Syntheses, structures, spectroscopic properties, and thermal behavior of nickel(II) mixed-ligand complexes with N,N,N′,N′- tetramethylethylenediamine, benzoylacetonate, and a halide anion

Article abstract of DOI:10.1246/bcsj.78.1061

A series of nickel(II) complexes comprising N,N,N′,N′- tetramethylethylenediamine (tmen), benzoylacetonate (bzac), and a halide anion (X), Ni(tmen)(bzac)X · n(H₂O)(n = 1-4, X = Cl, Br, I), have been synthesized. A crystallographic study revealed that the chloride anion coordinates to the central metal, while bromide and iodide anions are located in the outer coordination sphere as the counter anion; the metal has a slightly distorted octahedral geometry, and the two monodentate ligands (aqua and chloro) are in the cis-position. In bromide and iodide complexes, having two water molecules of crystallization, a ladder-like hydrogen bond network is formed among halide anions, aqua ligands, and water of crystallization. In a chloride complex having no water of crystallization, a dimer is formed by strong intermolecular hydrogen bonding between the aqua ligand and the chloro and the benzoylacetonate ligands of the neighboring molecule. The behaviors of the complexes in solution vary, depending on the nature of the solvents, including deaquation and disproportionation, causing contrasting color changes of the solutions. The presence of a proposed intermediate in the disproportionation reaction, namely a 5-coordinated complex, was confirmed. Thermal gravimetric analysis suggests that these complexes lose water of crystallization, undergo deaquation-anation, and then lose the coordinated water before disproportionation into two ternary complexes.

Full text of DOI:10.1246/bcsj.78.1061

Ó 2005 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 78, 1061–1071 (2005) 1061
Syntheses, Structures, Spectroscopic Properties, and Thermal
Behavior of Nickel(II) Mixed-Ligand Complexes with N,N,N0,N0-
Tetramethylethylenediamine, Benzoylacetonate, and a Halide Anion
ꢀ
Keiko Miyamoto, Mariko Sakamoto, Chikashi Tanaka,1 Ernst Horn,1 and Yutaka Fukuda
Department of Chemistry, Faculty of Science, Ochanomizu University,
2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610
1Department of Chemistry, Faculty of Science, Rikkyo (St. Paul’s) University,
3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501
Received December 9, 2004; E-mail: fukuda@cc.ocha.ac.jp
A series of nickel(II) complexes comprising N,N,N0,N0-tetramethylethylenediamine (tmen), benzoylacetonate
(bzac), and a halide anion (X), Ni(tmen)(bzac)X n(H2O)(n ¼ 1{4, X ¼ Cl, Br, I), have been synthesized. A crystallo-
ꢁ
graphic study revealed that the chloride anion coordinates to the central metal, while bromide and iodide anions are lo-
cated in the outer coordination sphere as the counter anion; the metal has a slightly distorted octahedral geometry, and
the two monodentate ligands (aqua and chloro) are in the cis-position. In bromide and iodide complexes, having two
water molecules of crystallization, a ladder-like hydrogen bond network is formed among halide anions, aqua ligands,
and water of crystallization. In a chloride complex having no water of crystallization, a dimer is formed by strong in-
termolecular hydrogen bonding between the aqua ligand and the chloro and the benzoylacetonate ligands of the neigh-
boring molecule. The behaviors of the complexes in solution vary, depending on the nature of the solvents, including
deaquation and disproportionation, causing contrasting color changes of the solutions. The presence of a proposed
intermediate in the disproportionation reaction, namely a 5-coordinated complex, was confirmed. Thermal gravimetric
analysis suggests that these complexes lose water of crystallization, undergo deaquation–anation, and then lose the
coordinated water before disproportionation into two ternary complexes.
One of our research focuses has been on the chromotropic
behavior of inorganic complexes of transition metals, such as
Ni(II) and Cu(II). In particular, nickel(II) complexes are
known with a six-coordinate octahedral configuration, with
five-coordinate square pyramidal or trigonal bi-pyramidal
structures, and with four-coordinate square planar or tetrahe-
dral configurations. It is a peculiarity of nickel(II)’s chemistry
that complexes of one configuration can be easily converted to
other configurations, usually accompanied by very contrasting
color changes.1 Due to this chromotropic behavior, Ni and Cu
complexes can be expected to have such applications as ther-
mosensitive coloring matters, various sensors (vapor sensor
for organic solvents or humidity sensor) or Lewis-acid–base
indicator, as well as, imaging materials.2 In the past, various
mixed-ligand nickel(II) and copper(II) complexes having chro-
motropic properties have been reported,3–5 but most of those
color changes were based on a change of the coordination
mode between Sp (square planar) and Oh (octahedral) config-
urations. On the other hand, Hoshino et al., found an interest-
ing disproportionation phenomenon of 6-coordinate Nickel(II)
mixed-ligand complexes with N,N,N0,N0-tetramethylethylene-
diamine (tmen), acetylacetonate (acac), and halide anion X
(X ¼ Cl, Br, and I).6 The complex, Ni(tmen)(acac)(H2O)X,
upon heating, or when dissolved in an organic solvent, turns
into two Nickel(II) mixed-ligand complexes, namely [NiX2-
(tmen)] (Td ¼ tetrahedral) and [Ni(acac)2(tmen)] (Oh). Since
then, no further study has been done on this peculiar phenom-
enon, except for related work by Saito et al., who conducted a
study on a series of mixed-ligand nickel(II) bis-diketonato
complexes, [Ni(ꢀ-dike)2(diam)], namely one of the products
resulting from the above-mentioned disproportionation.7 They
found that these bis-diketonate ternary complexes are all high-
ly volatile and highly soluble in non-polar solvents. Having
been interested in this disproportionation reaction, wherein
we can observe a rather unique color change of the Nickel(II)
complex between Td and Oh, we employed a different ꢀ-di-
ketonate ligand having an aromatic substituent, and synthe-
sized a new series of Nickel(II) mixed-ligand complexes, i.e.
Ni(tmen)(bzac)X n(H2O) (X ¼ Cl, Br, I, n ¼ 1{4). Here, we
ꢁ
report on their crystallographic structures and their behaviors
in the solid state and in solutions. Interestingly, the bis-diketo-
nate ternary complex resulting from the disproportionation of
this series of complexes turned out to be nonvolatile.
Results and Discussion
Crystal Structure of Compounds Ni(tmen)(bzac)-
X n(H O). The crystal and molecular structures of [NiCl-
ꢀ
2
(bzac)(tmen)(H2O)] (1) and [Ni(bzac)(tmen)(H2O)2]X 2H2O
ꢁ
(X ¼ Br or I) (2 and 3) were determined by X-ray analysis.8
The molecular geometry and the non-hydrogen atom labelling
scheme for these complexes are shown in Fig. 1, and selected
bond distances and angles are listed in Table 1. X-ray crystal-
lography revealed that the bromide 2 and the iodide 3 com-
plexes are isomorphous and isostructural, comprising two wa-
Published on the web June 6, 2005; DOI 10.1246/bcsj.78.1061

1062 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Ni Complex of Diamine, Diketonate, and Halide
Fig. 1. ORTEP drawings of [NiCl(bzac)(tmen)(H2O)] (1) (left), [Ni(bzac)(tmen)(H2O)2]Br 2H2O (2) (center), and
ꢁ
[Ni(bzac)(tmen)(H2O)2]I 2H2O (3) (right). Hydrogen atoms counter anions and water of crystallization are omitted for clarity.
