Bis(3-cyano-pentane-2,4-dionato) Co(II) as a linear building block for coordination polymers: Combinations with two polypyridines

Article abstract of DOI:10.1080/00958972.2013.800865

Two types of bis(β-diketonato) Co(II) complexes, [Co(CNacac)2] (CNacac = 3-cyano-pentane- 2,4-dionato), and [Co(dbm)2] (dbm = dibenzoylmethanato or 1,3-diphenyl-propane-1,3-dionato) were examined as linear building blocks for the construction of coordination polymers in combination with two oligopyridines, 1,4-bis(4,2':6',4'-terpyridin-4'-yl)benzene (L1) and 1,3-bis(3,2':6',3'- terpyridin-4'-yl)benzene) (L2). From combinations of [Co(CNacac)2] with L1 and L2, 2-D coordination polymers, [Co(CNacac)2]2(L1) (CHCl3)(CH3OH) (CoCN-1) and [Co(CNacac)2](L2)1/ 2(tetrachloroethane)3/2 (CoCN-2), are obtained. Both CoCN-1 and CoCN-2 have 2D (4,4) net structures, in which L1 and L2 are tetradentate. In contrast, combination of [Co(dbm)2] with L2 affords a 1-D coordination polymer, [Co(dbm)2](L2)4(CH3OH) (Codbm-1), in which L2 is bidentate. L2 as a tetradentate ligand was inhibited by bulky phenyl rings in [Co(dbm)2]. These results indicate that [Co(CNacac)2] with a relatively simplified structure is useful as a linear building block in combinations with bulky oligopyridines.

Full text of DOI:10.1080/00958972.2013.800865

This article was downloaded by: [Boston University]
On: 06 October 2014, At: 15:12
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Coordination Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/gcoo20
Bis(3-cyano-pentane-2,4-dionato)
Co(II) as a linear building block for
coordination polymers: combinations
with two polypyridines
Jun Yoshida a , Shin-ichi Nishikiori b & Hidetaka Yuge a
a Department of Chemistry , School of Science, Kitasato
University , Minami-ku, Sagamihara , Japan
b Department of Basic Science, Graduate School of Arts and
Sciences , The University of Tokyo , Tokyo , Japan
Accepted author version posted online: 02 May 2013.Published
online: 04 Jun 2013.
To cite this article: Jun Yoshida , Shin-ichi Nishikiori & Hidetaka Yuge (2013) Bis(3-cyano-
pentane-2,4-dionato) Co(II) as a linear building block for coordination polymers: combinations
with two polypyridines, Journal of Coordination Chemistry, 66:12, 2191-2200, DOI:
10.1080/00958972.2013.800865
To link to this article: http://dx.doi.org/10.1080/00958972.2013.800865
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Journal of Coordination Chemistry, 2013
Vol. 66, No. 12, 2191–2200, http://dx.doi.org/10.1080/00958972.2013.800865
Bis(3-cyano-pentane-2,4-dionato) Co(II) as a linear building
block for coordination polymers: combinations with two
polypyridines
JUN YOSHIDA*y, SHIN-ICHI NISHIKIORIz and HIDETAKA YUGEy
yDepartment of Chemistry, School of Science, Kitasato University, Minami-ku,
Sagamihara, Japan
zDepartment of Basic Science, Graduate School of Arts and Sciences, The University of
Tokyo, Tokyo, Japan
(Received 28 November 2012; in final form 6 February 2013)
Two types of bis(β-diketonato) Co(II) complexes, [Co(CNacac)2] (CNacac = 3-cyano-pentane-
2,4-dionato), and [Co(dbm)2] (dbm = dibenzoylmethanato or 1,3-diphenyl-propane-1,3-dionato)
were examined as linear building blocks for the construction of coordination polymers in combina-
tion with two oligopyridines, 1,4-bis(4,2’:6’,4”-terpyridin-4’-yl)benzene (L1) and 1,3-bis(3,2’:6’,3”-
terpyridin-4’-yl)benzene) (L2). From combinations of [Co(CNacac)2] with L1 and L2, 2-D
coordination polymers, [Co(CNacac)2]2(L1)·(CHCl3)·(CH3OH) (CoCN-1) and [Co(CNacac)2](L2)1/
2·(tetrachloroethane)3/2 (CoCN-2), are obtained. Both CoCN-1 and CoCN-2 have 2D (4,4) net
structures, in which L1 and L2 are tetradentate. In contrast, combination of [Co(dbm)2] with L2
affords a 1-D coordination polymer, [Co(dbm)2](L2)·4(CH3OH) (Codbm-1), in which L2 is biden-
tate. L2 as a tetradentate ligand was inhibited by bulky phenyl rings in [Co(dbm)2]. These results
indicate that [Co(CNacac)2] with a relatively simplified structure is useful as a linear building block
in combinations with bulky oligopyridines.
