Structures of Co, Pd and Ni complexes with iminopyridine ligands having an hydroxymethyl or acrylate pendant group

Article abstract of DOI:10.1016/j.poly.2009.04.050

Co(II), Pd(II) and Ni(II) complexes with iminopyridine ligands have different coordination structures in the solid state, depending on the metal, pendant group of the pyridyl ring and recrystallization conditions. The iminopyridine ligand having an acrylate group, Ar-N{double bond, long}CH-2,6-C₅H₃N-CH₂-OCO-CH{double bond, long}CH₂ (L¹: Ar = 2,6-diisopropylphenyl), forms a Co(II) complex whose metal center has a trigonal pyramidal coordination with two chloride ligands and an N,N'-bidentate ligand L¹. Both L¹ and the iminopyridine ligand with a CH₂OH pendant on the pyridyl ring, Ar-N{double bond, long}CH-2,6-C₅H₃N-CH₂-OH (L²: Ar = 2,6-diisopropylphenyl), coordinate to the PdCl₂ moiety, giving complexes with a square-planar coordination. The reaction of L¹ with [NiBr₂(H₂O)₃] and recrystallization of the products forms crystals which contain mono- and dinuclear complexes with aqua ligands and the N,N'-bidentate ligand. L² is coordinated to the Ni(II) center as an N,N',O-tridentate ligand. Recrystallization of the products of the reaction of L² with [NiBr₂(H₂O)₃] with and without excess H₂O in the solution yields crystals of the cationic octahedral complex with two aqua ligands [NiBr(H₂O)₂(L²)]Br and the neutral square pyramidal complex [NiBr₂(L²)], respectively.

Full text of DOI:10.1016/j.poly.2009.04.050

Polyhedron 28 (2009) 2459–2465
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Polyhedron
journal homepage: www.elsevier.com/locate/poly
Structures of Co, Pd and Ni complexes with iminopyridine ligands
having an hydroxymethyl or acrylate pendant group
1
*
Junpei Kuwabara , Daisuke Takeuchi, Kohtaro Osakada
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Co(II), Pd(II) and Ni(II) complexes with iminopyridine ligands have different coordination structures in
the solid state, depending on the metal, pendant group of the pyridyl ring and recrystallization condi-
tions. The iminopyridine ligand having an acrylate group, Ar–N@CH-2,6-C5H3N–CH2–OCO–CH@CH2
(L1: Ar = 2,6-diisopropylphenyl), forms a Co(II) complex whose metal center has a trigonal pyramidal
coordination with two chloride ligands and an N,N’-bidentate ligand L1. Both L1 and the iminopyridine
ligand with a CH2OH pendant on the pyridyl ring, Ar–N@CH-2,6-C5H3N–CH2–OH (L2: Ar = 2,6-diisopro-
pylphenyl), coordinate to the PdCl2 moiety, giving complexes with a square–planar coordination. The
reaction of L1 with [NiBr2(H2O)3] and recrystallization of the products forms crystals which contain
mono- and dinuclear complexes with aqua ligands and the N,N’-bidentate ligand. L2 is coordinated to
the Ni(II) center as an N,N’,O-tridentate ligand. Recrystallization of the products of the reaction of L2 with
[NiBr2(H2O)3] with and without excess H2O in the solution yields crystals of the cationic octahedral com-
plex with two aqua ligands [NiBr(H2O)2(L2)]Br and the neutral square pyramidal complex [NiBr2(L2)],
respectively.
Received 16 March 2009
Accepted 23 April 2009
Available online 21 May 2009
Keywords:
Iminopyridine ligand
Palladium
Cobalt
Nickel
Aqua complex
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
for polymerization [8]. During the study, we characterized mono-
nuclear Co(II), Pd(II) and Ni(II) complexes which were prepared
Iminopyridine derivatives have been extensively employed as
ligands of transition metal complexes. The aromatic ligands whose
conformation is fixed by coordination to a metal center act as a
mesogen of liquid crystalline molecules, and Cu complexes with
such ligands are expected to be liquid crystalline materials [1]. Imi-
nopyridine ligands provide convenient building blocks of supra-
molecules, partly because ligands with various functional groups
can be obtained easily by simple condensation reactions of amines
and 2-formylpyridine derivatives, forming a new C@N bond [2–4].