ꢁ
Displacement ellipsoids are drawn at 30% probability.
ꢀ
Table 1. Selected Bond Distances (A) and Angles (deg) for Ni(tmen)(bzac)X nH2O (n ¼ 1{4, X ¼ Cl, Br, I)
ꢁ
[NiCl(bzac)(tmen)(H2O)]
Ni(1)–Cl(1)
Ni(1)–O(3)
2.465(2)
2.122(3)
Ni(1)–O(1)
Ni(1)–N(1)
2.032(3)
2.195(4)
Ni(1)–O(2)
Ni(1)–N(2)
2.015(3)
2.191(5)
Cl(1)–Ni(1)–O(1)
Cl(1)–Ni(1)–N(1)
O(1)–Ni(1)–O(3)
O(2)–Ni(1)–O(3)
O(3)–Ni(1)–N(1)
94.0(1)
91.7(1)
87.4(1)
177.9(2)
92.4(2)
Cl(1)–Ni(1)–O(2)
Cl(1)–Ni(1)–N(2)
O(1)–Ni(1)–N(1)
O(2)–Ni(1)–N(1)
O(3)–Ni(1)–N(2)
93.2(1)
172.8(1)
174.2(2)
89.3(2)
Cl(1)–Ni(1)–O(3)
O(1)–Ni(1)–O(2)
O(1)–Ni(1)–N(2)
O(2)–Ni(1)–N(2)
N(1)–Ni(1)–N(2)
85.6(1)
90.9(1)
90.7(2)
92.1(2)
83.5(2)
89.2(2)
[Ni(bzac)(tmen)(H2O)2]Br 2H2O
ꢁ
Ni(1)–O(1)
Ni(1)–O(4)
2.012(2)
2.117(3)
Ni(1)–O(2)
Ni(1)–N(1)
2.039(2)
2.146(3)
Ni(1)–O(3)
Ni(1)–N(2)
2.081(3)
2.161(3)
O(1)–Ni(1)–O(2)
O(1)–Ni(1)–N(1)
O(2)–Ni(1)–O(4)
O(3)–Ni(1)–O(4)
O(4)–Ni(1)–N(1)
89.31(9)
88.5(1)
88.7(1)
89.8(1)
93.7(1)
O(1)–Ni(1)–O(3)
O(1)–Ni(1)–N(2)
O(2)–Ni(1)–N(1)
O(3)–Ni(1)–N(1)
O(4)–Ni(1)–N(2)
86.9(1)
92.7(1)
175.8(1)
95.2(1)
90.6(1)
O(1)–Ni(1)–O(4)
O(2)–Ni(1)–O(3)
O(2)–Ni(1)–N(2)
O(3)–Ni(1)–N(2)
N(1)–Ni(1)–N(2)
176.1(1)
88.3(1)
91.8(1)
179.6(1)
84.8(1)
[Ni(bzac)(tmen)(H2O)2]I 2H2O
ꢁ
Ni(1)–O(1)
Ni(1)–O(4)
2.005(3)
2.119(3)
Ni(1)–O(2)
Ni(1)–N(1)
2.036(3)
2.138(4)
Ni(1)–O(3)
Ni(1)–N(2)
2.086(4)
2.155(4)
O(1)–Ni(1)–O(2)
O(1)–Ni(1)–N(1)
O(2)–Ni(1)–O(4)
O(3)–Ni(1)–O(4)
O(4)–Ni(1)–N(1)
89.6(1)
88.4(1)
89.1(1)
89.1(2)
93.2(1)
O(1)–Ni(1)–O(3)
O(1)–Ni(1)–N(2)
O(2)–Ni(1)–N(1)
O(3)–Ni(1)–N(1)
O(4)–Ni(1)–N(2)
87.1(1)
93.0(1)
175.8(1)
95.8(2)
90.8(2)
O(1)–Ni(1)–O(4)
O(2)–Ni(1)–O(3)
O(2)–Ni(1)–N(2)
O(3)–Ni(1)–N(2)
N(1)–Ni(1)–N(2)
176.0(1)
87.8(1)
91.8(1)
179.6(2)
84.6(2)
ter molecules of crystallization, one halide anion as the counter
ion and a mononuclear complex unit consisting of a central
nickel(II) cation, N,N,N0,N0-tetramethylethylenediamine, ben-
zoylacetonate, and two aqua ligands. The central nickel(II) cat-
ion is coordinated by two nitrogen atoms of the tmen ligand,
two oxygen atoms of the bzac ligand and two oxygen atoms
of two aqua ligands, to give a slightly distorted octahedral
geometry.
For the iodide complex as an example, the Ni–N(tmen)
ꢀ
bond lengths (2.138(4) and 2.155(4) A and Ni–O(bzac)
ꢀ
2.005(3) and 2.036(3) A) are similar to those of [Ni2(CO3)-
(acac)2(tmen)2]: Ni–N 2.156(3), 2.123(3) and Ni–O 2.018(3),
9
ꢀ
2.004(3) A. Two aqua ligands are in a cis-geometry, similar
to the aqua ligand and the methanol in [Ni(acac)(tmen)-
(H2O)(CH3OH)]ClO4.10 The Ni–O(H2O) bond lengths of
ꢀ
2.086(4) and 2.119(3) A are not very different from the Ni–

K. Miyamoto et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1063
ꢀ
O(CH3OH) bond length of 2.094(3) A and that of the
ꢀ
Ni–O(H2O) bond, 2.160(3) A, of [Ni(acac)(tmen)(H2O)-
ꢀ
the Ni–O(bzac) bond lengths, 2.032(3) and 2.015(3) A, and
the bite angle, O(1)–Ni(1)–O(2) of 90.9(1)ꢂ, of bzac are simi-
lar to those of the iodide. However, the Ni–N(tmen) bond
ꢀ
lengths, 2.195(4) and 2.191(5) A, are slightly longer than those
(CH3OH)]ClO4. The difference in the bond length Ni–O-
(H2O) in the complexes 2 and 3 shows that in those complexes,
one of the water molecules more loosely coordinates to the
metal than the other. A slight distortion of the octahedron is
evident from the angles around nickel: the five-membered che-
late ring, i.e. N(1)–Ni–N(2) (Ni-tmen), observed as 84.6(2)ꢂ is
smaller than that of the six-membered ring O(1)–Ni–O(2) (Ni-
bzac) of 89.6(1)ꢂ, which is in good agreement with those of
ꢀ
of the iodide, 2.138(4) and 2.155(4) A, and the tmen bite angle,
N(1)–Ni(1)–N(2), of 83.5(2)ꢂ is smaller than that of the iodide
case, i.e. 84.6(2)ꢂ. This smaller bite angle gives the chloride
complex a more distorted octahedral environment than the
iodide or bromide complex.
