Preparations, structures, and properties of sulfato-bridged dinuclear and tetranuclear vanadium(III) complexes with a dinucleating ligand, 2-oxo-N,N′-bis(2-pyridylmethyl)-1,3-propanediamine-N,N′-diacetate

Article abstract of DOI:10.1246/bcsj.79.1881

New dinuclear and tetranuclear vanadium(III) complexes with sulfato bridge(s), [{V^III(H₂O)}₂(μ-hpnbpda)-(μ- OH)(μ-SO₄)]·5.25H₂O (1) and [V ^III₄(μ-hpnbpda)₂(μ-OH) ₂(μ-SO₄)₂]·12H₂O (2), where hpnbpda is an alkoxobridging dinucleating ligand, 2-oxo-N,N′-bis(2- pyridylmethyl)-1,3-propanediamine-N,N′-diacetate, were prepared, and their structures were determined by X-ray crystallography. The vanadium(III) center in 1 adopts heptacoordinate structure while that in 2 has a hexacoordinate structure. In 2, the two dinuclear vanadium(III) units bridged by the alkoxo group of hpnbpda are further linked by two hydroxo and two sulfato bridging groups, resulting in a dimer-of-dimers structure. Measurement of the temperature dependence of the magnetic susceptibility of 1 revealed that the two vanadium(III) ions are antiferromagnetically coupled with J = -5.9 cm ^-1 and g = 1.90.

Full text of DOI:10.1246/bcsj.79.1881

Ó 2006 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 79, No. 12, 1881–1888 (2006) 1881
Preparations, Structures, and Properties of Sulfato-Bridged
Dinuclear and Tetranuclear Vanadium(III) Complexes with
0
a Dinucleating Ligand, 2-Oxo-N,N -bis(2-pyridylmethyl)-
0
1
,3-propanediamine-N,N -diacetate
Kan Kanamori, 1 Naoto Matsui, Kentaro Takagi, Yoshitaro Miyashita, and Ken-ichi Okamoto
ꢀ
1
1
2
2
1Department of Chemistry, Faculty of Science, University of Toyama, 3190 Gofuku, Toyama 930-8555
2Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba,
1-1-1 Tennodai, Tsukuba 305-8571
Received May 8, 2006; E-mail: kanamori@sci.u-toyama.ac.jp
III
New dinuclear and tetranuclear vanadium(III) complexes with sulfato bridge(s), [{V (H2O)}2(ꢀ-hpnbpda)-
III
(
ꢀ-OH)(ꢀ-SO4)] 5.25H2O (1) and [V 4(ꢀ-hpnbpda)2(ꢀ-OH)2(ꢀ-SO4)2] 12H2O (2), where hpnbpda is an alkoxo-
ꢁ
ꢁ
0
0
bridging dinucleating ligand, 2-oxo-N,N -bis(2-pyridylmethyl)-1,3-propanediamine-N,N -diacetate, were prepared, and
their structures were determined by X-ray crystallography. The vanadium(III) center in 1 adopts heptacoordinate struc-
ture while that in 2 has a hexacoordinate structure. In 2, the two dinuclear vanadium(III) units bridged by the alkoxo
group of hpnbpda are further linked by two hydroxo and two sulfato bridging groups, resulting in a dimer-of-dimers
structure. Measurement of the temperature dependence of the magnetic susceptibility of 1 revealed that the two vana-
dium(III) ions are antiferromagnetically coupled with J ¼ ꢂ5:9 cmꢂ1 and g ¼ 1:90.
Interest in vanadium chemistry and biology have increasing
in the past decade.1–3 Vanadium is known to exist in a wide
Experimental
variety of oxidation states from ꢂI to V, of which only vana-
dium(V), -(IV), and -(III) are biologically relevant. Vana-
dium(V) is an essential element of vanadium-dependent halo-
peroxidase found in marine algae and terrestrial fungi and of
Compound Preparations. Reagents were obtained from com-
mercial sources and used without further purification. All of the
synthetic procedures for vanadium(III) complexes were performed
under an Ar atmosphere using standard Schlenk techniques or in a
N2-filled glove box.
4
vanadium nitrogenase from Azotobacter vinelandii. The vana-
dium(IV) species, named amavadin, has been found in the fly
0
N,N -Bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-
0
5
N,N -diacetic Acid Hydrobromide Trihydrate (H3hpnbpdaꢀ
according to the literature method.
agaric toadstool Amanita muscaria. Vanadium(IV) has been
6
HBrꢀ3H2O). H3hpnbpda HBr 3H2O (Scheme 1) was prepared
ꢁ ꢁ
shown to have insulin mimetic functions. Since Henze discov-
1
1
ered that vanadium(III), which is an unstable oxidation state,
accumulates in high levels in the blood cells of ascidians,
known as tunicates or sea squirts, vanadium(III) species have
been attracting the attention of chemists as well as biologists,
though the function of vanadium(III) in ascidian blood cells
has not yet been determined.7 Interestingly, sulfate always
co-exists with vanadium(III) in ascidian blood cells in spite
of the fact that chloride is the most abundant anion in sea wa-
ter. In order to obtain insight into the role of sulfate in tunicate
blood cells, it is important to examine the coordination modes
of sulfate to vanadium(III). In a previous paper, we reported
the structures of vanadium(III) complexes in which the sulfate
anion acted as a bidentate chelate ligand or a bridging ligand.10
In this paper, we report the syntheses, structures, and proper-
ties of new dinuclear and tetranuclear vanadium(III) com-
plexes containing alkoxo-bridging dinucleating ligand, 2-
III
[
{V (H2O)}2(ꢀ-hpnbpda)(ꢀ-OH)(ꢀ-SO4)]ꢀ5.25H2O (1).
3
12
To an aqueous solution (20 cm ) of anhydrous V2(SO4)3 (1.2 g,
3
.0 mmol) was added H3hpnbpda HBr 3H2O (1.6 g, 3.0 mmol).
ꢁ
ꢁ
ꢂ3
Adjusting the pH of the solution to 3.5 by adding 1 mol dm LiOH
yielded a dark reddish brown solution. Dark red plates crystallized
on standing at room temperature for one day. The crystals were
collected by filtration, washed with cold water, and then dried.
