Synthesis and crystal structures of decamethylferrocenium salts of anilate anions derived from bromanilic acid, chloranilic acid and cyananilic acid

Article abstract of DOI:10.1016/S0020-1693(01)00411-X

Four complexes were synthesized using bis(pentamethylcyclopentadienyl)iron Fe(C₅Me₅)₂ as an organometallic donor and three anilic acids (2,5-dibromo-3,6-dihydroxy-1,4-benzoquinone; BA, 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone; CA and 2,5-dicyano-3,6-dihydroxy-1,4-benzoquinone; CNA) as an organic acceptor. The molecular-based structures with different stoichiometric ratios [1:1, 1:1:1(H₂O) and 2:1] of these complexes have been determined by X-ray crystallographic analysis and elemental analysis. These complexes have a one-dimensional alternated stacking arrangement as ···D⁺A^-D⁺A^- ··· type. Close contacts between the bromine atoms and oxygen atoms of the BA units are observed in the structure [Fe(C₅Me₅)₂](BA) (1) of 1:1 composition. Interestingly, the structures [Fe(C₅Me₅)₂](CA)(H₂O) (2) and [Fe(C₅Me₅)₂](CNA)(H₂O) (3) of 1:1:1(H₂O) ratio contain one-dimensional molecular tape structures with the combination of the CA or the CNA units and water molecules via O-H···O hydrogen bonds. Different stoichiometric ratios and structures are found from the CNA complexes [Fe(C₅Me₅)₂](CNA)(H₂O) (3) and [Fe(C₅Me₅)₂]₂(CNA) (4).

Full text of DOI:10.1016/S0020-1693(01)00411-X

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Inorganica Chimica Acta 318 (2001) 127–134
Synthesis and crystal structures of decamethylferrocenium salts of
anilate anions derived from bromanilic acid, chloranilic acid and
cyananilic acid
Md. Badruz Zaman 1, Masaaki Tomura, Yoshiro Yamashita *
Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
Received 2 November 2000; accepted 28 February 2001
Abstract
Four complexes were synthesized using bis(pentamethylcyclopentadienyl)iron Fe(C5Me5)2 as an organometallic donor and three
anilic acids (2,5-dibromo-3,6-dihydroxy-1,4-benzoquinone; BA, 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone; CA and 2,5-di-
cyano-3,6-dihydroxy-1,4-benzoquinone; CNA) as an organic acceptor. The molecular-based structures with different stoichiomet-
ric ratios [1:1, 1:1:1(H2O) and 2:1] of these complexes have been determined by X-ray crystallographic analysis and elemental
analysis. These complexes have a one-dimensional alternated stacking arrangement as ···D+A−D+A−··· type. Close contacts
between the bromine atoms and oxygen atoms of the BA units are observed in the structure [Fe(C5Me5)2](BA) (1) of 1:1
composition. Interestingly, the structures [Fe(C5Me5)2](CA)(H2O) (2) and [Fe(C5Me5)2](CNA)(H2O) (3) of 1:1:1(H2O) ratio
contain one-dimensional molecular tape structures with the combination of the CA or the CNA units and water molecules via
O–H···O hydrogen bonds. Different stoichiometric ratios and structures are found from the CNA complexes
[Fe(C5Me5)2](CNA)(H2O) (3) and [Fe(C5Me5)2]2(CNA) (4). © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Crystal structures; Ferrocene complexes; Anilic acid complexes
interactions between organometallic molecules and or-
ganic components provides a path in transmitting the
spin and charge along the supramolecular structures
[2–4]. Thus crystal engineering with organometallic
and/or organic molecules has played a major role in
developing new molecular-based magnets [1–5].