Keywords: Coordination polymer; Linear building block; Polypyridines; β-Diketonato; Cobalt(II)
1. Introduction
Coordination polymers or metal-organic frameworks (MOFs) are typically formed from
self assembly of metal ions, which serve as nodes and ligands that act as bridges [1]. This
simple method has been applied to various combinations of metal ions and organic
ligands. However, structural control of the resulting polymeric structure is difficult [2].
One of the reasons is that metal ions can have several coordination geometries depending
on preparation conditions. For example, Ag(I) has often been used as a node with linear
geometry [3], while it also can have other coordination geometries, trigonal, tetrahedral,
trigonal pyramidal, and octahedral [3(b), 4]. Attempts to use a “bare” metal ion as a linear
node often result in failure.
Bis(β-diketonato) metal complexes, which have a planar structure and can accept
additional ligands at axial sites are known to function as linear building blocks [5, 6].
*Corresponding author. Email: yoshidaj@kitasato-u.ac.jp
Ó 2013 Taylor & Francis

2192
J. Yoshida et al.
Moreover, bis(β-diketonato) metal complexes have several useful characteristics. One is
that employment of various metal ions is possible. The bis(β-diketonato) complexes with
Mn(II) [6(a)], Co(II) [6(b)], Ni(II) [6(c,d)], Cu(II) [6(e,f)], and Zn(II) [6(g)] work as linear
building blocks and add different magnetic properties in the resulting coordination poly-
mers. The Lewis acidity of the metal center and stereochemistry of the whole building
block can be tuned by changing β-diketonato ligands. For example, acetylacetonate (acac-),
dibenzoylmethanate (dbm-), and 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac-) have been
used as ligands [6]. Metal center of [M(dbm)2] has high Lewis acidity compared to that of
[M(acac)2] [7]. Therefore, [M(dbm)2] has been used as a superior building block in combi-
nations with various ligands [6]. In contrast, the disadvantage of [M(dbm)2] is bulkiness
due to four phenyl rings, which could disturb linkage with specific ligands. It is necessary
to satisfy both simple planar structure and moderate Lewis acidity in bis(β-diketonato)
complexes for practical use as a linear building block.
We have focused on 3-cyano-pentane-2,4-dione (CNacacH) [8]. The electron-withdraw-
ing cyano introduced in the 3-position of pentane-2,4-dione was expected to enhance Lewis
acidity in the resulting bis(chelate) metal complexes, without hindering linkage with organic
ligands. We have examined bis(3-cyano-pentane-2,4-dionato) Co(II) complex, [Co(CNa-
cac)2] [9], as a linear building block in combinations with bi- and tri-dentate ligands [8].
In this article, we examine the combination of [Co(CNacac)2] with potentially tetradentate
oligopyridines to further examine feasibility as a linear building block (scheme 1). As oligo-
pyridine ligands, 1,4-bis(4,2’:6’,4”-terpyridin-4’-yl)benzene (L1) and 1,3-bis(3,2’:6’,3”-ter-
pyridin-4’-yl)benzene (L2) were used. L1 with 4-pyridyl moieties is expected to have a
single conformation, while L2 can have various conformations due to rotation of four termi-
nal 3-pyridyl moieties. Our interest was whether [Co(CNacac)2] and oligopyridines work as
a linear building block and tetradentate ligands, respectively. As comparison, we also inves-
tigated the combination of [Co(dbm)2] with the oligopyridines. The difference of the two
building blocks, [Co(CNacac)2] and [Co(dbm)2], clearly appear in the structures of resulting
polymeric compounds.
