Substituent effects on formation of cation dimers by weak hydrogen bonds in crystals of carbonyl pyridinium salts of ni(dmit)2

Article abstract of DOI:10.1246/bcsj.82.1152

Five 1:1 salts of 3-X-1-methylpyridinium (X = benzoyl, acetyl, methoxycarbonyl, carboxy, and aminocarbonyl; abbreviated as Ben, Ace, Met, Car, and Ami, respectively) cations with a [Ni(dmit)₂]^- anion ([Ben]⁺[Ni(dmit)₂]^- (1), Ace] ⁺[Ni(dmit)₂]^- (2), [Met]⁺[Ni(dmit) ₂]^- (3), [Car]⁺[Ni(dmit)₂] ^- (4), and [Ami]⁺[Ni(dmit)₂]^- (5)) have been synthesized and characterized by single-crystal X-ray analysis and conductivity measurements. In the crystals, three cations 1-3 were found to form dimers by weak C-H...O hydrogen bonds, and the arrangements of cations had a strong relation with the electronic effect of the substituents. The cations of 1-3 formed similar centrosymmetrically associated dimers constructed by weak C-H...O hydrogen bonds, whose geometric parameters had a correlation with the electronic effect of the substituents. A cation of 4 also formed centrosymmetrically associated dimer, but it was made by an O-H...O hydrogen bond as usually observed in the case of carboxylic acid. In contrast with other complex salts, cations of 5 formed one-dimensional structure by C-H...O hydrogen bonding. The conductivities of salts 1, 2, 3, 4, and 5 at room temperature were 1.00 × 10^-6, 1.10 × 10^-6, 2.86 × 10^-6, 9.77 × 10^-6, and 8.75 × 10 ^-7Scm^-1, respectively.

Full text of DOI:10.1246/bcsj.82.1152

1152 Bull. Chem. Soc. Jpn. Vol. 82, No. 9, 1152–1159 (2009)
© 2009 The Chemical Society of Japan
Substituent Effects on Formation of Cation Dimers by Weak Hydrogen
Bonds in Crystals of Carbonyl Pyridinium Salts of Ni(dmit)2
Kazuaki Tomono,* Ayako Koyano, Takashi Morita, and Kazuo Miyamura
Department of Chemistry, Faculty of Science, Tokyo University of Science,
1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601
Received January 26, 2009; E-mail: 1303667@may.rikadai.jp
Five 1:1 salts of 3-X-1-methylpyridinium (X = benzoyl, acetyl, methoxycarbonyl, carboxy, and aminocarbonyl;
¹
+
¹
abbreviated as Ben, Ace, Met, Car, and Ami, respectively) cations with a [Ni(dmit)2] anion ([Ben] [Ni(dmit)2] (1),
[
+
¹
+
¹
+
¹
+
¹
Ace] [Ni(dmit)2] (2), [Met] [Ni(dmit)2] (3), [Car] [Ni(dmit)2] (4), and [Ami] [Ni(dmit)2] (5)) have been
synthesized and characterized by single-crystal X-ray analysis and conductivity measurements. In the crystals, three
cations 1­3 were found to form dimers by weak C­H£O hydrogen bonds, and the arrangements of cations had a strong
relation with the electronic effect of the substituents. The cations of 1­3 formed similar centrosymmetrically associated
dimers constructed by weak C­H£O hydrogen bonds, whose geometric parameters had a correlation with the electronic
effect of the substituents. A cation of 4 also formed centrosymmetrically associated dimer, but it was made by an O­H£O
hydrogen bond as usually observed in the case of carboxylic acid. In contrast with other complex salts, cations of 5
formed one-dimensional structure by C­H£O hydrogen bonding. The conductivities of salts 1, 2, 3, 4, and 5 at room
¹6
¹6
¹6
¹6
¹7
¹1
temperature were 1.00 © 10 , 1.10 © 10 , 2.86 © 10 , 9.77 © 10 , and 8.75 © 10 S cm , respectively.
Physical properties of molecular conductors depend on the
molecular alignment in crystals. However, prediction of the
molecular alignment within a crystal is usually difficult, because
of the presence of many local minima of lattice energy derived
from van der Waals interaction which operates weakly and
rather isotropically. That is why compounds often exhibit
polymorphism. On the other hand, hydrogen bonding has a
strictly fixed orientation, and this intermolecular interaction
forms a characteristic structure in the crystal. The bonding
The metal complex Ni(dmit) (dmit = 1,3-dithiole-2-thione-
2
4,5-dithiolate) has been widely studied as a conductor or a
1
3­15
magnetic material.
Up to now, eleven molecular super-
conductors based on metal complexes of dmit ligand have been
1
6­24
discovered.
The counter cations used in the M(dmit) salts
2
can be closed shell as well as open shell cations. The former
cations do not make any contribution to the conduction path,
although their shapes and sizes play a crucial role on the mode
of stacking of anion complexes, which will determine the
electrical properties of the salts. Since the discovery of the
first closed shell molecular superconductor [N(CH ) ][Ni-
1
,2
schemes are therefore predictable to a certain extent.
Furthermore, non-covalent intermolecular forces play a major
role in determining the crystal structure, i.e., especially for
dielectric material and biological macromolecules.3 As for the
intermolecular interaction, the focus has been on the hydrophilic
interaction; X­H£Y (X = O, N and Y = O, N, and halogen)
hydrogen bonds are generally considered to be a major force in
selective and/or specific molecular recognition. However, it has
become accepted that supramolecular assemblies are achieved
not only by strong hydrogen bonds such as above-mentioned O­
H£O and N­H£O, but also by weak C­H£O hydrogen bonds.