1. Introduction
Bis(pentamethylcyclopentadienyl)iron
Fe(C5Me5)2,
i.e. decamethylferrocene, is well demonstrated as metal-
locenium donor (D) and combines with cyanocarbon
acceptors (A) to afford charge-transfer complexes com-
posed of ···D+A−D+A−··· type alternated stackings
[1]. These complexes exhibit cooperative magnetic phe-
nomena, that is, ferro-, antiferro-, ferri-, and metamag-
netism, which depend on stacking arrangements and
the inter- and intra- molecular interactions in the crys-
tal structure. Moreover, controlling of non-covalent
Our strategy is to synthesize crystals containing or-
ganic and organometallic molecules or ions with intra-
and intermolecular interactions to explore novel build-
ing blocks in organometallic crystal engineering. In
organic–organometallic systems the non-covalent inter-
molecular bonding capacity of the organic molecules [6]
can be combined with the coordination geometry, vari-
able ionic charges, oxidation and spin states typical of
organometallic complexes [7]. As organic counter part
with organometallic Fe(C5Me5)2, we have chosen anilic
acids, which possess electron accepting abilities with
multi-stage deprotonation and protonation processes,
to form characteristic intermolecular hydrogen-bonded
networks [8,9]. First we have examined the complexa-
tion of Fe(C5Me5)2 with chloranilic acid (CA), and
* Corresponding author. Present address: Department of Electronic
Chemistry, Interdisciplinary Graduate School of Science and Engi-
neering, Tokyo Institute of Technology, Nagatsuta, Midori-ku,
Yokohama 226-8502, Japan. Tel.: +81-45-9245571; fax: +81-45-
9245489.
E-mail address: yoshiro@echem.titech.ac.jp (Y. Yamashita).
1 Permanent address: Department of Applied Chemistry and
Chemical Technology, University of Dhaka, Dhaka-1000,
Bangladesh.
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00411-X

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M.B. Zaman et al. / Inorganica Chimica Acta 318 (2001) 127–134
observed an infinite one-dimensional molecular tape
structure via hydrogen bonding between CA and water
molecules. This preliminary result was reported in our
recent communication [9]. As an extension of this work,
it is of interest to investigate the complexes derived
from other anilic acids.
2.2.2. Synthesis of complex 2
Complex 2 was prepared by a diffusion method. In
the method, CA (10.5 mg, 0.05 mmol) and Fe(C5Me5)2
(16.4 mg, 0.05 mmol) were placed at the bottom of the
H-shaped tube and then the tube was filled with dry
acetonitrile. After 20–25 days dark brown crystals were
formed. D.p. 213–215°C. Anal. Calc. for (C20H30Fe)-
(C6HCl2O4)(H2O): C, 56.54; H, 6.02; N, 0.00. Found:
C, 56.59; H, 5.91; N, 0.00%.
In this paper we report the synthesis and structural
characterization
of
the
crystalline
complexes
[Fe(C5Me5)2](BA) (1), [Fe(C5Me5)2](CA)(H2O) (2),
[Fe(C5Me5)2](CNA)(H2O) (3) and [Fe(C5Me5)2]2(CNA)
(4), obtained by using bis(pentamethylcyclopentadi-
enyl)iron Fe(C5Me5)2 as organometallic donor and
anilic acids [2,5-dibromo-3,6-dihydroxy-1,4-benzo-
quinone (bromanilic acid); BA, 2,5-dichloro-3,6-dihy-
droxy-1,4-benzoquinone (chloranilic acid); CA and
2.2.3. Synthesis of complexes 3 and 4
A solution of CNA (9.6 mg, 0.051 mmol) in 10 ml of
dry acetonitrile was added to a solution of Fe(C5Me5)2
(16.3 mg, 0.050 mmol) in 8 ml of dry hot acetonitrile.
Slow evaporation of the dark brown solution during a
month gave two types of crystals, dark red crystals of 3
(D.p. 264–265°C) and dark green crystals of 4 (D.p.
244–245°C). Anal. Calc. for (C20H30Fe)(C8HN2O4)-
(H2O) for 3: C, 63.05; H 6.24; N, 5.25. Found: C, 63.11;
H, 5.99; N, 5.38%. Anal. Calc. for (C20H30Fe)2(C8N2O4)
for 4: C, 68.58; H, 7.19; N, 3.33. Found: C, 68.36; H,
7.19; N, 3.72%.
2,5-dicyano-3,6-dihydroxy-1,4-benzoquinone
(cyana-
nilic acid); CNA] as organic electron acceptors with
proton donating hydroxyl groups.
