Supramolecular assembly of ferrocenes via hydrogen bonds: Dimensional variation in ferrocenylpyrimidine complexes with carboxylic acids and aromatic alcohols

Article abstract of DOI:10.1039/b306699a

Co-crystallization of 5-ferrocenylpyrimidine (FcPM) with various carboxylic acids and aromatic alcohols produces hydrogen-bonded supramolecular architectures. Thus, reaction of FcPM with compounds containing two hydrogen-bonding sites gives 2:1 co-crystals with discrete structures of the type [(FcPM)₂·D] [where D = succinic acid (1), hydroquinone (2), resorcinol (3) and 2,2′-thiodiglycolic acid (4)]. A complex with a chiral chain structure, [FcPM·{(-R)-(+)-1,1′-bi-2-naphthol}] _n (5), is obtained by the combination of FcPM with (R)-(+)-1,1′-bi-2-naphthol. The binaphthol molecules form hydrogen-bonded helical chains, which carry ferrocene units as pendants. The combination of FcPM with trimesic acid and pyromellitic acid produces supramolecular complexes with tape structures, [FcPM·(trimesic acid)]_n (6) and [FcPM₂·(pyromellitic acid)]_n (7), respectively. The tape structure of 6 consists of repeating units of large hexagonal rings while that of 7 consists of rhomboidal rings. Combination of FcPM with phloroglucinol produces a layered structure complex, [FcPM· (phloroglucinol)·2H₂O]_n (8), exhibiting three-dimensional hydrogen bonding. In this complex, FcPM molecules link hydrogen-bonded sheets composed of phloroglucinol and water molecules. The dimensionality of the assembled structures is influenced by the number of hydrogen-bonding substituents on the donor molecules.

Full text of DOI:10.1039/b306699a

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P A P E R
Supramolecular assembly of ferrocenes via hydrogen bonds:
dimensional variation in ferrocenylpyrimidine complexes
with carboxylic acids and aromatic alcohols
Ryo Horikoshi, Chisato Nambu and Tomoyuki Mochida*
Department of Chemistry, Faculty of Science, Toho University, Funabashi, Chiba 274-8510,
Japan. E-mail: mochida@chem.sci.toho-u.ac.jp
Received (in Montpellier, France) 12th June 2003, Accepted 29th August 2003
First published as an Advance Article on the web 22nd October 2003
Co-crystallization of 5-ferrocenylpyrimidine (FcPM) with various carboxylic acids and aromatic alcohols
produces hydrogen-bonded supramolecular architectures. Thus, reaction of FcPM with compounds containing
two hydrogen-bonding sites gives 2:1 co-crystals with discrete structures of the type [(FcPM)2ꢀD] [where
D ¼ succinic acid (1), hydroquinone (2), resorcinol (3) and 2,20-thiodiglycolic acid (4)]. A complex with a chiral
chain structure, [FcPMꢀ{(R)-(þ)-1,10-bi-2-naphthol}]n (5), is obtained by the combination of FcPM with (R)-
(þ)-1,10-bi-2-naphthol. The binaphthol molecules form hydrogen-bonded helical chains, which carry ferrocene
units as pendants. The combination of FcPM with trimesic acid and pyromellitic acid produces supramolecular
complexes with tape structures, [FcPMꢀ(trimesic acid)]n (6) and [FcPM2ꢀ(pyromellitic acid)]n (7), respectively.
The tape structure of 6 consists of repeating units of large hexagonal rings while that of 7 consists of rhomboidal
rings. Combination of FcPM with phloroglucinol produces a layered structure complex,
[FcPMꢀ(phloroglucinol)ꢀ2H2O]n (8), exhibiting three-dimensional hydrogen bonding. In this complex, FcPM
molecules link hydrogen-bonded sheets composed of phloroglucinol and water molecules. The dimensionality
of the assembled structures is influenced by the number of hydrogen-bonding substituents on the donor
molecules.
non-linear optical materials.10 In particular, the redox activity
Introduction
of metallocenes leads to a variety of interesting electrical and
photophysical phenomena.11 So far, several hydrogen-bonded
supramolecules derived from metallocenes have been reported,
in which the organometallic component works as a hydrogen-
bond donor or as a hydrogen-bond acceptor.12 However,
hydrogen-bonded complexes of mono-substituted ferrocenes
have received less attention.13 In the present paper, we describe
the structural variation in hydrogen-bonded co-crystals of 5-
ferrocenylpyrimidine (FcPM), with the hydrogen-bond topol-
ogy ranging from discrete to three-dimensional. Together with
our previous study on the assembly of FcPM via coordination
bonds, our studies demonstrate the crystal engineering possibi-
lities of ferrocene-containing materials.