The importance of C­H£O hydrogen bonding is now widely
recognized especially in forming desired crystal structures. The
understanding and utilization of all non-covalent interactions
including allegedly weak interactions are of fundamental
importance for further development of crystal engineering,
3
4
1
7
(dmit)2]2, closed shell cations used so far have been mostly
of the tetraalkylammonium type. To date, we have been
,4
exploring methods to control the Ni(dmit) arrangement by
2
regulating intermolecular interaction of chemically modified
2
5­28
25
cations.
As shown in our previous report, the use of
geometric isomers of methoxycarbonyl-1-methylpyridinium
as cation resulted in formation of cation aggregate by weak
C­H£O hydrogen bonds in crystal structure. The synthesis of
such Ni(dmit)2 complex salt has drawn our attention to the role
of weak C­H£O hydrogen bonding involving carbonyl groups,
because such a weak interaction between cations (especially in
metal complex crystals) has not been discussed in detail.
In this study, in order to examine the ability of remarkably
weak C­H£O hydrogen bonds and the effect of electron-
5
­12
i.e., the tuning and the prediction of crystal structure.
The
releasing substituents in cations of the Ni(dmit) salts, we used
2
present study aims at investigating the importance of weak
hydrogen bonding (especially C­H£O hydrogen bonds) in the
crystals of metal complex salts and its influence on aggregated
structure of the cation domain to the cation domain of
aggregate form and also on geometric parameters by means
of single-crystal X-ray analysis and IR spectroscopy.
five pyridinium derivatives. The five counter cations of the
[Ni(dmit)2] complex used are 3-benzoyl-1-methylpyridinium
(abbreviated as Ben), 3-acetyl-1-methylpyridinium (abbreviat-
ed as Ace), 3-methoxycarbonyl-1-methylpyridinium (abbrevi-
ated as Met), 3-carboxy-1-methylpyridinium (abbreviated as
Car), and 3-aminocarbonyl-1-methylpyridinium (abbreviated
¹
Published on the web September 9, 2009; doi:10.1246/bcsj.82.1152

K. Tomono et al.
Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009) 1153
X = C H5
X = CH3 ( Ace)
X = OCH3 ( Met)
X = OH
X = NH2
918 (s). 5; Anal. Found: C, 26.51; H, 1.15; N, 4.58%. Calcd for
C13H9N2NiOS10: C, 26.52; H, 1.54; N, 4.76%. IR (KBr, cm ):
6
( Ben)
¹1
3
1
437 (w), 3315 (w), 3084 (w and br), 1688 (m, C=O), 1393 (m),
345 (m, C=C), 1121 (m), 1057 (s, C=S).
N
X
(
(
Car)
Ami)
X-ray Crystallography. A single crystal was mounted on a
O
glass capillary. Intensity data were collected at 300(1) K by a
Bruker AXS SMART diffractometer equipped with a CCD area
detector and Mo K¡ (­ = 0.71073 ¡) radiation. The structures of
S
S
S
S
S
S
1
­5 were solved and refined with SHELX-9731 using direct
S
Ni
S
method and expanded using Fourier techniques. All non-hydrogen
atoms were refined anisotropically by the full-matrix least-square
method. Some hydrogen atoms were found from experimental data
directly, and their position and isotropic thermal parameters were
refined. Selected crystallographic data are summarized in Table 1.
Crystallographic data have been deposited at the Cambridge
Crystallographic Data Centre: Deposit numbers CCDC-665665­
665661 for compounds 1­5, respectively. Copies of the data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html (or from the Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge, CB2 1EZ, U.K.; FAX: +44
1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
Measurements. IR spectra (KBr pellets) were measured with a
JASCO FT/IR-410 spectrophotometer. Elemental analyses were
performed with a Perkin-Elmer 2400II CHN analyzer. Conductiv-
ity measurements were carried out at ambient pressure using a
two-probe ac impedance method. Electrical contacts were prepared
using gold paste to attach 0.1 mmº gold wires (The Nilaco
CORPORATION) to the crystals.
S
S
Ni(dmit)2
Chart 1.
as Ami) ions. The functional groups ­C H , ­Me, ­OMe, ­OH,
6
5
and ­NH used in these cations are known as substituents
leading to ortho and para isomers in the substitution reaction of
benzene rings particular for electron-releasing substituents. The
2
29
electron-releasing ability is also in this order. Hereafter, the
+
¹
+
¹
+
crystals of [Ben] [Ni(dmit) ] , [Ace] [Ni(dmit) ] , [Met] -
2
2
¹
+
¹
+
¹
[
Ni(dmit) ] , [Car] [Ni(dmit) ] , and [Ami] [Ni(dmit) ] are
2 2 2
abbreviated as 1, 2, 3, 4, and 5, respectively (Chart 1).
Experimental
Materials.
(Bu4N)[Ni(dmit)2] was synthesized according
to the literature.30 3-Carboxy-1-methylpyridinium hydrochloride
was supplied by Kanto Chemical. 3-Benzoyl-1-methylpyridinium
iodide, 3-acetyl-1-methylpyridinium iodide, 3-methoxycarbonyl-
Results and Discussion
1
-methylpyridinium iodide, and 3-aminocarbonyl-1-methylpyridi-
Structure of the Anions.
ORTEP plots with atomic
nium iodide were prepared by a similar procedure as follows;
pyridine at 3-position by the corresponding substituent (20 mmol)
and methyl iodide (40 mmol) were stirred in acetone (25 mL) for a
few minutes. The resultant crude solid was filtered and washed
several times with acetone and Et2O to obtain the derivative of
each 1-methylpyridinium iodide. The crude products were used in
the second reaction without further purification, and also all
reagents including 3-carboxy-1-methylpyridinium hydrochloride
were of reagent grade and used without further purification.
