifted by only 0.79 Å in
the direction of the longer molecular axes, whereas for
the other pairs (AB, BC, CD) this shift is 2.07. The
distances between the planes of the TCNQ moieties are
between 3.25 Å for BC and 3.30 Å for AB. This is what
(52) Ward, M. D.; Calabrese, J . C.; Fagan, P. J . J . Am. Chem. Soc.
1989, 111, 1698-1719.

CT Salts of Octamethylferrocenyl Thioethers
Organometallics, Vol. 18, No. 18, 1999 3683
F igu r e 3. Side view of two TCNQF4 stacks with two
ferrocenium columns in 7. The anions form dimers with
an interplanar distance of 3.16 Å.
F igu r e 4. View of a layer of three stacks in 9. The
crystallographic independent molecules are marked with
A and B, or X and Y, respectively.
In [Fe(η5-C5Me4SMe)2](TCNQF4) (7) the ferrocenium
ions form two columns surrounded by four stacks of
TCNQF4. The structure is quite similar to that of
[Fe(η5-C5Me4SMe)2][Ni(mnt)2].1 The TCNQF4 anions
form dimers, within which the single units are shifted
against each other by 1.1 Å along the main molecule
axis with an interplanar distance of 3.16 Å. This is
shorter than what is expected for a van der Waals
distance and also shorter than in the 1:1 charge-transfer
complex with ferrocene (3.23 Å),20 where segregated
stacks of TCNQF4 and ferrocenium cations are observed.
Therefore, an attractive interaction between these two
anions must be operating. The interdimer distance is
slightly larger (3.42 Å), but also shorter than in the
above-mentioned ferrocenium complex (3.67 Å). Two
neighbored dimers are shifted parallel to the ring plane
by 5.10 Å with respect to one another. This leads to a
zigzag arrangement along the centers of the anions with
alternating long (6.15 Å) and short (3.34 Å) distances.
A side view of two stacks of TCNQF4 anions with two
ferrocenium colums between them is shown in Figure
3.
Like in the corresponding [Ni(mnt)2] salt,1 the sym-
metry of the cation is C1. The two Cp planes are almost
parallel, with an interplanar angle of 1°, and are rotated
against each other by 98°. The Fe-Fe distance along
the stacking direction is 8.78 Å (unit cell axis a) and
8.44 Å perpendicular to the columns. The shortest S-S
distance is 3.94 Å between two ferrocenes in a column.
In contrast to the three structures above, in [Fe(η5-
C5Me4S)2S](TCNQF4) (9) no segregated stacks of anions
and cations are observed. The structure is best described
by a D+D+A-A-D+D+A-A- motif, which can be com-
pared to what is found in crystals of [Fe(η5-C5HEt4)2]-
(TCNQF4).39 There are two crystallographically inde-
pendent ferrocenophanium molecules X and Y as well
rounded by ferrocenophanium cations. The middle
sulfur atom of the cation X was found to be disordered
and occupying two different positions (S2 und S2B).
Position S2B has an occupancy of only 10%, which
corresponds to an electron density of about two elec-
trons. Thus, it is very unlikely that this position (S2B
)
is occupied at the same time in two neighbored mol-
ecules, such that the distance of 2.24 Å between such
two S2B atoms is irrelevant. However, the distance
between an atom in position S2B and a sulfur atom S1
in a neighboring molecule is very short (3.21 Å), possibly
indicating at least a weak attractive interaction between
these two cations. Similarly, the cations Y form a unit
with quite a short intermolecular S-S distance of 3.63
Å (S1 positions). The sulfur atoms of such a unit can be
viewed as forming a six-membered ring assuming a
chairlike conformation. The interplanar distances be-
tween acceptor molecules within the dimers are quite
similar (3.17 Å for A-A and 3.15 Å for B-B). Also the
shift of one molecule with respect to the other, parallel
to the respective planes and perpendicular to the longer
molecular axis, is 0.57 Å for A-A and 0.71 Å for B-B.
However, there are important differences between the
two acceptor dimers that are worth noting. The six-
membered rings in dimer A are almost parallel (inter-
planar angle of 3°); a more significant deviation from
this situation is observed in dimer B, with an inter-
planar angle of 10°. Whereas the TCNQF4 units A are
as expected almost planar, the corresponding units B
are not. The planar exocyclic dicyanomethylene groups
in B are rotated by 11° with respect to the plane of the
six-membered ring, this probably being due to steric
reasons. A similar but more pronounced distortion of
this kind (with an angle of 33°, as mentioned) has been
2-
observed for the TCNQF4
dianion in the 2:1 CT
as two different TCNQF4 molecules A and B. The order
complex with decamethylferrocene reported by Miller
and co-workers.33 In contrast, in A only two of the four
nitrile groups lie slightly out of the plane defined by the
six-membered ring and the four fluorine atoms. The
distance of the nitrogen atoms from this plane, however,
is less than 0.5 Å.
