Control of magnetic spin states by various mixed anionic ligands in trinickel complexes: Synthesis, crystal structures and physical properties

Article abstract of DOI:10.1039/b612123c

This study provides an opportunity to control the magnetic spin of nickel atoms using various mixed anionic ligands. A series of linear trinickel complexes supported by two kinds of ligands, oligo-α-pyridylamido and sulfonyl amido/amido, were synthesized and their structures were determined by X-ray diffraction. The three nickel atoms of [Ni₃(Lpts) ₂(dpa)₂] (1) (dpa^- = dipyridylamido, Lpts ^2- = N,N′-bis(p-toluenesulfonyl)pyridyldiamido) display short Ni-N (～1.90 A) bond distances, which are consistent with a low spin state of Ni(ii) ions, and exhibit spin states of (0, 0, 0) for the three Ni(ii) ions. One of the terminal Ni(ii) ions of [Ni₃(Lms) ₂(dpa)₂(H₂O)] (2) (Lms^2- = N,N′-bis(4-methylsulfonyl)-pyridyldiamido) and [Ni₃(Lpts) ₂(pepteaH₂)] (4) (pepteaH₂^2- = pentapyridyldiamidodiamine) bonded with an axial ligand exhibits a square pyramidal (NiN₄X) geometry with long Ni-N bond distances (～2.10 A) which are consistent with a high spin Ni(ii) configuration. The spin states of these trinickel complexes are (1, 0, 0). Complex 2 and 6 can be interchanged by the removal or addition of an axial water molecule. The structural features of 6 are comparable with those of 1. Both the terminal Ni(ii) ions in [Ni₃(LAc)₂(dpa)₂] (3) (Lac ^2- = N,N′-biacetyl-pyridyldiamido) are in square pyramidal geometry and exhibit high spin. The spin states of the nickel ions in 3 are (1, 0, 1), and the two terminal nickel ions exhibit antiferromagnetic interactions. The molecular structure of [Ni₃(Lpts)₂(dpa) ₂](BF₄) (5), which was obtained by the one-electron oxidation of 1, is similar to those of the neutral analogue 1, except for the presence of a counter anion to compensate for the positive charge on the Ni ₃ core. All of the Ni-Ni bond lengths of 5 are slightly shorter (ca. 0.05 A) than those in the neutral analogues. This is attributed to the formation of partial Ni-Ni bonding. The Royal Society of Chemistry.

Full text of DOI:10.1039/b612123c

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Control of magnetic spin states by various mixed anionic ligands in trinickel
complexes: synthesis, crystal structures and physical properties
Ming-Yi Huang,a Chen-Yu Yeh,b Gene-Hsiang Leea and Shie-Ming Peng*a,c
Received 22nd August 2006, Accepted 18th October 2006
First published as an Advance Article on the web 31st October 2006
DOI: 10.1039/b612123c
This study provides an opportunity to control the magnetic spin of nickel atoms using various mixed
anionic ligands. A series of linear trinickel complexes supported by two kinds of ligands, oligo-a-
pyridylamido and sulfonyl amido/amido, were synthesized and their structures were determined by
X-ray diffraction. The three nickel atoms of [Ni3(Lpts)2(dpa)2] (1) (dpa− = dipyridylamido, Lpts2−
=
ꢀ
˚
N,N -bis(p-toluenesulfonyl)pyridyldiamido) display short Ni–N (∼1.90 A) bond distances, which are
consistent with a low spin state of Ni(II) ions, and exhibit spin states of (0, 0, 0) for the three Ni(II) ions.