Introduction of a polar hydroxy group on the iminopyridine ligand
allows the formation of supramolecular assemblies with the mole-
cules having a hydrogen-bond acceptor group, via hydrogen bonds
[3,4]. Catalysis is another important research topic for transition
metal complexes with iminopyridine ligands [5]. In particular,
bis(imino)pyridine complexes of Fe and Co exhibit high activity
for olefin polymerization [6,7]. Recently, we reported the synthesis
of heterobimetallic complexes having Co, Pd and Ni metal centers
and iminopyridine ligands, and their unique behavior as catalysts
as intermediates for dinuclear complexes, and found different
coordination modes of the ligand depending on the metal and
the ligand. Herein, we report the syntheses and crystal structures
of Co(II), Pd(II) and Ni(II) complexes having iminopyridine ligands
with hydroxy or acrylate groups, and the interaction between the
metal centers and these groups in the crystalline state.
2. Results and discussion
Iminopyridine ligands having an acrylate group, Ar–N@CH-2,6-
C5H3N–CH2–OCO–CH@CH2 (L1; Ar = 2,6-diisopropylphenyl) [8],
and a hydroxy group, Ar–N@CH-2,6-C5H3N–CH2–OH (L2), were
synthesized by the condensation reactions of 2,6-diisopropylani-
line with the corresponding aldehyde (Chart 1). The reaction of
O
HO
N
N
O
N
N
* Corresponding author. Fax: +81 45 924 5224.
E-mail address: kosakada@res.titech.ac.jp (K. Osakada).
Present address: Tsukuba Research Center for Interdisciplinary Materials Science
(TIMS), Graduate School of Pure and Applied Science, University of Tsukuba, 1-1-1
Tennoudai, Tsukuba 305-8573, Japan.
L1
L2
1
Chart 1.
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.04.050

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J. Kuwabara et al. / Polyhedron 28 (2009) 2459–2465
O
N
N
CoCl2
O
O
N
Co
N
O
Cl
Cl
L1
1
Scheme 1.
Cl1–Co–Cl2 angles (353.46°) is close to 360°, and the coordination
is recognized to be distorted trigonal pyramidal with the N2 atom
at the apical position. The ether oxygen atom (O1) of the acrylate
group seems to occupy the remaining apical site by a weak inter-
action with the Co center, with a distance of 2.690 Å. The Zr–Co
bimetallic complex, with a similar coordination of the iminopyri-
dine to Co, has a slightly longer Co–O distance (2.774 Å). Co com-
plexes with acetyl- or ester-substituted iminopyridine ligands
have a penta-coordinated structure with coordination of the car-
bonyl group (Co–O lengths = 2.327 and 2.374 Å) [9,10]. The bond
parameters around Co are similar between CoCl2(Ar–N@CH-2,6-
C5H3N–CO–CH3) (Ar = 2,6-diisopropylphenyl) and 1, with the
exception of the short Co–O bond in the former complex.
Fig. 1. ORTEP drawing of 1 with thermal ellipsoids shown at the 30% probability
level. Hydrogen atoms are omitted for clarity.
The reactions of L1 and L2 with [PdCl2(cod)] (cod = 1,5-cyclo-
octadiene) afforded complexes 2 and 3, respectively (Scheme 2).
Fig. 2 shows the crystal structures of the Pd complexes with the
N,N0-bidentate iminopyridine ligands. Each Pd center has a dis-
torted square–planar geometry without any remarkable interac-
tion with the acrylate or hydroxy pendant group. The square
L1 with CoCl2 afforded the Co-iminopyridine complex 1 (Scheme
1). The crystal structure of 1 is shown in Fig. 1. Table 1 summarizes
selected bond parameters. Sum of the N1–Co–Cl1, N1–Co–Cl2 and
Table 1
Selected bond distances (Å) and angles (°) for complexes 1–5b.