2. Experimental
All reagents and solvents were purchased from commercial sources and used without puri-
1
fication. H NMR spectra were recorded on a JEOL α-500 spectrometer. NMR spectra of
L1 and L2 were measured in CDCl3 with a drop of CH3OH. 3-Cyano-pentane-2,4-dione
(CNacacH), [Co(CNacac)2], and [Co(dbm)2(H2O)2] were synthesized according to the
reported procedure [10, 11].
2.1. Syntheses of ligands
1,4-Bis(4,2’:6’,4”-terpyridin-4’-yl)benzene, L1. L1 was synthesized by modifying the
reported procedure [12]. 4-Acetyl-pyridine (3.63 g, mol) was added to an ethanol (120 mL)
solution of isophthalaldehyde (1.00 g, 7.46 mmol). This solution was stirred until complete
dissolution. KOH pellets (2.3 g, 30.0 mmol) and aqueous NH3 (28%, 45 ml) were succes-
sively added. The color of the solution turned yellow and gradually black. The reaction
mixture was stirred for 4 h. During the stirring, a precipitate formed. The precipitate was
filtered off and washed with water. Pinkish white solid was obtained (1.29 g, 32% yield).

Bis(3-cyano-pentane-2,4-dionato) Co(II)
2193
Scheme 1. Schematic representation of the syntheses of CoCN-1, CoCN-2 and Codbm-1.
1H NMR (500 MHz, CDCl3, δ): 8.76–8.74 (m, 8H), 8.23–8.22 (m, 12H), 8.13 (s, 1H),
7.96 (dd, J = 7.5, 1.8 Hz, 2H), 7.83 (t, J = 7.5 Hz, 1H). Anal. Calc. for C36H25N6O0.5
(L1·(H2O)0.5): C, 78.67; H, 4.58; N, 15.29%. Found: C, 78.38; H, 4.66; N, 14.64%.
1,3-Bis(3,2’:6’,3”-terpyridin-4’-yl)benzene, L2. L2 was synthesized according to the
similar procedure to L1 by using terephthalaldehyde and 3-acetyl-pyridine instead of
isophthalaldehyde and 4-acetyl-pyridine, respectively. Recrystallization from methanol and
chloroform mixture gave a yellowish white solid (3.45 g, 26% yield).
1H NMR (500 MHz, CDCl3, δ): 9.37 (d, J = 2.0, 4H), 8.68 (dd, J = 5.0, 1.5 Hz, 4H), 8.63–
8.61 (m, 4H), 8.10 (s, 4H), 8.01 (s, 4H), 7.59–7.56 (m, 4H). Anal. Calc. for C36H26N6O
(L1·(H2O)): C, 77.40; H, 4.69; N, 15.04%. Found: C, 77.96; H, 4.73; N, 14.72%.
2.2. Syntheses of coordination polymers
[Co(CNacac)2]2(L1)·(CHCl3)·(CH3OH) (CoCN-1). Methanol solution of [Co(CNacac)2]
(15 mM, 6 ml) was added to a methanol–chloroform mixed solution (methanol/chloro-
form = 1/2, v/v) of L1 (10 mM, 4.5 ml). After the mixture was left for a few days, pink
crystals were obtained (60 mg, 53% yield). Anal Calcd. for C62H53O9N10Cl3Co2: C, 57.00;
H, 4.09; N, 10.72%. Found: C, 56.05; H, 4.25; N, 10.25%.

2194
J. Yoshida et al.
[Co(CNacac)2](L2)1/2(tetrachloroethane)3/2 (CoCN-2). Methanol solution of [Co(CNacac)2]
(15 mM, 5 ml) was added to a methanol–tetrachloroethane mixed solution (methanol/tetra-
chloroethane = 1/1, v/v) of L2 (5 mM, 10 ml). After leaving the mixture for a week, pink
crystals were obtained. Anal. Calcd. for C66H54O8N10CL22Co2: C, 47.80; H, 3.28; N,
8.45%. Found: C, 48.07; H, 3.48; N, 8.15%.