One of the terminal Ni(II) ions of [Ni3(Lms)2(dpa)2(H2O)] (2) (Lms2− = N,Nꢀ-bis(4-methylsulfonyl)-
2−
pyridyldiamido) and [Ni3(Lpts)2(pepteaH2)] (4) (pepteaH2 = pentapyridyldiamidodiamine) bonded
with an axial ligand exhibits a square pyramidal (NiN4X) geometry with long Ni–N bond distances
˚
(∼2.10 A) which are consistent with a high spin Ni(II) configuration. The spin states of these trinickel
complexes are (1, 0, 0). Complex 2 and 6 can be interchanged by the removal or addition of an axial
water molecule. The structural features of 6 are comparable with those of 1. Both the terminal Ni(II)
ions in [Ni3(LAc)2(dpa)2] (3) (Lac2− = N,Nꢀ-biacetyl-pyridyldiamido) are in square pyramidal geometry
and exhibit high spin. The spin states of the nickel ions in 3 are (1, 0, 1), and the two terminal nickel
ions exhibit antiferromagnetic interactions. The molecular structure of [Ni3(Lpts)2(dpa)2](BF4) (5),
which was obtained by the one-electron oxidation of 1, is similar to those of the neutral analogue 1,
except for the presence of a counter anion to compensate for the positive charge on the Ni3 core. All of
˚
the Ni–Ni bond lengths of 5 are slightly shorter (ca. 0.05 A) than those in the neutral analogues. This is
attributed to the formation of partial Ni–Ni bonding.
Introduction
Results and discussion
The study of metal–metal interactions in transition metal com-
plexes has been an interesting and important subject in inorganic
chemistry.1 In the past decade, the study of metal–metal interac-
tions has focused on the extension of dinuclear metal complexes2–4
to metal string complexes supported by oligo-a-pyridylamido
ligands such as [M3(dpa)4X2] (M = Cr, Co, Ni, Cu, Rh, Ru),5–10
[M5(tpda)4X2] (M = Cr, Co, Ni; tpda2− = tripyridyldiamido),11–13
[M7(teptra)4X2] (M = Cr, Ni; teptra3− = tetrapyridyltriamido)14–15
and [M9(peptea)4X2] (M = Ni).16 Recently, we have been interested
in exploring the coordination chemistry of multidentate ligands
other than oligopyridylamines such as LptsH2 and LAcH2. The
unique feature of these ligands is that they are tridentate and
dianionic when depronated. In this paper, we describe a new type
of metal string complex in which the trimetal core is supported
by two kinds of oligo-a-pyridylamido and sulfonyl amido/amido
ligands and exhibits different magnetic spin states.
Synthesis and structures
The synthetic procedures for compounds 1–6 are summarized in
Scheme 1. Compounds 1–4 are synthesized by the reaction of
Ni(OAc)2·4H2O with the appropriate ligands using naphthalene as
the solvent. In our previous reports on multinuclear metal string
complexes,7,9,11–13 the preparation of these complexes involved the
use of an additional base for the deprotonation of the ligands. In
the modified procedure using Ni(OAc)2·4H2O instead of NiCl2,
it is not necessary to use an additional base for deprotonation
since it can be accomplished by the OAc− anion. The one-electron
oxidized product [Ni3(Lpts)2(dpa)2](BF4) (5) was obtained by
reacting the neutral complexes with nitrosyl tetrafluoroborate, the
redox potential of which is more anodic than the formal potential
for the first oxidation of the neutral complex. Compound 6 can be
obtained by putting 2 under vaccum at 120 ◦C for 48 h. Summaries
of the structural data for compounds 1–6 are given in Table 1.
Table 2 gives some selected bond distances for compounds 1–6.
The structure of compound 1 is depicted in Fig. 1. The trinickel
core is linear and supported by two Lpts2− and two dpa− ligands,
in which the same ligands are trans to each other. Each of the three
Ni(II) ions are coordinated by four nitrogen atoms with a square
planar arrangement. All the Ni–N distances lie in the range of
For clarity, the trinickel complexes presented in this paper
are as follows: [Ni3(Lpts)2(dpa)2] (1), [Ni3(Lms)2(dpa)2(H2O)]
(2), [Ni3(LAc)2(dpa)2] (3), [Ni3(Lpts)2(pepteaH2)] (4), [Ni3(Lpts)2-
(dpa)2](BF4) (5), [Ni3(Lms)2(dpa)2] (6).
aDepartment of Chemistry, National Taiwan University, Taipei, Taiwan
bDepartment of Chemistry, National Chung Hsing University, Taichung,
Taiwan
˚
1.89–1.95 A, which indicates that the nickel ions are in a low spin
cInstitute of Chemistry, Academia Sinica, Taipei, Taiwan. E-mail: smpeng@
ntu.edu.tw
state. In this class of multinuclear metal complexes, examples of
compounds without axial ligands are rare.