1
2
3
4a
4b
5a
5b
(M@Co, X@Cl)
(M@Pd, X@Cl)
(M@Pd, X@Cl)
(M@Ni, X@Br)
(M@Ni, X@Br)
(M@Ni, X@Br)
(M@Ni, X@Br)
M–X1
M–X2
M–N1
M–N2
M–O1
M–O2
M–O3
X1–M–X2
X1–M–N1
X1–M–N2
X2–M–N1
X2–M–N2
N1–M–N2
2.2420(6)
2.2290(7)
2.063(2)
2.105(2)
2.2819(6)
2.2625(7)
2.121(2)
2.009(2)
2.302(2)
2.258(2)
2.096(7)
2.021(6)
2.4408(5)
2.4296(5)
2.094(3)
2.025(3)
2.5085(6)
2.4338(6)
2.078(3)
2.043(3)
2.3935(7)
2.4134(9)
2.005(3)
2.135(3)
2.137(4)
2.4690(7)
2.006(2)
2.127(3)
2.248(2)
2.049(3)
2.089(2)
2.107(3)
139.55(2)
91.97(9)
108.70(9)
93.95(9)
111.73(9)
80.0(2)
113.13(2)
129.51(6)
100.44(5)
110.82(6)
117.66(5)
79.66(7)
86.61(2)
101.86(5)
175.33(6)
171.43(5)
91.12(6)
80.53(8)
86.99(9)
101.0(2)
172.3(2)
172.0(2)
92.0 (2)
80.1(3)
144.94(2)
89.10(9)
104.70(9)
91.40(8)
109.97(9)
80.7(2)
107.86(3)
150.7(2)
102.33(9)
100.8(1)
100.6(1)
77.9(2)
172.8(1)
106.23(9)
79.2(2)
In the case of 4b (dimer complex), X1, X2, N1 and N2 indicate Br3, Br4, N3 and N4, respectively.
O
N
O
N
PdCl2(cod)
O
N
O
Cl Pd
N
Cl
L1
2
HO
HO
N
Cl Pd
Cl
PdCl2(cod)
N
N
N
L2
3
Scheme 2.

J. Kuwabara et al. / Polyhedron 28 (2009) 2459–2465
2461
Fig. 3. 1H NMR spectra of the hydroxymethyl region of 3 at 25–100 °C in C2D2Cl4
(8.2 mM).
Fig. 2. ORTEP drawing of (a) 2 and (b) 3.1.5CHCl3 with thermal ellipsoids shown at
the 30% probability level. Hydrogen atoms are omitted for clarity. Hydrogen atoms
and solvating CHCl3 molecules are omitted for clarity.
dent change of the spectra may also suggest O–HꢀꢀꢀCl hydrogen
bonds in solution.
Elemental analysis of the product from the reaction of L1 and
[NiBr2(H2O)3] indicates the formation of the aqua complex,
[NiBr2(H2O)L1] (4a) [8], but X-ray crystallography of the crystals
obtained from CHCl3 revealed the presence of 4a and a dinuclear
plane is orthogonally-oriented to the 2,6-diisopropylphenyl group
owing to the sterically bulky isopropyl groups [6,7]. The CH2–OH
bond is orientated towards the Cl ligand with the distance Cl1–
O1 = 3.046 Å, which indicates intramolecular hydrogen bonding
in the crystal structure (Fig. 2b). The 1H NMR spectrum of 3
(25 °C, CDCl3) exhibits a triplet (JHH = 8 Hz) assigned to the OH
hydrogen at 4.67 ppm, which is at a much lower magnetic field
than that of L2. Appearance of H–H coupling between the OH and
CH2 hydrogen of 3, as well as the shift of the OH peak position,
upon coordination of the ligand suggests Pd–ClꢀꢀꢀH–O intramolecu-
lar hydrogen bonding in solution [11–13]. Fig. 3 shows the variable
temperature 1H NMR spectra of 3 in ClCD2CD2Cl. The triplet signal
of the OH hydrogen shifts downfield by ca 0.17 ppm on raising the
temperature from 25 to 100 °C. The OH and CH2 hydrogen signals
became somewhat broadened at 100 °C. The temperature-depen-
complex with two bridging Br ligands, [NiBr(l
-Br)L1]2, (4b) in a
1:1 ratio (Scheme 3). Fig. 4 shows the structure of the mononuclear
and dinuclear complexes contained in the crystal lattice. Complex
4a undergoes partial dissociation of the aqua ligand to yield the
anhydrous dinuclear complex 4b during the recrystallization.
Chart 2 lists the penta-coordinated Ni(II) complexes with two Br,
one aqua and one iminopyridine ligand, similar to 4a [14,15].
The coordination of 4a resembles that of a complex with an imino-
pyridine ligand with a methyl group next to the pyridine group
(right in Chart 2), although the other complex (left) has different
ligand positions. The reaction of an iminopyridine ligand with
[NiBr2(dme)] (dme = 1,2-dimethoxyethane) gives dinuclear com-
O
N
O
N
NiBr2(H2O)3
Br
O
O
N
Ni
N
Br
OH2
L1
4a
+
O
N
O
Ni
N
Br
Br
Br
O
Br
N
Ni
N
O
4b
Scheme 3.