The crystals tend to effloresce and are oxidized on exposure to
air. The crystals were, therefore, kept under Ar atmosphere. Yield
–9
65%. Anal. Calcd for C H N O
4
1
9
36:5
17:25
2 2
SV = [V (hpnbpda)(OH)-
(SO )(H O) ] 5.25H O: C, 31.21; H, 5.04; N, 7.67%. Found: C,
4
2
2
2
ꢁ
31.48; H, 4.74; N, 7.77%. Selected IR data (KBr disk): 1653
(ꢁas(COO)), 1484, 1445, 1383, 1335, 1307, 1245, 1192, 1166,
-OOC
COO-
N
0
0
N
N
oxo-N,N -bis(2-pyridylmethyl)-1,3-propanediamine-N,N -diace-
tate (hpnbpda), and sulfato ligand. The vanadium(III)–
hpnbpda complexes with a carboxylato bridge were also pre-
pared to compare their properties with those of the sulfato-
bridged complexes.
O-
N
hpnbpda
Scheme 1.
Published on the web December 13, 2006; doi:10.1246/bcsj.79.1881

1
882 Bull. Chem. Soc. Jpn. Vol. 79, No. 12 (2006)
Dinuclear and Tetranuclear VIII Complexes
III
1
7
117 (ꢁ(SO4)), 1044 (ꢁ(SO4)), 1027, 1006, 982, 964, 931, 771,
Table 1. Crystallographic Data of [{V (H2O)}2(ꢀ-
ꢂ1
III
33, 701, 632 cm
.
hpnbpda)(ꢀ-SO4)(ꢀ-OH)] 5.25H2O (1) and [V 4(ꢀ-
ꢁ
[
reddish brown solution was obtained by the same procedure as
VIII4(ꢀ-hpnbpda)2(ꢀ-OH)2(ꢀ-SO4)2]ꢀ12H2O (2). A dark
hpnbpda)2(ꢀ-SO4)2(ꢀ-OH)2] 12H2O (2)
ꢁ
3
1
2
shown above. The solution was concentrated to ca. 10 cm by
ꢃ
warming at 70 C. Dark green plates crystallized on standing at
ꢃ
Formula
fw
Temperature/K
˚
C19H36:5N4O17:25SV2 C38H68N8O32S2V4
60 C for a long period. The crystals were collected by filtration,
washed with cold water, and then dried. Yield. 24%. Anal. Calcd
730.96
296
0.71069
1416.88
296
0.71069
monoclinic
P21=c
11.070(3)
12.154(3)
21.444(3)
for C38H68N8O32S2V4 = [V2(hpnbpda)2(OH)2(SO4)2] 12H2O: ꢃ(Mo Kꢂ)/A
C, 32.21; H, 4.85; N, 7.91%. Found: C, 31.89; H, 4.67; N, 7.75%.
Selected IR data (KBr disk): 1653 (ꢁas(COO)), 1482, 1449, 1355,
ꢁ
Crystal system
Space group
triclinic
ꢀ
P1
˚
1
316, 1299, 1190, 1162, 1122 (ꢁ(SO4)), 1039 (ꢁ(SO4)), 999, 931,
a/A
12.8868(5)
13.3741(5)
19.4059(9)
90.4059(11)
106.6966(11)
108.0905(11)
2972.92(19)
4
ꢂ1
˚
8
61, 836, 777, 732, 680, 644, 604 cm
[
.
b/A
{VIII(H2O)}2(ꢀ-hpnbpda)(ꢀ-O2CC2H5)(ꢀ-OH)]Brꢀ7H2O
˚
c/A
(
3). A suspension containing anhydrous V2(SO4)3 (0.8 g, 2.0 ꢂ/deg
ꢃ
mmol) and BaBr2 2H2O (2.1 g, 6.0 mmol) was warmed at 60 C ꢄ/deg
for 24 h to yield a solution of VBr3. Barium sulfate precipitated ꢅ/deg
91.890(13)
ꢁ
˚
V/A
3
was removed by filtration. To the filtrate was added an aqueous
3
2883.5(10)
2
1.632
8.000
1464
solution (20 cm ) of H3hpnbpda HBr 3H2O (1.04 g, 2.0 mmol)
Z
ꢁ
ꢁ
3
ꢂ3
and an excess amount of propionic acid (2 cm , ca. 40 mmol).
ꢂ3
Dcalcd/g cm
ꢀ/cm
1.633
7.816
1514
ꢂ1
The pH of the solution was adjusted to 3.5 by adding 1 mol dm
of LiOH. When this solution was evaporated, orange crystals were
deposited. The crystals were re-dissolved in minimum amount of
Fð000Þ
No. of reflections
Total
Unique
ꢃ
water by heating at 50 C, and the resulting solution was allowed
24359
13392
6959
6623
5246
400
0.056
0.099
1.003
to stand at room temperature for three days. Orange plates were
collected by filtration, washed with cold water, and then dried.
The crystals tend to effloresce, and the complex is oxidized on ex-
posure to air. The crystals were, therefore, kept under Ar atmo-
sphere. Yield. 58%. Anal. Calcd for C22H45N4O17BrV2 = [V2-
(hpnbpda)(O2CC2H5)(OH)(H2O)2]Br 7H2O: C, 32.43; H, 5.32;
N, 6.52%. Found: C, 32.24; H, 5.55; N, 6.84%. Selected IR data
(KBr disk): 1629 (ꢁas(COO), hpnbpda), 1557 (ꢁas(COO), propio-
nate), 1459, 1428, 1397, 1295, 1234, 1123, 1018, 996, 954, 926,
Observed (I >3ꢆðIÞ) 11195
No. of variables
Ra) (I >3ꢆðIÞ)
826
0.045
0.085
1.004
b),c)
Rw
GOF
(I >3ꢆðIÞ)
ꢁ
2
a) R ¼ ðꢁjðjFoj ꢂ jFcjÞ=ꢁðjFojÞ. b) Rw ¼ ðꢁwðjFoj ꢂ jFcjÞ =
2 1=2
2
2
ꢁ
wðjFoj Þ . c) w ¼ 4ðFoÞ =s ðFoÞ.
ꢂ1
7
64, 723, 692, 566 cm
Measurements.
.
UV–vis spectra were measured using a
C9
C17
C8
C6
C16
C18
C19
C10
JASCO Ubest 50 spectrophotometer under argon atmosphere. Dif-
fuse reflectance spectra were obtained for complexes diluted with
MgO. Infrared spectra were recorded on a JASCO FT/IR-8000S.
Since the vanadium(III) complexes obtained here are moderately
stable to air oxidation in the solid state, the diffuse reflectance
and infrared spectra were measured in air. The magnetic suscepti-
bility was measured using the SQUID method on a Quantum
Design MPMS-5S.