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Scheme 1 General route for the preparation of linear trinuclear nickel string mixed ligand complexes.
˚
and 2.3516(8) A in compound 1 are longer than those in 7
˚
(2.3269(6), 2.3010(6) and 2.3280(6) A) and slightly shorter than
˚
those in 8 (2.368(1) A). The Ni–N bond distances in these three
˚
compounds are comparable, all being in the range of 1.89–1.95 A,
which are consistent with a low spin state of Ni(II). The two
˚
C(Py)–N(amido) bond distances are 1.377(4) and 1.391(4) A in
18
˚
compound 1, which are longer than those in 8 (1.358 A). This
means that the negative charge is more localized at the N(amido)
in compound 1 than in 8, because toluenesufonyl (Ts) is a stronger
electron withdrawing group than phenyl. Lo´pez et al. have shown
that substitution of phenyls with toluenesulfonyls in 8 results in a
spin state change from diamagnetic to quintet ground state.19
Fig. 2 and 3 show the crystal structures of compounds 2 and
4. It is noted that the identity of the axial ligands could influence
the Ni–Ni and Ni–N bond distances. In compounds 2 and 4, one
of the terminal nickel ions is five-coordinate and the Ni–N bond
˚
˚
distances (ca. 2.10 A) and Ni–Ni bond distances (ca. 2.39 A) are
longer than those of the other terminal nickel ion without axial
ligands. This indicates that the five-coordinate nickel ion is in a
high spin state. Both structures have trans geometry.
The crystal structure of compound 3 is shown in Fig. 4. The
linear trinickel core is helically wrapped by two dpa− and two
LAc2− ligands with cis configuration. The two terminal nickel ions
are five-coordinate. Interestingly, one of the nitrogen atoms of the
LAc2− ligands is not involved in coordination to the nickel ions and
the axial ligands are provided by one of the oxygen atoms of the
LAc2− ligands. The central nickel atom is square planar with four
Fig. 1 Crystal structure of 1. Thermal ellipsoids are drawn at the 30%
probability level. Hydrogen atoms are omitted for clarity.
˚
short Ni–N bond distances in the range of 1.86–1.90 A, which are
In 1999, we reported the structure of a tetranickel complex
7.17 Soon after the publication of our report, another trinickel
complex 8 without axial ligands was synthesized (Scheme 2).18 In
comparison with 7 and 8, the Ni–Ni bond distances of 2.3573(8)
consistent with a low spin (S = 0) square planar Ni(II) ion. Both
the terminal Ni(II) atoms are in a square pyramidal environment
˚
with long Ni–N distances in the range of 2.05–2.11 A. This is
consistent with a high spin (S = 1) Ni(II) configuration.
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˚
Table 2 Selected bond distances (A) for compounds 1–6
1
2
3
4
5
6
Ni(1)–Ni(2)
Ni(2)–Ni(3)
Ni(1)–Neq
Ni(1)–Oeq
Ni(2)–Neq
Ni(3)–Neq
Ni(3)–Oeq
Ni(3)–Y
2.3573(8)
2.3516(8)
1.917(2)
—
1.921(2)
1.927(2)
—
2.3484(8)
2.3881(8)
1.911(4)
—
1.914(4)
2.081(4)
—
2.4055(6)
2.4015(6)
2.054(3)
2.074(3)
1.895(3)
2.059(3)
2.071(3)
1.957(3)
2.3581(10)
2.3908(9)
1.912(4)
—
1.915(3)
2.073(3)
—
2.3086(8)
2.3047(7)
1.914(4)
—
1.901(4)
1.909(4)
—
2.3464(11)
2.3611(11)
1.919(6)
—
1.914(5)
1.934(7)
—
—
2.035(4)
1.993(5)
—
—
Y is the axial ligand, eq = equatorial.
Scheme 2
Fig. 2 Crystal structure of 2. Thermal ellipsoids are drawn at the 50%
probability level. Hydrogen atoms are omitted for clarity.