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J. Kuwabara et al. / Polyhedron 28 (2009) 2459–2465
O
Cl
Cl
EtOC
H2O
N
N
H2O Ni
Br
Ni
Br
N
N
OSiMe3
Br
Br
Chart 2.
plexes with two bridging Br ligands (Chart 3) [16,17]. In the crystal
structures of 4a and 4b, the acrylate group of the ligand does not
interact with the Ni(II) centers.
The reaction of the ligand with the CH2OH pendant, L2, with
[NiBr2(H2O)3] yielded a Ni complex, 5a, having an N,N0,O-coordina-
tion (Scheme 4). The crystal structure of 5a shows a five-coordinate
square pyramidal geometry with a Br atom (Br2) at the apical
position (Fig. 5a). The Ni center lies 0.43 Å out of the basal plane
composed of the N1, N2, Br1 and O1 atoms. A similar N,N0,O-coordi-
nation was observed in Ni(II) complexes with Ar–N@CCH3-2,6-
C5H3N–COCH3 (Ar = 2,6-diisopropylphenyl) and Ar–N@CCH3-2,6-
C5H3N–COOCH2CH3 (Ar = 2,6-dimethylphenyl) [10,14], which have
longer Ni–O bonds (2.334 and 2.402 Å) than that of 5a (2.137 Å)
(Chart 4). Recently, Gibson and co-workers reported a Fe(II) com-
plex with a similar ligand to L2, Ar–N@CCH3-2,6-C5H3N–C(CH3)2OH
Fig. 4. ORTEP drawing of 4a and 4b with thermal ellipsoids shown at the 30%
probability level. Hydrogen atoms except for O–H hydrogens are omitted for clarity.
Atoms with asterisks are crystallographically equivalent to those having the same
number without asterisks.
N
N
Ni
N
Ni
N
Br
Br
Br
Br
Br
Br
Br
Br
N
Ni
N
N
Ni
N
Chart 3.
HO
N
N
NiBr2(H2O)3
H O
Br
Ni
N
N
Br
L2
5a
-
Br
N
N
+ 2H2O
+
O
Ni
N
H O
Br
H
Ni
N
H2O
OH2
Br
Br
5a
5b
Scheme 4.

J. Kuwabara et al. / Polyhedron 28 (2009) 2459–2465
2463
(Ar = 2,6-diisopropylphenyl), in which the OH group is coordinated
to Fe with a Fe–O bond distance of 2.173 Å (Chart 4) [18]. The bond
length of the Ni and imine nitrogen (N2) is 0.13 Å longer than that of
Ni and the pyridine nitrogen (N1). In contrast, 4a and 4b have short-
er Ni–imine bonds than Ni–pyridine bonds. Therefore, coordination
of the hydroxy group is likely to elongate the Ni–imine bond due to
the trans influence of the O-ligand [19,20]. Other Ni-iminopyridine
complexes with N,N’,O-tridentate coordination have Ni–imine
bonds approximately 0.1 Å longer than the Ni–pyridine bonds
(Chart 4) [10,14,18]. Recrystallization of 5a in the presence of an ex-
cess amount of H2O caused dissociation of a Br ligand, resulting in
the formation of the cationic aqua complex 5b (Fig. 5b). The struc-
ture has a distorted octahedral geometry with two aqua ligands at
trans positions. In analogy to 5a, 5b has longer Ni–imine bonds
(2.127 Å) than Ni–pyridine bonds (2.006 Å). A similar replacement
of a Br ligand with an aqua ligand was reported in a Ni(II) complex
with the bidentate diphenyl(dipyrazolyl)methane ligand [21].
Intermolecular hydrogen bonding was observed in the aqua
complexes 4a and 5b, as shown in Fig. 6. In the structure of 4a,
the short distance of H1ꢀꢀꢀBr1* (2.596 Å) and the angle of H1–
Br1*–Ni* (105.8°) indicate hydrogen bonding [22]. The distance
H2ꢀꢀꢀO2* (2.451 Å) is also related to an intermolecular interaction,
although the non-linear O3–H2–O2* bonding (139.8°) suggests
that the contribution of the H2–O2* hydrogen bond is minor. The
structure of 5b shows that H1 in the hydroxy group and H2 in
the aqua ligand have an interaction with the free Br anion (Br2)
Fig. 6. Association of (a) 4a and (b) 5b via hydrogen bonding. Hydrogen atoms
except for O–H hydrogens and solvating THF molecules are omitted for clarity.