+
of the molecules in an alternating stack is DX+DY
-
AB-AB-DY+DX+AA-AA-, and so forth, with a symmetry
center located between two acceptor molecules. A view
of the structure of 9 is illustrated in Figure 4.
The relative arrangement of the molecules is such
that one acceptor dimer is almost completely sur-
[Fe(η5-C5Me4StBu)2](Br3) (11) crystallizes in the mono-

3684 Organometallics, Vol. 18, No. 18, 1999
Zu¨rcher et al.
F igu r e 5. Comparison of the two similar structures of 11
and 14 (thermal ellipsoids are drawn at the 50% probability
level at 293 K).
clinic space group P21/ n with one ferrocenium cation
and one tribromide anion on a symmetry center. The
anions and cations are alternating along the cell axes
a. The middle bromine atom and the carbon atoms C(3)
and C(4) of the Cp ring are very close (3.55 and 3.58 Å,
respectively). Alternating stacks of compound 11 and
its very similar companion 14, ([Fe(η5-C5Me4StBu)2](I3)),
are depicted in Figure 5.
F igu r e 6. Projection of the elementary cell of 11 along c
(top), and illustration of two S3(Br3)2S3 chains (bottom,
thermal ellipsoids are drawn at the 50% probability level
at 293 K).
However, as opposed to 14, (vide infra) the Br3 anion
is not parallel to the Cp ring; thus three different
distances of the three bromine atoms to the Cp plane
are observed (3.08 Å for Br(1), 3.49 Å for Br(2), and 3.89
Å for Br(1′)). On the other hand, in 14, which crystallizes
in the orthorhombic space group Pnnm, the ferrocenium
cation and the triiodide simultaneously lie on a sym-
metry plane and coincide with a symmetry center. Also
in this case, the distance of the middle halide atom to
the carbon atom C(3) of the Cp ring is quite short (3.77
Å), and the distance to the plane of the Cp ring is 3.70
Å. In both cases, the outer halide atoms display short
distances to proximate methyl groups of 3.51 and 3.52
Å for 11 and 4.10 and 4.11 Å for 14, respectively. The
distance of the two iron atoms along the stack is for both
compounds very similar (11, 10.57 Å; 14, 11.0 Å).
[Fe(η5-C5Me4S)2S](Br3) (12) crystallizes in the triclinic
space group P1h with the anion and the cation in general
positions. The most interesting structural feature is that
two Br3- units together form a chain with ends on both
sides with an S3 bridge of a cation. A projection of the
elementary cell and two such chains is depicted in
Figure 6.
an anion are very similar (2.51 and 2.57 Å). Finally, the
Cp rings in the ferrocenophanium are eclipsed with an
interplanar angle of 4.4°.
Crystals of [Fe(η5-C5Me4S)2S](I3) (15) are orthorhom-
bic (space group Pbca) with the cation and the anion in
general positions. Along the cell axis c, one observes
layers containing ferrocenophanium cations and tri-
iodide anions. Zigzag chains of triiodide anions are
connected by the three sulfur atoms of the ferro-
cenophanium, thus forming a two-dimensional network
with shortest S-I distances of 3.80 and 3.76 Å. Such a
network, a view of which is provided in Figure 7, may
also be described as a net of intersecting S3I4 chains,
with the Fe(C5Me4)2 units filling the gaps between the
chains (such as balls caught in a wire-mesh).
The I-I distance between the anions is 3.95 Å, and
the angle between the two triiodides is 80°. The anions
are not perfectly linear but slightly bent with an I-I-I
angle of 176.7°. Finally, the two different I-I distances
in each anion are 2.87 and 3.00 Å, and the angle
between the planes of the eclipsed Cp rings is 4.5°.
In fr a r ed Sp ectr oscop y. For the three CT complexes
with TCNQ (4-6), IR spectra quite typical for semicon-
ductors are observed. Thus, above 1600 cm-1 for 4 and
5 and above about 1000 cm-1 for 6, the three compounds
The shortest S-Br distance is 3.66 Å, and the Br-
Br distance between two anions is 3.59 Å. The latter
are almost parallel (the angle between them is 1°),
however not collinear, and the Br-Br distances within

CT Salts of Octamethylferrocenyl Thioethers
Organometallics, Vol. 18, No. 18, 1999 3685
F igu r e 8. ln(1/ R) vs (1/ T) plot for the three TCNQ
compounds 4-6 in the temperature range 200-350 K. The
straight lines are linear regressions leading to the energy
gap δE in the corresponding temperaure range.