As shown in Fig. 5, the molecular structure of the one-electron
oxidized compound 5 is similar to that of the neutral analogue
1, except for the presence of a counter anion to compensate for
the positive charge on the Ni3 core. We expected that some of
the interatomic bond distances would be shorter compared to
those in the neutral compounds. However, the Ni–N distances
for all the nickel atoms were only slightly changed upon one-
electron oxidation. Moreover, all the Ni–Ni bond lengths are
Fig. 3 Crystal structure of 4. Thermal ellipsoids are drawn at the 30%
probability level. Hydrogen atoms are omitted for clarity.
characterizations of compound 6 are different from those of
compound 2 and identical to those of compound 1. The trinickel
core is linear and supported by two Lms2− and two dpa− ligands,
in which the same ligands are trans to each other. Each of the three
Ni(II) ions are coordinated by four nitrogen atoms with a square
planar arrangement. All the Ni–N distances lie in the range of
˚
slightly shorter (ca. 0.05 A) than those in the neutral analogues
due to the formation of partial Ni–Ni bonds.
The crystal structure of compound 6 is shown in Fig. 6. Because
compound 6 has no axial ligation, the structural and magnetic
˚
1.89–1.95 A.
5686 | Dalton Trans., 2006, 5683–5690
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Fig. 4 Crystal structure of 3. Thermal ellipsoids are drawn at the 30%
probability level. Hydrogen atoms are omitted for clarity.
Fig. 6 Crystal structure of 6. Thermal ellipsoids are drawn at the 30%
probability level. Hydrogen atoms are omitted for clarity.
Fig. 7 The cyclic voltammograms of linear trinuclear string complexes
1–4 in CH2Cl2 containing 0.1 M TBAP.
Fig. 5 Crystal structure of 5. Thermal ellipsoids are drawn at the 30%
probability level. Hydrogen atoms are omitted for clarity.
Electrochemistry
Cyclic voltammograms of compounds 1–4 in CH2Cl2 containing
0.1 M TBAP are shown in Fig. 7. In the case of compounds 1 and
2, three redox couples were observed at +0.85, −0.58, and −1.12 V
for 1 and +0.86, −0.51, and −1.09 V for 2. For compounds 3 and
4, all the electrochemical reactions are irreversible.
Fig. 8 UV-Vis spectral changes for the first oxidation of compound 1
in CH2Cl2 with 0.1 M TBAP at various applied potentials: +0.42, +0.78,
+0.81, +0.84, +0.87, +0.90, +0.93, +0.96, +1.11, and +1.13 V; i = +0.42 V
and f = +1.13 V.
To improve understanding of the electrochemical properties
of compound 1, spectroelectrochemical studies were carried out.
Fig. 8 shows the spectral changes for compound 1 at applied
potentials from +0.42 to +1.130 V in CH2Cl2 containing 0.1 M
TBAP. The peaks at 358, 430, 641 and 800 nm increase during the
oxidation of compound 1. The resulting spectrum is similar to that
of the one-electron oxidized product of 1, obtained by a chemical
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method, suggesting that the oxidation is a metal-centered reaction.
Based on the spectral changes observed for 1 at various applied
potentials, the number of electrons transferred was calculated to
be one.20
of 0.9998. The negative J13 value of 3 reveals an antiferromagnetic
interaction between the two terminal high-spin Ni(II) ions by the
intra-Ni(1)· · ·Ni(3) interaction through the Ni(2) ions with the
˚
Ni(1)· · ·Ni(3) distance of 4.807 A.
Magnetic properties
Conclusions
Variable temperature magnetic susceptibility measurements were
performed on crushed single crystals of 1 and 5 at 10 000 G from
300 to 5 K. The vMT values of ∼0.098 and 0.429 emu K mol−1 at
300 K are in agreement with the expected the values of 0 and 0.375
emu K mol−1 for nickel ions with S = 0 and S = 1/2, respectively.
For compounds 2 and 4, the vMT values of ∼1.142 and 1.214 emu
K mol−1 at 300 K are in agreement with the expected value of 1 emu
K mol−1 for one five-coordinate nickel ion (high spin state of S = 1).
The vMT value of ∼0.096 emu K mol−1 at 300 K for 6 is consistent
with a system with a spin state of S = 0. The molar magnetic
susceptibilities vM and vMT with respect to temperature (Fig. 9) for
compound 3 are similar to those for [Ni3(dpa)4Cl2]. The theoretical
simulation curves (solid line) agree well with the measurements.