Selected non-bonded contacts for all of the complexes are
given in Table 2. Figure 2 illustrates the H-bonded dimeriza-
tion in the chloride complex 1, and the ladder-like hydrogen
bond network formed in the bromide and iodide complexes
2 and 3. In the complexes (2 and 3), two layers of halide com-
plexes (each layer is represented by only one molecule in the
[Ni2(ox)(acac)2(tmen)2] 2TCE (TCE = 1,1,2,2-tetrachloro-
ethane): N(1)–Ni–N(2) (Ni-tmen) and O(1)–Ni–O(2) (Ni-acac)
of 84.4(2)ꢂ and 89.9(2)ꢂ, respectively.10
ꢁ
The chloride complex has a similar configuration where the
chloro ligand and the aqua ligand are again in a cis-position;
Table 2. Non-Bonded Contacts for Ni(tmen)(bzac)X n(H2O) (X ¼ Cl, Br, and I, n ¼ 1{4)
ꢁ
ꢀ
Non-bonded contacts out to 3.60 A for [NiCl(bzac)(tmen)(H2O)]
Cl(1)–O(3)a)
O(3)–C(10)b)
C(16)–C(16)d)
3.160(4)
3.507(8)
3.31(1)
O(1)–O(3)a)
O(3)–Cl(5)a)
2.861(5)
3.551(6)
O(3)–O(3)a)
C(9)–C(15)c)
3.219(8)
3.578(9)
ꢀ
Non-bonded contacts out to 3.60 A for [Ni(bzac)(tmen)(H2O)2]Br 2H2O
ꢁ
Br(1)–O(6)e)
Br(1)–O(3)e)
O(3)–O(6)g)
3.326(4)
3.368(3)
2.696(5)
Br(1)–O(5)
O(2)–O(5)
O(5)–O(6)
3.334(3)
2.741(4)
2.771(5)
Br(1)–O(4)f)
O(4)–O(5)
O(5)–C(14)f)
3.407(3)
2.845(5)
3.448(6)
ꢀ
Non-bonded contacts out to 3.74 A for [Ni(bzac)(tmen)(H2O)2]I 2H2O
ꢁ
I(1)–O(5)h)
I(1)–O(4)i)
O(4)–O(5)i)
3.524(4)
3.653(4)
2.791(6)
I(1)–O(6)i)
O(2)–O(5)i)
O(5)–O(6)
3.526(4)
2.731(4)
2.796(6)
I(1)–O(3)
O(3)–O(6)
O(5)–C(14)
3.596(4)
2.720(6)
3.530(7)
Symmetry operations: a) ꢃx þ 2, ꢃy, ꢃz þ 2. b) x, y ꢃ 1, z. c) ꢃx þ 1, ꢃy þ 1, ꢃz þ 2. d) ꢃx þ 1, ꢃy, ꢃz þ 2.
e) x, ꢃy ꢃ 1=2, z þ 1=2. f) ꢃx þ 1, y ꢃ 1=2, ꢃz þ 1=2. g) ꢃx þ 1, ꢃy, ꢃz. h) ꢃx þ 2, y ꢃ 1=2, ꢃz ꢃ 1=2.
i) x þ 2, ꢃy, ꢃz.
O1'
O2'
O3'
I1'
O5'
O4'
O6'
O4
O6'
O5
O3
I1
O2
O1
Fig. 2. ORTEP drawings of two dimerically hydrogen bonded [NiCl(bzac)(tmen)(H2O)] molecules (left) and hydrogen bond net-
work formed in [Ni(bzac)(tmen)(H2O)2]I 2H2O (right). Hydrogen atoms are omitted for clarity. Displacement ellipsoids are
ꢁ
drawn at 30% probability. The primed or asterisked atoms are related to the unique set by a center of symmetry, i.e. ꢃx, ꢃy, ꢃz.

1064 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Ni Complex of Diamine, Diketonate, and Halide
Fig. 3. Thermal analysis of [NiCl(bzac)(tmen)(H2O)].
Fig. 5. Thermal analysis of [Ni(bzac)(tmen)(H2O)2]I 2H2O.
ꢁ
which occur in 5 steps, as suggested by the corresponding
DTA peaks, particularly the last one with a big exotherm
(probably combustion). As the residue, we obtained NiO (mass
loss found, 83.2%; calculated, 81.7%). In the case of the iodide
complex, the close examination of the DTA peak predicts that
the afore-mentioned removal of crystallization water actually
occurs in two steps. This dehydration process is followed by
the elimination of one coordinated water (presumably it must
be the one that coordinates more loosely to the Ni(II)). Com-
plex 3 then undergoes three big mass losses. In particular,
the last weight loss is also accompanied by a prominent
exotherm. The residue was NiO (mass loss found, 86.8%;
calculated, 86.1%).
A
V
I
II
III
IV
Detailed Thermal Reaction and Possible Reaction
Mechanism. The bromide complex 2 loses 3 water molecules
in one step, as is evident from the TG and DTA curves (shown
as phase I in Fig. 4). This means that two water molecules of
crystallization and one coordinated water are removed at the
same time. We repeated the measurement at a slower heating
rate of 2 ꢂC/min, but obtained an identical result. The last wa-
ter molecule is released from complex 2 between ca. 90 and ca.
Fig. 4. Thermal analysis of [Ni(bzac)(tmen)(H2O)2]Br
ꢁ
2H2O. 3H2O are lost in phase I, one H2O is lost in phase
II, disproportionation yields a mixture of [NiBr2(tmen)]
and [Ni(bzac)2(tmen)] in phase A, tmen is released in
phase III, NiBr2 is maintained in phase IV, bzac moiety
is released and NiBr2 is decomposed oxidatively in phase
V to yield NiO.
ꢂ
170 C (phase II), apparently in two steps. Then, complex 2
again undergoes three major weight losses, but different from
complexes 1 and 3; here, the last two major losses occur con-
tinuously. The residue was NiO (mass loss found, 86.85%; cal-
culated, 84.7%). In order to observe the thermal color change
of the bromide complex, complex 2 was heated at 120 ꢂC
under a vacuum in a transparent glass tube. The original pale
figure) are separated by a sort-of-inorganic channel comprising
water of crystallization and halide anions, while in complex 1,
two neighboring molecules are tightly bonded by strong H
bonds to form a dimer.