[Co(dbm)2](L2)·4(CH3OH) (Codbm-1). [Co(dbm)2(H2O)2] was dissolved in a 1:1 mixed
solution of methanol and chloroform (8 mM, 1 ml). To this solution, a chloroform–metha-
nol mixed solution of L2 (8 mM, 1 ml) was added. After the mixture was left for a week,
the pink crystals of [Co(dbm)2](L2)·4(CH3OH) were obtained (6 mg, 66% yield).
2.3. Single crystal X-ray diffraction and structure determination
The crystal structures of the three coordination polymers (CoCN-1, CoCN-2 and Codbm-1)
were determined by single crystal X-ray diffraction and their crystallographic and experi-
mental data are summarized in table 1. Each crystal was coated with epoxy resin to prevent
spontaneous liberation of the neutral guest. For the collection of diffraction data, a Rigaku
R-AXIS RAPID imaging plate diffractometer was used. All measurements were carried out
at 153 K. The structures were solved by direct methods using SHELXS-97 [13]. The refine-
ment and all further calculations were carried out using SHELXL-97 [13]. The nonH atoms
were refined anisotropically using weighted full-matrix least-squares on F2. Hydrogens were
generated geometrically.
Table 1. Crystallographic and experimental data for CoCN-1, CoCN-2, and Codbm-1.
Compound
CoCN-1
62H53Cl3Co2N10O9
1306.35
Monoclinic
P 21/c
15.1718(3)
14.8239(3)
42.5645(7)
90
139.329(1)
90
CoCN-2
Codbm-1
Formula
Formula weight
Crystal system
Space group
a/Å
b/Å
c/Å
α/°
C
C33H27Cl6Co N5O4
829.23
C35H31Co0.5N3O4
587.10
Triclinic
P ꢀ 1
Triclinic
P ꢀ 1
10.870(5)
12.677(5)
14.946(5)
105.810(5)
107.144(5)
93.760(5)
1869.6(13)
2
11.5807(4)
11.7297(4)
12.7257(5)
67.6410(10)
68.6070(10)
73.6640(10)
1468.00(9)
2
β/°
γ/°
V/Å3
6238.8(2)
4
1.391
Z
Dc/Mg mꢀ3
1.473
1.328
T
153(2)
153(2)
153(2)
Dimensions/mm
μ(Mo-Kα)/mmꢀ1
F(0 0 0)
0.52 ꢁ 0.33 ꢁ 0.25
0.40 ꢁ 0.29 ꢁ 0.18
0.50 ꢁ 0.20 ꢁ 0.19
0.724
0.931
0.356
2688.0
842.0
615.0
Reflections collected/unique
Used reflections with I > 2σ(I)
Parameters
102768/21240
7216
778
0.860
0.0767
30329/8284
5572
450
1.322
0.1018
18439/6696
6052
389
1.114
0.0609
aGOF on F2
bR [I > 2σ(I)]
cwR(F2) [all data]
0.2500
0.3432
0.1650
P
½wðF02 ꢀ Fc2Þ ꢂ=ðn ꢀ pÞꢂ1=2(n: number of reflections; p: total number of
2
aGOF = {Σ[w(Fo2 ꢀ Fc2)2]/(n ꢀ p)]}1/2
parameters refined). R1 = Σ(|Fo| ꢀ |Fc|)/Σ|Fo|. wR2 = {Σ[w(F2o – (F2c )2]/[w(Fo2)2]}1/2
.
b
c

Bis(3-cyano-pentane-2,4-dionato) Co(II)
2195
3. Results and discussion
3.1. Preparation and crystal structure of CoCN-1
A planar complex [Co(CNacac)2] has weakly coordinated nitrile groups and empty axial
sites. Therefore, [Co(CNacac)2] itself forms a 3-D polymeric structure by alternate linkage
[9]. Polymeric [Co(CNacac)2]∞ is insoluble to common organic solvents. However, it is
soluble in methanol by destroying the polymeric structure with ultrasonic wave. To metha-
nol solution of [Co(CNacac)2], a chloroform–methanol mixed solution of L1 was added.