The electronic configurations derived from structural analyses are
in good agreement with the experimental magnetic measurements,
with the central Ni(II) ion being in a low spin (S = 0) state and
two terminal Ni(II) ions being in high spin (S = 1) states. Based
on an isotropic interaction between two S = 1 centers with the
This work describes the preparation, crystal structures, and
properties of linear trinuclear nickel metal string complexes with
mixed ligands, including both neutral and one-electron oxidized
compounds. The symmetrical and unsymmetrical structures of
these complexes with different mixed ligands were confirmed by
X-ray crystal structure analysis.
Due to these axial interactions, compounds 1–4and compound
6 show dramatic differences in their molecular structures and mag-
netic properties. In conclusion, structural and magnetic evidence
shows that a Ni atom lacking an axial coordination should be in a
low spin (S = 0) ground state. However, a Ni atom exhibited axial
coordination is in a high spin (S = 1) ground state. For example,
the spin state of each Ni atom in compound 1, 2 and 3 are (0, 0, 0),
(1, 0, 0), and (1, 0, 1), respectively. In addition, the neutral and
one-electron oxidized molecules 1 and 5 exhibit spin states of S =
0 and 1/2, respectively.
Experimental
ˆ
ˆ
spin Hamiltonian H = −2JS1·S6, the simulated curve of vMT was
fitted using the following equation:11
General
xM = (1 − P)Cꢀ (2e2x + 10e6x)/(1 + 3e2x + 5e6x)
All reagents and solvents were obtained from commercial sources
and were used without further purification, unless otherwise
noted. CH2Cl2, used for the electrochemistry, was dried over
CaH2 and freshly distilled prior to use. Tetra-n-butylammonium
perchlorate (TBAP) was recrystallized twice from ethyl acetate
+ P(2Ng2b2/3kT) + Na
where Cꢀ = Ng2b2/k(T − h), x = J13/KT, N = 6.022 × 1023, g is the
g-factor, b is the Bohr magneton, k (Boltzmann) = 0.695 cm−1 K−1,
T is the absolute temperature in K, J13 is the coupling constant
between Ni(1) and Ni(3), v is the Weiss temperature (or Weiss
constant), Na is the temperature-independent paramagnetism
(TIP), and P is the relative content (fraction) for paramagnetic
impurity where spin state S = 1 is assumed.
and dried under vacuum. The dpaH,5–7 pepteaH4,16 LptsH2 and
21
21
LmsH2 ligands were synthesized according to the literature.
Physical measurements
Absorption spectra were recorded on Hewlett Packard model 8453
or JASCO V-570 spectrophotometers. IR spectra were obtained
using a Nicolet Fourier-Transform IR spectrometer in the range
of 500–4000 cm−1. FAB-MS mass spectra were obtained with a
JEOL HX-110 HF double focusing spectrometer operating in the
positive ion detection mode. Molar magnetic susceptibility was
recorded in the range of 5–300 K on a SQUID system with a
10 000 Ga external magnetic field. Electrochemical measurements
were performed with a three electrode potentiostat (CHI 750)
in a CH2Cl2 solution deoxygenated by purging with purified
nitrogen gas. Cyclic voltammetry was conducted with the use of a
homemade three electrode cell equipped with a BAS glassy carbon
(0.07 cm2) or platinum (0.02 cm2) disc as the working electrode,
a platinum wire as the auxiliary electrode, and a homemade
Ag/AgCl (sat’d) reference electrode. The reference electrode was
separated from the bulk solution by a double junction filled with
electrolyte solution. Potentials were reported vs. Ag/AgCl (sat’d)
and referenced to the ferrocene/ferrocenium (Fc/Fc+) couple
which occurs at E1/2 = +0.54 V vs. Ag/AgCl (sat’d). The working
electrode was polished with 0.03 lm aluminium on Buehler felt
pads and was treated with ultrasound for 1 min prior to each
experiment. The reproducibility of individual potential values
Fig. 9 Temperature dependent vMT (᭹) for compound 3. The solid line
represents the results of theoretical simulation.