Currently, there is much interest in the synthesis of materials
possessing desired crystallographic architectures as well as spe-
cific physical and chemical properties.1 Coordination bonds
and hydrogen bonds can be used to control the organization
of molecules or ions in the solid state and both have been
widely used in crystal engineering and supramolecular
design.2,3 To synthesize redox-active supramolecules with
organometallic motifs, we have designed several ferrocene-
based supramolecular building blocks and assembled them
via coordination bonds; side-chain coordination polymers,
main-chain polymers as well as ferrocene clusters have been
synthesized so far.4 As the next target, we focused on the use
of hydrogen bond for assembling these organometallic compo-
nents. Among the molecules we designed, 5-ferrocenylpyrimi-
dine (FcPM)4a,b is interesting for supramolecule construction
because the pyrimidine moiety can act not only as a metal
coordination site, but also as a hydrogen-bond accepting site.
For example, several functional molecular assemblies, which
show guest inclusion properties, catalytic activities, etc., have
been synthesized using the hydrogen-bonding abilities of pyri-
midine derivatives.5
Thus, to design hydrogen-bonded molecular assemblies con-
taining ferrocenes, we combined FcPM and various organic
hydrogen-bond donors, shown in Fig. 1, which are frequently
employed as building blocks of hydrogen-bonded crystals.3,6
Hydrogen-bond donors, carrying two, three or four hydrogen-
bonding substituents, have been selected to investigate hydro-
gen-bond topology and dimensionality. We used phenol deriva-
tives such as hydroquinone, resorcinol, (R)-(þ)-1,10-bi-2-
naphthol and phloroglucinol, and carboxylic acids: succinic
acid, 2,20-thiodiglycolic acid, trimesic acid and pyromellitic acid.
Metallocenes7 play important roles in the field of materials
science, as components of catalysts,8 molecular magnets9 and
Results and discussion
A. Synthesis
FcPM and various hydrogen-bond donors were mixed in a
ratio of 1:1 and dissolved in methanol or acetonitrile. The solu-
tions were left to evaporate slowly at room temperature in air.
Single crystals of carboxylic acid complexes were obtained
from methanol solutions, while those of phenol complexes
(except for complex 5) were from acetonitrile solutions. Com-
pounds 1–8 were all isolated in good yields as the sole pro-
ducts. The composition of the products was either 1:1 or 2:1
FcPM:donor stoichiometry and were not affected by changes
in the stoichiometry of FcPM and donors used in the reaction.
Crystal data, data collection parameters and analysis statistics
for complexes 1–8 are listed in Table 1. In all compounds, O–
Hꢀ ꢀ ꢀN hydrogen bonds are formed, as summarized in Table 2.
The hydrogen-bond distances in carboxylic acid complexes (1,
˚
4, 6, and 7) are 2.67–2.78 A and those in phenol complexes (2,
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
26
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 6 – 3 3

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Fig. 1 Building blocks used for the synthesis of the ferrocene-based hydrogen-bonded supramolecules 1–8: FcPM ¼ 5-ferrocenylpyrimidine, (a)
succinic acid, (b) hydroquinone, (c) resorcinol, (d) 2,20-thiodiglycolic acid, (e) (R)-(þ)-1,10-bi-2-naphthol, (f) trimesic acid, (g) pyromellitic acid and
(h) phloroglucinol.
14
˚
3, 5, and 8) are 2.69–2.81 A, which are typical values. Other
hydrogen-bond donors, such as 1,2,3- and 1,2,4- benzenetri-
carboxylic acid, oxalic acid, malonic acid, squaric acid and
catechol, were also tested but they failed to co-crystallize with
FcPM.
the two nitrogen atoms of FcPM is involved in hydrogen
bonding, while the other is free. The discrete units of 1 and 2
lie on inversion centres, while that of 4 has no inversion sym-
metry. The resorcinol molecule in 3 shows two-fold disorder
around the centre of the benzene ring with a site occupancy
of 1:1; the discrete unit was observed to have an apparent
inversion centre. In Fig. 2(c), only one disordered site of the
resorcinol molecule is shown for simplicity. The crystal struc-
tures, packing modes and cell parameters of 1–3 are very simi-
lar and they are almost isomorphous with each other. It is
highly interesting that such a similarity is observed, indepen-
dent of the nature of the hydrogen-bonding species (i.e., car-
boxylic acids or phenols) or substituent position (i.e., meta
or para isomers). The common feature in these complexes is
that the intermolecular N(1)ꢀ ꢀ ꢀN(1*) separations through the
.