2.3. X-ray crystallographic studies
Single crystals of 1–4 were individually mounted on
the end of a glass fiber and optically centered in the
X-ray beam. The intensity data for complexes 1, 2 and
4 were collected on an Enraf-Nonius CAD4 diffrac-
,
tometer using Cu Ka radiation (u=1.54178 A) at 296
2. Experimental
K. In this case, absorption corrections were applied
using empirical procedures based on azimuthal „ scans
of seven reflections having an Eulerian angle, , near
90°. On the other hand, intensity data for complex 3
was collected on a Rigaku AFC-7R diffractometer us-
2.1. Materials
Bis(pentamethylcyclopentadienyl)iron
Fe(C5Me5)2
was commercially obtained and purified by recrystal-
lization followed by sublimation in vacuum. 2,5-Di-
bromo- and 2,5-dichloro-3,6-dihydroxy-1,4-benzo-
quinones (BA and CA) were used without further
,
ing Mo Ka radiation (u=0.71069 A) at 296 K and no
absorption and decay correction was applied. All struc-
tures were solved using direct methods with SHELXS-97
[11] and refined by full-matrix least-squares on F2 with
SHELXL-97 [12]. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were placed geometri-
cally and refined by using a riding model. The data for
collected parameters and details of measurements for
complexes 1, 3 and 4 are summarized in Table 1.
purification.
2,5-Dicyano-3,6-dihydroxy-1,4-benzo-
quinone (CNA) was synthesized via five steps starting
from 1,4-dimethoxybenzene [10].
2.2. Preparation of crystalline complexes
2.2.1. Synthesis of complex 1
A solution of BA (14.9 mg, 0.05 mmol) in distilled
hot acetonitrile (6–8 ml) was mixed with a solution of
Fe(C5Me5)2 (16.4 mg, 0.05 mmol) in distilled hot aceto-
nitrile (5–6 ml). Within a day the solution became
brown and solids appeared in the flask. Black crystals
suitable for X-ray crystallographic analysis were grown
at room temperature by slow evaporation for 4 weeks.
D.p. 218–219°C. Anal. Calc. for (C20H30Fe)-
(C6HBr2O4): C, 50.11; H, 5.01; N, 0.00. Found: C,
49.95; H, 5.02; N, 0.00%.
3. Results and discussion
This paper focuses on three anilic acids that act as
proton donor and electron acceptor, and are useful for
building novel organic–organometallic crystalline com-
plexes [8,9]2. The complexes of Fe(C5Me5)2 with the
2 Detail of the magnetic properties of the complexes 1–4 will be
reported elsewhere.

M.B. Zaman et al. / Inorganica Chimica Acta 318 (2001) 127–134
129
Table 1
Crystallographic data for [Fe(C5Me5)2](BA) (1), [Fe(C5Me5)2](CNA)(H2O) (3) and [Fe(C5Me5)2]2(CNA) (4)a
1
3
4
Formula
C26H31O4Br2Fe
623.18
C28H34O5N2Fe
532.41
orthorhombic
Imm2 (no. 44)
13.703(2)
C48H60O4N2Fe2
840.68
Molecular weight
Crystal system
Space group
monoclinic
P21/n (no. 14)
9.942(1)
14.505(1)
17.739(2)
98.17(1)
2532.3(3)
4
1.635
0.20×0.15×0.08
1260
8.715 (Cu Ka)
7.90–148.46
5467
5164
3229
308, 0
0.0607
0.1527
1.022
monoclinic
C2/m (no. 12)
14.672(1)
14.543(1)
9.731(1)
90.62(1)
2076.2(2)
2
1.345
0.25×0.20×0.05
892
5.964 (Cu Ka)
8.56–148.36
2338
2209
1568
150, 10
0.0604
0.1544
1.040
,
a (A)
,
b (A)
10.566(1)
9.300(2)
,
c (A)
i (°)
3
,
V (A )
Z
1346.5(3)
2
1.313
0.35×0.10×0.02
560
0.599 (Mo Ka)
4.86–54.96
830
830
612
108, 33
0.0572
0.1519
1.098
zcalc (g cm−3
)
Crystal size (mm3)
F(000)
v (mm−1
)
Measured 2q range (°)
Number of reflections measured
Number of independent reflections
Number of reflections with I\2|(I)
Parameters, restrains
a
R1 [I\2|(I)]
b
wR2 [I\2|(I)]
Goodness-of-fit S on F2
c
a R1=ꢀ(ꢁꢁFoꢁ−ꢁFcꢁꢁ)/ꢀ(ꢁFoꢁ).