J13 values were obtained by minimizing the function R = R
calcd
(XM
− XMobs)2/(R XMobs)2. The best fitting parameters obtained
were J13 = −125 cm−1, g = 2.0, TIP = 1.58 × 10−4, P = 0.017, and
h = −7.86 × 10−8 for compound 3 with a correlation coefficient
5688 | Dalton Trans., 2006, 5683–5690
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was within 5 mV. The spectroelectrochemical experiments were
accomplished with the use of a 1 mm cuvette, a 100 mesh platinum
gauze as working electrode, a platinum wire as auxiliary electrode,
and an Ag/AgCl (sat’d) reference electrode.
to remove the mononuclear complex. Crystals were obtained
by crystallization via slow diffusion of diethyl ether vapor into
−1
=
benzene. Yield 0.21 g (47%). IR (KBr, cm ) : 1686 (C O), 1601,
1530, 1434 (py); UV/Vis (CH2Cl2) kmax/nm (e/dm3 mol−1 cm−1):
290 (37 800), 322 (36 100), 366 (14 400); MS(FAB) m/z: 897
([Ni3(LAc)2(dpa)2]+); Anal. Calcd for C38H34N12Ni3O4: C, 50.78;
H, 3.81; N, 18.70; found C, 49.89; H, 3.93; N, 18.43%.
Syntheses
Preparation of N, Nꢀ-biacetylpyridyldiamine (LAcH2). Under
a nitrogen atmosphere, 2,6-diaminopyridine (5 g, 0.046 mol) was
added to a solution of acetic anhydride (10.4 mL, 0.055 mol) in 1,4-
dioxane (100 mL). The reaction mixture was heated at reflux for
24 h. After cooling to room temperature, the solvent was removed
using a rotary evaporator. Unreacted 2,6-diaminopyridine and
acetic anhydride were rinsed away with water. The resulting dark
material was purified by chromatography using silica gel and
dichloromethane–acetone (1 : 1) as the eluent to afford LAcH2
Preparation of [Ni3(Lpts)2(pepteaH2)] (4). LptsH2 (0.417 g,
1.0 mmol), pepteaH4 (0.447 g, 1.0 mmol), Ni(OAc)2·4H2O (0.375 g,
1.5 mmol) and naphthalene (20 g) were placed in an Erlenmeyer
flask. The resulting solution was stirred at 220 ◦C for 3 h.
After cooling the mixture to 80 ◦C, hexane (100 mL) was
added and the resulting precipitate was collected by filtration.
The solid was washed with CH2Cl2 and methanol to remove
the residual ligands and mononuclear complex. Crystals were
obtained by crystallization via slow diffusion of diethyl ether
vapor into DMF. Yield 0.23 g (32%). IR (KBr, cm−1): 1138,
1
as a white powder. Yield 6.31 g (72%). H NMR (400 MHz, d6-
dmso, d): 10.04 (s, 2H), 7.69 (m, 3H), 2.09 (s, 6H). Anal. Calcd for
C9H11N3O2: C, 55.95; H, 5.74; N, 21.75; found C, 55.37; H, 5.81;
N, 21.34%.
=
1085 (S O), 1577, 1447, 1430 (py); UV/Vis (DMF) kmax/nm
(e/dm3 mol−1 cm−1): 340 (49 300), 374 (26 300); MS (FAB) m/z:
1451 ([Ni3(Lpts)2(pepteaH2)]+), Anal. Calcd for C63H53N15Ni3O4:
C, 52.09; H, 3.68; N, 14.46; found C, 51.29; H, 3.81; N, 14.18%.