B. Discrete complexes with 2:1 stoichiometry: [(FcPM)2 D]
[D ¼ succinic acid (1), hydroquinone (2), resorcinol (3) and
2,20-thiodiglycolic acid (4)]
The combination of FcPM with organic molecules that have
two hydrogen-donor substituents, such as succinic acid, hydro-
quinone, resorcinol and 2,20-thiodiglycolic acid, produced dis-
crete complexes with a 2:1 stoichiometry: [(FcPM)2ꢀD] [with
D ¼ succinic acid (1), hydroquinone (2), resorcinol (3) and
2,20-thiodiglycolic acid (4)]. The structures of 1–4 have been
determined crystallographically. In these complexes, two
FcPM molecules are bridged by the donor molecule via the
O–Hꢀ ꢀ ꢀN hydrogen bonds, as shown in Fig. 2. Thus, one of
˚
hydrogen bonds are about 10 A, which may presumably result
in similar packing structures. In the crystals of 1–4, the Nꢀ ꢀ ꢀN
˚
distances are 10.62, 9.77, 9.76 and 9.86 A, respectively, and the
intramolecular Oꢀ ꢀ ꢀO distances in the hydrogen-bond donors
˚
are 5.92, 5.52, 4.66 and 6.34 A, respectively.
Table 1 Selected crystallographic data for 1–8
1
2
3
4
5
6
7
8
Formula
Formula weight 646.31
C32H30N4O4Fe2 C34H30N4O2Fe2 C34H30N4O2Fe2 C32H30N4O4SFe2 C34H26N2O4Fe C23H18N2O6Fe C34H30N4O8Fe2 C20H22N2O5Fe
638.33
Monoclinic
P21/n (No.14)
10.801(5)
7.696(5)
17.052(4)
90
638.33
Monoclinic
P21/n (No.14)
10.766(3)
7.576(3)
17.452(4)
90
678.37
Monoclinic
P21/c (No.14)
7.406(3)
19.131(7)
20.727(3)
90
550.44
Monoclinic
P21 (No.4)
9.320(4)
10.951(5)
13.149(4)
90
474.25
Triclinic
P¯ı (No.2)
11.037(2)
12.652(4)
7.518(5)
104.42(3)
96.41(3)
88.21(2)
1010.4(8)
2
782.37
Monoclinic
C2/c (No. 15)
12.474(4)
13.687(3)
19.390(3)
90
426.25
Orthorhombic
Pbcm (No.57)
7.997(3)
14.278(2)
17.219(2)
90
Crystal system
Space group
Monoclinic
P21/n (No.14)
9.755(4)
8.478(3)
17.791(3)
90
˚
a/A
˚
b/A
˚
c/A
a/deg
b/deg
g/deg
95.72(2)
90
95.10(3)
90
94.59(2)
90
92.42(3)
90
99.32(3)
90
94.10(2)
90
90
90
3
˚
U/A
1464.1(8)
2
10.34
1411(1)
2
10.66
1418.9(6)
2
10.61
2933(1)
4
11.04
1324.3(9)
2
6.04
3302(1)
4
4.93
1966.3(10)
4
8.00
Z
m/cmꢁ1
T/K
7.91
296
296
3797
296
3653
296
3679
296
7461
296
3391
296
3777
296
2703
Measured
reflections
Observed
reflections
(I > 2.0s(I)]
b R1
4892
2305
2729
2071
4327
3385a
2935
3926
1437
0.060
0.180
0.050
0.148
0.049
0.143
0.041
0.129
0.042
0.137
0.042
0.112
0.052
0.164
0.057
0.171
b Rw
I > 0.0s(I) R1 ¼ S||Fo| ꢁ |Fc||/S|Fo|; Rw ¼ [Sw(Fo ꢁ Fc2)2/Sw(Fo2)2]1/2
.
a
b
2
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 6 – 3 3
27

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Table 2 Hydrogen bond distances in 1–8
C. Chiral chain complex with ferrocenyl pendants:
0
.