0.60 eV (∼4900 cm-1) and a room-temperature conduc-
F igu r e 7. Projection of a layer of 15 along c. The triiodide
anions and the sulfur bridges form a two-dimensional
network (thermal ellipsoids are drawn at the 50% prob-
ability level at 293 K).
tivity of 0.26 S cm-1
.
1/R ) (1/R)0 e-δE/(2kT)
(1)
are opaque. Because the measurement was done at room
temperature, no sharp absorption edge but only a
“round” transition was observed. The band gaps deter-
mined by a temperature-dependent resistivity measure-
ment (see below) confirm the interpretation of the
infrared spectra. On the other hand, the three TCNQF4
salts (4-9) are transparent in the whole measured
range of 250-4400 cm-1, in agreement with their
insulator behavior. The CN stretching vibrations are
observed at 2194 and 2175 cm-1 for 7, at 2192 and 2170
cm-1 for 8, and at 2195 and 2177 cm-1 for 9, values very
similar to those reported in the literature.20 The six
trihalogenide salts do not show any exceptional features
in the infrared spectra.
Con d u ctivity Mea su r em en ts. For the three semi-
conducting compounds (4-6), temperature-dependent
two-point resistivity measurements were carried out on
pressed pellets. The room-temperature conductivities
are in the range of about 0.1-0.3 S cm-1 for 4 and 5 to
3.4 S cm-1 for 6. A plot ot the natural logarithm of the
conductivity (1/R) vs the reciprocal temperature (1/T)
is depicted in Figure 8.
The semiconductor nature of 4 and 5 is made plau-
sible by their structural features. The acceptor stacks
are responsible for the conductivity, whereas the fer-
rocenes serve as spacers and as electron reservoirs. The
sharp bends in the TCNQ stacks after seven or three
units, respectively, lead to a band gap at the Fermi level.
They possibly could be attributed to Peierls distortion,53
although experiments aimed at proving this have not
been performed. The temperature dependence of the
resistivity of 4 obeys the equation of a semiconductor
only above 250 K54-56 (eq 1), with a band gap of about
Below 250 K there is a fast decrease of the slope in
the ln(1/R) vs (1/T) plot, and in the range between 200
and 250 K the activation energy (δE) is only 0.25 eV.
This effect can tentatively be explained by localized
structural defects, similar to what is found for a doped
semiconductor, and from which empty energy levels
between the valence and the conduction band arise.
However, more detailed studies would be needed in
order to fully characterize the observed conductivity
behavior.
The room-temperature conductivity of 5 is smaller
(0.1 S cm-1) than that of 4, although its behavior is very
similar to that of 4 with a band gap of 0.32 eV (∼2600
cm-1) in the temperature range of 200-285 K. By
heating the compound to 350 K, the activation barrier
increases to 0.63 eV (∼5000 cm-1).
Compound 6, whose solid-state structure is not known,
displays a behavior similar to the former two com-
pounds. However, the band gap in the temperature
range of 200-285 K is smaller (0.18 eV (∼1600 cm-1))
and the room-temperature conductivity is more than 10
times larger (3.4 S cm-1). An explanation of this could
be the dendritic growth of the crystals, leading to a bad
crystal quality of the material, thus producing a large
number of structural defects. By heating the compound
to 350 K, again the activation energy increases to 0.58
eV (∼4700 cm-1).
Ma gn etic Mea su r em en ts. Magnetic susceptibility
measurements were carried out for the 12 compounds
4-15 using a SQUID susceptometer in the temperature
(54) Wedler, G. Lehrbuch der Physikalischen Chemie; VCH: Wein-
heim, 1987; pp 722-725.
(55) Kortu¨m, G.Lehrbuch der Elektrochemie; Verlag Chemie: Wein-
heim, 1972; pp 258-261.
(53) Peierls, R. E. Quantum Theory of Solids; Oxford University
Press: Oxford, 1955.
(56) Meier, H.Organic Semiconductors; Verlag Chemie: Weinheim,
1974; pp 39-71.