Synthesis of (Ben)[Ni(dmit)2] (1). Single crystals of 1 were
prepared by cation exchange and slow interdiffusion of an
acetonitrile solution (25 mL) of (Bu4N)[Ni(dmit)2] (0.05 mol) and
a chloroform/methanol (15:1) solution (45 mL) of (Ben)I (0.1 mol)
for several days at room temperature. Anal. Found: C, 34.91; H,
numbering scheme of all compounds 1­5 are given in Figure 1.
There was one crystallographically independent Ni(dmit) ion
2
and one counter cation within an asymmetric unit. [Ni(dmit)2]
in each crystal was almost planar (maximum deviations from
the least-square plane: 1, 0.1585(8) ¡ [S(2)]; 2, 0.3981(34) ¡
[
S(5)]; 3, 0.879(13) ¡ [S(7)]; 4, 0.1027(10) ¡ [S(6)]; and 5,
0.3318(9) ¡ [S(7)]). The cation:anion ratios were 1:1 giving
the Ni(dmit)2 unit a formal charge of ¹1. The selected bond
lengths and angles are listed in Table 2. There were no
significant differences in bond lengths and angles of Ni(dmit)2
anion within an asymmetric unit, except for 4. A strong band
¹
1
around 1350 cm in IR spectra assigned as the C=C stretching
band, was known to exhibit large shift depending on the formal
1
2
.56; N, 2.11%. Calcd for C19H12NNiOS10: C, 35.12; H, 1.86; N,
.15%. IR (KBr, cm ): 3077 (w and br), 1657 (m, C=O), 1332 (s,
¹1
0.29¹
¹1
charge of Ni(dmit) ; 1260 cm for [Ni(dmit) ]
, 1350 cm
2
2
¹1
¹
¹1
2¹ 32
for [Ni(dmit) ] , and 1440 cm
results (1328­1345 cm ) showed that the Ni(dmit) unit of
for [Ni(dmit) ] . The
2
2
C=C), 1061 (s, C=S).
Syntheses of (Ace)[Ni(dmit)2] (2), (Met)[Ni(dmit)2] (3),
¹1
2
all 1­5 was monovalent, consistent with the crystal data. Since
space groups of 1, 3, and 5 were P2(1)/c or /n, anions were
orientated in two directions forming two different stacking
(
2
Car)[Ni(dmit)2] (4), (Ami)[Ni(dmit)2] (5). Single crystals of
, 3, 4, and 5 were prepared in a similar way to 1 using (Ace)I
(
(
0.1 mmol), (Met)I (0.1 mmol), (Car)Cl (0.5 mmol), and (Ami)I
0.1 mmol), respectively, instead of (Ben)I. 2; Anal. Found: C,
ꢀ
structures, while for those of 2 and 4 adopting P1, only a single
type of stacking was present (Figure 2).
Crystal Structures of (Ben)[Ni(dmit)2] (1), (Ace)[Ni-
2
1
8.81; H, 1.42; N, 2.34%. Calcd for C14H10NNiOS10: C, 28.61; H,
.71; N, 2.38%. IR (KBr, cm ): 3077 (w), 1698 (m, C=O), 1342
¹1
(
dmit) ] (2), and (Met)[Ni(dmit) ] (3). In Figure 2, inter-
2 2
(
m, C=C), 1067 (m and br, C=S). 3; Anal. Found: C, 28.25; H,
3
3
molecular S£S contacts shorter than 3.70 ¡, the sum of
van der Waals radii of S atoms, are shown by dashed lines
1
2
1
2
.35; N, 2.29%. Calcd for C14H10NNiO2S10: C, 27.85; H, 1.66; N,
¹1
.32%. IR (KBr, cm ): 3071 (w), 1718 (m, C=O), 1338 (s, C=C),
064 (s and br, C=S). 4; Anal. Found: C, 26.66; H, 0.97; N,
.38%. Calcd for C13H8NNiO2S10: C, 26.48; H, 1.36; N, 2.37%. IR
(
Table 3). The crystal structure of 3 differed from the already
2
5
reported structure. The exact reason of the crystal polymorph
is uncertain, but differences in the solvent used during crystal
formation and the applied crystallization technique could be
¹1
(
KBr, cm ): 3857 (w), 3674 (w and br), 1725 (m, C=O), 1328
s, C=C), 1257 (s), 1183 (m and br), 1064 (s), 1040 (s), 1023(s),
(

¹
1154 Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009)
Substituent Effect in [Ni(dmit)2] Salts
Table 1. Crystallographic Data of Complex Salts 1­5
1
2
3
4
5
Formula
Fw
C19H12NNiOS10
649.61
C14H10NNiOS10
587.54
C14H10NNiO2S10
603.54
C13H8NNiO2S10
589.51
C13H9N2NiOS10
588.53
Crystal system
Space group
Monoclinic
P2(1)/n
Triclinic
ꢀ
P1
Monoclinic
P2(1)/c
Triclinic
ꢀ
P1
Monoclinic
P2(1)/c
Unit cell
a/¡
b/¡
c/¡
12.4854(10)
12.3668(10)
16.3463(14)
7.494(2)
12.034(4)
12.526(4)
77.410(3)
80.381(6)
82.180(6)
1081.1(6)
2
1.805
1.870
594
1.099
11.649(7)
26.144(7)
7.694(7)
7.5505(8)
11.5469(12)
13.5068(14)
105.623(2)
99.563(2)
105.707(2)
1054.82(19)
2
1.856
1.921
594
1.071
0.0378
0.0498
0.1011
0.1204
6.7640(6)
45.244(4)
7.4079(6)
¡
/degree
/degree
¢
104.1010(10)
105.882(7)
113.5830(10)
£/degree
Volume/¡3
Z
2447.9(3)
4
1.763
1.662
1316
0.929
0.0378
0.0552
0.0734
0.0788
2253.7(14)
4
1.779
1.800
1220
0.927
0.0374
0.0698
0.0814
0.1260
2077.7(3)
4
1.881
1.948
1188
1.077
0.0379
0.0482
0.0918
0.0953
¹
3
¤
®
calcd/Mg m
/mm
¹
1
F(000)
a)
GOF
Final R
indices [I > 2·(I)]
R indices
all data)
R1b)
0.0836
0.1029
0.2593
0.2698
c)
wR2
b)
R1
c)
(
wR2
2
2
2 2
2 2 1/2
a) Goodness-of-fit on F . b) R1 = ­««Fo« ¹ «Fc««/­«Fo«. c) wR2 = ­[w(Fo ¹ Fc ) ]/­[w(Fo ) ]
.