[FcPM {(R)-(þ)-1,1 -bi-2-naphthol}]n (5)
˚
Complex
D–Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA/A
Symmetry code
To construct a chiral supramolecular assembly of FcPM, we
used commercially available (R)-(þ)-1,10-bi-2-naphthol, which
is a representative chiral molecule with two hydrogen-bonding
sites. The combination of this molecule with FcPM produced a
1:1 complex, [FcPMꢀ{(R)-(þ)-1,10-bi-2-naphthol}]n (5). The
absolute structure of 5 was confirmed by referring to the Flack
parameter. Fig. 3 shows the hydrogen-bonded chain structure
of 5, in which binaphthols are linked via O1–Hꢀ ꢀ ꢀO2* intermo-
1
2
3
O1a –H15ꢀ ꢀ ꢀN1
O1b –H14ꢀ ꢀ ꢀN1
O1b –H14ꢀ ꢀ ꢀN1
O2b –H26ꢀ ꢀ ꢀN1
O1a –H25ꢀ ꢀ ꢀN1
O3a –H30ꢀ ꢀ ꢀN3
O1b –H13ꢀ ꢀ ꢀO2
O2b –H20ꢀ ꢀ ꢀN2
O1a –H16ꢀ ꢀ ꢀN1
O3a –H17ꢀ ꢀ ꢀN2
O5a –H18ꢀ ꢀ ꢀO6
O1a –H13ꢀ ꢀ ꢀN1
O3a –H14ꢀ ꢀ ꢀN2
O1b –H10ꢀ ꢀ ꢀN
O2b –Hc ꢀ ꢀ ꢀO3w
O3w–Hc ꢀ ꢀ ꢀO1
O3w–Hc ꢀ ꢀ ꢀO3w
2.681(5)
2.805(4)
2.793(8)
2.882(8)
2.697(5)
2.695(5)
2.812(6)
2.686(7)
2.673(3)
2.695(3)
2.678(3)
2.778(3)
2.737(4)
2.742(5)
2.715(4)
2.787(4)
2.667(8)
x, ꢁ1 þ y, z
x, ꢁ1 þ y, z
1/2 ꢁ x, 1/2 þ y, 1/2 ꢁ z
1/2 ꢁ x, 1/2 þ y, 1/2 ꢁ z
x, 1/2 ꢁ y, 1/2 þ z
ꢁ1 þ x, ꢁ1 þ y, z
ꢁx, 1/2 þ y, 1 ꢁ z
1 ꢁ x, ꢁ1/2 þ y, 1 ꢁ z
ꢁ1 ꢁ x, ꢁ1 ꢁ y, ꢁ1 ꢁ z
ꢁ1 ꢁ x, ꢁy, ꢁz
4
5
6
˚
lecular hydrogen bonds [2.812(6) A] to form a chiral chain.
The O2 atoms are further bonded to FcPM molecules via the
˚
O2–Hꢀ ꢀ ꢀN2 hydrogen bond [2.686(7) A]. Thus, FcPM mole-
ꢁ2 ꢁ x, ꢁ1 ꢁ y, ꢁz
cules are attached to the helical chain of binaphthol molecules
as pendants. Only one nitrogen atom of FcPM is involved in
hydrogen bonding. The ferrocene moieties along the chain
are arranged in the same direction, which leads to the polar
structure of the crystal.
7
8
3/2 ꢁ x, ꢁ1/2 ꢁ y, 2 ꢁ z
ꢁx, ꢁ1/2 þ y, z
ꢁ1 þ x, y, z
Among the hydrogen-bond donors we used, this was the
only molecule that has chirality. The control of chirality in fer-
rocene-based materials is interesting from the viewpoint of
nonlinear optical properties. As a related example, Lee and
Chung13b have reported the synthesis and structure of hydro-
gen-bonded supramolecules composed of 1,10-bis(ethenyl-4-
pyridiyl)ferrocene and 1,10-bi-2-naphthol. In their system, con-
trol of the assembled structures was achieved by changing the
recrystallization solvent and the relationship between the
hydrogen-bonded ferrocene assembled structures and SHG
efficiencies has been demonstrated. In the present study, we
tried to obtain different co-crystals by changing solvents and
also tried to co-crystallize FcPM with racemic 1,10-bi-2-
naphthol, but both strategies were unsuccessful.
ꢁx, ꢁ1 ꢁ y, ꢁ1 ꢁ z
a
Carboxylic acid oxygen. b Phenolic oxygen. c Disordered hydrogen.
Fig. 2 Structures of the discrete units in (a) 1, (b) 2, (c) 3 and (d) 4.