C7
C15
C14
C11
V1
N4
C2
N2
C3
C1
N3
N1
O1
C12
C13
C4
V2
C5
O6
O2
O4
O10
O11
O12
O3
O5
O8
O7
X-ray Structure Determination.
data are summarized in Table 1. A crystal of [{V (H2O)}2(ꢀ-
The crystallographic
III
S1
O9
III
hpnbpda)(ꢀ-OH)(ꢀ-SO4)] 5.25H2O (1) or [V 4(ꢀ-hpnbpda)2-
ꢁ
III
(
ꢀ-OH)2(ꢀ-SO4)2] 12H2O (2) was mounted on a glass fiber,
Fig. 1. Perspective view of [{V (H2O)}2(ꢀ-hpnbpda)-
(ꢀ-OH)(ꢀ-SO4)] (1).
ꢁ
coated with epoxy resin as a precaution against solvent loss, and
centered on a Rigaku AFC7S four-circle diffractometer (for 1)
or a Rigaku Mercury CCD system (for 2) using graphite-mono-
chromated Mo Kꢂradiation. Data reduction and the application
of Lorentz, polarization, linear decay correction (for 1), and em-
CCDC-616321 for 1 and 2, 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, UK; Fax: +44
pirical absorption corrections based on a series of
carried out.
scans were
1
223 336033; e-mail: deposit@ccdc.cam.ac.uk).
The structure was solved by direct methods, SIR9713 for 1 and
SHELX9714 for 2. Some remaining atom positions were found by
successive Fourier techniques, DIRDIF99.15 All of the non-hydro-
gen atoms were refined anisotropically. Hydrogen atoms were
included but not refined. All calculations were performed using
the CrystalStructure crystallographic software package.16 Crystal-
lographic data have been deposited with Cambridge Crystallo-
graphic Data Centre: Deposition numbers CCDC-616320 and
Results and Discussion
III
X-ray Structures of [{V (H O)} (ꢀ-hpnbpda)(ꢀ-OH)-
2
III
2
(
ꢀ-SO4)]ꢀ5.25H2O (1) and [V 4(ꢀ-hpnbpda)2(ꢀ-OH)2-
(ꢀ-SO4)2]ꢀ12H2O (2). From the X-ray analysis, the unit cell
of 1 contains two crystallographically independent complexes;
however, their structures are almost the same. Figure 1 depicts
the structure of one of the two complexes in the unit cell. Se-

K. Kanamori et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 12 (2006) 1883
˚
III
Table 2. Selected Bond Distances (A) and Angles (degree) for [{V (H2O)}2(ꢀ-hpnbpda)(ꢀ-SO4)(ꢀ-OH)] 5.25H2O (1)
ꢁ
Complex A
V1–O1
V1–O2
V1–O6
V1–O7
V1–O11
V1–N1
V1–N2
V1ꢁꢁꢁV2
2.006(2)
2.100(2)
1.988(2)
2.0993(15)
2.118(2)
2.255(2)
2.1505(19)
3.2537(6)
V2–O1
V2–O4
V2–O6
V2–O8
V2–O12
V2–N3
V2–N4
2.015(2)
2.073(2)
2.0135(19)
2.1016(18)
2.109(2)
2.265(2)
2.143(2)
O1–V1–O2
O1–V1–O6
O1–V1–O7
O1–V1–O11
O1–V1–N1
O1–V1–N2
O2–V1–O6
O2–V1–O7
O2–V1–O11
O2–V1–N1
O2–V1–N2
O6–V1–O7
O6–V1–O11
O6–V1–N1
O6–V1–N2
O7–V1–O11
O7–V1–N1
O7–V1–N2
O11–V1–N1
O11–V1–N2
N1–V1–N2
131.53(9)
70.33(8)
85.75(7)
150.79(9)
73.61(8)
98.96(8)
151.35(8)
76.94(7)
75.52(9)
70.91(8)
101.84(8)
88.39(8)
80.52(8)
137.72(9)
90.36(9)
91.65(7)
110.34(8)
174.42(8)
133.67(8)
82.78(8)
74.07(9)
O1–V2–O4
O1–V2–O6
O1–V2–O8
O1–V2–O12
O1–V2–N3
O1–V2–N4
O4–V2–O6
O4–V2–O8
O4–V2–O12
O4–V2–N3
O4–V2–N4
O6–V2–O8
O6–V2–O12
O6–V2–N3
O6–V2–N4
O8–V2–O12
O8–V2–N3
O8–V2–N4
O12–V2–N3
O12–V2–N4
N3–V2–N4
133.22(9)
69.64(8)
85.69(8)
148.52(8)
73.15(9)
98.57(9)
151.54(8)
77.85(8)
76.07(8)
71.30(8)
99.86(9)
89.30(7)
79.01(8)
137.15(8)
91.11(8)
91.34(8)
108.47(8)
175.59(10)
136.63(10)
84.43(9)
74.06(9)
Complex B
V3–O13
V3–O14
V3–O18
V3–O19
V3–O23
V3–N5
V3–N6
V3ꢁꢁꢁV4
2.012(2)
2.072(2)
1.995(2)
2.094(2)
2.1287(18)
2.267(2)
2.146(2)
3.2553(7)
V4–O13
V4–O16
V4–O18
V4–O20
V4–O24
V4–N7
2.001(2)
2.077(2)
2.003(2)
2.094(2)
2.133(2)
2.254(2)
2.142(2)
O13–V3–O14
O13–V3–O18
O13–V3–O19
O13–V3–O23
O13–V3–N5
O13–V3–N6
O14–V3–O18
O14–V3–O19
O14–V3–O23
O14–V3–N5
O14–V3–N6
O18–V3–O19
O18–V3–O23
O18–V3–N5
O18–V3–N6
O19–V3–O23
O19–V3–N5
O19–V3–N6
O23–V3–N5
O23–V3–N6
N5–V3–N6
135.64(8)
69.53(7)
85.64(8)
148.50(9)
73.20(9)
96.97(9)
149.86(7)
78.35(9)
74.45(9)
71.45(8)
98.72(10)
89.76(9)
78.97(9)
138.68(9)
92.52(9)
94.12(8)
104.70(8)
177.00(11)
136.34(10)
84.42(8)
74.77(8)
O13–V4–O16
O13–V4–O18
O13–V4–O20
O13–V4–O24
O13–V4–N7
O13–V4–N8
O16–V4–O18
O16–V4–O20
O16–V4–O24
O16–V4–N7
O16–V4–N8
O18–V4–O20
O18–V4–O24
O18–V4–N7
O18–V4–N8
O20–V4–O24
O20–V4–N7
O20–V4–N8
O24–V4–N7
O24–V4–N8
N7–V4–N8
135.89(8)
69.60(7)
85.77(8)
148.59(8)
73.86(9)
94.90(10)
148.55(7)
77.67(10)
74.66(8)
71.43(8)
101.34(11)
88.61(9)
79.16(9)
139.93(9)
92.31(10)
96.88(8)
104.70(8)
179.00(11)
134.29(10)
82.93(9)
74.81(9)
V4–N8
lected bond distances and angles are summarized in Table 2.