Selected angles for 4a (°): H1–Br1*–Ni* 105.7, O3–H1–Br1* 160.2, O3–H2–O2*
138.9, Ni–O3–Br1* 102.8, Ni–O3–O2* 138.6. Selected angles for 5b (°): H4–Br1*–Ni
86.1, O1–H1–Br2 177.4, O2–H2–Br2 160.2, O3–H4–Br1* 155.5, O3–H5–O1* 150.9,
Ni–O1–Br2 105.8, Ni–O2–Br2 105.8, Ni–O3–Br1* 120.6, Ni–O3–O1* 125.7.
Fig. 5. ORTEP drawing of (a) 5a.C4H8O and (b) 5b.C4H8O with thermal ellipsoids
shown at the 30% probability level. Hydrogen atoms except for O–H hydrogens and
solvating THF molecules are omitted for clarity.
EtO
N
Ni
Cl
N
N
N
O
Cl
N
O
Br
Ni
Br
N
H O Fe
Cl
Cl
Chart 4.

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J. Kuwabara et al. / Polyhedron 28 (2009) 2459–2465
with distances of 2.289 and 2.398 Å, respectively. The other aqua
ligand shows hydrogen bonding with the Br1* and O1* atoms in
the neighboring molecule in the crystal packing.
and acetic acid (1 drop) in EtOH (3 mL) was stirred for 14 h at room
temperature. After the volatiles were evaporated under reduced
pressure, the residue was washed with hexane (2 mL ꢁ 4) and
dried under reduced pressure to give 2-hydroxymethyl-6-[(2,6-
diisopropylphenyl)iminomethyl]pyridine as a pale yellow solid
(275.6 mg, 90%). Anal. Calc. for C19H24N2O: C, 76.99; H, 8.16; N,
9.45. Found: C, 76.30; H, 7.99; N, 9.30%. 1H NMR (300 MHz, CDCl3):
d 8.31 (s, 1H, N@CH), 8.19 (d, 1H, J3 = 8 Hz, CH in pyridyl group),
7.78 (t, 1H, J3 = 8 Hz, CH in pyridyl group), 7.38 (d, 1H, J3 = 8 Hz,
CH in pyridyl group), 7.20–7.11 (m, 3H, CH in aromatic group),
4.85 (s, 2H, CH2), 3.90 (br, 1H, OH), 2.96 (quint, 2H, J3 = 7 Hz, CH),
1.18 (d, 12H, J3 = 7 Hz, CH3). 13C{1H} NMR (75 MHz, CDCl3):
d162.9 (s, N@CH), 159.2 (s, ipso), 153.8 (s, ipso), 148.6 (s, ipso),
137.7 (s, CH in pyridyl group), 137.4 (s, ipso), 124.8 (s, CH in pyridyl
group), 123.3 (s, CH in aromatic group), 122.4 (s, CH in aromatic
group), 120.1 (s, CH in pyridyl group), 64.2 (s, CH2), 28.2 (s, CH),
23.7 (s, CH3).
3. Conclusions
The crystal structures of iminopyridine complexes with an acry-
late or a hydroxy pendant group were revealed by single-crystal
X-ray diffraction studies. The weak interaction of the acrylate pen-
dant group to the metal center was observed only in the case of the
Co(II) complex. Coordination of the carbonyl oxygen atoms is unfa-
vorable partly because it requires the formation of unstable
7-membered metallacycles. In the iminopyridine complexes with
an hydroxy pendant group (L2), the ligand coordinates to the Ni(II)
center in an N,N0,O-tridentate coordination fashion. Since coordina-
tion of an aqua ligand to Ni(II) caused the dissociation of the Br li-
gand in the presence of the coordinated hydroxy group, the
coordination of the hydroxy group is presumably stronger than
that of Br because of the chelate effect.