(
Figure 2(3)). The average interplanar distances between anion
and cation of 3 was ca. 3.53 ¡. However, cations were found to
form centrosymmetrically associated dimers by two types
2
3
of weak C(sp and sp )­H£O hydrogen bonds, which were
2
5
also present in the polymorph (Figure 3(3)). Although the
crystallization technique of this study, i.e., inter-diffusion, was
different from that in Ref. 25, i.e., solvent evaporation, dimer
of the same structure was present. Thus, this fact indicates the
high stability of the dimeric structure shown in Figure 3(3).
Ace ions also formed similar centrosymmetrically associated
dimers. The geometric parameters listed in Table 4 satisfied
the following criteria reported for general C­H£O hydrogen
bonding, i.e., C£O and H£O distances being 3.0­4.0 and
3
5­37
2
.4­3.0 ¡, respectively.
Also, anions of 2 formed a zig-zag
sheet via S£S contacts between neighboring anions along b and
c axes (Figure 2(2) and Table 3), and further S£S contacts
along a axis were present between the sheets. Therefore these
S£S contacts form a three-dimensional S£S network. The
average interplanar distance between anion and cation of 2
were ca. 3.58 ¡, slightly longer than that of 3.
Furthermore, anions of 1 formed a deeply folded zig-zag
structure like screen via S£S contacts between neighboring
anions along a and c axes (Figure 2(1) and Table 3). There
were also many S£S contacts between the sheets along the b
axis. Consequently, S£S contacts in 1 also formed a three-
dimensional network. The average interplanar distances be-
tween anion and the nearest pyridinium ring of the cation was
ca. 3.50 ¡. Unexpectedly, it was found that Ben cations also
formed centrosymmetrically associated dimers similar to Met
and Ace. Due to the bulkiness of the phenyl group, we expected
a characteristic aggregation structure made by ³£³ stacking
involving phenyl groups. The common structural feature of
Figure 1. ORTEP III views of 1­5, showing 50% prob-
ability ellipsoids with atom numbering scheme.
responsible.34 Since S£S contacts did not occur in the direction
of the b axis, anions formed a knit fabric-like structure
possessing a two-dimensional S£S network along a and c axes
2
3
cation dimers led us to conclude that weak C(sp and sp )­
H£O hydrogen bonds effectively functioned to form dimer

K. Tomono et al.
Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009) 1155
(
1)
(
2)
3)
(
(
(
4)
5)
Figure 2. Crystal packing of [Ni(dmit)2] anions in 1­5
viewed along two different directions; Dashed lines
indicate the short S£S contacts.
(
Figures 3(1)­3(3)). In addition, the dihedral angle between the
pyridinium ring and phenyl group of a cation in 1 was 52.2°,
while inter-planar dihedral angles between anion and neigh-
boring cation were 5.04° for pyridinium ring, and 37.52° for
phenyl ring. The fact that the positively charged pyridium ring
preferably aligned parallel to the negatively charged anions,
indicates the presence of Coulombic interaction between them.
Crystal Structure of (Car)[Ni(dmit) ] (4) and (Ami)[Ni-
2
(
dmit) ] (5). Although the anions of 4 are similarly arranged
2

¹
1156 Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009)
Substituent Effect in [Ni(dmit)2] Salts
Table 3. Distances (¡) of S£S Contacts in 1­5
an ­NH2 group which can form a much stronger N­H£O
hydrogen bond. The reason why a weak C­H£O hydrogen
bond was formed instead of a strong N­H£O hydrogen bond is
still uncertain. However, according to the reported crystal
structures of iodide, chloride, and picrate salts of Ami ion, N­
H£O hydrogen bonding was present in iodide, but not in
a)
c)
d)
f)
b)
a)
e)
e)
g)
i)
1
2
S2£S9
S4£S8
S3£S5
S4£S8
3.5658(10)
3.5653(11)
3.595(4)
S3£S9
S7£S7
S4£S7
S4£S9
S9£S9
S3£S9
S5£S9
S1£S5
S4£S8
S9£S9
S6£S9
3.3811(10)
3.5142(14)
3.550(3)
3.576(3)
3.521(5)
3.4737(19)
3.671(2)
3.6207(13)
3.6211(14)
3.4402(19)
3.6433(11)
3.480(3)
f)
S4£S10
3.540(4)
4
1
h)
chloride. In the case of picrate anion known as a strong
3
4
S3£S4
S5£S7
3.5392(18)
3.5704(17)
3.5894(11)
3.6530(15)
3.4667(16)
3.6016(11)
4
2
j)
i)
electron acceptor, Ami ion formed a N­H£O hydrogen bond
with the OH group of picrate anion and also a very short
k)
l)
S1£S6
S1£S5
2
k)
m)
n)
i)
C(sp )­H£O hydrogen bond. Selection between existing
k)
S6£S6
S1£S7
possible interactions is still an open question, but the one-
dimensional chain structure of Ami observed here might be a
i)
5
stable arrangement when combined with Ni(dmit) known as an
2
Symmetry codes: a) 2 ¹ x, 2 ¹ y, 2 ¹ z; b) ¹1 + x, y, z; c) ¹1/
acceptor molecule. It is noteworthy that the crystal structures of
Ace (2), Car (4), and Ami (5) salts are totally different although
their size and shape are similar. Planarity, electron density,
strong hydrogen bond, etc., contribute to crystal structure, but
the result shows that the weak C­H£O hydrogen bond also has
a non-trivial influence.