Pink crystals of [Co(CNacac)2]2(L1)·(CHCl3)·(CH3OH) (CoCN-1) were obtained after
leaving the solution at ambient temperature for a few days.
Figure 1 shows the crystal structure of CoCN-1, where [Co(CNacac)2] and L1 are linear
building block and tetradentate ligand, respectively. Alternate linkage of [Co(CNacac)2]
and L1 forms a 2-D hexagonal structure. The 2-D net structure is classified into 2-D (4,4)
net by regarding [Co(CNacac)2]2(L1)2 as a pseudo-tetradentate ligand (figure 1(a) and (b))
[14]. Three equivalent 2-D (4,4) networks are woven through large hexagonal windows
into a threefold interpenetrated structure. Such a triply interpenetrated structure was
previously found in the 2-D coordination polymer formed with [Co(CNacac)2] and a
tridentate polypyridyl ligand, 2’,4’,6’-tri(4-pyridyl)pyridine [8(a)]. π-interactions are
observed between the triply interpenetrated nets (distances and angles are summarized in
table 2). The triply interpenetrated 2-D sheets further stack along the a axis, incorporating
methanol and chloroform molecules between the sheets. The cyano group in [Co(CNa-
cac)2] forms a hydrogen bond with methanol (table 3).
Figure 1. (a) 2-D (4,4) net in CoCN-1 and (b) ORTEP representation of the pseudo-tetradentate ligand with
ellipsoids drawn at 50% probability level (symmetry code; x, 1 ꢀ y, 1 ꢀ z). Triply interpenetrated 2-D (4,4) nets in
CoCN-1 (shown in black, violet and orange and guest molecules were omitted for clarity) are shown (c) normal
and (d) edge-on to the nets (see http://dx.doi.org/10.1080/00958972.2013.800865 for color version).

2196
J. Yoshida et al.
In CoCN-1, [Co(CNacac)2] keeps its planar structure and works as a linear building
block. CoII is six-coordinate by four oxygens of two CNacac ligands (Co-O for 2.025–
2.054 Å) and two nitrogens of L1 at the axial positions (Co-N for 2.136–2.171 Å, table
4). These Co-O and Co-N lengths are comparable with reported values (Co-O for 2.036–
2.058 Å and Co-N for 2.123–2.155 Å) observed in polymeric structures formed with [Co
(CNacac)2] and bi- and tri-dentate ligands [8].
3.2. Preparation and crystal structure of CoCN-2
To methanol solution of [Co(CNacac)2], a mixed solution of methanol and tetrachloroeth-
ane containing L2 was added. Pink crystals were obtained after leaving the solution at
ambient temperature for a week. Single crystal X-ray diffraction found that it has a 2-D
polymeric structure with the formula of [Co(CNacac)2](L2)1/2·(tetrachloroethane)3/2
(CoCN-2). In CoCN-2, L2 is tetradentate, alternately bridged by [Co(CNacac)2], making a
2-D (4,4) net (figure 2). The 2-D (4,4) nets obliquely stack along the a axis without inter-
penetration. Normal-to-weak interactions, long centroid–centroid distances (>3.9 Å), large
slip angles (>30°), and vertical displacements (>2.0 Å) between the ring centroids, are
observed between the pyridyl planes of stacked L2 [15]. These parameters for π-interac-
tions in CoCN-2 are summarized in table 2. As a result of π-stacking, 1-D channels are
formed along the a axis. In the channel, tetrachloroethane molecules are included as a
guest. No specific interaction is observed between the host structure and guest molecule.