4.3. Synthesis of dichloro{2-hydroxymethyl-6-
[(2,6-diisopropylphenyl)iminomethyl]pyridine}palladium(II) (3)
4. Experimental
A mixture of 2-hydroxymethyl-6-[(2,6-diisopropylphenyl)imi-
nomethyl]pyridine (68.0 mg, 0.23 mmol) and [PdCl2(cod)]
(65.3 mg, 0.23 mmol) in THF (20 mL) was stirred for 12 h at room
temperature. After the volatiles were evaporated under reduced
pressure, the residue was extracted with THF. Crystallization from
THF/Et2O gave 3 as yellow solid (91.9 mg, 78%). Anal. Calc. for
C19H24N2OCl2Pd: C, 48.17; H, 5.11; N, 5.91; Cl, 14.97. Found: C,
47.92; H, 5.32; N, 5.92; Cl, 15.38% 1H NMR (300 MHz, CDCl3):
d8.17 (t, 1H, J3 = 8 Hz, CH in pyridyl group), 8.07 (s, 1H, N@CH),
7.84 (d, 1H, J3 = 8 Hz, CH in pyridyl group), 7.80 (d, 1H, J3 = 8 Hz,
CH in pyridyl group), 7.36 (t, 1H, J3 = 8 Hz, CH in aromatic group),
7.20 (d, 2H, J3 = 8 Hz, CH in aromatic group), 5.15 (d, 2H,
J3 = 8 Hz, CH2), 4.67 (t, 1H, J3 = 8 Hz, OH), 3.31 (double quartet,
2H, J3 = 7 Hz, CH), 1.41 (d, 6H, J3 = 7 Hz, CH3), 1.14 (d, 6H,
J3 = 7 Hz, CH3). The low solubility of the complex made it impossi-
ble to obtain a 13C{1H} NMR spectrum.
4.1. General
6-Hydroxymethyl-2-pyridinecarboxaldehyde [23], [PdCl2(cod)]
[24], 1 (green solid), 2 (yellow solid) and 4 (orange solid) were pre-
pared according to the literature methods [8]. [NiBr2 (H2O)3] and
other chemicals were used as received from commercial suppliers.
NMR spectra (1H and 13C{1H}) were recorded on Varian Mercury
300 and JEOL JNM LA-500 spectrometers. Elemental analyses were
carried out with a Yanaco MT-5 CHN autocorder.
.
4.2. Synthesis of 2-hydroxymethyl-6-
[(2,6-diisopropylphenyl)iminomethyl]pyridine (L2)
A
mixture of 6-hydroxymethyl-2-pyridinecarboxaldehyde
(141.0 mg, 1.0 mmol), 2,6-diisopropylaniline (0.200 mL, 1.1 mmol)
Table 2
Crystal data and details of structure refinement of complexes 1–5b.
1
2
3ꢀ1.5CHCl3
4
5aꢀC4H8O
5bꢀC4H8O
Chemical formula
Formula weight
Crystal system
Space group
a (Å)
C22H26Cl2CoN2O2
480.30
Monoclinic
P21/c (No. 14)
9.200(2)
C22H26Cl2N2O2Pd
527.77
Orthorhombic
P212121 (No. 19)
12.022(3)
2C19H24Cl2N2OPdꢀ3CHCl3 C44H54Br4N4Ni2O5 C19H24Br2N2NiOꢀC4H8O C19H28Br2N2NiO3ꢀC4H8O
1303.55
1155.95
587.03
623.06
Orthorhombic
P21212 (No. 18)
12.435(2)
21.765(2)
9.974(2)
Monoclinic
P21/c (No. 14)
10.216(2)
22.678(3)
20.599(3)
Monoclinic
P21/n (No. 14)
9.468(2)
13.707(3)
19.654(5)
Triclinic
P1 (No. 2)
ꢀ
9.9948(4)
10.1121(4)
13.9053(5)
78.734(2)
85.777(2)
76.073(2)
1337.27(1)
2
b (Å)
c (Å)
15.087(2)
16.460(3)
12.905(3)
14.881(4)
a
(°)
b (°)
91.980(3)
97.398(2)
93.247(4)
c
(°)
V (Å3)
2283.3(6)
4
10.054
996
2308.7(9)
4
10.552
1072
2699.6(5)
2
4733(1)
4
2547(1)
4
Z
l
(cmꢂ1
)
13.463
1304
1.604
42.294
2328
1.622
39.299
1192
1.531
37.520
636
1.547
F(0 0 0)
Dcalc, (g cmꢂ3
)
1.397
1.518
Crystal size (mm)
Exposure rate sec. (°)
Number of date
Number of unique date
Number of used reflections
0.40 ꢁ 0.12 ꢁ 0.10 0.20 ꢁ 0.20 ꢁ 0.20 0.45 ꢁ 0.20 ꢁ 0.12
0.20 ꢁ 0.17 ꢁ 0.15 0.12 ꢁ 0.10 ꢁ 0.10
0.50 ꢁ 0.15 ꢁ 0.15
20.0
10.0
40.0
80.0
80.0
60.0
16 961
5070
4249
15 716
5194
5076
20 296
6161
5848
34 856
10 775
8917
18 884
5771
3832
13 241
6040
4635
(I > 2
Number of variables
R (I > 2 (I))
R (All reflections)
RW (All reflections)
Goodness-of-fit (GOF)
r(I))
263
263
243
541
276
310
r
0.042
0.054
0.113
1.07
0.026
0.027
0.068
1.13
0.085
0.088
0.230
1.07
0.049
0.065
0.118
1.13
0.057
0.088
0.168
1.08
0.044
0.065
0.128
1.11

J. Kuwabara et al. / Polyhedron 28 (2009) 2459–2465
2465
4.4. Synthesis of dibromo{2-hydroxymethyl-6-
[(2,6-diisopropylphenyl)iminomethyl]pyridine}nickel(II) (5a)
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
.