3686 Organometallics, Vol. 18, No. 18, 1999
Ta ble 3. Su r vey of Ma gn etic Da ta for Com p ou n d s 4-15
Zu¨rcher et al.
compd
Curie const. C [cm3 K/mol]
Weiss const. θ [K]
J AA [cm-1
]
J DD [cm-1
]
gD
q × 10-6 [cm3/mol]
4
5
6
7
8
0.65(2)
0.87(1)
0.506(2)
0.67(1)
0.74(1)
0.600(5)
0.458(3)
0.526(3)
0.61(1)
0.61(1)
0.531(7)
0.490(6)
-1(1)
1609(79)
2520(45)
2441(12)
1043(63)
1235(44)
754(21)
659(14)
512(14)
320(59)
219(38)
324(26)
358(23)
-2.0(5)
-22(1)
-920(67)
>1000
>1000
>1000
+54(7)
-0.56(3)
0
+2.0(2)
-0.32(5)
2.48(2)
2.702(4)
3.07(1)
3.28(1)
2.901(3)
2.20
2.37
2.55
2.55
2.38
0.0(1)
0(1)
+0.8(7)
-0.4(4)
+3.4(4)
+0.6(3)
+0.6(12)
-0.8(8)
+0.3(6)
+0.4(6)
9
10
11
12
13
14
15
2.29
range between 2 and 300 K and a constant external
magnetic field of 1000 G. A survey of the fitted magnetic
data is given in Table 3. All 12 compounds (4-15) obey
a modified Curie-Weiss expression ømol ) C/(T + θ) +
q, where q is the sum of core diamagnetism and
temperature-independent paramagnetism (TIP). For all
compounds q is positive, meaning that øTIP is about
twice the diamagnetic component øDia, which can easily
be calculated (øDia ) mMr × 10-6 cm3 mol-1, with m )
0.4-0.5).57,58
Because of their relative simplicity, the six trihalo-
genide salts 10-15 shall be discussed first. Except for
the tribromide 10, no significant interactions between
the cations can be deducted (Weiss constants θ ) 0 K
for 11-15). However, in compound 10 a weak ferro-
magnetic interaction between the cations could be
operating, as indicated by the slightly positive Weiss
constant θ of 3.4(4) K, although no increase in the øT
vs T plot was observed even below 10 K. Despite this
observation, we conclude that the magnetic properties
of these six compounds derive from the cations alone,
therefore giving access to average Lande´-g factors gD
for the three ferrocenium cations generated from 1-3
(Table 3). For the two cations from 1 and 3, two different
values are obtained for the tribromide and the triiodide
salt, respectively. This can be explained by the different
arrangement of the cations in the solid state. In the case
of the trithiaferrocenophane 3 the structures of both
compounds are known. In the tribromide salt 12 the
cations are oriented all in the same direction, whereas
in the triiodide salt 15 a pairwise arrangement of the
cations, approximately orthogonal to each other, is
observed. This different structural feature is probably
responsible for the higher value of gD in 12, as
compared to 15. The two salts 11 and 14, containing
the cation from 3, have more or less the same solid-state
structure and thus the same gD -value. For the salts
resulting from 1, unfortunately no solid-state structure
is known. The different gD -values indicate that the
cations must have a different relative arrangement in
the solid state. These results show that one should be
very cautious in using Lande´-g factors of anisotropic
molecules to interpret magnetic susceptibility data,
without knowing the structure of the compounds.
Plots of the reciprocal susceptibility 1/ømol for the six
compounds (4-9) and ømol vs T, respectively, are shown
in Figures 9 and 10. [Fe(η5-C5Me4SMe)2]3(TCNQ)7 (4)
F igu r e 9. Reciprocal susceptibility data for the charge-
transfer complexes 4-9, measured in the temperature
range of 2-300 K in an external field of 1000 G. The lines
correspond to the best fit of the modified Curie-Weiss
expression (see text).
to µeff ) (3kømolT/Nâ2)1/2), calculated per 1 mol of iron.
In the case of a complete charge transfer from the
ferrocenes to the acceptor, two unpaired electrons would
result per ferrocenium/(TCNQ)7/3 unit and a spin of S
) 2 × 1/2 should be expected. Thus, one would antici-
pate a Curie constant larger than 0.75 because the gD
-
value of the anisotropic ferrocenium cation should be
larger than 2.0. One has to note that for decamethyl-
ferrocenium a g -value of 2.8 (g ) 4.4 and g ) 1.3)
||
was found by ESR spectroscopy.50,51 Furthermore, from
the magnetic data of [1][M(mnt)2] (M ) Ni, Co, Pt), gD
-
values between 2.0 and 3.21 were found (with g -values
for [M(mnt)2]- known from the literature59), whereas
for the tribromide and the triiodide salts of 1,60 gD
-
values of 2.20 and 2.55, respectively, were found (Table
3). From these values, a Curie constant between 0.75
and 1.3 can be calculated for 4. This means that only
50-85% of the ferrocenes exist in the oxidized form in
the solid state for this compound. From the length of
has a Curie constant C of 0.65(2) cm3 K mol-1 (µeff
)
2.28, as obtained from high-temperature data according
(59) McCleverty, J . A. Prog. Inorg. Chem. 1968, 10, 50-215.