Dashed lines indicate hydrogen bonds. Hydrogen atoms bonded to
carbon atoms are omitted for clarity. For complex 3, only one disor-
dered site of the resorcinol molecule is shown for clarity.
Fig. 3 Part of the chiral chain structure of 5. Dashed lines indicate
hydrogen bonds. Hydrogen atoms bonded to carbon atoms are
omitted for clarity.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
28
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 6 – 3 3

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unit in 7 is tilted, because neighbouring carboxyl groups of
pyromellitic acid are perpendicular to each other. The inver-
sion centre of 7 lies at the centre of pyromellitic acid.
D. Tape-structure complexes with hydrogen-bonded cyclic
.
.
motifs: [FcPM (trimesic acid)]n (6) and [(FcPM)2 (pyromellitic
acid)]n (7)
Fig. 6 shows a schematic illustration of the expanded struc-
tures of 6 and 7. The tape structures in both complexes are
double-chain structures, which are composed of alternate link-
ing of FcPM and hydrogen-bond donors. The trimesic acid in
6 is dimerized through self-complementary hydrogen bonding
and works as a unit that contains four hydrogen bonding sites.
Thus, from the viewpoint of hydrogen-bonding topology, tri-
mersic acid in 6 plays the same role as pyromellitic acid in 7.
To expand the dimensionality of FcPM complexes, we com-
bined FcPM with trimesic acid and pyromellitic acid, which
have three and four carboxyl groups, respectively. Combina-
tion of FcPM with trimesic acid produced a 1:1 complex,
[FcPMꢀ(trimesic acid)]n (6). Fig. 4 shows the tape structure
of 6, which runs along the [0,1,1] direction. The tape is formed
by a large hexagonal ring repeating unit consisting of four
molecules of trimesic acid and two molecules of FcPM. Two
of the carboxyl groups of trimesic acid link FcPM via O–
Hꢀ ꢀ ꢀN hydrogen bonds, while the other carboxyl group forms
a homomeric self-complementary hydrogen bond. Two ferro-
cene moieties of adjacent tapes are located inside the hexago-
nal ring. The inversion centre lies at the centre of the self-
complementary hydrogen bond. Judging from the normal
E. Three-dimensional hydrogen-bonded complex with a layered
.
structure: [FcPM (phloroglucinol) 2H2O]n (8)
.
The combination of FcPM with phloroglucinol, which con-
tains three hydroxyl groups, produced a three-dimensionally
hydrogen-bonded complex, [FcPMꢀ(phloroglucinol)ꢀ2H2O]n
(8). The complex crystallizes in the space group Pbcm and
the asymmetric unit is comprised of a half molecule of FcPM,
a half molecule of phloroglucinol and one H2O molecule. Due
to the crystallographically imposed mirror symmetry on
FcPM, the Cp ring and pyrimidine ring are co-planar. This
is somewhat exceptional because the rings in FcPM are gener-
ally twisted due to the steric hindrance of the ring hydrogens,
as observed in the crystals of FcPM, complexes 1–7 and in
some metal complexes.4a,b
˚
˚
=
bond lengths of 1.299(4) A (C–OH) and 1.234(4) A (C O),
there seems to be no proton transfer occurring along the
hydrogen bonds1f,15 within the carboxylic acid dimer.
On the other hand, the combination of FcPM with pyromel-
litic acid produced a 2:1 complex, [(FcPM)2ꢀ(pyromellitic
acid)]n (7). This complex also exhibits a tape structure, which
runs along the a axis. Fig. 5 shows the tape structure, which
consists of a square ring repeating unit formed from two mole-
cules of pyromellitic acid and two molecules of FcPM. In con-
trast to the planar hexagonal repeating unit in 6, the square
Complex 8 has a layered structure, composed of two-dimen-
sional phloroglucinol–water sheets that are linked by FcPM
molecules via hydrogen bonds. Fig. 7(a) shows the structure
of the hydrogen-bonded sheet, which extends within the ab
plane. The hydroxyl groups of phloroglucinol form hydrogen
bonds with water molecules. Two of the phenolic hydrogens
are further hydrogen-bonded to FcPM molecules that are
located outside the sheet. The hydrogen bond distances of
˚
O1. . .N and O1. . .O3w are 2.747(4) and 2.787(4) A, respec-
tively. Thus, FcPM molecules are located between the phloro-
glucinol–water sheets, as shown in Fig. 7 (c). Fig. 7 (d) shows
the connection between FcPM and phloroglucinol molecules
along the c axis. Several examples of hydrogen-bonded co-
crystals of phloroglucinol have been reported so far16 and in
particular, the structure of phloroglucinolꢀ2H2O is interesting
with reference to the present structure: it consists of two-
dimensional sheets formed by phloroglucinol and water mole-
cules,17 in which each phenol group is hydrogen-bonded to two
water molecules. Therefore, complex 8 may be regarded as an
insertion product of FcPM into phloroglucinolꢀ2H2O,
although the hydrogen-bonding topology of the sheets is not
exactly the same.