b wR2={ꢀ[w(Fo 2−Fc 2)2]/ꢀ[w(Fo 2)2]}1/2
.
c S={ꢀ[w(Fo 2−Fc 2)2]/(Nreflns−Nparam)}1/2
.
Fig. 1. One-dimensional alternated stacking structure of (a) [Fe(C5Me5)2](BA) (1), (b) [Fe(C5Me5)2](CNA)(H2O) (3) and (c) [Fe(C5Me5)2]2(CNA)
(4).
complexes 3 and 4 were obtained from the same batch.
In all the crystalline complexes, a one-dimensional al-
ternated stacking of D and A molecules was observed
(Fig. 1).
In the unit cell of 1 there is a crystallographically
independent pair of Fe(C5Me5)2 and BA. Each
anilic acids have been prepared from dry solvent. The
D–A ratios of the complexes 1, 2, 3 and 4 were
determined by both of elemental analyses and X-ray
crystallographic analyses. Even if a water-free solvent
was used for preparation of the crystals, the complexes
2 and 3 containing water molecules were obtained. The

130
M.B. Zaman et al. / Inorganica Chimica Acta 318 (2001) 127–134
,
Fig. 2. Molecular structure of [Fe(C5Me5)2](BA) (1) with atomic labeling scheme. Selected bond lengths (A): Fe(1)–C(3) 2.090(5), Fe(1)–C(4)
2.096(5), Fe(1)–C(5) 2.099(5), Fe(1)–C(2) 2.099(5), Fe(1)–C(15) 2.100(5), Fe(1)–C(14) 2.102(5), Fe(1)–C(13) 2.103(5), Fe(1)–C(12) 2.103(5),
Fe(1)–C(1) 2.106(5), Fe(1)–C(11) 2.106(5), O(1)–C(22) 1.253(7), O(2)–C(23) 1.316(7), O(3)–C(25) 1.201(8), O(4)–C(26) 1.225(7), Br(1)–C(21)
1.902(6), Br(2)–C(24) 1.888(7), C(1)–C(2) 1.416(8), C(1)–C(5) 1.445(8), C(1)–C(6) 1.493(8), C(2)–C(3) 1.423(8), C(2)–C(7) 1.503(8), C(3)–C(4)
1.406(9), C(3)–C(8) 1.505(8), C(4)–C(5) 1.419(7), C(4)–C(9) 1.508(8), C(5)–C(10) 1.490(8), C(11)–C(15) 1.421(8), C(11)–C(12) 1.426(7),
C(11)–C(16) 1.495(7), C(12)–C(13) 1.423(7), C(12)–C(17) 1.488(8), C(13)–C(14) 1.424(8), C(13)–C(18) 1.497(7), C(14)–C(15) 1.436(8), C(14)–
C(19) 1.498(8), C(15)–C(20) 1.507(8), C(21)–C(22) 1.384(8), C(21)–C(26) 1.403(9), C(22)–C(23) 1.500(10), C(23)–C(24) 1.341(10), C(24)–C(25)
1.439(9), C(25)–C(26) 1.554(9).
molecule was not located on the special positions. The
atomic labeling scheme is shown in Fig. 2. No hydro-
gen atom of the BA unit was found in the Fourier map.