blue–green color of [Ni(bzac)(tmen)(H2O)2]Br 2H2O turned
ꢁ
to yellowish green after 20 hours, dark brown after 50 hours,
and finally the compound became a black/purple resinous sol-
id (after 74 hours). The IR spectrum of the yellowish-green
product was very similar to that of the starting material, sug-
gesting that a major structural change did not occur at this
stage. The black/purple material was very hygroscopic, which
did not allow us to conduct an IR measurement employing
KBr; however, the spectrum taken with Nujol-mull revealed
that this material contained bzac and tmen moieties, but did
not contain any water. Therefore, the chemical formula of this
material shall be expressed as Ni(tmen)(bzac)Br. The black/
Thermochemical Reactions of the Halide Complexes in
the Solid State. The results of a TG-DTA analysis of three
complexes are shown in Figs. 3, 4, and 5. The weight losses
observed in the TG curves of bromide 2 and iodide 3 before
100 ꢂC and the corresponding endothermic DTA peaks are
due to the liberation of the water of crystallization. This is
consistent with the previously reported results of bis-diamine
complexes of Ni(II).11,12 The chloride complex (1), on the oth-
er hand, loses one coordinated water molecule between ca. 90
and ca. 130 ꢂC. Complex 1 then shows three big weight losses,

K. Miyamoto et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1065
Table 3. Mass Spectra of [NiBr2(tmen)], [Ni(bzac)2(tmen)], and Black/Purple Substance
m=z
58(Niþ, 100%), 116(tmenþ, 8%), 253(Ni(tmen)79Br, 20%), 255(Ni(tmen)81Br, 28%),
332(Ni(tmen)79Br2, 3%), 334(Ni(tmen)79Br81Br, 6%), 336(Ni(tmen)81Br2, 5%)
[NiBr2(tmen)]
[Ni(bzac)2(tmen)]
58(Niþ, 100%), 77(phenylþ, 39%), 105(benzoylþ, 80%), 161(bzacþ, 30%),
162(bzacHþ, 42%), 219(Ni(bzac), 27%), 220(Ni(bzacH), 68%), 365(Ni(bzac)2–
methyl, 43%), 380(Ni(bzac)2, 100%), 382(Ni(bzacH)2, 67%)
Black/purple
substance
58(Niþ, 100%), 77(phenylþ, 28%), 105(benzoylþ, 61%), 116(tmenþ, 20%),
161(bzacþ, 18%), 162(bzacHþ, 18%), 219(Ni(bzac), 20%), 220(Ni(bzacH), 55%),
253(Ni(tmen)79Br, 73%), 255(Ni(tmen)81Br, 98%), 365(Ni(bzac)2–methyl, 35%),
380(Ni(bzac)2, 100%), 382(Ni(bzacH)2, 55%)
I
II
II
I
IV
III
Fig. 6. Thermal analysis of [NiBr2(tmen)(H2O)2]. 2H2O
are lost in phase I. HBr is released in phase II, tmen is
eliminated in phase III.
Fig. 7. Thermal analysis of [Ni(bzac)2(tmen)]. Tmen is
released in phase I, bzac moiety is oxidatively lost in
phase II.
purple color suggested that this material was a mixture of
disproportionation products, i.e. [NiBr2(tmen)] (purple) and
[Ni(bzac)2(tmen)] (blue). We synthesized [NiBr2(tmen)]13
and [Ni(bzac)2(tmen)],14 and compared their respective mass
spectrum. Table 3 lists the peaks of the black/purple substance
given together with those of the disproportionation products.
Superimposition of the spectrum of [NiBr2(tmen)] and that
of [Ni(bzac)2(tmen)] resulted in the spectrum of the black/
purple substance, supporting the presumption that this was a
mixture of these disproportionation products. Coming back
to the TG/DTA chart of the bromide complex, we can now
propose a hypothetical idea that complex 2 undergoes dispro-
portionation during the relatively flat period (shown as phase A
in Fig. 4) after dehydration and before a big drop in the mass,
yielding [NiBr2(tmen)] and [Ni(bzac)2(tmen)] at around 150
ꢂC. What attracted our attention was that both of the dispropor-
tionation products were present at this stage as a mixture, and
that the nickel(II) bis-diketonato complex that we obtained
was nonvolatile, in contrast to the results of the previous
work.7
paring Fig. 4 with the TG/DTA curves obtained on [NiBr2-
(tmen)] and [Ni(bzac)2(tmen)].
Figures 6 and 7 show the results of the TG-DTA analysis of
[NiBr2(tmen)(H2O)2] and [Ni(bzac)2(tmen)] respectively.
[NiBr2(tmen)(H2O)2] loses the two coordinated water between
ꢂ
ꢂ
ca. 35 C and ca. 180 C (phase I) to become [NiBr2(tmen)],
loses 3.1% of the initial weight during an eminent endothermic
reaction (phase II)16 then loses 31.3% of the initial weight
(which corresponds to a molecular mass of 116 = tmen) in
phase III, turning into NiBr2 which is apparently stable up to
ca. 440 ꢂC (phase IV). The phase III and the phase IV in
Fig. 4 bear a striking resemblance to the phase III and the
phase IV of Fig. 6; we can therefore presume that [NiBr2-
(tmen)] produced in phase A releases tmen in phase III, yield-
ing NiBr2, which is stable during phase IV, and then undergoes
an oxidation process in phase V, yielding the final product,
NiO.
The other species coꢂ-existing in phase A, [Ni(bzac)2(tmen)],
melted at around 140 C, as shown in Fig. 7, then a total of
85.8% of weight loss was obsꢂerved with two exotherms,
ꢂ
Now that we had confirmed the substance existing in phase
A is a mixture of two disproportionation products, analyses of
the phase III, phase IV, and phase V were carried out by com-
around 300 C and around 450 C, respectively; the residue
was NiO (mass loss found, 85.8%; calculated, 85.0%). It is
most likely that here again the complex lost tmen in the first

1066 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Ni Complex of Diamine, Diketonate, and Halide
exothermic process, since firstly the corresponding DTA peaks
were of the same order; secondly, the release of tmen took
place at around 300 ꢂC; thirdly, since tmen is a molecular sub-
stance and bzac is an ionic ligand, tmen more easily dissoci-
ates from the central metal than bzac. Therefore, we presume
that [Ni(bzac)2(tmen)] releases tmen in phase I, followed by
elimination of the bzac moiety in phase II, leaving NiO as
the final product. A comparison between Fig. 4 and Fig. 7,
gives us an assumption that [Ni(bzac)2(tmen)] produced in
phase A releases tmen in phase III, and then the bzac moiety
undergoes an oxidation process in phase V, yielding the final
product, NiO. The assumed thermal reaction and reaction
mechanism are summarized in the scheme given in Fig. 8.
Spectral Behavior of Complexes 1–3 in Various Organic
Solvents. All of these three complexes showed significant
solvatochromism. The original green color of complex 3
is changed when dissolved in various organic solvents (see
Fig. 9). The electronic spectra of [NiCl(bzac)(tmen)(H2O)],
[Ni(bzac)(tmen)(H2O)2]Br 2H2O,
ꢁ
and
(H2O)2]I 2H2O in various organic solvents with different
donor/acceptor abilities were measured, and are shown in
Figs. 10–12, with their ꢁmax values summarized in Table 4.