Complex 1 is a dinuclear vanadium(III) complex triply bridged
by a deprotonated alkoxo group of hpnbpda, a hydroxo group,
and a sulfato group. Taking into account the charge balance in
1, we concluded that the bridging group is a hydroxo, not an
oxo ligand. A similar triply bridged structure has been found
plane through atoms C1, O1, O6, and S1. As a consequence,
the two asymmetric nitrogen atoms have an opposite absolute
configuration with each other (namely, a meso form). Each
vanadium(III) center has a heptacoordinate geometry. Hepta-
coordination is not unusual for vanadium(III) complexes and
has been found in several complexes containing a multidentate
III
3þ
III
17
III
18
for [{V (H2O)}2(ꢀ-bza)(ꢀ-OH)(ꢀ-tphpn)] (bza: benzoate;
ligand, such as K[V (edta)(H2O)], K[V (cydta)(H2O)],
0
0
III
19
III
tphpn: 2-oxo-N,N,N ,N -tetra(2-pyridylmethyl)-1,3-propanedi-
amine), in which a benzoate group bridges two vanadium(III)
ions instead of a sulfato group.11 The two pyridylmethyl
groups (and thus the two acetate groups) of hpnbpda are locat-
ed on the same side, and thus, the complex has a quasi-mirror
[V (nta)(H2O)3], K2[V 2(ꢀ-Hdpot)2] (dpot: 2-oxo-1,3-pro-
0
0
20
III
11
panediamine-N,N,N ,N -tetraacetate), [V 2(ꢀ-hpnbpda)2],
III
11
and [{V (H2O)}2(ꢀ-bza)(ꢀ-OH)(ꢀ-tphpn)]Cl3. The ideal-
ized coordination polyhedrons for heptacoordinated complexes
can be classified into three forms: a pentagonal bipyramid, a

1
884 Bull. Chem. Soc. Jpn. Vol. 79, No. 12 (2006)
Dinuclear and Tetranuclear VIII Complexes
˚
O1
Table 3. Selected Bond Distances (A) and Angles (degree)
O7
for [VIII4(ꢀ-hpnbpda)2(ꢀ-OH)2(ꢀ-SO4)2] 12H2O (2)a)
ꢁ
O6
N1
V1–O1
V1–O2
V1–O6
V1–O7
V1–N1
V1–N2
V1ꢁꢁꢁV2
2.042(2)
1.984(2)
1.871(2)
2.040(3)
2.174(3)
2.118(3)
3.7436(8)
V2–O1
V2–O4
V2–O6
V2–O8
V2–N3
V2–N4
2.036(2)
1.988(2)
1.888(2)
2.046(3)
2.175(3)
2.111(3)
3.5320(7)
O1
O2
7
0.33°
73.61°
O6
O7
ꢀ
ꢀ
N1
7
0.91°
O2
8
0.52°
O11
7
5.52°
O11
N2
ꢀ
V1ꢁꢁꢁV2
Side View
Top View
O1–V1–O2
O1–V1–O6
O1–V1–O7
O1–V1–N1
O1–V1–N2
O2–V1–O6
O2–V1–O7
O2–V1–N1
O2–V1–N2
O6–V1–O7
O6–V1–N1
O6–V1–N2
O7–V1–N1
O7–V1–N2
N1–V1–N2
89.64(10)
93.14(10)
173.14(10)
83.22(10)
90.19(11)
107.20(11)
85.77(12)
78.76(11)
154.15(12)
93.09(11)
173.07(11)
98.63(12)
90.87(11)
91.71(13)
75.55(12)
O1–V2–O4
O1–V2–O6
O1–V2–O8
O1–V2–N3
O1–V2–N4
O4–V2–O6
O4–V2–O8
O4–V2–N3
88.66(10)
91.83(10)
173.97(10)
82.63(11)
93.52(12)
108.28(11)
85.71(11)
78.38(12)
153.26(13)
91.98(11)
171.32(13)
98.30(12)
94.11(12)
90.55(13)
75.49(13)
Fig. 2. Side and top views of the coordination polyhedron in 1.
ꢀ
ꢀ
O5
C1
C3
C12
C2
C4
C14
O3
N1
C13
N3
C16
C17
C5
O7
ꢀ
ꢀ
C6
C7
C8
O4
C15
N4
O1
O2
C9
C10
O8*
V2
V1 N2
O6
O9*
C19
S1*
O4–V2–N4
O6 –V2–O8
C11
C18
O10
O6*
ꢀ
O6 –V2–N3
ꢀ
O10*
C18*
O8
C11*
N2* V1*
ꢀ
O6 –V2–N4
C19*
V2*
S1
O9
C10*
C9*
O7*
ꢀ
O8 –V2–N3
ꢀ
O8 –V2–N4
O2*
N4*
C15*
N3* C13*
C17*
O1*C8* C7* C6*
ꢀ
N3–V2–N4
O4*
C5*
C16*
O3*
N1*
C1*
O5*
C14*
C4*
C2*
C12*
C3*
a) Symmetry operators: ꢂX þ 1, ꢂY þ 1, ꢂZ þ 1.
Fig. 3. Perspective view of [VIII4(ꢀ-hpnbpda)2(ꢀ-OH)2-
ꢀ-SO4)2] (2).
(
bridging dinucleating ligand. Interestingly, each vanadium(III)
center has a hexacoordinate structure, which is different from
the heptacoordinate structure found in the dinuclear hpnbpda
complex 1. The terminal terdentate moiety of hpnbpda coordi-
nates to vanadium(III) center in a meridional fashion bringing
about a highly distorted octahedron, which is represented
capped octahedron, and a capped trigonal prism. However, the
real complex usually adopts an intermediate structure. From
Fig. 2, the coordination polyhedron of the present complex
is a pentagonal bipyramid, which is different from that found
III
ꢃ
in the related triply bridged complex [{V (H2O)}2(ꢀ-
by small trans angles of O2–V1–N2 (154.15(12) ) and O4–
ꢃ
3
þ
11
bza)(ꢀ-OH)(ꢀ-tphpn)] , which had a capped octahedron
V2–N4 (153.26(13) ). The coordination mode (meridional or
III
11
but is similar to that found in [V 2(ꢀ-hpnbpda)2]. Atoms
O1 (alkoxo oxygen), N1 (amino nitrogen), O2 (carboxylato
oxygen), O11 (aqua oxygen), and O6 (hydroxo oxygen) com-
plete the pentagonal plane, and atoms N2 (pyridyl nitrogen)
and O7 (sulfato oxygen) occupy the axial positions. However,
the pentagonal bipyramid adopted by 1 is fairly distorted from
ideal geometry as shown in Fig. 2.
facial) of the terminal terdentate moiety of an alkoxo-bridging
dinucleating ligand seems to depend on the arrangement of
other bridging groups.2
1–24
The coordination bond distances in 2 are shorter than the
corresponding ones in 1, reflecting a decrease of the coordina-
tion number. The alkoxo bridging angle, V1–O1–V2 in 2
ꢃ
(133.25(11) ) is rather large compared to that in 1 (av.