(60) Zu¨rcher, S. Ferrocenhaltige molekulare Materialien. Ph.D.
Thesis No. 12895, Eidgeno¨ssische Technische Hochschule (ETH),
Zu¨rich, 1998.
(57) Kahn, O. Molecular Magnetism; VCH: Weinheim, 1993.
(58) Epstein, A. J .; Miller, J . S. Angew. Chem. 1994, 106, 399-432.

CT Salts of Octamethylferrocenyl Thioethers
Organometallics, Vol. 18, No. 18, 1999 3687
the trihalogenide salts (Br3 and I3) of 2 afford gD -values
of 2.37 and 2.38, respectively. A Curie constant between
0.9 and 1.1 cm3 K mol-1 results, meaning that 80-100%
of the ferrocene molecules are in the oxidized state.
Again, the exocyclic double bonds of the three TCNQ
fragments display an average bond length of 1.389(10)
Å (between 1.383(4) and 1.392(4) Å). This is in good
agreement with one negative charge per three TCNQ
units. As opposed to 4, however, 5 shows a small but
significant antiferromagnetic coupling, as indicated by
the negative Weiss constant θ of -1.9 ( 0.5 K. In the
øT vs T plot (Figure 10a), a strong decrease below 50 K
with a plateau at about 6 K is observed. This can be
explained with antiferromagnetically coupled electrons
on the TCNQ stacks (J AA of -22(1) cm-1) and ferromag-
netically coupled electrons in the ferrocenium layers (J DD
of +54(7) cm-1), with coupling constants resulting from
a fitting of the data according to eq 2.
gD 2SD(SD + 1)
gA 2SA(SA + 1)
Nâ2
kT
ø )
+
(2)
(
)
DD/kT
AA/kT
3 + e-J
3 + e-J
[Fe(η5-C5Me4S)2S](TCNQ)2 (6) displays a very small
Curie constant C of 0.506(2) cm3 K mol-1 (µeff ) 2.01)
and a Weiss constant θ of 0.0(1). In the øT vs T plot
(Figure 10 a), a small decrease below 10 K is observed,
whereas in the high-temperature range, the curve is not
fully linear but slightly concave. By fitting the data with
eq 2, a large negative coupling constant J AA of
-920(67) cm-1 turns out, meaning that there is a strong
antiferromagnetic coupling of the negative charges
associated with the TCNQ units. The decrease of the
øT data below 10 K is explained by a weak antiferro-
magnetic interaction of the ferrocenium ions (J DD
)
-0.56(3) cm-1). Since no structural data are available
for this compound, a more detailed interpretation of the
magnetic data is not possible.
F igu r e 10. øT vs T plot for the six charge-transfer
complexes 4-9: for the three materials containing TCNQ
(a) and for the three compounds containing TCNQF4 (b).
The lines correspond to the best fit according to eq 2.
Because of the relatively large difference of the redox
potentials of donor and acceptor, one would anticipate
complete oxidations of the ferrocene molecules in 7
([Fe(η5-C5Me4SMe)2](TCNQF4)), concomitant with a
Curie constant larger than 0.75 cm3 K mol-1. However,
the strong dimerization in the anion stacks suggests a
diamagnetic ground state (S ) 0). Taking into account
the exocyclic double bond of the TCNQ anions the
charge of the molecule can be inferred. The exocyclic
double bonds of the seven TCNQ units have an average
bond length of 1.39(1) Å (between 1.384(6) and
1.397(5) Å). This is closer to the value for TCNQ1/2-
(1.390(3) and 1.394(4) Å)28 than for the neutral TCNQ
(1.374(4) Å).61 Therefore, from both the magnectic data
and structural parameters, we conclude that roughly
two to three delocalized negative charges are associated
with each seven-TCNQ unit, with the TCNQ molecules
within such a unit being electronically equivalent.
Finally, there is no significant coupling between the
spins, as indicated by the linearity of the øT vs T plot
of Figure 10 and a Weiss constant θ of -1(1) K.
a
gD -value of 2.5 and a spin S ) 1/2, a value of the
Curie constant C of 0.59 cm3 K mol-1 results, which is
only slightly below the measured value of 0.67(1) cm3
K mol-1 (µeff ) 2.32). A similar situation was reported
for the 1:1 salts [M(η5-C5Me5)2](TCNQF4) (M ) Fe, Co,
Cr),33 also containing S ) 0 (TCNQF4)2 dianions. A
2-
cooperative interaction of the remaining spins of the
cations cannot be deduced, as indicated by the Weiss
constant θ ) 0(1) K) and as it is also shown by the linear
øT vs T plot of Figure 10 b).