2
2
+ x, 3/2 ¹ y, 1/2 + z; d) ¹x, 2 ¹ y, 1 ¹ z; e) ¹x, 1 ¹ y,
¹ z; f) x, 1 + y, z; g) 1 ¹ x, ¹y, 2 ¹ z; h) x, 1/2 ¹ y, 1/2 + z;
i) 1 + x, y, z; j) 1 + x, 1/2 ¹ y, 1/2 + z; k) 1 ¹ x, 1 ¹ y, 1 ¹ z;
l) ¹x, ¹y, 1 ¹ z; m) ¹1 + x, ¹1 + y, z; n) 1 ¹ x, 2 ¹ y, 2 ¹ z.
Table 4. Geometries (¡, degree) of C­H£O and O­H£O
Comparison with Similar Aggregation via C­H£O
Hydrogen Bonds. When five crystal structures of 1­5 were
thoroughly investigated, two structural characteristics for cation
arrangement were observed in common. First, the oxygen atom
of the carbonyl group sticks out to the near-side of the nitrogen
in pyridinium ring. Second, pyridinium moieties and anions are
almost parallel to each other. The dihedral angles between the
plane of anion and the pyridinium ring of cation were 5.04,
Hydrogen Bonds
D­H£A
D£H H£A
D£A
(D­H£A)
1
2
3
C7­H7£O1a)
0.93
0.96
0.93
0.96
0.92
0.96
0.93
0.95
0.98
2.37 3.240(3)
2.83 3.340(4)
2.35 3.212(10)
2.44 3.251(12)
2.31 3.203(5)
2.71 3.538(6)
1.73 2.649(3)
2.94 3.296(4)
2.31 3.014(4)
155
114
155
142
164
145
172
104
128
a)
b)
C12­H12C£O1
b)
C7­H7£O1
C12­H12A£O1
c)
C7­H7£O1
c)
C12­H12A£O1
9
(
.15, 2.24, 7.83, and 3.37°, for 1­5, respectively. However, [2-
2-methoxycarbonylethyl)-1-pyridinium][Ni(dmit)2] complex
salt reported previously also satisfied this second characteristic,
d)
4
5
O2­H2£O1
C9­H9£O1
e)
e)
C10­H10£O1
2
8
despite the fact that the cation was not planar in geometry.
Symmetry code: a) 1 ¹ x, 2 ¹ y, 1 ¹ z; b) 1 ¹ x, 1 ¹ y, 1 ¹ z;
c) 2 ¹ x, ¹y, 2 ¹ z; d) ¹x, ¹y, ¹z; e) ¹1 + x, y, z.
Therefore, this second characteristic is essential not of the
planar cation, but rather of the positive-charge of pyridinium.
Cation bonding in 1­5 is shown in Figure 3. As described
above, Ben, Ace, and, Met cations in their complex salt formed
similar dimeric structure involving C­H£O hydrogen bonding,
although three cations possessed substituents of different shape
and size. IR spectral peaks assignable to C=O stretching were
as those in 2, the arrangement of Car cations in 4 was totally
different; i.e., zig-zag sheet in 2 and three-dimensional S£S
network in 4 (Figures 2(2) and 2(4)). As for the arrangement of
Car shown in Figure 3(4), Car formed centrosymmetrically
¹1
associated dimers by O­H£O hydrogen bonds, often observed
1663, 1689, and 1729 cm for Ben, Ace, and Met, which were
also seen in their salts 1­3 (Table 2). The data clearly show that
the C=O band is strengthened by electron donation (Table 5a).
for carboxylic acids.3
8,39
As reported in Refs. 38 and 39, the
compounds possessing carboxylic acid has a strictly fixed
orientation by strong O­H£O hydrogen bonding, and this
hydrogen bond shows a remarkable tendency to form a
characteristic structure in the crystal. Therefore, the strong
O­H£O hydrogen bond between carboxylic groups predomi-
nated to change the crystal structure from those of 1­3.
However, we have already reported the crystal structure of Car
2
Furthermore, Table 5 shows that C(sp )­H£O tended to
shorten as the electron-donating ability of substituents increas-
ed. This means that the increase in electron density of oxygen
2
atom by electron donation strengthened the C(sp )­H£O
hydrogen bond. These two results, formation of similar dimeric
2
structure and systematic change in C(sp )­H£O distance,
40
cation and Ni(dmit) anion in partially oxidized state. In this
implied the non-negligible effect of weak hydrogen bonding
on the crystal structure although Coulombic interaction still
dominates.
2
report, we also observed that Car cations formed centrosym-
metrically associated dimers similar to 1­3 by O­H£O and C­
H£O hydrogen bonds.
C­H£S Interaction between Anions and Cation. Similar
discussion may apply to C­H£S interaction between cation and
In contrast to other complex salts, (Ami)[Ni(dmit) ] (5)
2
4
3­48
3
2
showed absolutely different crystal structure. As for the
arrangements of cation and anion shown in Figures 2(5) and
(5), two S£S contacts between neighboring anions occur
anion.