[Ni(bzac)(tmen)-
ꢁ
Dimethylsulfoxide (DMSO):
The spectral patterns of
complexes 1, 2, and 3 in DMSO are very similar, since each
complex has two absorption peaks (ꢁ1 and ꢁ2 transitions
9.43, 15.90 (1), 9.41, 15.90 (2), and 9.40, 15.92 (3) (unit:
3
3
3
3
ꢄ103 cmꢃ1) are assigned as A2g! T2g, A2g! T1g, respec-
tively), indicating that these mixed-ligand complexes form 6-
coordinate species in DMSO. The electric molar conductances
of the solutions ranging between 22.36 and 28.77 [Standard
[Ni(bzac)(tmen)(H2O)2]Br • 2 H2O
phase I
Ni(bzac)(tmen)(H2O)Br
phase II −H2O
Ni(bzac)(tmen)Br
phase A disproportion
−3H2O
ACO
NM
DCE
DMSO
[NiBr2(tmen)]
[Ni(bzac)2(tmen)]
phase III −tmen phase III
−tmen
phase IV NiBr2
phase V
phase V
(oxidative process)
NiO NiO
−bzac
Fig. 10. Electronic spectra of complex 1 in various solvents
(concentration: 1:00 ꢄ 10ꢃ2 mol dmꢃ3, measured at room
temperature).
Fig. 8. Assumed thermal reaction and reaction mechanism
of [Ni(bzac)(tmen)(H2O)2]Br 2H2O.
ꢁ
NM
ACO
DCE
DMSO
Fig. 9. [Ni(bzac)(tmen)(H2O)2]I 2H2O in 4 different or-
ꢁ
ganic solvents, namely nitromethane (NM), 1,2-dichloro-
ethane (DCE), acetone (ACO), and dimethylsulfoxide
(DMSO) (from the left).
Fig. 11. Electronic spectra of complex 2 in various solvents
(concentration: 1:00 ꢄ 10ꢃ2 mol dmꢃ3, measured at room
temperature).

K. Miyamoto et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1067
Table 4. Spectral Data of Solutions of the Halide Complexes 1, 2, and 3 in Various Organic
Solvents ꢁmax/103 cmꢃ1
Solvent
DMSO
Complex
ꢁmax
1
2
3
9.43
9.41
9.40
15.90
15.90
15.92
1
2
3
10.09
9.92
11.37
11.05 (sh)
11.81
11.53
15.90
15.97
19.84
19.53
NM
DCE
ACO
20.59
22.07
22.11
1
2
3
9.93
9.81
9.64
11.41
11.06 (sh)
11.87
11.52
14.43
15.43
14.5 (sh)
19.80
19.02
17.60
1
2
3
10.05
9.89
9.54
11.42
11.03 (sh)
11.86
11.53
16.29
15.78
14.5 (sh)
19.73
19.05
17.71
3
DCE
NM
DMSO
ACO
1
2
Fig. 12. Electronic spectra of complex 3 in various solvents
(concentration: 1:00 ꢄ 10ꢃ2 mol dmꢃ3, measured at room
temperature).
Fig. 13. Electronic spectra of complexes 1, 2, and 3 in NM.
weak donor solvent, the positively charged Sp species is stabi-
lized in solution.
value of the 1:1 electrolyte solution = ca. 32 (ꢁM/S cm2
molꢃ1)]17 show that the halide anions exist as free anions, i.e.
do not coordinate to nickel cations. Therefore, the species pres-
ent in this highly polar and strong coordinating solvent can be
most probably expressed as [Ni(bzac)(tmen)(dmso)2]þ and Xꢃ,
because the aqua ligands are naturally replaced by the strong
coordinating solvent molecules, and these spectra are similar
to the corresponding [Ni(bzac)(tmen)](BPh4) in the solvent.15
Nitromethane (NM): The spectral behaviors of the com-
plexes in nitromethane are different among the complexes
(Fig. 13). The fact that the iodide complex 3 has only one ab-
In the spectra of chloride and bromide complexes (1 and 2),
four more peaks including shoulders were observed in addition
to a big absorption peak around 19 ꢄ 103 cmꢃ1, suggesting the
occurrence of a disproportionation reaction. Besides, the ab-
sorption peak of complex 2 at 19:53 ꢄ 103 cmꢃ1 is somewhat
tilted to the left, suggesting the presence of the Sp species hav-
ing a ꢁmax value of around 20:4 ꢄ 103 cmꢃ1; we measured the
absorption spectra of [NiBr2(tmen)](Td), [Ni(bzac)2(tmen)]-
(Oh), and [Ni(bzac)(tmen)](BPh4)(Sp) and compared them
with that of complex 2 (Fig. 14). It is clearly shown that the
solid line obtained by adding the spectra of Td, Oh, and Sp
species overlaps the spectrum of complex 2 very well. This
means that complex 2 undergoes both deaquation (yielding
Sp) and disproportionation (yielding Td and Oh). On the other
hand, complex 1 in the solvent has a peak at 19:84 ꢄ 103
cmꢃ1, which has a symmetric form, and is free from any sign
of the Sp species; we conclude that the chloride complex
undergoes only disproportionation.
1
1
sorption peak at 20:6 ꢄ 103 cmꢃ1 (assigned as A1g! B1g)
suggests that complex 3 has a square–planar geometry in nitro-
methane. Showing the same spectra as that of [Ni(bzac)-
(tmen)](BPh4) in this solvent (20:4 ꢄ 103 cmꢃ1),15 this also
proves complex 3, just like [Ni(acac)(tmen)(H2O)2](ClO4),
releases two water molecules when dissolved in nitromethane,
and exists as a cation having a square–planar geometry.15,18
Since nitromethane is a medium-level acceptor and a very

1068 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Ni Complex of Diamine, Diketonate, and Halide
complex 2
15 min
N
Td+Sp+Oh
[NiBr2(tmen)]
Ni
Br
N
Br
[Ni(bzac)(tmen)]+
[Ni(bzac)2(tmen)]
N
N
Br
O
O
0 min
Fig. 14. Composition of the spectra of [NiBr2(tmen)] (Td
species), [Ni(bzac)(tmen)]þ (Sp species), [Ni(bzac)2-
(tmen)] (Oh species), and complex 2 in NM.
Fig. 15. Time-course change in the absorbance of [Ni-
(bzac)(tmen)(H2O)2]Br 2H2O dissolved in DCE.
ꢁ
1,2-Dichloroethane (DCE): The spectral patterns of com-
plexes 1, 2, and 3 in DCE (see Figs. 10–12) suggest that these
complexes undergo a disproportionation reaction again in DCE
and yield the Td and Oh species. As it is clear from Fig. 14, the
absorption of the Oh species is negligible compared to that of
the Td species; we can presume that these ꢁmax values are
attributable mainly to the Td species. On this basis, the bands
at 9.93, 9.81, and 9.64 (unit: ꢄ103 cmꢃ1) are assigned to ꢁ2
3T1(F)! A2(F), and the bands at 19.80, 19.02, and 17.60 (unit:
3
3
ꢄ103 cmꢃ1) as ꢁ3 3T1(F)! T1(P). (The bands to be assigned
3
3
to ꢁ1 transition T1(F)! T2(F) were not observed.) The two
peaks (or a shoulder) at 11.06–11.87 (unit: ꢄ103 cmꢃ1) ob-
served with complexes 1 and 2 are assigned to a spin-forbidden
transition to an upper state arising from the 1D state of the free
ion.19 The band observed with complex 3 at 22:07 ꢄ 103 cmꢃ1
can be assigned to a charge-transfer transition. What is left is
the bands observed with three complexes at 14.43, 15.43, and
14.5(sh) (unit: ꢄ103 cmꢃ1), respectively. In order to investi-
gate the origin of this band, we measured the time-course
change in the absorbance of complex 2 dissolved in DCE.