Preparation of [Ni3(Lpts)2(dpa)2] (1). LptsH2 (0.417 g,
1.0 mmol), dpaH (0.171 g, 1.0 mmol), Ni(OAc)2·4H2O (0.375 g,
1.5 mmol) and naphthalene (20 g) were placed in an Erlenmeyer
Preparation of [Ni3(Lpts)2(dpa)2](BF4) (5). To a solution of
[Ni3(Lpts)2(dpa)2] (134 mg, 0.10 mmol) in CH2Cl2 (50 mL) was
added NOBF4 (23 mg, 0.2 mmol) in CH3OH (1 mL). The resulting
mixture was stirred for 1 h and the precipitate removed by filtra-
tion. The solvent was removed under reduced pressure. Crystals
were obtained by crystallization via slow diffusion of diethyl ether
vapor into the solution. Yield 0.031 g (23%). IR (KBr, cm−1): 1138,
◦
flask. The resulting solution was stirred at 220 C for 3 h. After
cooling the mixture to 80 ◦C, hexane (100 mL) was added and the
resulting precipitate was filtered out. The solid was extracted with
CH2Cl2 and recrystallized from CH2Cl2 and methanol to remove
the mononuclear complex. The solid was filtered and then washed
with THF to remove the by-product Ni3(dpa)4(OAc)2. Crystals
were obtained by crystallization via slow diffusion of diethyl ether
vapor into the CH2Cl2. Yield 0.32 g (48%). IR (KBr, cm−1) :
=
1107 (S O), 1581, 1467, 1428 (py); UV/Vis (CH2Cl2) kmax/nm
(e/dm3 mol−1 cm−1): 320 (48 400), 366 (23 200), 420 (60 400), 640
(2580); MS (FAB) m/z: 1346 ([Ni3(Lpts)2(dpa)2]+); Anal. Calcd
for C58H50BF4N12–Ni3O8S4: C, 48.57; H, 3.51; N, 11.72; found C,
48.15; H, 3.54; N, 11.65%.
=
1140, 1109 (S O), 1583, 1467, 1431 (py); UV/Vis (CH2Cl2)
kmax/nm (e/dm3 mol−1 cm−1): 272 (55 600), 320 (73 300),366 (36
600); MS(FAB) m/z: 1346 ([Ni3(Lpts)2(dpa)2]+); Anal. calcd for
C58H50N12Ni3O8S4: C, 51.70; H, 3.74; N, 12.47; found C, 51.29; H,
3.83; N, 12.25%.
Preparation
of
[Ni3(Lms)2(dpa)2]
(6). Crystals
of
[Ni3(Lms)2(dpa)2(H2O)] (104 mg, 0.10 mmol) were left under
vacuum at 120 ◦C for 48 h. The color of the crystals changed from
dark black to brown. Crystals were obtained by crystallization
Preparation of [Ni3(Lms)2(dpa)2(H2O)] (2). LmsH2 (0.265 g,
1.0 mmol), dpaH (0.171 g, 1.0 mmol), Ni(OAc)2·4H2O (0.375 g,
1.5 mmol) and naphthalene (20 g) were placed in an Erlenmeyer
via slow diffusion of diethyl ether vapor into CH2Cl2. Yield 0.09 g
−1
◦
=
(98%). IR (KBr, cm ): 1128, 1081 (S O), 1604, 1574, 1470,
flask. The resulting solution was stirred at 220 C for 3 h. After
1430 (py); UV/Vis (CH2Cl2) kmax/nm (e/dm3 mol−1 cm−1): 316
(44 800), 366 (21 300); MS (FAB) m/z: 1042 ([Ni3(Lms)2-(dpa)2]+);
Anal. Calcd for C38H44N12Ni3O9S4: C, 40.85; H, 3.97; N, 15.05.11;
found C, 40.31; H, 3.88; N, 15.94%.
cooling the mixture to 80 ◦C, hexane (100 mL) was added and the
resulting precipitate was filtered out. The solid was extracted with
CH2Cl2 and recrystallized from CH2Cl2 and hexane. The solid
was filtered and then washed with THF to remove the by-product
[Ni3(dpa)4(OAc)2]. Crystals were obtained by crystallization via
X-Ray crystallographic determinations
slow diffusion of diethyl ether vapor into the CH2Cl2. Yield 0.28 g
−1
=
(54%). IR (KBr, cm ): 1128, 1081 (S O), 1604, 1574, 1470, 1430
Crystallographic information for 1–6 is summarized in Tables 1
and 2. The chosen crystals were mounted on a glass fiber. X-Ray
diffraction data for 1, 3, 4 and 6 were collected at 150 K on a
Nonius Kappa CCD diffractometer installed with monochroma-
(py); UV/Vis (CH2Cl2) kmax/nm (e/dm3 mol−1 cm−1): 316 (44 800),
366 (21 300); MS (FAB) m/z: 1042 ([Ni3(Lms)2-(dpa)2]+); Anal.
calcd for C34H34N12Ni3O8S4: C, 39.15; H, 3.29; N, 16.11; found C,
39.01; H, 3.38; N, 15.94%.