The Curie constant C of [Fe(η5-C5Me4StBu)2](TCNQ)3
(5) is 0.88 cm3 K mol-1 (µeff ) 2.65). This is only slightly
less than what one would expect for an almost com-
pletely oxidized ferrocene and one negative charge per
three TCNQ molecules. For the cation resulting from
2, gD -values between 2.3 and 2.7 are observed from
the magnetic properties of the corresponding [M(mnt)2]
salts (M ) Ni, Co, Pt),1 whereas the magnetic data of
The analogous complex [Fe(η5-C5Me4StBu)2](TCNQF4)
(8) displays a slightly larger Curie constant (C ) 0.75
cm3 K/mol; µeff ) 2.45), corresponding exactly to the
theoretical value for an S ) 2 × 1/2 spin system ( gD
)
2). Unfortunately, no structural data for this compound
are available. However, the CN stretching vibrations
2-
of 2192 and 2170 cm-1 suggest that S ) 0 (TCNQF4)2
dianions are present. The relatively large value of C can
be explained with the anisotropic gD -value of the
cation. Below 10 K, an increase of øT in the øT vs T
(61) Long, R. E.; Sparks, R. A.; Trueblood, K. N. Acta Crystallogr.
1965, 18, 932-939.

3688 Organometallics, Vol. 18, No. 18, 1999
Zu¨rcher et al.
as black needles, suited for the X-ray analysis. Mp: 185-190
°C. Anal. Calcd for C32H30N4F4S2Fe: C, 57.66; H, 4.54; N, 8.41.
Found: C, 57.90; H, 4.51; N, 8.46. IR (KBr): 2928, 2849, 2194,
2175, 1635, 1536, 1497, 1695, 1337, 1264, 1196, 1141, 1026,
969, 870, 788, 717, 700, 564, 542, 464.
[F e(η5-C5Me4StBu )2](TCNQF 4) (8) was obtained as de-
scribed for 4 from 170 mg (0.36 mmol) of Fe(η5-C5Me4StBu)2
(2)60 and 100 mg (0.36 mmol) of TCNQF4. Yield: 127 mg (46%).
Mp: 201 °C. Anal. Calcd for C38H42N4F4S2Fe: C, 60.80; H, 5.64;
N, 7.46. Found: C, 60.82; H 5.59; N, 7.60. IR (KBr): 2962,
2192, 2170, 1533, 1498, 1476, 1378, 1334, 1197, 1165, 1140,
1024, 965, 548.
plot is observed, indicating a small but significant
ferromagnetic interaction (J DD ) +2.0(2) cm-1; Weiss
constant θ ) 0.8(7) K) between the ferrocenium cations.
Finally, a slightly different situation, however cor-
roborated by structural data, is encountered for [Fe(η5-
C5Me4S)2S](TCNQF4) (9) (C 0.600(5) cm3 K mol-1, µeff
) 2.19, and θ of -0.4(4) K). The crystal structure clearly
shows that the compound contains diamagnetic S ) 0
(TCNQF4)22- dianions. Only a very small antiferromag-
netic coupling between the donor molecules is observed
(J DD ) -0.32(5) cm-1).
[F e(η5-C5Me4S)2S](TCNQF 4) (9) was obtained as described
for 4 from 50 mg (0.13 mmol) of Fe(η5-C5Me4S)2S (3)60 and 35
mg (0.13 mmol) of TCNQF4. Yield: 70 mg (81%) as black
prisms which could be used directly for the X-ray analysis.
Mp: >260 °C (dec). Anal. Calcd for C30H24N4F4S3Fe: C, 53.89;
H, 3.62; N, 8.38. Found: C, 53.85; H 3.61; N, 8.47. IR (KBr):
2923, 2195, 2177, 1632, 1535, 1496, 1395, 1338, 1264, 1196,
1142, 1021, 968, 870, 787, 714, 630, 560, 442, 524, 453.
[F e(η5-C5Me5SMe)2](Br 3) (10). A 50 mg (0.128 mmol)
sample of Fe(η5-C5Me5SMe)2 (2) was dissolved in a minimal
amount of 1,2-dichloroethane, and 1 mL (0.23 mmol) of a
bromine solution (0.23 M in 1,2-dichloroethane) was added.
The green solution was filtered. Slow diffusion of tert-butyl-
methyl ether into this solution yielded 10 as black plates.