The result is shown in Fig. 15. It is clear from the chart that
the amount of the Td species (which is indicated by the absorp-
N
N
Br
O
O
Fig. 16. Time-course change in absorbance of DCE in
which [Ni(bzac)(tmen)](BPh4) and tetrabutylammonium
bromide were mixed.
tion at ꢁmax of 9.81, 11.06(sh), 11.52, and 19:02 ꢄ 103 cmꢃ1
)
obtained with complex 2. Therefore, it may be reasonable to
conclude that complex 2 undergoes disproportionation in
DCE via a 5-coordinated intermediate complex:
increases with time, while an unknown species having the ab-
sorption at 14:73 ꢄ 103 cmꢃ1 decreases. This suggests that
complex 2 in DCE undergoes disproportionation via an inter-
mediate compound having a ꢁmax of around 15 ꢄ 103 cmꢃ1. L.
Sacconi has reported that a five-coordinate Nickel(II) contain-
ing tris(2-dimethylaminoethyl)amine and a bromide anion has
an absorption peak at 14:5 ꢄ 103 cmꢃ1.1 These data suggest
that the above-mentioned intermediate of this disproportiona-
tion reaction having a ꢁmax of 14:73 ꢄ 103 cmꢃ1 is also a 5-co-
ordinate species. Assuming that [NiBr(bzac)(tmen)] (5-coordi-
nate) can be produced by a reaction between [Ni(bzac)-
(tmen)](BPh4) and tetrabutylammonium bromide, we mixed
equimolar amounts of [Ni(bzac)(tmen)](BPh4) and tetrabutyl-
ammonium bromide in DCE and measured the time-course
change of the spectrum of the resulting solution. Figure 16
shows exactly the same change in the spectral pattern as we
[Ni(bzac)(tmen)(H2O)2]Br 2H2O ! [NiBr(bzac)(tmen)]
þ 4H2O ! 1/2[Ni(bzac)2(tmen)] þ 1/2[NiBr2(tmen)]: ð1Þ
ꢁ
Acetone (ACO): The spectra of complexes 1, 2, and 3 in
ACO are conformal to those in DCE, and we could ultimately
obtain exactly the same spectral change as those obtained in
DCE when we mixed equimolar amounts of [Ni(bzac)(tmen)]-
(BPh4) and tetrabutylammonium bromide in ACO. Therefore,
we can conclude that three complexes undergo disproportiona-
tion in acetone as well.
Conclusion
Ni(tmen)(bzac)X n(H2O)(n ¼ 1 for X ¼ Cl, and n ¼ 4 for
ꢁ
X ¼ Br or I) undergo deaquation and disproportionation both

K. Miyamoto et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1069
in various organic solvents and in the solid state. Their behav-
ior in solution depends on the coordination ability of the
anions (Xꢃ), and the nature of the solvents, more specifically,
on the acceptor and/or donor properties of the solvents.
1) In a strong donor solvent such as DMSO, all of com-
plexes 1, 2, and 3 are subject to deaquation, followed by sol-
vent coordination, yielding the Oh species:
lar solvent, such as hexane.7 The solubility of [Ni(bzac)2(tmen)]
in nonpolar solvents is lower than that of [Ni(acac)2(tmen)],
which suggests that the bis-bzac ternary complex has a higher
molecular interaction than that of the bis-acac analogue; there-
fore, the volatility is decreased.
Experimental
Ni(tmen)(bzac)X n(H2O) þ 2 solvent
Instrumentation. Electronic spectra between 400 nm and
1200 nm of the solutions were obtained on a Shimadzu UV-
3100PC UV–vis Scanning Spectrophotometer using 10 mm quarts
cells at a concentration of 1:0 ꢄ 10ꢃ2 mol dmꢃ3. IR spectra
between 330 and 5000 cmꢃ1 were measured on a Perkin-Elmer
FT-IR SPECTRUM 2000 using the KBr method and Nujol-mull.
Electric conductances of the solutions (concentrations of 1:0 ꢄ
10ꢃ3 M) were measured with a TOA Conductivity Outfit Model
CM 40-G at 25 ꢅ 0:1 ꢂC. Elemental analyses were performed
on a Perkin-Elmer 2400II CHN analyzer. Thermal analyses (TG
and DTA) were carried out using a Shimadzu ‘‘Stand Alone’’ ther-
mal analyzer (TGA-50H, DTA-50) and the associated data acqui-
sition and handling system, TA-50 WSI, in static air up to 1000
ꢂC, at a heating rate of 10 ꢂC/min, unless otherwise stated. A
sample of ca. 7 mg was placed in an uncovered alumina cell,
and highly sintered ꢂ-Al2O3 (Shimadzu) was employed as a
DTA reference material. Mass spectra (EI, 70 eV) were taken
on a JEOL JMS-700 MStation. All of the measurements were
carried out at room temperature, unless otherwise specified.
Materials. All materials used were purchased from Wako
Pure Chemical Industries Ltd. of reagent grade (extra pure) or
spectroscopic grade, and were used without further purification.
Synthesis of [NiCl(bzac)(tmen)(H2O)] (1). To a transparent
ꢁ
! [Ni(bzac)(tmen)(solvent)2]þ þ Xꢃ þ nH2O:
ð2Þ
The resulting Oh species is stable, as Ni(II) with the d8 con-
figuration preferring the Oh configuration from the view point
of the structural preference energies;20 the complex cation is
solvated and stabilized by DMSO having a large donor number
(DN ¼ 29:8). In addition to that, the relatively large acceptor
capacity of DMSO also stabilizes the resulting halide anion,
Xꢃ.
2) In a medium-level acceptor and a very weak donor sol-
vent, such as NM, complex 1 undergoes only a disproportiona-
tion reaction, yielding the Td and Oh species; complex 2 un-
dergoes both deaquation and disproportionation, yielding the
Sp, Td, and Oh species; and complex 3 undergoes only de-
aquation, yielding the Sp species:
Ni(tmen)(bzac)X n(H2O)
ꢁ
! [Ni(bzac)(tmen)]þ þ Xꢃ þ nH2O;
ð3Þ
ð4Þ
2fNi(tmen)(bzac)X n(H2O)g
ꢁ
! [Ni(bzac)2(tmen)] þ [NiX2(tmen)] þ 2nH2O:
If tmen and bzac are regarded as being strong ligands, then
the Ni(II) ions prefer a low-spin state and the Sp configuration,
and only deaquation will take place. This is the case of iodide,
which is bulky and has a weak coordination power. However,
since the chloride anion has a higher ligand field strength and
smaller size, the resulting Td species, i.e. [NiCl2(tmen)], is
more stable; in addition to this, the by-produced tris chelate
product, [Ni(bzac)2(tmen)], is very stable due to its Oh config-
uration and chelating effect; the [Ni(bzac)(tmen)]þ and Xꢃ
will further undergo a disproportionation reaction. The bro-
mide ion, having an intermediate coordination capacity and
size, follow both reaction schemes (Equations 3 and 4).