Thus to determine the ionicity of the BA unit we have
calculated the bond lengths of the BA monoanion. The
experimental data for the BA unit are consistent with
the calculated values of the BA monoanion (see Table
2) and those of partially deprotonated BA monoanion
[13]. On the other hand, the bond lengths of
Fe(C5Me5)2 unit in 1 are almost similar to those of
Fe(C5Me5)2 molecules (Table 3) reported previously
[14]. These facts suggest that the charges on the BA and
Fe(C5Me5)2 unit in 1 are −1 and +1, which supports
the 1:1 ratio of 1. The close intermolecular contacts
observed with a dramatic change in the crystal struc-
ture, which are also reflected in a different color of the
crystalline complexes. The colors of 3 with the ratio of
1:1:1(H2O) and 4 with the ratio of 2:1 are dark red and
dark green, respectively. On the other hand, Yamochi
et al. have obtained
a
different crystal of
[Fe(C5Me5)2](CNA) with the ratio of 1:1 [8]. Interest-
ingly, the black crystal of [Fe(C5Me5)2](CNA), which
was obtained from a benzene–MeCN solution, is crys-
Table 2
Calculated and observed bond lengths for BA monoaniona
,
(3.24 A) between the bromine atom and the oxygen
atom of the BA unit were observed. The ribbon type
structure of the BA units formed with the Br···O con-
tacts is shown in Fig. 3.
The alternated stacking of the structure 1 along the
[−1 0 1] direction is shown in Fig. 1(a). The distances
and the angles between the least-squares planes of the
Bond
Obsd. in 1
Calc., PM3 a
Calc., 3-21G* b
,
,
,
(A)
(A)
(A)
,
BA unit and the two C5Me5 rings are 3.64 and 3.68 A
C6–O1
C2–O2
C3–O3
C5–O4
C1–C2
C2–C3
C3–C4
C4–C5
C6–C1
C1–Br
C4–Br
1.201
1.316
1.253
1.225
1.342
1.499
1.384
1.403
1.554
1.888
1.902
1.216
1.353
1.240
1.228
1.342
1.519
1.394
1.416
1.542
1.866
1.867
1.211
1.338
1.252
1.222
1.322
1.524
1.370
1.416
1.551
1.889
1.895
and 2.2 and 2.3°, respectively, which are similar to
those in [Fe(C5Me5)2][A] [A=2,3-dichloro-5,6-dicyano-
1,4-benzoquinone (DDQ), 7,7,8,8-tetracyanoquino-
dimethane (TCNQ) and tetracyanoethylene (TCNE)]
[15]. The C5Me5 rings are almost eclipsed by the BA
rings in the stacking. The interstacking Fe–Fe distances
,
are within the range of 8.5–9.0 A.
When Fe(C5Me5)2 was reacted with CNA (cyananilic
acid) in MeCN at room temperature, two types of
crystalline complexes, 3 and 4, were produced at the
same time. The different stoichiometric ratios were
a Ref. [20].
b Ref. [21].

M.B. Zaman et al. / Inorganica Chimica Acta 318 (2001) 127–134
131
Table 3
Summary of average bond lengths for [Fe(C5Me5)2] units a
Fe–C
C–C
C–Me
Fe–C5Me5 ring a
Ref.
[Fe(C5Me5)2]
[Fe(C5Me5)2][C(CN)3]
[Fe(C5Me5)2](TCNE)
[Fe(C5Me5)2]2{Mo[S2C2(CF3)2]3}
[Fe(C5Me5)2](BA) (1)
[Fe(C5Me5)2](CA)(H2O) (2)
[Fe(C5Me5)2](CNA)(H2O) (3)
[Fe(C5Me5)2]2(CNA) (4)
2.050
2.092
2.086
2.086
2.100
2.080
2.067
2.087
1.419
1.423
1.418
1.400
1.423
1.387
1.484
1.405
1.502
1.498
1.499
1.504
1.498
1.510
1.493
1.502
1.656
1.710
1.700
[15]
[15]
[15]
[18]
this work
[9]
this work
this work
1.715
1.710
1.705
1.710
a The average distance between the least-squares plane of the C5Me5 ring and the iron atom.
tallographically isomorphous with the BA complex 1,
and the intermolecular close –HO···NC– contacts (2.80
,
A) between the oxygen atom and the nitrogen atom of
the CNA unit were observed in the structure of
[Fe(C5Me5)2](CNA) [16].3
The crystals of 2 and 3 have the orthorhombic crystal
system with space groups Pnnm and Imm2, respectively.