˚
tized Mo Ka radiation, k = 0.71073 A. Complexes 2, and 5 were
Preparation of [Ni3(LAc)2(dpa)2] (3). LAcH2 (0.193 g,
1.0 mmol), dpaH (0.171 g, 1.0 mmol), Ni(OAc)2·4H2O (0.375 g,
1.5 mmol) and naphthalene (20 g) were placed in an Erlenmeyer
collected at 150 K on a Bruker Smart ApexCCD diffractometer
˚
installed with monochromatized Mo Karadiation, k = 0.71073 A,
using SAINT (Version 6.22, Bruker) for cell constants from
global refinement. Cell parameters were retrieved and refined
using DENZOSMN software on all observed reflections.22 Data
reduction was performed with the DENZOSMN software.22 An
empirical absorption based on the symmetry-equivalent reflection
◦
flask. The resulting solution was stirred at 220 C for 3 h. After
cooling the mixture to 80 ◦C, hexane (100 mL) was added and
the resulting precipitate was filtered out. The solid was extracted
with CH2Cl2 and recrystallized from CH2Cl2–methanol (1 : 4)
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and absorption corrections was applied with the SORTAV
program.23 All the structures were solved by using SHELXS-97
8 (a) F. A. Cotton, L. M. Daniels, C. A. Murillo and I. Pascual, J. Am.
Chem. Soc., 1997, 119, 10223; (b) F. A. Cotton, L. M. Daniels, C. A.
Murillo and X. Wang, Chem. Commun., 1998, 39.
9 J. T. Sheu, C. C. Lin, I. Chao, C. C. Wang and S. M. Peng, Chem.
Commun., 1996, 315.
10 (a) F. A. Cotton, L. M. Daniels and G. T. Jordan IV, Chem. Commun.,
1997, 421; (b) F. A. Cotton, L. M. Daniels, G. T. Jordan IV and C. A.
Murillo, J. Am. Chem. Soc., 1997, 119, 10377.
11 S. J. Shieh, C. C. Chou, G. H. Lee, C. C. Wang and S. M. Peng, Angew.
Chem., Int. Ed. Engl., 1997, 36, 56.
24
software and refined with SHELXL-9725 by full-matrix least
squares on F2 values. Hydrogen atoms were fixed at calculated
positions and refined using a riding mode.
CCDC reference numbers 618763–618768. For crystallographic
data in CIF or other electronic format see DOI: 10.1039/b612123c
12 C. C. Wang, W. C. Lo, C. C. Chou, G. H. Lee, J. M. Chen and S. M.
Peng, Inorg. Chem., 1998, 37, 4059.
13 H. C. Chang, J. T. Li, C. C. Wang, T. W. Lin, H. C. Lee, G. H. Lee and
S. M. Peng, Eur. J. Inorg. Chem., 1999, 1243.
14 (a) S. Y. Lai, T. W. Lin, Y. H. Chen, C. C. Wang, G. H. Lee, M. H.
Yang, M. K. Leung and S. M. Peng, J. Am. Chem. Soc., 1999, 121, 250;
(b) S. Y. Lai, C. C. Wang, Y. H. Chen, C. C. Lee, Y. H. Liu and S. M.
Peng, J. Chin. Chem. Soc., 1999, 46, 477.
15 Y. H. Chen, C. C. Lee, C. C. Wang, G. H. Lee, S. Y. Lai, F. Y. Li, C. Y.
Mou and S. M. Peng, Chem. Commun., 1999, 1667.
16 S. M. Peng, C. C. Wang, Y. L. Jang, Y. H. Chen, F. Y. Li, C. Y. Mou
and M. K. Leung, J. Magn. Magn. Mater., 2000, 209, 80.
17 S. Y. Lai, T. W. Lin, Y. H. Chen, C. C. Wang, G. H. Lee, M. H. Yang,
M. K. Leung and S. M. Peng, J. Am. Chem. Soc., 1999, 121, 250.
18 F. A. Cotton, L. M. Daniel, C. A. Murillo and X. Wang, Inorg. Chem.,
2001, 40, 2778.
Acknowledgements
The authors acknowledge the National Science Council and
Ministry of Education of Taiwan for financial support.
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5690 | Dalton Trans., 2006, 5683–5690
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The Royal Society of Chemistry 2006
©