3) In rather inert solvents with weak acceptor and weak do-
nor properties, such as DCE and ACO, all complexes, 1, 2, and
3 undergo the disproportionation reaction. The donor and ac-
ceptor properties of these solvents are not strong enough to sol-
vate and stabilize the ionic species, i.e. the positively charged
complex ions and the negatively charged halide anions. The
presence of a proposed intermediate (5-coordinate compound)
suggests that the halide anion is coordinated to the Ni(II) after
deaquation, and then disproportionation takes place.
When compared to the former study carried out by Hoshino
et al.,6 the largest difference found between the Ni(tmen)-
(acac)X and Ni(tmen)(bzac)X (X ¼ halide) systems is that
during the thermal reaction, the [Ni(bzac)2(tmen)] does not
evaporate following the disproportionation, thereby providing
a mixture of dihalo and bis(benzoylacetonato) complexes. As
we expected, a nonvolatile bis-ꢀ-diketonate ternary complex
was synthesized by the use of the ꢀ-diketone having an aro-
matic substituent. Ni(tmen)(acac)2 is very soluble in a nonpo-
yellow–green solution of 10 mmoles of NiCl2 6H2O in 30 mL of
ꢁ
ethanol, was added 15 mmoles of tmen dropwise with vigorously
stirring; the solution turned into a green suspension. Upon the ad-
dition of 10 mmoles of benzoylacetone dissolved in 10 mL of hot
ethanol, the solution turned bluish green. After stirring for 2 hours,
a yellow–green precipitate was formed. Sodium carbonate (5
mmoles) was added thereto and stirred for 30 minutes; then, a
blue–green clear solution containing a white precipitate was
obtained. After the suspension was filtered and concentrated, the
obtained solid was recrystalized from DCE in a freezer to give
1 as a green powder. Yield: 47.1%. Anal. Found: C, 49.46; H,
7.32; N, 7.31%. Calcd for C16H27ClN2NiO3: C, 49.40; H, 7.20;
N, 6.94%. Monocrystal was obtained from ethanolic solution of
the compound by slow evaporation at room temperature. IR
(KBr): ꢁ (O–H) 3370, ꢃ (O–H) 1655, ꢁ (C=C) 1598, ꢁ (C=O)
1519 cmꢃ1
.
Synthesis of [Ni(bzac)(tmen)(H O) ]Br 2H O (2). The pro-
cedure described for synthesis of 1 was repeated, except that
ꢀ
NiBr2 and triethylamine were employed instead of NiCl2 6H2O
2
2
2
ꢁ
and sodium carbonate, respectively. Blue–green single crystals
of 2 were obtained by recrystallization from ethanol at room tem-
perature. Yield: 50.0%. Anal. Found: C, 39.11; H, 6.71; N, 5.63%.
Calcd for C16H33BrN2NiO6: C, 39.30; H, 6.80; N, 5.73%. IR
(KBr): ꢁ (O–H) 3370, ꢃ (O–H) 1656, ꢁ (C=C) 1599, ꢁ (C=O)
1518 cmꢃ1
.
Synthesis of [Ni(bzac)(tmen)(H O) ]I 2H O (3). The proce-
dure described for the synthesis of 1 was repeated, except that NiI2
ꢀ
was employed as the starting material and [Ni(bzac)(tmen)-
2
2
2
(H2O)2]I 2H2O was obtained as a green single crystal by recrys-
tallization from ethanol. Yield: 19.8%. Anal. Found: C, 33.76; H,
5.68; N, 4.86%. Calcd for C16H33IN2NiO6: C, 35.90; H, 6.21; N,
ꢁ

1070 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Ni Complex of Diamine, Diketonate, and Halide
Table 5. Crystallographic Data
[NiCl(bzac)(tmen)(H2O)]
[Ni(bzac)(tmen)(H2O)2]Br
2H2O
[Ni(bzac)(tmen)(H2O)2]I
2H2O
ꢁ
ꢁ
Formula
M
C16H27ClN2NiO3
389.55
triclinic
C16H33BrN2NiO6
485.03
monoclinic
P21=c (no. 14)
0.71069
C16H33IN2NiO6
535.05
monoclinic
P21=c (no. 14)
0.71069
15.093(2)
9.925(1)
15.575(2)
90
102.900(4)
90
Crystal system
Space group
ꢂ
P1 (no. 2)
ꢀ
ꢄ/A
0.71069
9.159(1)
9.507(1)
11.849(1)
76.332(4)
72.599(3)
79.097(4)
948.8(2)
2
ꢀ
a/A
14.761(1)
9.9208(7)
15.449(1)
90
102.361(1)
90
2210.0(3)
4
1.458
ꢀ
b/A
ꢀ
c/A
ꢂ/ꢂ
ꢀ/ꢂ
ꢅ/ꢂ
ꢀ 3
V/A
2274.2(5)
4
1.563
Z
Dcalc/g cmꢃ3
Crystal size/mm3
2ꢆ Range/ꢂ
ꢇ/cmꢃ1
1.363
0:11 ꢄ 0:33 ꢄ 0:48
5.85–56.5
11.96
0:14 ꢄ 0:25 ꢄ 0:41
4.90–56.6
27.22
0:48 ꢄ 0:43 ꢄ 0:24
4.70–56.6
22.41
Total reflections
Unique reflections
Observed
4512
2706
2061½I > 2:50ꢈðIÞꢆ
13955
5185
3624½I > 2:50ꢈðIÞꢆ
14313
5312
4013½I > 2:50ꢈðIÞꢆ
reflections
Ra), Rw
b)
0.042, 0.046
0.17
9.91
0.039, 0.038
0.05
10.41
0.038, 0.038
0.07
11.53
Goodness of fit
Reflection/
Parameter Ratio
2
2
1=2
2
a) R ¼ ꢃjjFoj ꢃ jFcjj=ꢃjFoj, b) Rw ¼ ½ꢃðwðjFoj ꢃ jFcjÞ =ꢃwjFoj Þꢆ with w ¼ 4Fo2=½ꢈ2ðFo Þꢆ.
5.23%.21 IR (KBr): ꢁ (O–H) 3400, ꢃ (O–H) 1660, ꢁ (C=C) 1597,
The authors thank Prof. Yoichi Ishii, Chuo University, for
his help with elemental analysis, Dr. Marilena Ferbinteanu,
University of Bucharest, for her help with thermal analysis,
and Dr. Yukie Mori, Ochanomizu University, for her valuable
discussions.
ꢁ (C=O) 1520 cmꢃ1
X-ray Crystallography. The three complexes [NiCl(bzac)-
.