The asymmetric unit in the CoCN-2 crystal contains two independent cobalts. Each CoII
is six-coordinate by four oxygens of two CNacac and two nitrogens of L2. Co-O lengths
(Co-O for 2.045–2.059 Å, table 4) are comparable with those observed in CoCN-1. The
bond length of 2.149(5) Å for Co(2)–N(4) is also comparable with those observed in
CoCN-1, while the bond length of 2.232(5) Å for Co(1)–N(2) Å is slightly longer. The
[Co(CNacac)2] unit with Co(2) is linked with L2 with its long molecular axis perpendicu-
lar to L2, while the [Co(CNacac)2] unit with Co(1) stands sideways toward L2. As a
result, methyl and cyano groups in the unit are positioned near the p-phenylene ring of L2
(figure 2(b), (c)). To minimize steric repulsion, linkage between [Co(CNacac)2] and L2
(Co(1)–N(2) length) is slightly long.
Table 2. Distances/Å and angles/° for the π-contacts in CoCN-1, CoCN-2, and Codbm-1, where α = dihedral
angle between planes I and J, β = angle Cg(I) → Cg(J) vector and normal to plane I, γ = angle Cg(I) → Cg(J)
vector and normal to plane J and Cg-Cg = distance between ring centroids.
Cg-Cg/Å
3.668(3)
α/°
β/°
γ/°
Cg-Cg/Å
3.405(2)
CoCN-1a
Ring N(6)–ring N(8)
CoCN-2b
Ring N(2)–ring N(3)
12.1(3)
17.23
21.86
4.109(4)
4.364(4)
6.3(3)
0
27.98
34.23
26.24
34.23
3.628(2)
3.608(2)
Ring N(3)–ring N(3)
Codbm-1c
Ring N(1)–ring N(2)
Ring N(3)–ring N(3)
4.472 (2)
3.747(2)
22.25(16)
0
47.74
20.84
30.56
20.84
3.008(1)
3.502(2)
aCoCN-1, ring N(6): N(6), C(30)–C(34); ring N(8): N(8), C(46)–C(50).
bCoCN-2, ring N(2): N(2), C(7)–C(11); ring N(3): N(3), C(12)–C(16).
cCodbm-1, ring N(3): N(1), C(16)-C(20); ring N(2): N(2), C(21)–C(25); ring N(3): N(3), C(27)–C(30).

Bis(3-cyano-pentane-2,4-dionato) Co(II)
2197
Table 3. Hydrogen bond lengths/Å and angles/° for CoCN-1 and Codbm-1.
D–H…A
d(D–H)/Å
d(Hꢃ ꢃ ꢃA)/Å
d(Hꢃ ꢃ ꢃA)/Å
D–Hꢃ ꢃ ꢃA/°
CoCN-1
O(9)-H(52)ꢃ ꢃ ꢃN(4)
Codbm-1
O(3)-H(24)ꢃ ꢃ ꢃO(1)
O(4)-H(31)ꢃ ꢃ ꢃN(3)
0.84
2.21
2.973(14)
152
0.84
0.84
2.08
2.01
2.881(4)
2.810(5)
158
159
3.3. Preparation and crystal structure of Codbm-1
The use of [Co(dbm)2] as a building block was also examined for a comparison with [Co
(CNacac)2]. [Co(dbm)2(H2O)2] was dissolved in a mixed solution of methanol and
chloroform. To this solution, chloroform–methanol mixed solutions of L1 and L2 were
added, respectively. No crystalline compound has been obtained for L1. In contrast, for
L2, pink crystals of [Co(dbm)2](L2)·4(CH3OH) (Codbm-1) were obtained after leaving
the solution at ambient temperature for a week. Figure 3 shows the crystal structure of
Codbm-1, where [Co(dbm)2] and L2 are a linear building block and a bidentate ligand,
Figure 2. (a) The crystal structure of CoCN-2 is shown along the a axis. The packing of tetrachloroethane
molecules were drawn with space-filling model, while host framework was drawn by stick model. (b) ORTEP
representation with ellipsoids drawn at 50% probability level and (c) space-filling representation of the repeating
unit. (Symmetry code; II: 1 ꢀ x, 1 ꢀ y, ꢀz).

2198
J. Yoshida et al.
Table 4. Selected bond distances/Å in CoCN-1, CoCN-2, and Codbm-1.