Fig. 7(b) shows a schematic representation of the phloroglu-
cinol–water sheet. It is interesting to note that the sheet
involves one-dimensional hydrogen-bonded chains, which are
formed by O2 atoms of phloroglucinol and water molecules,
as shown in the shaded part of Fig. 7(b). X-Ray structure ana-
lysis revealed that phloroglucinol lies on a two-fold screw axis
and the hydrogen positions in this one-dimensional chain are
disordered. Thus, the chain is observed as the averaged struc-
ture of ꢀ ꢀ ꢀO2–Hꢀ ꢀ ꢀO3w–Hꢀ ꢀ ꢀO2–Hꢀ ꢀ ꢀ and ꢀ ꢀ ꢀH–O2ꢀ ꢀ ꢀH–
O3wꢀ ꢀ ꢀH–O2ꢀ ꢀ ꢀ, which indicates that the hydrogen atoms
are either statistically or dynamically disordered. Indeed,
one-dimensional hydrogen-bonded systems are of interest
from the viewpoint of proton dynamics involving the mechan-
ism of solitonic excitation.18 Study of a possible dynamical
behaviour in this solid is in progress in our laboratories by
means of solid-state NMR and dielectric spectroscopy.
We also investigated the release of the water molecules from
the crystals of 8. Thermogravimetric analysis revealed a gra-
dual weight loss of ca. 8–9% of the original weight between
70–130 ꢂC, which corresponds to the loss of the two H2O mole-
cules (calcd 8.4%).
Fig. 4 Part of the tape structure of 6. Dashed lines indicate hydrogen
bonds. Hydrogen atoms bonded to carbon atoms are omitted for
clarity.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 6 – 3 3
29

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Fig. 5 Part of the tape structure of 7. Dashed lines indicate hydrogen bonds. Hydrogen atoms bonded to carbon atoms are omitted for clarity.
F. Dimensionality in hydrogen-bonded supramolecules of
FcPM
(1,3,5-tricarboxybenzene) and pyromellitic acid (1,2,4,5-tetra-
carboxybenzene) produce the tape complexes 6 and 7, while
phloroglucinol (1,3,5-trihydroxybenzene) forms a layered com-
plex with three-dimensional hydrogen bonds. FcPM can there-
fore be considered a flexible hydrogen-bond acceptor, which
will lead to a diversity of architectures. It has been demon-
strated that the hydrogen-bonding supramolecules involving
trimesic acid show honeycomb 2-D structures or laminates
and accommodate guest molecules in the cavities.19 However,
complex 6 does not have such an extended structure, presum-
ably because of the bulkiness of the ferrocenyl moiety, which
occupies the honeycomb cavities. On the other hand, the tape
structure of pyromellitic acid complexes as in 7 is more com-
mon, as can be found in the crystal structure of pyromellitic
acidꢀ2DMSO.20
As shown above, the combination of FcPM with various
hydrogen-bond donors produces supramolecular architectures
formed by O–Hꢀ ꢀ ꢀN hydrogen bonds. The hydrogen-bonding
ability of FcPM may be better than that of pyrimidine, due
to the strong electron-releasing effect of the ferrocenyl group.
We can recognize some correlations between the number of
hydrogen-bonding substituents and the dimensionality of the
supramolecular architectures; upon increasing the number of
hydrogen-bonding substituents on the donor molecule the
dimensionality of the assembled structure increases. The
dimensionality of the hydrogen bonding in the present com-
plexes can be summarized as follows: hydrogen-bond donors
with two hydrogen-bonding sites give low-dimensional struc-
tures, that is , discrete complexes (1–4) and a one-dimensional
complex (5), in which only one of the nitrogen atoms of FcPM
forms a hydrogen bond. However, for donors with more than
three hydrogen-bonding substituents, the resulting complexes
show high-dimensional structures, in which both nitrogen
atoms of FcPM are involved in hydrogen bonds: trimesic acid
In our previous study on the assembly of ferrocene-based
materials via coordination bonds, topologically interesting
architectures, such as redox-active molecular chains, 2-D
structures and metallocene clusters, were obtained.4 In the pre-
sent work, we have demonstrated the hydrogen-bond directed
organization of organometallic components, which leads to a
variation of the dimensionality, ranging from discrete to
three-dimensional. In particular, the correlation between the
dimensionality and the kind of hydrogen-bond donors has
been shown. One of the advantages of the bulk assembled
materials is the ease of structural characterization by crystallo-
graphy. Studies on the assembly of redox-active components
will further build the foundations for the construction and
analysis of functional 2-D surfaces organized by hydrogen
bonds or coordination bonds.