Yield: 5.3 mg (7%). Mp: 161 °C. Anal. Calcd for C20H30Br3-
FeS2: C, 38.12; H, 4.80; S, 10.18. Found: C, 38.36; H, 481; S,
10.06. IR (KBr): 2912, 1422, 1376, 1309, 1020, 467.
[F e(η5-C5Me5StBu )2](Br 3) (11) was obtained as described
for 10 from 50 mg (0.105 mmol) of Fe(η5-C5Me5StBu)2 (3) in
1,2-dichloroethane and 0.83 mL (0.19 mmol) of a bromine
solution (0.23 M in 1,2-dichloroethane). Yield: 35.8 mg (48%).
Mp: 185 °C. Anal. Calcd for C26H42Br3FeS2: C, 43.72; H, 5.93;
S, 8.98. Found: C, 43.84; H, 5.88; S, 9.03. IR (KBr): 2979,
2958, 2918, 2891, 1473, 1454, 1376, 1362, 1222, 1165, 1025,
574, 533, 491, 452.
[F e(η5-C5Me5S)2S](Br 3) (12) was obtained as described for
10 from 50 mg (0.127 mmol) of Fe(η5-C5Me5S)2S (4) in 1,2-
dichloroethane and 0.83 mL (0.19 mmol) of a bromine solution
(0.23 M in 1,2-dichloroethane). Yield: 64.4 mg (80%). Mp: 161
°C. Anal. Calcd for C18H24Br3FeS3: C, 34.20; H, 3.83; S, 15.22.
Found: C, 34.21; H, 3.77; S, 15.12. IR (KBr): 2912, 1494, 1379,
1148, 1016, 522.
[F e(η5-C5Me5SMe)2](I3) (13) was obtained as described for
10 from 100 mg (0.256 mmol) of Fe(η5-C5Me5SMe)2 (2) and 97
mg (0.768 mmol) of iodine in 5 mL of 1,2-dichloroethane.
Yield: 142 mg (72%). Mp: 170 °C. Anal. Calcd for C20H30I3-
FeS2: C, 31.15; H, 3.92; S, 8.32. Found: C, 31.40; H, 3.86; S,
8.55. IR (KBr): 2950, 2911, 1438, 1374, 1311, 1019, 976, 668,
570.
[F e(η5-C5Me5StBu )2](I3) (14) was obtained as described for
10 from 100 mg (0.21 mmol) of Fe(η5-C5Me5StBu)2 (3) and 80
mg (0.63 mmol) of iodine. Yield: 160 mg (88%). Mp: 221 °C.
Anal. Calcd for C26H42I3FeS2: C, 36.51; H, 4.95; S, 7.50.
Found: C, 36.50; H, 4.76; S, 7.53. IR (KBr): 2963, 2923, 2899,
2863,1474, 1452, 1377, 1363, 1223, 1166, 1026, 574, 533, 491,
452.
[F e(η5-C5Me5S)2S](I3) (15) was obtained as described for
10 from 100 mg (0.25 mmol) of Fe(η5-C5Me5S)2S (4) and 97
mg (0.765 mmol) of iodine. Yield: 190 mg (96%). Mp: 222 °C.
Anal. Calcd for C18H24I3FeS3: C, 27.96; H, 3.13; S, 12.44.
Found: C, 27.94; H, 2.99; S, 12.18. IR (KBr): 2909, 1472, 1439,
1376, 1022, 623, 526, 456, 400, 370, 334.
X-r a y Cr ysta llogr a p h ic Stu d y of 4, 5, 7, 9, 11, 12, 14,
a n d 15. Crystals suited for an X-ray analysis were obtained
by slow evaporation of the solvent at room temperature or slow
cooling to -20 °C of a hot saturated solution for the TCNQ-
and TCNQF4-containing compounds (4, 5, 7, and 9) and by
slow diffusion of tert-butylmethyl ether into a saturated
solution, in the case of the trihalogenide salts (11, 12, 14, and
Con clu sion s
We have shown that the stoichiometry of charge-
transfer salts of structurally related sulfur-containing
ferrocene electron donors with the acceptor TCNQ very
much depends on the relative size and orientation of
the two components in the solid state. Thus, for ex-
ample, the unusual donor-acceptor ratio of 3:7 for
compound 4 derives from an almost ideal fit, in terms
of shape and volume, of a row of three ferrocenes 1 with
a stack of 7 TCNQ’s. On the other hand, the higher
reduction potential of TCNQF4, combined with its strong
tendency to form dimers in the anionic form, leads
invariably to 1:1 stoichiometries. Finally, a study of the
conductivity and magnetic properties of the CT com-
plexes has demonstrated how subtle and unpredictable
structural changes influence the physical characteristics
of such materials.