CoCN-1
CoCN-2
Codbm-1
Co(1)–O(2) 2.025(4)
Co(1)–O(1) 2.028(3)
Co(1)–O(3) 2.046(3)
Co(1)–O(4) 2.032(3)
Co(1)–N(5) 2.171(3)
Co(1)–N(10) 2.169(3)
Co(2)–O(5) 2.030(3)
Co(2)–O(6) 2.052(3)
Co(2)–O(7) 2.054(3)
Co(2)–O(8) 2.038(3)
Co(2)–N(7) 2.136(3)
Co(2)–N(9) 2.159(3)
Co(1)–O(1) 2.045(4)
Co(1)–O(2) 2.051(4)
Co(2)–O(3) 2.059(4)
Co(2)–O(4) 2.048(4)
Co(1)–N(2) 2.232(5)
Co(2)–N(4) 2.149(5)
Co(1)–O(1) 2.061(2)
Co(1)–O(2) 2.034(2)
Co(1)–N(1) 2.169(3)
respectively. Two pyridyl moieties at diagonal positions in L2 coordinate to axial sites of
[Co(dbm)2]. As a result, a 1-D zigzag chain structure is formed. In the asymmetric unit of
this crystal, there are two methanols. One forms hydrogen bonds with non-coordinating
pyridyl, while another one forms hydrogen bond with O of acac. The distance and angle
of the hydrogen bonds are summarized in table 3. The 1-D chains further stack along the
a axis through weak interactions between pyridyl planes of L2 (table 4).
In our previous study, we compared [Co(acac)2] and [Co(CNacac)2] as building blocks
with different Lewis acidity [8(a)]. When they were linked with tridentate ligands, their
difference was clearly observed in the bond length between cobalt and nitrogen at the axial
site. [Co(acac)2], in which its metal center has lower Lewis acidity as compared to [Co
(CNacac)2] with electron-withdrawing cyano, which has a longer Co-N distance. CoII in
Codbm-1 is six-coordinate by four oxygens of two dbm and two nitrogens of L2 at axial
positions. Co-O distances (2.034(2) and 2.061 Å) and Co-N distance (2.169 Å) were
observed in Codbm-1 are comparable with those observed in CoCN-1 and CoCN-2. The
result indicates that metal center in [Co(dbm)2] has Lewis acidity almost equivalent to that
of [Co(CNacac)2]. Steric hindrance between the four phenyl rings in [Co(dbm)2] and
Figure 3. (a) Crystal structure of Codbm-1 viewed from the a axis and (b) ORTEP representation of the
repeating unit in the 1-D chain with ellipsoids drawn at 50% probability level (symmetry code; III: 1 ꢀ x, 1 ꢀ y,
1 ꢀ z).

Bis(3-cyano-pentane-2,4-dionato) Co(II)
2199
oligopyridine is probably the reason why L2 does not function as a tetradentate ligand in
combination with [Co(dbm)2].
4. Conclusions
Three coordination polymers (CoCN-1, CoCN-2, and Codbm-1) were synthesized using
[Co(CNacac)2] and [Co(dbm)2] as linear building blocks in combinations with oligopyridines
(L1 and L2). Both CoCN-1 and CoCN-2 have 2-D (4,4) net structures formed by the alter-
nate linkage of [Co(CNacac)2] and tetradentate oligopyridines. In contrast, L2 is bidentate in
Codbm-1, in which a 1-D chain structure is formed. The four bulky phenyl rings in [Co
(dbm)2] present L2 as a tetradentate ligand. These results indicate the usability of [Co(CNa-
cac)2] as a linear building block with moderate Lewis acidity and less-hindered structure.
Supplementary material
Crystallographic data for the structural analyses have been deposited to the Cambridge
Crystallographic Data Center, CCDC Nos. 912488–912490. Copies of this information
may be obtained free of charge from the Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (Fax: þ44–1223-336033; Email: deposit@ccdc.cam.ac.uk, or http://www.
ccdc.cam.ac.uk).
Acknowledgment
We acknowledge the financial support from a Kitasato University Research Grant for
Young Researchers.
References
[1] (a) S. Kitagawa, M. Kondo. Bull. Chem. Soc. Jpn., 71, 1739 (1998); (b) S.R. Batten, R. Robson. Angew.