Thus, the crystal of 2 contains a crystallographically
independent fourth part of the CA unit and fourth part
of the Fe(C5Me5)2, whereas the crystal of 3 contains a
crystallographically independent half of CNA unit and
fourth part of the Fe(C5Me5)2. The cell parameters, the
stacking arrangement and the pattern of the one-dimen-
sional molecular tape structure of 2 and 3, however, are
approximately similar. The structure of 2 can be viewed
in our preliminary communication [9] and is not shown
here. The atomic labeling scheme of 3 is shown in Fig.
4. The CNA unit of 3 has two crystallographically
In complexes 2 and 3 the C5Me5 rings have eclipse
conformation with the CA or CNA rings and the
one-dimensional alternated unistackings as ···DADA···
type along the b axis are formed (Fig. 1(b)). The
distances between the least-squares planes of the C5Me5
rings and the CA or the CNA rings within the stackings
,
,
are 3.59 A for 2 and 3.57 A for 3.
The crystal of 4 contains a crystallographically inde-
pendent half of Fe(C5Me5)2 and fourth part of the
CNA unit. The CNA unit of 4 lies on a mirror plane
with an inversion center (Fig. 6) and has the only
,
independent C–O bond [C(14)–O(1) 1.217(6) A]. The
,
independent C–O bonds [C(8)–O(1) 1.247(7) A and
,
C(9)–O(2) 1.245(7) A]. These bond lengths are almost
equivalent and are similar to those of the CA anion of
2. Other bond lengths in the CNA unit of 3 are
consistent with the geometry of the reported CNA
monoanion (Table 4). Thus, the following resonance
valance structure can be proposed to contribute to the
CNA monoanion structure of 3. Similarly to the com-
plex 2, each oxygen atom in the CNA anions of 3 is
coordinated to the water molecules and constructs the
one-dimensional molecular tape structure along the c
axis. The tape structure through an infinite O–H···O
linkage in 3 is shown in Fig. 5. The characteristic
feature of the tape structure in 3 is that the CNA units
and water molecules are linked via two different O···O
,
distances (2.60 and 2.77 A) within the tapes, in contrast
with the case of 2.
3 Crystal data of the 1:1 complex, [Fe(C5Me5)2](CNA): monoclinic,
Fig. 3. Crystal structure of [Fe(C5Me5)2](BA) (1) viewed perpendicu-
lar to the [1 0 −1] plane. Dotted lines show close intermolecular
Br···O contacts.
,
space group P21/n, a=9.915(2), b=14.572(3), c=17.671(2) A,
3
,
i=96.21(1)°, V=2538.7(8) A , Z=4. Data obtained from [16].

132
M.B. Zaman et al. / Inorganica Chimica Acta 318 (2001) 127–134
,
Fig. 4. Molecular structure of [Fe(C5Me5)2](CNA)(H2O) (3) with atomic labeling scheme. Selected bond lengths (A): Fe(1)–C(1) 2.04(2),
Fe(1)–C(1*) 2.04(2), Fe(1)–C(3) 2.047(10), Fe(1)–C(3%) 2.047(10), Fe(1)–C(3*) 2.047(10), Fe(1)–C(3%%) 2.047(10), Fe(1)–C(2*) 2.113(16), Fe(1)–
C(2%%) 2.113(16), Fe(1)–C(2) 2.113(16), Fe(1)–C(2%) 2.113(16), N(1)–C(10) 1.136(13), O(1)–C(8) 1.247(7), O(2)–C(9) 1.245(7), C(1)–C(2) 1.384(6),
C(1)–C(2%) 1.384(6), C(1)–C(4) 1.50(2), C(2)–C(3) 1.384(7), C(2)–C(5) 1.498(17), C(3)–C(3%) 1.385(8), C(3)–C(6) 1.480(14), C(7)–C(9) 1.411(7),
C(7)–C(8) 1.412(7), C(7)–C(10) 1.410(12), C(8)–C(8**) 1.527(7), C(9)–C(9**) 1.526(7). Symmetry operations: (*) −x, −y, z; (%) −x, y, z; (%%)
x, −y, z; (**) −x+1, −y, z.