ꢃ
It is of interest to compare the bond distances in the present
complex with those of the related triply bridged complex,
108.22 ). Thus, the small alkoxo bridging angle in 1 must be
a consequence of the triple bridge. The hydroxo bridging
III
3þ 11
ꢀ
(av. 136.84 ) in 2 are also large compared to those in 1
ꢃ
[
{V (H2O)}2(ꢀ-bza)(ꢀ-OH)(ꢀ-tphpn)]
,
though the coor-
angle, V1–O6–V2 (139.95(14) ) and the V–O–S angles
ꢃ
dination polyhedrons are different with each other as men-
tioned above. The V–O(alkoxo), V–O(hydroxo), V–O(aqua),
˚
and V–N(amine) distances agree within 0.035 A. However,
˚
the V–N(pyridine) distance in complex 1 (av. 2.147 A) is a
little bit shorter than the corresponding one in the latter com-
˚
plex (av. 2.231 A).
ꢃ
ꢃ
(108.82(9) and av. 129.61 , respectively). The O–S–O angles
are rigid, and they do not differ so much in 1 and 2: the aver-
ꢃ
age angle is 109.5 for both complexes. The VꢁꢁꢁV distances
˚
ꢀ
are in the order of V1ꢁꢁꢁV2 in 1 (av. 3.2543 A) <V1ꢁꢁꢁV2
˚
˚
in 2 (3.5320(7) A) <V1ꢁꢁꢁV2 in 2 (3.7436(8) A), reflecting
the number of bridging groups, i.e., 3, 2, and 1, respectively.
All of the waters of crystallization in 1 and 2 were found to
A perspective view of 2 is shown in Fig. 3, and selected
bond distances and angles are summarized in Table 3. Two
dinuclear vanadium(III) units bridged by the alkoxo group of
hpnbpda are further linked by the two hydroxo and the two sul-
fato bridging groups, resulting in a tetranuclear structure (so-
called dimer-of-dimers). The tetranuclear unit has a center of
symmetry. A similar dimer-of-dimers structure has been found
˚
take part in hydrogen bonding. The OꢁꢁꢁO contacts within 3 A
are summarized in Table 4. The carboxylate oxygen atoms
and the sulfate oxygen atoms in 1 and 2, as well as the aqua
ligand in 1, are all linked by a hydrogen bond to the waters
of crystallization. The hydrogen bonds between the water
molecules of crystallization also exist.
2
1,22
23,24
for iron
and manganese
complexes with an alkoxo-

K. Kanamori et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 12 (2006) 1885
˚
Table 4. Various Types of Hydrogen Bond (within 3 A)
Involving Water of Crystallization for 1 and 2
A
Typea)
1
2
OwꢁꢁꢁOcarbox, u O25ꢁꢁꢁO5
O26ꢁꢁꢁO3
2.743(4)
2.756(4)
O26ꢁꢁꢁO15 2.653(3)
O11ꢁꢁꢁO3
O16ꢁꢁꢁO5
2.763(6)
2.866(8)
O29ꢁꢁꢁO17 2.856(4)
B
O33ꢁꢁꢁO5
2.800(5)
O33ꢁꢁꢁO17 2.897(4)
O34ꢁꢁꢁO15 2.755(5)
OwꢁꢁꢁOcarbox, c O27ꢁꢁꢁO2
2.801(3)
O31ꢁꢁꢁO14 2.924(4)
O31ꢁꢁꢁO16 2.839(4)
O14ꢁꢁꢁO2
O14ꢁꢁꢁO4
2.949(7)
2.895(7)
OwꢁꢁꢁOsulfate, u O28ꢁꢁꢁO9
2.802(4)
O28ꢁꢁꢁO22 2.944(3)
O30ꢁꢁꢁO21 2.859(4)
O35ꢁꢁꢁO10 2.969(10)
O11ꢁꢁꢁO9 2.884(6)
O15ꢁꢁꢁO10 2.897(7)
2000
1500
1000
500
~
-1
ν/cm
OwꢁꢁꢁOaq
OwꢁꢁꢁOw
O26ꢁꢁꢁO11 2.717(3)
O27ꢁꢁꢁO12 2.679(3)
O29ꢁꢁꢁO24 2.778(5)
O31ꢁꢁꢁO23 2.986(6)
O33ꢁꢁꢁO23 2.992(5)
Fig. 4. Infrared spectra of 3 (A) and 4 (B).
2.0
B
1
.5
O25ꢁꢁꢁO26 2.722(4)
O25ꢁꢁꢁO27 2.827(4)
O25ꢁꢁꢁO30 2.836(5)
O28ꢁꢁꢁO32 2.834(5)
O29ꢁꢁꢁO34 2.815(7)
O32ꢁꢁꢁO34 2.800(8)
O12ꢁꢁꢁO13 2.827(9)
O12ꢁꢁꢁO16 2.794(8)
O14ꢁꢁꢁO15 2.818(9)
1.0
0
0
.5
.0
A
a) Ow: water of crystallization, Ocarbox, u: uncoordinated car-
boxylate oxygen, Ocarbox, c: coordinated carboxylate oxygen,
Osulfate, u: uncoordinated sulfate oxygen, Oaq: aqua ligand.
3
00
400
500
600
700
800
900
λ/nm
Fig. 5. Diffuse reflectance and absorption spectra of 3: A,
diffuse reflectance spectrum; B, absorption spectrum in
ꢂ3
Estimation of the Structures of the Carboxylato-Bridg-
III
EtOH (5.0 mmol dm /V).
ing Complexes, [{V (H2O)}2(ꢀ-hpnbpda)(ꢀ-O2CC2H5)-
(
III
ꢀ-OH)]Brꢀ7H2O (3) and [{V (H2O)}2(ꢀ-hpnbpda)(ꢀ-
bidentate ligand, or a bridging ligand. The COO stretching
vibrations are diagnostic for the coordination modes.25 Al-
though the difference between the two COO stretching modes
(ꢁasðCOOÞ ꢂ ꢁsðCOOÞ) has been considered to be the most re-
O2CC6H5)]Cl2ꢀ2H2O (4).