[NiBr2 (H2O)3] (54.5 mg, 0.20 mmol) was added to a solution of
2-hydroxymethyl-6-[(2,6-diisopropylphenyl)iminomethyl]pyridine
(59.3 mg, 0.20 mmol) in THF (10 mL). After stirring at room tem-
perature for 18 h, the solvent was reduced under vacuum. Et2O
was added to the solution to cause the separation of 5a as an or-
ange solid (68.9 mg, 67%). Anal. Calc. for C19H24Br2N2Ni.C4H8O: C,
47.06; H, 5.49; N, 4.77; Br, 27.22. Found: C, 46.91; H, 5.52; N,
4.77; Br, 27.26%.
Acknowledgements
This work was supported by the Ministry of Education, Science,
Sports and Culture, Japan and by a 21st Century COE program ‘‘Cre-
ation of Molecular Diversity and Development of Functionalities”. J.
K. acknowledges a JSPS Research Fellowship for a Young Scientist.
4.5. Synthesis of bisaqua(bromo){2-hydroxymethyl-6-
[(2,6-diisopropylphenyl) iminomethyl]pyridine}nickel(II) bromide (5b)
References
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Complex 5a (19.1 mg, 0.037 mmol) was stirred in a mixture of
THF and H2O (30/1) for 20 h. After the solution was dried with
MgSO4, the solvent was slowly evaporated to cause the separation
of 5b as green crystals (11.5 mg, 59%). Anal. Calc. for
C19H28Br2N2O3Ni.C4H8O: C, 44.34; H, 5.82; N, 4.50; Br, 25.65.
Found: C, 44.12; H, 6.06; N, 4.40; Br, 25.63%.
4.6. Crystal structure determination
Intensity data were collected on a Rigaku Saturn CCD area
detector or a Rigaku R-AXIS Rapid diffractometer with Mo Ka radi-
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ation. Crystals of 1–5b suitable for an X-ray diffraction study were
mounted on glass capillary tubes. Crystallographic data and details
of refinement of the complexes are summarized in Table 2. A full
matrix least-squares refinement was used for non-hydrogen atoms
with the anisotropic thermal parameters method by the SHELXL-97
program. In the structure of 3ꢀ1.5CHCl3, disordered CHCl3 mole-
cules, C1 and O1 atoms were refined isotropically. The positional
parameters for O–H hydrogen atoms, except for those in
3ꢀ1.5CHCl3, were refined isotropically, but other hydrogens were
located by assuming an ideal geometry and were included in the
structure calculation without further refinement of the parameters
[25].
Supplementary data
[23] Y. Okuyama, H. Nakano, C. Kabuto, E. Nozawa, K. Takahashi, H. Hongo,
Heterocycles 58 (2002) 457.
[24] D. Drew, J.R. Doyle, Inorg. Synth. 13 (1972) 47.
[25] International Tables for X-ray Crystallography, vol. 4, Kynoch: Birmingham,
UK, 1974.
CCDC 719682, 719683, 719684, 719685, 719686, 719687 con-
tains the supplementary crystallographic data for 1, 2, 3, 4, 5a
and 5b, respectively. These data can be obtained free of charge