Chem. Int. Ed., 37, 1460 (1998); (c) S.L. James. Chem. Soc. Rev., 32, 276 (2003); (d) A.Y. Robin, K.M.
Fromm. Coord. Chem. Rev., 250, 2127 (2006).
[2] (a) J. Lefebvre, R.J. Batchelor, D.B. Leznoff. J. Am. Chem. Soc., 126, 16117 (2004); (b) D. Braga, F. Grepi-
oni. Chem. Commun., 3635 (2005); (c) J.-P. Zhang, X.-C. Huang, X.-M. Chen. Chem. Soc. Rev., 38, 2385
(2009).
[3] (a) O.–S. Jung, Y.J. Kim, Y. Lee, J.K. Park, H.K. Chae. J. Am. Chem. Soc., 122, 9921 (2000); (b) A.N.
Khlobystov, A.J. Blake, N.R. Champness, D.A. Lemenovskii, A.G. Majouga, N.V. Zyk, M. Schröder. Coord.
Chem. Rev., 222, 155 (2001).
[4] L. Carlucci, G. Ciani, D.M. Proserpio, A. Sironi. J. Am. Chem. Soc., 117, 4562 (1995).
[5] (a) D.P. Graddon, E.C. Watton. J. Inorg. Nucl. Chem., 21, 49 (1961); (b) D.P. Graddon. Coord. Chem. Rev.,
4, 1 (1969).
[6] (a) C.B. Aakeröy, J. Despera, J. Valdés-Martínez. CrystEngComm, 6, 413 (2004); (b) B.–Q. Ma, S. Gao, T.
Yi, G.–X. Xu. Polyhedron, 20, 1255 (2001); (c) Y. Cui, H.L. Ngo, W. Lin. Chem. Commun., 1388 (2003);
(d) D.V. Soldatov, I.L. Moudrakovski, C.I. Ratcliffe, R. Dutrisac, J.A. Ripmeester. Chem. Mater., 15, 4810
(2003); (e) D.V. Soldatov, J.A. Ripmeester, S.I. Shergina, I.E. Sokolov, A.S. Zanina, S.A. Gromilov, Yu.A.
Dyadin. J. Am. Chem. Soc., 121, 4179 (1999); (f) J.K. Clegg, L.F. Lindoy, J.C. McMurtrie, D. Schilter. Dal-
ton Trans., 857 (2005); (g) D.V. Soldatov, P. Tinnemans, G.D. Enright, C.I. Ratcliffe, P.R. Diamente, J.A.
Ripmeester. Chem. Mater., 15, 3826 (2003).
[7] U. El-Ayaan, F. Murata, Y. Fukuda. Monatsh. Chem., 132, 1279 (2001).
[8] (a) J. Yoshida, S. Nishikiori, R. Kuroda. Chem. Lett., 36, 678 (2007); (b) J. Yoshida, S. Nishikiori, R. Kuroda.
Chem. Eur. J., 14, 10570 (2008); (c) J. Yoshida, S. Nishikiori, R. Kuroda. Bull. Chem. Soc. Jpn., 82, 1377
(2009).

2200
J. Yoshida et al.
[9] O. Angelova, J. Macicek, M. Atanasov, G. Petrov. Inorg. Chem., 30, 1943 (1991).
[10] C.M. Silvernali, G. Yap, R.D. Sommer, A.L. Rheingold, V.W. Day, J.A. Belot. Polyhedron, 20, 3113 (2001).
[11] (a) F.A. Cotton, R.H. Holm. J. Am. Chem. Soc., 82, 2979 (1960); (b) F.A. Cotton, R.C. Elder. Inorg. Chem.,
5, 423 (1966).
[12] J. Wang, G.S. Hanan. Synlett, 1251 (2005).
[13] G.M. Sheldrick. Acta Crystallogr., Sect. A, 64, 112 (2008).
[14] A.F. Wells, Structural Inorganic Chemistry, Chap. 3, Oxford University Press, Oxford, (1984).
[15] C. Janiak. J. Chem. Soc., Dalton Trans., 3885 (2000).