Two carboxylato (propionato
and benzoato) bridging complexes were prepared in order to
compare the properties with those of the sulfato-bridging com-
plexes. Preparation of a complex with an acetato bridge was
also tried; however, it could not be isolated due to poor crys-
tallinity. Although the preparation of 4 has been reported in an
liable diagnosis, unambiguous assignment of the ꢁ(COO) of
s
the present complexes was difficult because of the complexity
ꢂ1
of the IR spectrum in the region of 1300–1500 cm , in which
the ꢁ(COO) is expected to appear. However, the following
facts indicate that the complexes 3 and 4 contain a bridging
1
1
earlier paper, its structure was discussed only very briefly.
The structure of 4 will be estimated here in comparison with
that of 3.
s
carboxylato group: (1) the ꢁ (COO) generally appears around
as
ꢂ1
Since we could not obtained X-ray quality of crystals of 3
and 4, the structures of the carboxylato-bridging complexes
were estimated on the basis of their elemental analyses, IR
spectra, and UV–vis spectra. From elemental analysis and
charge balance considerations, complex 3 consists of two
vanadium(III) ions, one hpnbpda ligand, one propionate, one
hydroxide, one bromide, and nine water molecules, and com-
plex 4 consists of two vanadium(III) ions, one hpnbpda ligand,
one benzoate, two chloride, and four water molecules.
The IR spectra of 3 and 4 are shown in Fig. 4. A carboxylate
anion can coordinate to metal ion as an unidentate ligand, a
1550 cm for bridging carboxylate ions whereas it appears
ꢂ1
above 1600 cm for terminal carboxylate ions; (2) complexes
ꢂ1
3 and 4 exhibit intense bands at 1557 and 1537 cm , respec-
tively, which can be assigned to the ꢁas(COO) of a bridging
carboxylato group, in addition to bands at 1629 and 1654 cm
ꢂ1
due to the ꢁ (COO) of the terminal carboxylato group of the
hpnbpda ligand; (3) complexes 3 and 4 contain only one pro-
pionate or benzoate ion per dimeric unit.
Figure 5A shows a diffuse reflectance spectrum of the com-
plex 3. It is known that heptacoordinate vanadium(III) com-
plexes exhibit an absorption bands around 800 nm while the
as

1
886 Bull. Chem. Soc. Jpn. Vol. 79, No. 12 (2006)
Dinuclear and Tetranuclear VIII Complexes
3
3
2
2
1
1
0
0
.5
.0
.5
.0
.5
.0
.5
.0
4.0
3
3
2
2
1
1
.5
.0
.5
.0
.5
.0
B
B
A
A
C
0.5
0.0
300
400
500
600
λ/nm
700
800
900
300
400
500
600
λ/nm
700
800
900
Fig. 6. Diffuse reflectance and absorption spectra of 4:
A, diffuse reflectance spectrum; B, absorption spectrum
in DMSO (1.0 mmol dm /V).
Fig. 7. Diffuse reflectance and absorption spectra of 1:
A, diffuse reflectance spectrum; B, absorption spectrum
ꢂ3
ꢂ3
in DMSO (5.0 mmol dm /V); C, absorption spectrum in
ꢂ3
water (2.5 mmol dm /V).
band is absent for hexacoordinate complexes.20,26 The broad
band around 800 nm observed for complex 3, thus, indicates
a heptacoordinate structure. Taking this into consideration,
complex 3 most likely has a heptacoordinate structure, bridged
by an alkoxo group of hpnbpda, a propionato group, and a
from a concentrated solution at a higher crystallizing temper-
ꢃ
ature (60 C vs room temperature for the dinuclear complex).
It is conceivable that concentrating the solution makes the
formation of the complex with a higher nuclearity more favor-
able. The dinuclear and tetranuclear structures of the vana-
III
hydroxo group, and can be formulated as [{V (H2O)}2(ꢀ-
2
ꢂ
hpnbpda)(ꢀ-O2CC2H5)(ꢀ-OH)]Br 7H2O. A similar structure
dium(III)–hpnbpda–SO4 complexes seem to be formed by
so-called ‘‘spontaneous self-assembly’’ on crystallization.
The choice of counter ion may more or less contribute to the
structure of vanadium(III)–hpnbpda complexes. We used bro-
mide instead of chloride in the preparation of 3. It is not clear,
at present, if the heptacoordinate structure of 3 is the result of
using bromide as a counter ion, since the corresponding chlo-
ride was not obtained due to its low crystallinity.
ꢁ
III
has been found for [{V (H2O)}2(ꢀ-O2CC6H5)(ꢀ-OH)(ꢀ-
tphpn)]Cl3.
1
1,27
A diffuse reflectance spectrum of the complex 4 is shown in
Fig. 6A. In contrast to the spectrum of 3, that of 4 lacks a band
characteristic to a heptacoordination around 800 nm, indicating
that 4 adopts a hexacoordinate structure. Thus, complex 4 can
III
be formulated as [{V (H2O)}2(ꢀ-hpnbpda)(ꢀ-O2CC6H5)]-
Cl2 2H2O. A similar coordination environment has been found
Structures in Solution. Since vanadium(III) complexes
are substitutionally labile, the structures found in the solid
states are not necessarily kept intact in solutions. In order to
know if the solid-state structure is maintained in solution,
the absorption spectra of 1 and 2 in DMSO were compared
with those of the diffuse reflectance spectra. The diffuse reflec-
tance spectrum of 1 (Fig. 7, spectrum A) exhibits the band at
780 nm characteristic of heptacoordination, which is consistent
with the X-ray structure. However, this 780-nm band disap-
peared in DMSO, and the spectral feature was completely
different from that in the solid state (spectrum B). This fact
suggests that the sulfato or hydroxo bridge is decomposed in
DMSO to yield a hexacoordinate species. Since the hexa-
and heptacoordinate species would be expected to have a rath-
er different stability with each other, it is not likely that these
two species coexist at equilibrium in DMSO. In water, 1 exhib-
ited a different spectral feature from those obtained in the solid
state as well as in DMSO (see spectrum C). Although this
spectral change may indicate that another type of decomposi-
tion occurred in water, we will not consider further the struc-
ture of the complex in water since the structure of the substitu-
tionally labile complex depends on its concentration and tem-
perature, and especially on the pH in water.