Exp er im en ta l Section
General experimental techniques have been described ear-
lier.3
[F e(η5-C5Me4SMe)2]3(TCNQ)7 (4). Fe(η5-C5Me4SMe)2 (1)60
(100 mg; 0.256 mmol) and TCNQ (121 mg; 0.597 mmol) were
dissolved in a minimal amount of acetonitrile, filtered, and
cooled to -20 °C. The product crystallized as black thin
platelets. Yield: 116 mg (52%). Mp: 185 °C (dec). Anal. Calcd
for C144H118N28S6Fe3: C, 66.51; H, 4.57; N, 15.08. Found: C,
66.53; H, 4.69; N, 15.32. IR (KBr): 2163, 1562, 1523, 1420,
1322, 1125, 953, 834, 700, 597. Single crystals for an X-ray
analysis were obtained by dissolving the product in a minimal
amount of acetonitrile followed by slow evaporation of the
solvent at room temperature.
[F e(η5-C5Me4StBu )2](TCNQ)3 (5) was obtained as de-
scribed for 4 from 40 mg (0.084 mmol) of Fe(η5-C5Me4StBu)2
(2)60 and 69 mg (0.32 mmol) of TCNQ. Yield: 76 mg (83%) as
black crystals. Mp: 195-200 °C (dec). Anal. Calcd for
C
62H54N12S2Fe: C, 68.50; H, 5.01; N, 1546. Found: C, 68.65;
H, 4.96; N, 15.47. IR (KBr): 2168, 1566,1331, 1136, 695. Single
crystals for an X-ray analysis have been obtained by dissolving
the product in a minimal amount of acetonitrile and slow
evaporation of the solvent at room temperature.
[F e(η5-C5Me4S)2S](TCNQ)2 (6) was obtained as described
for 4 from 50 mg (0.13 mmol) of Fe(η5-C5Me4S)2S (3),60 58 mg
(0.28 mmol) of TCNQ, and 600 mg (NBu4)(BF4) in hot aceto-
nitrile. The solvent was slowly evaporated over 1 week at 58
°C. Yield: 90 mg (89%) as black dendritic crystals. Mp: 200
°C (dec). Anal. Calcd for C42H32N8S3Fe: C, 62.99; H, 4.03; N,
13.99. Found: C, 63.04; H, 4.21; N, 13.80. IR (KBr): strong
absorption above 1000 cm-1, broad band at 700 cm-1
.
[F e(η5-C5Me4SMe)2](TCNQF 4) (7) was obtained as de-
scribed for 4 from 100 mg (0.27 mmol) of Fe(η5-C5Me4SMe)2
(1)60 and 71 mg (0.27 mmol) of TCNQF4.62 Yield: 98 mg (57%)
(62) Martin, E. L.; Wheland, R. C. J . Org. Chem. 1975, 40, 3101-
3109.

CT Salts of Octamethylferrocenyl Thioethers
Organometallics, Vol. 18, No. 18, 1999 3689
15). Selected crystallographic and relevant data collection
parameters are listed in Tables 1 and 2. Data were measured
at room temperature (293(2) K) with variable scan speed to
ensure constant statistical precision on the collected intensi-
ties. One standard reflection was measured every 120 reflec-
tions, and no significant variation was detected. The structures
were solved by direct or Patterson methods and refined by full-
matrix least-squares using anisotropic displacement param-
eters for all non-hydrogen atoms. The contribution of the
hydrogen atoms in their idealized position (riding model with
fixed isotropic U ) 0.080 Å2) was taken into account but not
refined. All calculations were carried out by using the Siemens
SHELX93 (VMS) system.
Con d u ctivity Mea su r em en ts. Samples of the CT com-
plexes (ca. 80-100 mg) were pressed into pellets, and tem-
perature-dependent conductivity was measured by the stan-
dard two-probe method.
Ma gn etic Mea su r em en ts. The magnetic susceptibility ø
of the charge-transfer complexes 4-15 was measured in the
temperature range 2-300 K in an external variable magnetic
field, by means of a Quantum Design superconducting quan-
tum interference device (SQUID) magnetometer. The poly-
crystalline samples were mounted in a sample holder tube
made of quartz glass in order to keep the magnetic background
as low as possible. Routine corrections for core diamagnetism,
temperature-independent paramagnetism, and the sample
holder were applied.
Ack n ow led gm en t. S.Z. is grateful to the Swiss
National Science Foundation for financial support (Grant
20-41974.94).
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates, complete listing of bond distances and angles,
tables of anisotropic displacement coefficients, and coordinates
of hydrogen atoms, as well as ORTEP representations and
atom-numbering schemes for 4, 5, 7, 9, 11, 12, 14, and 15.
This material is available free of charge via the Internet at
http://pubs.acs.org. Tables of calculated and observed structure
factors may be obtained from the authors upon request.
OM9902075