The C(sp and sp )­H£S interaction has rarely been
discussed in the literature despite the widespread presence of
sulfur in many synthetic and natural molecular architectures.
However, some recent reports have discussed the role of
C­H£S interaction and the influence of weak contacts on
3
along the a axis, thereby forming a one-dimensional S£S
2
network. Two weak C(sp )­H£O hydrogen bonds at the
4
9­53
carbonyl groups of Ami were found to connect the neighboring
cations along the a axis, despite the Ami cation possessing
molecular packing of organic crystals.
Potrzebowski et al.
reported the geometric criteria for the general C­H£S

K. Tomono et al.
Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009) 1157
interaction as follows; the C£S distances and C­H£S angles
(
1)
(2)
(4)
5
2
being 3.55­4.10 ¡ and 80­180°, respectively. In Figure 4 and
Table 6 are given the C­H£S interaction that matched the
criteria. In all crystal structures, terminal sulfur atoms of
the respective anions were placed near the protonated pyridi-
4
3
nium and/or methyl groups. As reported by Miyazaki and
4
4
Veldhuizen et al. considerable deviation from planarity in
Ni(dmit) units resulted not only from the S£S interactions but
2
also from the N­H£S hydrogen bonds. The dihedral angle
(
3)
(
(
(
1)
2)
3)
(5)
Figure 3. C­H£O and O­H£O hydrogen bonds between
the cations in 1­5, shown by dashed lines.
(4)
Table 5. Distances (¡) and Angles (degree) Related to C7­
H7£O1=C13 Hydrogen Bond in the Centrosymmetrically
Associated Dimers
(θ )
(
5)
.
..
C(sp2)-H O=C
(b) (a)
(c)
Ben
Ace
Met
(a)
(b)
(c)
(ª)
O=C
C£O
C£C
C£O=C
1.215(3)
3.240(3)
4.343(4)
155
1.207(9)
3.212(10)
4.387(11)
155
1.200(5)
3.203(5)
4.379(6)
164
Figure 4. C­H£S and N­H£S hydrogen bonds between a
cation and surrounding anions in 1­5, shown by dashed
lines.
Table 6. Geometries (¡, degree) of Hydrogen Bonds (Interactions) between Anions and Cation
D­H£A
D£H
H£A
D£A
(D­H£A)
C=S
1
2
C19­H19£S5a)
0.93
0.93
0.93
0.93
0.96
0.91
0.96
0.93
0.95
0.97
0.85
0.83
2.78
2.81
2.88
2.81
2.98
2.83
2.96
2.87
2.84
2.72
2.84
2.85
3.560(3)
3.733(3)
3.602(9)
3.615(11)
3.935(6)
3.710(3)
3.612(3)
3.540(4)
3.775(3)
3.670(3)
3.585(4)
3.664(4)
142
170
136
146
172
162
126
130
169
169
147
170
1.634(3)
1.642(3)
1.648(7)
1.648(7)
1.634(4)
1.646(3)
1.646(3)
1.647(4)
1.640(3)
1.632(3)
1.640(3)
1.640(3)
b)
C11­H11£S10
c)
C9­H9£S10
d)
C11­H11£S10
e)
3
4
C14­H14C£S10
f)
C7­H7£S5
g)
C12­H12A£S5
h)
C11­H11£S10
C9­H9£S5
i)
5
C11­H11£S10
j)
N2­H2A£S5
N2­H2B£S5
i)
Symmetry codes: a) 1 ¹ x, 2 ¹ y, 2 ¹ z; b) ¹1 + x, y, z; c) x, 1 + y, z; d) 1 ¹ x, ¹y, 2 ¹ z; e) 1 + x, y, 1 + z;
f) ¹x, ¹y, 1 ¹ z; g) x, 1 + y, z; h) 1 ¹ x, 2 ¹ y, 1 ¹ z; i) ¹x, 1/2 + y, 3/2 ¹ z; j) 1 ¹ x, 1/2 + y, 3/2 ¹ z.

¹
1158 Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009)
Substituent Effect in [Ni(dmit)2] Salts
between two dmit ligands in [Ni(dmit) ] were 4.84, 8.69,
Although the electrostatic interaction predominates and con-
trols the crystal packing of the metal complex salts, the cations
formed structurally similar dimers constructed by weak C­
H£O hydrogen bonding, and the geometric parameters had
correlation with electron-releasing ability of the substitutent
linked to the carbonyl group (C=O). Although we need more
consideration of crystallization parameters, the present results
indicate that the pyridinium cations substituted at the 3-position
by relatively weak electron-releasing substituent tends to form
2
2
.51, 5.14, and 11.76°, for 1­5, respectively. In the case of 5,
possessing N­H£S hydrogen bonds, apparent deviation was
observed, as was the case in Refs. 43 and 44. Other salts
exhibited smaller deviation, and no apparent relation between
the length of terminal C=S and the C£S distance of possible
C­H£S interaction could be found. Since other stronger
interactions such as Coulombic interaction and O­H£O or
C­H£O hydrogen bonding are already present, the effect of the
C­H£S interaction, if present, should be limited to a certain
extent.
structurally-unique dimers by weak C­H£O hydrogen bonds in
¹
[Ni(dmit) ] salts.
2
Conductivity Measurements. The electric conductivities
of single crystals of 1­5 measured at room temperature by two-
Authors thank Mr. Totsuka and Prof. Furukawa for perform-
ing the conductivity measurements.