ꢁ
III
in [{V (H2O)}2(ꢀ-dpot)(ꢀ-m-hbza)] (m-hbza is meta-hy-
2
8
droxybenzoate). Interestingly, the hpnbpda ligand, which
has an intermediate structure of tphpn and dpot, yields hepta-
coordinate as well as hexacoordinate dinuclear vanadium(III)
complexes found for the tphpn and dpot complexes, respec-
tively, depending on the carboxylate ions employed as a sec-
ond bridging group.
Preparation of the hpnbpda Complexes. It is appropriate
to mention here the general view toward the preparation of the
vanadium(III) complexes with hpnbpda. We have prepared
five different types of vanadium(III)–hpnbpda complexes in-
III
III
cluding [{V (H2O)}2(ꢀ-hpnbpda)(ꢀ-bza)]Cl2 (4) and [V 2-
(
11
ꢀ-hpnbpda)2] reported earlier. The composition and the
structure of the complexes deposited from the reaction solution
seem to depend on the nature of the additional bridging ligand
and the anion in the reaction. The pH and the concentration of
the reaction solution and the crystallizing temperature also
III
affect the structure of the complex. [V 2(ꢀ-hpnbpda)2] was
found to be easiest to crystallize in the absence of the addition-
al bridging ligand. In fact, this complex often precipitated
simultaneously with the other complexes. Controlling the pH
of the reaction solution seems to be an important factor to
obtain the desired complex.
The sulfato-bridging complexes 1 and 2 could be crystal-
lized separately by regulating both the concentration and the
temperature of the reaction mixture, from which the crystals
were grown. Namely, the tetranuclear complex 2 was isolated
Figure 8 shows the absorption spectrum and the diffuse re-
flectance spectrum of 2. In this case, the absorption spectrum
in DMSO corresponds well to the diffuse reflectance spectrum,
suggesting the solid-state structure is kept intact in DMSO.
This is distinct from the behavior of 1, indicating that the tetra-

K. Kanamori et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 12 (2006) 1887
1
1
1
0
0
0
0
0
.4
.2
.0
.8
.6
.4
.2
.0
0.016
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
0
0
0
0
.014
.012
.010
.008
.006
B
A
0.004
3
00
400
500
600
700
800
900
0
50
100
150
200
250
λ/nm
T/K
Fig. 8. Diffuse reflectance and absorption spectra of 2: A,
diffuse reflectance spectrum; B, absorption spectrum in
DMSO (1.0 mmol dm /V).
Fig. 10. Plot of the magnetic susceptibility and the effec-
tive magnetic moment against temperature for 2.
ꢂ3
cally isolated VIII (d ) ion (2.83 ꢀ ). The ꢀ decreases with
2
B
eff
0
0
0
0
0
0
.025
.020
.015
.010
.005
.000
3.0
2.5
2.0
1.5
1.0
0.5
decreasing temperature, indicating antiferromagnetic coupling.
The temperature dependence of the magnetic susceptibility
was analyzed on the basis of the spin-Hamiltonian H ¼
ꢂ2JS1 S2 (S1 ¼ S2 ¼ 1). Temperature-independent paramag-
ꢁ
netism was neglected in the calculation. The rapid increase
in ꢇ below 6 K may be due to a paramagnetic impurity and
a
those data were omitted in the calculation. A least-squares fit
to the experimental data, given as a solid line in Fig. 9, yield-
ꢂ1
ed J ¼ ꢂ5:9 cm and g ¼ 1:90. The J value of 1 is compara-
ble to that obtained for the heptacoordinate di(alkoxo)-bridg-
III
2ꢂ
ed dinuclear vanadium(III) complex, [V 2(ꢀ-Hhedtra)2]
(
0
50
100
150
200
250
0
0
Hhedtra = N-hydroxyethyl-1,2-ethanediamine-N,N ,N -triace-
ꢂ1 29
T/K
tate) (J ¼ ꢂ8:6 cm ).
Fig. 9. Plot of the magnetic susceptibility and the effective
magnetic moment against temperature for 1.
The temperature dependence of ꢇ and ꢀ for 2 exhibited
a
eff
a complex feature (Fig. 10). The ꢀeff at 300 K (2.61 ꢀ ) also
B
III
corresponds to that expected for a magnetically isolated V
2
eff
nuclear structure would be less strained as a whole than the di-
nuclear one. The small V–O(alkoxo)–V and V–O(hydroxo)–V
angles in 1 compared with those in 2 may be a reason for the
strain.
(d ) ion. The ꢀ decreased gradually from 300 to 50 K and
then slightly increased followed by a rapid decrease. Although
we tried to reproduce the temperature dependence of the mag-
netic susceptibility, including the coupling constant of the
alkoxo-bridging moiety (J12 ¼ J ꢀ ꢀ) and that of the sulfato-
The absorption spectrum of 3 in ethanol is shown in
Fig. 5B. A DMSO solution exhibited a similar spectrum.
The 780-nm band indicates that heptacoordination is kept in
ethanolic and DMSO solutions. The blue shift of the bands
compared with the solid-state spectrum may be due to a sol-
vent effect. Figure 6B shows the absorption spectrum of 4 in
DMSO. Although a blue shift was also observed, the spectrum
in DMSO corresponds well to that in the solid state, suggesting
that the coordination environment in the solid state is main-
tained in DMSO. In other words, the carboxylato-bridged di-
nuclear vanadium(III) complexes are more stable at least in
DMSO than the corresponding sulfato-bridged complex (1).
Magnetic Properties. Dinuclear vanadium(III) complexes
show a variety of intramolecular spin-exchange coupling from
a strong ferromagnetic coupling to a strong antiferromagnetic
1
2
and hydroxo-bridging moiety (J ꢀ ¼ J ꢀ ), as well as a space-
1
2
1 2
through coupling constant (J11ꢀ ¼ J ꢀ ), a satisfactory fit could
22
not be obtained so far using spin-Hamiltonian H ¼ ꢂ2J12S1
ꢁ
S ꢂ2J ꢀ ꢀS ꢀ S ꢀ ꢂ2J ꢀS S ꢀ ꢂ2J ꢀ S ꢀ S ꢂ2J ꢀ S S ꢀ ꢂ
2
1 2
1
ꢁ
2
12
1
ꢁ
2
1 2
1
ꢁ
2
11
1
ꢁ
1
2J ꢀ S2 S ꢀ (the numbering scheme corresponds to the crystal-
2
2
ꢁ
2
lographic numbering for V atoms in Fig. 3).