Experimental
General methods
All reagents and solvents were commercially available except
for 5-ferrocenylpyrimidine (FcPM),4b which was synthesized
by following the literature procedure. Infrared spectra were
recorded on a JASCO FT-IR 230 spectrometer as KBr pellets
in the 4000–400 cmꢁ1 range. Thermogravimetric analysis was
performed on a Seiko TG/DTA 6200. Elemental analyses were
performed on a Perkin–Elmer 2400CHN Elemental Analyzer.
Fig. 6 Schematic illustrations of the tape structures in (a) 6 and (b) 7.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
30
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 6 – 3 3

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Fig. 7 Crystal structure of 8. (a) Two-dimensional sheet composed of phloroglucinol and two H2O molecules and (b) a schematic illustration in
which the shaded part indicates hydrogen-bonded chains (see text). (c) Packing diagram of 8 viewed along the a axis. (d) One-dimensional hydro-
gen-bonded chain of FcPM and phloroglucinol. Dashed lines indicate hydrogen bonds. Hydrogen atoms bonded to carbon atoms are omitted for
clarity.
Preparations
calcd for C34H30N4O2Fe2 : C, 63.98; H, 4.74; N, 8.78; found:
C, 63.00; H, 5.12; N, 7.19%.
.
[(FcPM)2 (succinic acid)] (1). To a solution of FcPM (26
mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of methanol, a solution of succinic
acid (12 mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of methanol was added.
After standing for a few days, orange crystals were formed in
good yield (40–75%) as the sole product, which was character-
ized by X-ray diffraction, infrared spectra and elemental analy-
sis. FT-IR v/cmꢁ1: 3100–2200 br (OH) and 1697 s (CO). Anal.
calcd for C32H30N4O4Fe2 : C, 59.47; H, 4.68; N, 8.67; found C,
59.67; H, 4.73; N, 8.64%.
[(FcPM)2ꢀ(2,20–thiodiglycolic acid)] (4). Prepared as for 1
using FcPM (26 mg, 1.0 ꢃ 10ꢁ4 mol) and 2,20-thiodiglycolic
acid (15 mg, 1.0 ꢃ 10ꢁ4 mol). Orange plate-like crystals. FT-
IR v/cmꢁ1: 3300–2400 br (OH) and 1706 s (CO). Anal. calcd
for C32H30N4O4Fe2S: C, 56.66; H, 4.46; N, 8.26; found: C,
56.46; H, 4.53; N, 7.99%.
[FcPMꢀ{(R)-(þ)-1,10-bi-2-naphthol}]n (5). Prepared as for 1
using FcPM (26 mg, 1.0 ꢃ 10ꢁ4 mol) and (R)-(þ)-1,1’-bi-2-
naphthol (29 mg, 1.0 ꢃ 10ꢁ4 mol). Orange prismatic crystals.
[(FcPM)2ꢀ(hydroquinone)] (2). Prepared as for 1 using FcPM
(26 mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of acetonitrile and hydroqui-
none (11 mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of acetonitrile. Orange
prismatic crystals. FT-IR v/cmꢁ1: 3300–2400 br (OH). Anal.
calcd for C34H30N4O2Fe2 : C, 63.98; H, 4.74; N, 8.78; found:
C, 63.87; H, 4.73; N, 8.77%.
FT-IR v/cmꢁ1
: 3600–2800 br (OH). Anal. calcd for
C34H26N2O2Fe: C, 74.19; H, 4.76; N, 5.09; found: C, 73.94;
H, 4.85; N, 4.93%.
[FcPMꢀ(trimesic acid)]n (6). Prepared as for 1 using FcPM
(26 mg, 1.0 ꢃ 10ꢁ4 mol) and trimesic acid (21 mg, 1.0 ꢃ 10ꢁ4
mol). Orange prismatic crystals. FT-IR v/cmꢁ1: 3300–2500
br (OH) and 1698 s (CO). Anal. calcd for C23H18N2O6Fe: C,
58.25; H, 3.83; N, 5.91; found: C, 58.45; H, 3.87; N, 5.89%.