Table 4
Summary of average bond lengths for CNA units a
Charge of CNA
C–O
C–C in ring
C–N
Ref.
(CNA)(H2O)6
0
−1
−1
−1
−2
1.242
1.257
1.240
1.246
1.217
1.415, 1.533
1.407, 1.532
1.407, 1.530
1.411, 1.527
1.425, 1.556
1.149
1.140
1.139
1.136
1.139
[19]
[8]
[16]
this work
this work
(TMTTF)2(CNA) a
[Fe(C5Me5)2](CNA)
[Fe(C5Me5)2](CNA)(H2O) (3)
[Fe(C5Me5)2]2(CNA) (4)
a TMTTF=tetramethyltetrathiafulvalene.
Fig. 5. One-dimensional molecular tape structure in [Fe(C5Me5)2](CNA)(H2O) (3). Dotted lines show intermolecular O···O linkages.
In the crystal structure of 4, the alternated stackings
consist of two Fe(C5Me5)2 cations and one CNA dian-
ion. The one-dimensional ···DDADDA··· type stackings
are parallel to the [−1 0 1] direction (Fig. 1(c)). The
intracolumnar short distances between the least-squares
planes of the two C5Me5 rings, the C5Me5 ring and the
CNA unit, and the two iron atoms are 3.91, 3.48 and
C–O bond length is shorter than those in other CNA
dianion structures [17]. The bond lengths for the two
independent C–C bonds in the six-membered ring are
,
,
1.425(6) A for C(13)–C(14) and 1.556(12) A for C(14)–
C(14*). Therefore, the following resonance valance
structures can be proposed to depict the CNA dianion
structures of 4.
,
7.31 A, respectively. To the best of our knowledge, the
complex, [Fe(C5Me5)2]2{Mo[S2C2(CF3)2]3} is the only
example of decamethylferrocenium salts with the ratio
of 2:1 [18].4
4 Mo[S2C2(CF3)2]3=tris[bis(trifluromethyl)ethylene-1,2-dithiolato]-
molybdate.

M.B. Zaman et al. / Inorganica Chimica Acta 318 (2001) 127–134
133
4. Conclusion
alternated stackings of ···DDADDA··· type that are
rare and attractive. The structural units with inter-
molecular interactions in (i) and (ii) may be useful for
constructing crystalline materials with anilic acids.
Studies on the characterization of physical properties of
the complexes 1–4 and the construction of novel struc-
tures using anilic acids are now in progress.
In this study three anilic acids (bromanilic acid,
chloranilic acid and cyananilic acid) have been used to
prepare crystalline complexes with organometallic de-
camethylferrocene. This combination could afford vari-
ous and unique crystal structures because of the
electron accepting abilities with multi-stage deprotona-
tion and protonation processes of anilic acids. There
are three important structural features obtained from
these complexes: (i) in the structure of the 1:1 complex
1, the BA monoanion units form the ribbon type
structure through close Br···O contacts. The
–HO···NC– contacts were found in the complex
[Fe(C5Me5)2](CNA) [8] and the intermolecular interac-
tions of these two complexes are geometrically similar.
(ii) In 1:1:1(H2O) complexes, 2 and 3, the CA or the
CNA units and water molecules are linked via O–H···O
hydrogen bonds and form the one-dimensional molecu-
lar tape structure. (iii) The 2:1 complex 4 contains
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 158468–158470 for com-
plexes 1, 3 and 4, respectively. The crystal data for
complex 2 was deposited previously with the Cam-
bridge Crystallographic Data Centre, CCDC no. 1350/6
and will not be reported here. Copies of this informa-
tion may be obtained from The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK (fax: +44-
1233-336 033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Acknowledgements
We thank Professor K. Nakasuji, Drs. J. Toyoda and
Y. Morita of Osaka University for their continuous
encouragement and advice for this work. The authors
are grateful to Dr. H. Yamochi and Professor G. Saito
of Kyoto University for supplying the data of the 1:1
complex, [Fe(C5Me5)2](CNA). M.B.Z. thanks the Insti-
tute for Molecular Science for postdoctoral fellowships.
This work was supported by a grant-in-aid for scientific
research from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
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