In conclusion, it was found that an alkoxo-bridging di-
nucleating ligand, hpnbpda, yields a variety of multinuclear
vanadium(III) complexes mainly depending on the nature of
additional bridging ligands and the crystallization conditions.
III
Namely, [V 2(ꢀ-hpnbpda)2] is preferentially formed when
11
an additional bridging ligand is absent. When the carboxyl-
ates were used as an additional bridging ligand, the hexacoor-
dinate dinuclear complex doubly bridged by hpnbpda and a
carboxylate (4) or the heptacoordinate dinuclear complex tri-
ply bridged by hpnbpda, a carboxylate, and an extra hydroxo
group (3) were obtained, probably depending on the nature
of the carboxylate ligand used. Sulfato group can also function
as a bridging ligand. The heptacoordinate dinuclear complex
(1) and hexacoordinate tetranuclear complex (2) were obtained
separately by controlling the crystallization condition.
9
coupling, depending on the bridging mode. We studied the
magnetic properties of complexes 1 and 2, of which structures
were determined by X-ray crystallography. Figure 9 shows the
magnetic susceptibility (ꢇ/V) and the effective magnetic mo-
a
ment (ꢀ /V) of 1 as a function of temperature in the region
eff
of 2 to 300 K. The effective magnetic moment at 300 K is
2
.56 ꢀ , which is comparable to that expected for a magneti-
B

1
888 Bull. Chem. Soc. Jpn. Vol. 79, No. 12 (2006)
Dinuclear and Tetranuclear VIII Complexes
We are very grateful to Prof. Wasuke Mori of Kanagawa
University for his help in the measurement of the magnetic
susceptibility and a useful discussion with him.
Refinement from Diffraction Data, University of G o¨ ttingen,
G o¨ ttingen, Germany, 1997.
15 P. T. Beurskens, G. Admiraal, G. Beurskens, W. P.
Bosman, R. de Gelder, R. Israel, J. M. M. Smits, The DIRDIF-
9
9 Program System, Technical Report on the Crystallography
References
Laboratory, University of Nijmergen, The Netherlands, 1999.
16 CrystalStructure 3.7.0: Crystal Structure Analysis Package,
Rigaku and Rigaku/MSC, 2000–2005. 9009 New Trails Dr. The
Woodlands TX 77381 U.S.A.
17 M. Shimoi, Y. Saito, H. Ogino, Chem. Lett. 1989, 1675.
18 M. Shimoi, S. Miyamoto, H. Ogino, Bull. Chem. Soc. Jpn.
1991, 64, 2549.
1
Vanadium and Its Role in Life in Metal Ions in Biological
Systems, ed. by H. Sigel, A. Sigel, Marcel Dekker, New York,
995, Vol. 31.
Vanadium in the Environment in Advances in Environmen-
1
2
tal Science and Technology, ed. by J. O. Nriagu, John Wiley &
Sons, New York, 1998, Vol. 30.
3
Special Issue: New Direction in Chemistry and Biological
Chemistry of Vanadium. Coord. Chem. Rev. 2003, 237.
R. Wever, W. Hemrika, Vanadium in the Environment,
19 K. Okamoto, J. Hidaka, M. Fukagawa, K. Kanamori, Acta
Crystallogr., Sect. C 1992, 48, 1025.
20 J. C. Robles, Y. Matsuzaka, S. Inomata, M. Shimoi, W.
Mori, H. Ogino, Inorg. Chem. 1993, 32, 13.
21 D. L. Jameson, C. L. Xie, D. N. Hendrickson, J. A.
Potenza, H. J. Schugar, J. Am. Chem. Soc. 1987, 109, 740.
22 S. Yano, T. Inagaki, Y. Yamada, M. Kato, M. Yamasaki,
K. Sakai, T. Tsubomura, M. Sato, W. Mori, K. Yamaguchi, I.
Kinoshita, Chem. Lett. 1996, 61.
4
Part 1 in Advances in Environmental Science and Technology,
ed. by J. O. Nriagu, John Wiley & Sons, New York, 1998,
Vol. 30, pp. 285–305.
5
Engl. 1987, 26, 545.
E. Bayer, E. Koch, G. Anderegg, Angew. Chem., Int. Ed.
6
H. Sakurai, A. Tsuji, Vanadium in the Environment, Part 2
in Advances in Environmental Science and Technology, ed. by
J. O. Nriagu, John Wiley & Sons, New York, 1998, Vol. 30,
pp. 297–315.
23 R. T. Stibrany, S. M. Gorun, Angew. Chem., Int. Ed. Engl.
1990, 29, 1156.
24 M. L. Kirk, M. K. Chen, W. H. Armstrong, E. I. Solomon,
J. Am. Chem. Soc. 1992, 114, 10432.
25 K. Nakamoto, Infrared and Raman Spectra of Inorganic
and Coordination Compounds, Part B, 5th ed., John Wiley &
Sons, New York, 1997, pp. 59–62.
7
94.
8
M. Henze, Hoppe-Seyler’s Z. Physiol. Chem. 1911, 72,
4
H. Michibata, N. Yamaguchi, T. Uyama, T. Ueki, Coord.
Chem. Rev. 2003, 237, 41.
9
0
K. Kanamori, Coord. Chem. Rev. 2003, 237, 147.
K. Kanamori, E. Kameda, K. Okamoto, Bull. Chem. Soc.
26 K. Kanamori, K. Ino, H. Maeda, K. Miyazaki, M.
Fukagawa, J. Kumada, T. Eguchi, K. Okamoto, Inorg. Chem.
1994, 33, 5547.
27 K. Kanamori, T. Okayasu, K. Okamoto, Chem. Lett. 1995,
105.
1
Jpn. 1996, 69, 2901.
K. Kanamori, K. Yamamoto, T. Okayasu, N. Matsui, K.
Okamoto, W. Mori, Bull. Chem. Soc. Jpn. 1997, 70, 3031.
1
1
1
1
2
3
J. C. Claunchi, M. M. Jones, Inorg. Synth. 1963, 7, 92.
A. Altomare, M. Burla, M. Camalli, G. Cascarano, C.
28 K. Kanamori, K. Yamamoto, K. Okamoto, Chem. Lett.
1993, 1253.
Giacovazzo, A. Guagliardi, A. Moliterni, G. Polidori, R. Spagna,
J. Appl. Crystallogr. 1999, 32, 115.
29 T. K. Shepherd, W. E. Hatfield, D. Ghosh, C. D. Stout,
F. J. Kristine, J. R. Ruble, J. Am. Chem. Soc. 1981, 103, 5511.
1
4
G. M. Sheldrick, SHELX97 Program for Crystal Structure