¹
6
¹6
probe alternating current were 1.00 © 10 , 1.10 © 10 ,
¹
6
¹6
¹6
¹1
2
.86 © 10 , 9.77 © 10 , and 0.875 © 10 S cm , respec-
¹
tively. Among highly conductive [Ni(dmit) ] salts, Reefman
et al. reported the (tmiz)[Ni(dmit) ] (tmiz = 1,2,3-trimethyl-
References
2
5
4
2
1
1018.
2
P. Murray-Rust, J. P. Glusker, J. Am. Chem. Soc. 1984, 106,
imidazolium) salt featuring a cation that can be regarded as
an intermediate between an open-shell and closed-shell cation.
This compound showed a very high conductivity of 0.21
M. C. Etter, Acc. Chem. Res. 1990, 23, 120.
3
T. E. Creighton, in Proteins: Structure and Molecular
¹1
S cm compared with other 1:1 [Ni(dmit) ] complex salts.
Properties, 2nd ed., ed. by W. H. Freeman, NY, 1998.
S. Horiuchi, F. Ishii, R. Kumai, Y. Okimoto, H. Tachibana,
N. Nagaosa, Y. Tokura, Nat. Mater. 2005, 4, 163.
S. Horiuchi, H. Yamochi, G. Saito, K. Sakaguchi, M.
Kusunoki, J. Am. Chem. Soc. 1996, 118, 8604.
2
Also, (MeQ)[Ni(dmit) ] (MeQ = N-methylquinolinium) was
4
2
characterized by single-crystal X-ray analysis and exhibited
¹
3
¹1 55
5
a relatively high conductivity of 10 S cm . These com-
pounds crystallize in a non-segregated manner, displaying a
face-to-face stacking mode of the anions and cations. These
results suggested that the ³£³ interaction between both cations
and anions might be responsible for the high conductivity.
6
153.
7
A. Gavezzotti, G. Filippini, J. Am. Chem. Soc. 1996, 118,
7
1
1
K. A. Hirsch, S. R. Wilson, J. S. Moore, Chem.®Eur. J.
997, 3, 765.
¹
However, [Ni(dmit)2] salts that exhibit high conductivity
8
739.
9
S. Kitagawa, M. Kondo, Bull. Chem. Soc. Jpn. 1998, 71,
are comparatively rare, and their high conductivity may be
attributed to the effective arrangement between anions and
cations, as well as the formation of multi-dimensional S£S
network between anions, or the partial auto-oxidation of anions
which might be a cause of high conductivity. The conductivity
of all complexes examined in this study were of the same level,
and these complexes exhibited lower conductivity compared
with the above rare cases. On the other hand, the crystal of
N-ethylpyridinium cation,56 whose structure was similar to
cations examined in this study, with Ni(dmit)2 formed crystal in
a non-segregated manner, and the conductivity of this com-
C. Janiak, J. Chem. Soc., Dalton Trans. 2000, 3885.
1
0
Rudresh, M. Gupta, S. Ramakumar, V. S. Chauhan, Pept.
Sci. 2005, 80, 617.
H. An, D. Xiao, E. Wang, C. Sun, L. Xu, J. Mol. Struct.
005, 743, 117.
L. Jiang, L. Lai, J. Biol. Chem. 2002, 277, 37732.
11
2
1
2
13 P. Cassoux, Coord. Chem. Rev. 1999, 185­186, 213.
14 T. Akutagawa, T. Nakamura, Coord. Chem. Rev. 2000, 198,
297.
15 R. Kato, Chem. Rev. 2004, 104, 5319.
16 L. Brossard, M. Ribault, L. Valade, P. Cassoux, Physica
B+C 1986, 143, 378.
¹
7
¹1
pound was 5 © 10 S cm . Also, 3-(4- and 3-alkylpyri-
dinium)-1,5-diphenylverdazyl radical cations with Ni(dmit)2
formed crystal in a non-segregated manner, and the conduc-
1
7
A. Kobayashi, H. Kim, Y. Sasaki, R. Kato, H. Kobayashi,
S. Moriyama, Y. Nishio, K. Kajita, W. Sasaki, Chem. Lett. 1987,
819.
¹4
¹6
¹1 57
tivity of these compounds were 10 ­10 S cm . Hence, we
consider that the conductivities of 1­5 in this study were at the
same level. As previously mentioned, the average distances
between anion and cation of 1­5 were ca. 3.50, 3.58, 3.53,
1
1
8
L. Brossard, M. Hurdequint, M. Ribault, L. Valade, J. P.
Legros, P. Cassoux, Synth. Met. 1988, 27, 157.
L. Brossard, M. Ribault, L. Valade, P. Cassoux, J. Phys. Fr.
989, 50, 1521.
A. Kobayashi, H. Kobayashi, A. Miyamoto, R. Kato, R. A.
Clark, A. E. Underhill, Chem. Lett. 1991, 2163.
H. Kobayashi, K. Bun, T. Naito, R. Kato, A. Kobayashi,
Chem. Lett. 1992, 1909.
H. Tajima, M. Inokuchi, A. Kobayashi, T. Ohta, R. Kato, H.
Kobayashi, H. Kuroda, Chem. Lett. 1993, 1235.
R. Kato, N. Tajima, M. Tamura, J. Yamaura, Phys. Rev. B
1
9
3
.41, and 3.53 ¡, respectively. The fact that 4 has the closest
1
contact and the highest conductivity compared with other
complexes implies the presence of ³£³ interaction.
2
0
2
1
Conclusion
We have prepared five 1:1 complex salts composed of
2
2
¹
[
Ni(dmit)2] anion and 3-X-1-methylpyridinium cations (X;
benzoyl, acetyl, methoxycarbonyl, carbonyl, and, aminocar-
bonyl) to examine the importance of weak C­H£O hydrogen
bonding on crystal structures of metal complex salts. We
obtained preliminary results related to crystal engineering
though improvement of conductivity was not achieved.