(tmen)(H2O)] (1), [Ni(bzac)(tmen)(H2O)2]Br 2H2O (2), and
[Ni(bzac)(tmen)(H2O)2]I 2H2O (3) were recrystallized from etha-
ꢁ
ꢁ
nol–water mixtures by slow evaporation at room temperature to
give transparent blue–green plates, aqua-blue blocks, and green
blocks, suitable for single-crystal X-ray analysis, respectively.
Crystals of complexes 1, 2, and 3 mounted on a glass fibers were
irradiated with graphite monochromated Mo Kꢂ radiation at 23 ꢂC
on a Bruker Smart APEX CCD diffractometer with 10, 15, and 10
sec/frame exposure times, respectively. All of the data were cor-
rected for Lorentz and polarization effects and crystal absorption
(SMART and SAINT (SADABS)).22 However, no crystal decay
corrections were necessary. The structures were solved by direct
methods (SIR92)23 and expanded using Fourier techniques
(DIRDIF94).24 The non-hydrogen atoms were refined anisotropi-
cally, while only the hydrogen atom coordinates were refined.
The final cycle of full-matrix least-squares refinement25 was based
on 2061, 3624, and 4013 observed reflections and 208, 348, and
352 variable parameters and converged with unweighted agree-
ment factors (R) equal to 0.042, 0.039, and 0.038, respectively.
References
1
L. Sacconi, ‘‘Electronic Structure and Stereochemistry of
Ni(II),’’ in ‘‘Transition Metal Chemistry,’’ Marcel Dekker, Inc.,
New York (1968), Vol. 4.
2
R. Yamamoto and T. Maruyama, Jpn. Kokai Tokkyo
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Olsina, Talanta, 36, 945 (1989).
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K. Sone and Y. Fukuda, ‘‘Inorganic Thermochromism,’’ in
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Neutral atom scattering factors were taken from Cromer and
27
Waber.26 Anomalous dispersion effects were included in Fcalc
;
the values for Df0 and Df00 were those of Creagh and McAuley.28
The values for the mass-attenuation coefficients are those of
Creagh and Hubbel.29 All calculations were performed using the
teXsan30 crystallographic software package of Molecular Struc-
ture Corporation. Selected crystallographic data and refinement
parameters are given in Table 5.
4
281, 113 (2001).
W. Linert, Y. Fukuda, and A. Camard, Coord. Chem. Rev.,
5
6
H. Ohtsu and K. Tanaka, Inorg. Chem., 43, 3024 (2004).
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7

K. Miyamoto et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1071
Chem. Soc. Jpn., 54, 196 (1981).
8
18 A. B. P. Lever, ‘‘Inorganic Electronic Spectroscopy,’’
Elsevier, Amsterdam (1984).
CCDC 236626, CCDC 236627, and CCDC 236628 contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data request/cif.
9 K. Yamada, K. Hori, and Y. Fukuda, Acta Crystallogr.,
C49, 445 (1993).
19 L. Sacconi, I. Bertini, and F. Mani, Inorg. Chem., 6, 262
(1967).
20 K. F. Purcell and J. C. Kotz, ‘‘Inorganic Chemistry,’’ W. B.
Saunders Company, Hong Kong (1977).
21 The difference between the calculated value and the ob-
served value may be attributed to absorption of water. During
the storage, we observed that once-transparent mono crystal
turned opaque.
22 SMART and SAINT, Siemans (1995), Siemans Analytical
X-ray Instrument Inc., Madison, Wisconsin, USA.
23 A. Altomare, M. C. Burla, M. Camalli, M. Cascarano, C.
Giacovazzo, A. Guagliardi, and G. Polidori, J. Appl. Crystallogr.,
27, 435 (1994).
10 K. Yamada, Y. Fukuda, T. Kawamoto, Y. Kushi, W. Mori,
and K. Unoura, Bull. Chem. Soc. Jpn., 66, 2758 (1993).
11 D. M. L. Goodgame and L. M. Venanzi, J. Chem. Soc.,
1963, 616.
12 R. Tsuchiya, S. Joba, A. Uehara, and E. Kyuno, Bull.
Chem. Soc. Jpn., 46, 1454 (1973).
13 [NiBr2(tmen)] was obtained as a purple microcrystalline
powder by dehydrating a green powder of [NiBr2(tmen)(H2O)2]
in vacuum at 120 ꢂC for 3 days; [NiBr2(tmen)(H2O)2] was synthe-
sized from an ethanolic solution of [NiBr2] by addition of
tmen; Anal. Found: C, 19.98; H, 5.42; N, 7.61%. Calcd for
C6H20Br2N2NiO2: C, 19.44; H, 5.44; N, 7.56%.
14 [Ni(bzac)2(tmen)] was synthesized in a process analogous
to that reported;15 Anal. Found: C, 62.02; H, 6.86; N, 5.58%.
Calcd for C26H34N2NiO4: C, 62.80; H, 6.89; N, 5.63%.
15 Y. Fukuda and K. Sone, J. Inorg. Nucl. Chem., 34, 2315
(1972).
24 P. T. Beurskens, G. Admiraal, G. Beurskens, W. P.
Bosman, R. de Gelder, R. Israel, and J. M. M. Smits, ‘‘The
DIRDIF Program System: Technical Report of the Crystallography
Laboratory,’’ University of Nijmegen, The Netherlands (1994).
2
25 Least-Squares: Function minimized: ꢃw ðjFoj ꢃ jFcjÞ
where w ¼ 1=½ꢈ2ðFoÞꢆ ¼ ½ꢈc ðFoÞ þ p2Fo2=4ꢆꢃ1, sc(Fo) = e.s.d.
2
based on counting statistics, p ¼ p-factor.
26 D. T. Cromer and J. T. Waber, ‘‘International Tables for X-
ray Crystallography,’’ The Kynoch Press, Birmingham, England
(1974), Vol. IV, Table 2.2 A.
16 The green powder of Ni(tmen)(H2O)2Br2 on heating yields
purple microcrystals of Ni(tmen)Br2 mixed with a small amount
of a pale green substance. This pale green substance could not
be eliminated even by prolonged heating. We now assume that
this green substance is a trimer of Ni(tmen)Br2 which is formed
according to the formula;
27 J. A. Ibers and W. C. Hamilton, Acta Crystallogr., 17, 781
(1964).
28 D. C. Creagh and W. J. McAuley, ‘‘International Tables
for Crystallography,’’ ed by A. J. C. Wilson, Kluwer Academic
Publishers, Boston (1992), Vol. C, p. 219, Table 4.2.6.8.
29 D. C. Creagh and J. H. Hubbell, ‘‘International Tables
for Crystallography,’’ ed by A. J. C. Wilson, Kluwer Academic
Publishers, Boston (1992), Vol. C, p. 200, Table 4.2.4.3.
30 teXsan: Crystal Structure Analysis Package, Molecular
Structure Corporation (1985 & 1999).
3 Ni(tmen)Br2 þ H2O ! Ni3(tmen)3Br5(OH) þ HBr:
We have observed this trimer formation of Ni(tmen)Br2 in various
organic solvents and this will be reported elsewhere.
17 W. J. Geary, Coord. Chem. Rev., 7, 81 (1971).