[(FcPM)2ꢀ(resorcinol)] (3). Prepared as for 1 using FcPM (26
mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of acetonitrile and resorcinol (11
mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of acetonitrile. Orange prismatic
crystals. FT-IR v/cmꢁ1: 3300–2400 br (OH). Anal.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 2 6 – 3 3
31

View Online
Soc., Dalton Trans., 2000, 3483; (k) G. F. Swiegers and T. J.
[(FcPM)2ꢀ(pyromellitic acid)]n (7). Prepared as for 1 using
FcPM (26 mg, 1.0 ꢃ 10ꢁ4 mol) and pyromellitic acid (25 mg,
Malefetse, Chem. Rev., 2000, 100, 3483; (l) S. Leininger, B.
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(a) N. Shan, A. D. Bond and W. Jones, New J. Chem., 2003, 27,
365; (b) R. D. B. Walsh, M. W. Bradner, S. Fleischman, L. A.
Morales, B. Moulton, N. Rodriguez-Hornedo and M. J.
Zaworotko, Chem. Commun., 2003, 186; (c) N. Shan, A. D. Bond
and W. Jones, Cryst. Eng., 2002, 5, 9; (d ) C. B. Aakero¨y, A. M.
Beatty and B. A. Helfrich, J. Am. Chem. Soc., 2002, 124,
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MacGillivray, J. Am. Chem. Soc., 2002, 124, 11 606; ( f ) G. S.
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Torigoe and Y. Yamamoto, Eur. J. Inorg. Chem., 2002, 3197;
(e) R. Horikoshi, K. Hagiwara and T. Mochida, submitted.
(a) T. Tanaka, T. Tasaki and Y. Aoyama, J. Am. Chem. Soc.,
2002, 124, 12 453; (b) M. Naito, Y. Sasaki, T. Dewa, Y. Aoyama
and Y. Okahara, J. Am. Chem. Soc., 2001, 123, 11 037.
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1.0 ꢃ 10ꢁ4 mol). Orange prismatic crystals. FT-IR v/cmꢁ1
:
3100–2500 br (OH) and 1722 s (CO). Anal, calcd for
C34H30N4O8Fe2 : C, 58.34; H, 3.87; N, 7.16; found: C, 58.11;
H, 3.94; N, 7.03%.
[FcPMꢀ(phloroglucinol)ꢀ2H2O]n (8). Prepared as for 1 using
FcPM (26 mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of acetonitrile and
phloroglucinolꢀ2H2O (16 mg, 1.0 ꢃ 10ꢁ4 mol) in 2 mL of acet-
onitrile. Orange plate-like crystals. FT-IR v/cmꢁ1: 3100–2500
br (OH). Anal. calcd for C20H22N2O5Fe: C, 56.36; H, 5.20; N,
6.57; found: C, 56.24; H, 5.17; N, 6.64%.
3
Crystal structure analysis
X-Ray diffraction data for single crystals were collected on a
Rigaku AFC-5S four-circle diffractometer equipped with a
graphite crystal and incident beam monochromator using
˚
Mo-Ka radiation (l ¼ 0.71073 A) at 296 K. All calculations
were performed using the teXsan crystallographic software
package.21 These structures were solved by direct methods
(SIR 9222) and expanded using Fourier techniques. Refine-
ments were carried out on F2 and an absorption correction
was applied (f scan). The hydrogen atoms attached to carbon
atoms were inserted at the calculated positions and allowed to
ride on their respective parent atoms. The hydrogen atoms
attached to oxygen atoms were located on the electron density
maps and refined at fixed distances from the respective parent
atoms, except for the water hydrogen atoms in compound 8,
which could not be located. The absolute structure of 5 was
determined based on the Flack parameter.y
4
5
6
Acknowledgements
This work was supported by the Morino Foundation for
Molecular Science. We acknowledge JST (Japan Science and
Technology Corporation) for the loan of experimental equip-
ment. We are grateful to Mr. K. Takazawa for his assistance
with the synthesis. We thank Mr. H. Iwata and Prof. T. Kita-
zawa (Toho University) for their help with the thermogravi-
metric (TG) analysis. We also thank Mr. M. Nakama
(WarpStream Ltd., Tokyo) for constructing the Web-DB sys-
tem.
7
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