2
3
2
002, 66, 20508.
24 A. Tajima, A. Nakao, R. Kato, J. Phys. Soc. Jpn. 2005, 74,
412.
25 K. Tomono, K. Ogawa, Y. Sasaki, K. Miyamura, Inorg.

K. Tomono et al.
Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009) 1159
Chim. Acta 2008, 361, 269.
42 G. Briegleb, H. Delle, Z. Elektrochem. 1960, 64, 347.
43 A. Miyazaki, A. Izuoka, T. Sugawara, Bull. Chem. Soc.
Jpn. 1992, 65, 2528; A. Miyazaki, A. Izuoka, T. Sugawara, Bull.
Chem. Soc. Jpn. 1993, 66, 2832.
2
6
K. Onozaki, K. Miyamura, Bull. Chem. Soc. Jpn. 2006, 79,
8
76.
2
7
Y. Soneta, T. Midorikawa, K. Miyamura, Bull. Chem. Soc.
Jpn. 2006, 79, 1060.
T. Koori, K. Tomono, K. Miyamura, Acta Crystallogr.,
Sect. E 2006, 62, m256.
J. Mcmurry, Organic Chemistry, 4th ed., Cornell University
Press, Ithaca, NY, 1996.
G. Steimecke, H.-J. Sieler, R. Kirmse, E. Hoyer, Phos-
phorus, Sulfur Silicon Relat. Elem. 1978, 7, 49.
G. M. Sheldrick, SHELX-97 and SHELXL-97, Program
44 Y. S. J. Veldhuizen, N. Veldman, A. L. Speak, C. Faulmann,
J. G. Haasnoot, J. Reedijk, Inorg. Chem. 1995, 34, 140.
45 W. Xu, D. Zhang, C. Yang, X. Jin, Y. Li, D. Zhu, Synth.
Met. 2001, 122, 409.
46 J. Liu, J.-H. Zhang, D.-Q. Wang, J.-M. Dou, Acta
Crystallogr., Sect. E 2005, 61, m1652.
47 Y.-L. Wang, W.-T. Yu, D. Xu, X.-Q. Wang, W.-F. Guo,
G.-H. Zhang, Acta Crystallogr., Sect. E 2005, E61, m2408.
48 E. Tomiyama, K. Tomono, K. Miyamura, Acta Crystallogr.,
Sect. E 2007, 63, m2741.
2
8
2
9
3
0
3
1
for the Solution of Crystal Structures, University of Göttingen,
Germany, 1997.
3
2
L. Valade, J.-P. Legros, M. Bousseau, P. Cassoux, M.
Garbaskas, L. V. Interrante, J. Chem. Soc., Dalton Trans. 1985,
83.
49 J. J. Novoa, M. C. Rovira, C. Rovira, J. Veciana, J. Tarrés,
Adv. Mater. 1995, 7, 233.
7
50 C. Rovira, J. J. Novoa, Chem. Phys. Lett. 1997, 279, 140.
51 H. Borrmann, I. Persson, M. Sandströn, C. M. V.
Stalhandske, J. Chem. Soc., Perkin Trans. 2 2000, 393.
52 M. J. Potrzebowski, X.-B. Yang, K. Misiura, W. R.
Majzner, M. W. Wieczorek, S. Kazmierski, S. Olejniczak, W. J.
Stec, Eur. J. Org. Chem. 2001, 1491.
53 M. Hartmann, S. D. Wetmore, L. Radom, J. Phys. Chem. A
2001, 105, 4470.
54 D. Reefman, J. P. Cornelissen, J. G. Haasnoot, R. A. G. de
Graaff, J. Reedijk, Inorg. Chem. 1990, 29, 3933.
55 J. P. Cornelissen, E. J. Creyghton, R. A. G. de Graaff, J.
Reedijk, Inorg. Chim. Acta 1991, 185, 97.
3
3
L. Pauling, The Nature of the Chemical Bond, 2nd ed.,
Cornell University Press, Ithaca, NY, 1948.
A. D. Bond, R. Boese, G. R. Desiraju, Angew. Chem., Int.
Ed. 2007, 46, 615.
G. R. Desiraju, Acc. Chem. Res. 1996, 29, 441; G. R.
Desiraju, Acc. Chem. Res. 2002, 35, 565.
F. Allen, J. P. M. Lommerse, V. J. Hoy, J. A. K. Howard,
G. R. Desiraju, Acta Crystallogr., Sect. B 1996, 52, 734.
Y. In, H. Ohishi, H. Miyagawa, K. Kitamura, Y. Igarashi, T.
Ishida, Bull. Chem. Soc. Jpn. 2006, 79, 126.
M. Szafran, Z. Dega-Szafran, M. Grundwald-Wyspiańska,
P. Barczyński, M. Pankowski, Pol. J. Chem. 2002, 76, 1191.
3
4
3
5
3
6
3
7
3
8
56 G. Xue, W.-T. Xu, W. Yu, Q. Fang, Acta Crystallogr.,
Sect. C 2003, 59, m27.
3
9
G. R. Desiraju, Angew. Chem., Int. Ed. Engl. 1995, 34,
2
311.
57 K. Mukai, D. Shiba, K. Yoshida, K. Mukai, H. Hisatou, K.
Ohara, Y. Hosokoshi, N. Azuma, Bull. Chem. Soc. Jpn. 2005, 78,
2114.
40
1
K. Tomono, K. Miyamura, Chem. Lett. 2007, 36, 1466.
G. R. Freeman, C. E. Bugg, Acta Crystallogr., Sect. B 1974,
4
3
0, 431.