Zinc(II) and nickel(II) complexes based on schiff base ligands: Synthesis, crystal structure, luminescent and magnetic properties

Article abstract of DOI:10.1002/zaac.201300279

Three new phenolate oxygen bridged transition metal complexes [Zn ₃(HL¹)₃(μ₃-CH₃O)] ·(ClO₄)₂(H₂O)₃ (1), [Ni ₂(HL¹)₂(μ_1,1-N ₃)(o-vanillin)]·H₂O (2), [Ni₃(HL ²)₂(PhCOO)₂(PhCOOH)₂(EtOH) ₂] (3) have been synthesized by metal ions and potentially multidentate Schiff base ligands (H₂L¹ = 2-((1-hydroxy-2-methylpropan-2-ylimino) methyl)-6-methoxyphenol; H ₃L² = (E)-1-((2-hydroxy-3-methoxy-benzylidene)amino) ethane-1,2-diol). All the three complexes 1, 2, and 3 have been characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction studies. Crystal structures reveal that complex 1 is a trinuclear incomplete cubane-like zinc cluster whereas complex 2 is a dinuclear nickel complex bridged by azide, and compound 3 is a trinuclear nickel complex. The luminescent property for complex 1 and magnetic behaviors for complexes 2 and 3 have been investigated. Copyright

Full text of DOI:10.1002/zaac.201300279

ARTICLE
DOI: 10.1002/zaac.201300279
Zinc(II) and Nickel(II) Complexes Based on Schiff Base Ligands: Synthesis,
Crystal Structure, Luminescent and Magnetic Properties
Xiaoting Qin,[a] Yufei Ji,[a] Yanfei Gao,[a] Lei Yan,[a] Shuai Ding,[a] Yanqin Wang,[a] and
Zhiliang Liu*[a,b]
Keywords: Schiff base ligands; Zinc; Nickel; Luminescence; Magnetic properties
Abstract. Three new phenolate oxygen bridged transition metal com-
3 have been characterized by elemental analysis, FT-IR spectroscopy,
plexes [Zn3(HL1)3(μ3-CH3O)]·(ClO4)2(H2O)3 (1), [Ni2(HL1)2(μ1,1-N3) and single-crystal X-ray diffraction studies. Crystal structures reveal
(o-vanillin)]·H2O (2), [Ni3(HL2)2(PhCOO)2(PhCOOH)2(EtOH)2] (3) that complex 1 is a trinuclear incomplete cubane-like zinc cluster
have been synthesized by metal ions and potentially multidentate whereas complex 2 is a dinuclear nickel complex bridged by azide,
Schiff base ligands (H2L1 = 2-((1-hydroxy-2-methylpropan-2-ylimino)
methyl)-6-methoxyphenol; H3L2
(E)-1-((2-hydroxy-3-methoxy-
and compound 3 is a trinuclear nickel complex. The luminescent prop-
erty for complex 1 and magnetic behaviors for complexes 2 and 3 have
=
benzylidene)amino)ethane-1,2-diol). All the three complexes 1, 2, and been investigated.
Scheme 1). The Schiff base H2L1 is a tetradentate ligand fea-
Introduction
turing NO3 (one nitrogen atom and three oxygen atoms) donor
sites whereas H3L2 is a new pentadentate Schiff base ligand
accompanying NO4 (one nitrogen atom and four oxygen
atoms) donor sites. Our intention is the use of these two Schiff
base ligands with zinc and nickel ions to construct numbers of
new polynuclear complexes with aesthetically pleasing struc-
tures and fascinating properties. Finally, three new complexes
were synthesized and structurally characterized by single-crys-
tal X-ray diffraction.
Transition-metal complexes are of unabated interest because
of their fascinating structural topologies, such as poly-nuclear
clusters,[1] one-dimensional chains,[2] two-dimensional lay-
ers,[3] and three-dimensional frameworks especially MOFs
(metal-organic frameworks),[4] and potential applications in a
wide range of areas as functional materials including magnet-
ism,[5] luminescence,[6] catalysis,[7] sensors,[8] nonlinear op-
tics,[9] and ion exchange.[10] In general, the structural motifs
and properties of these hybrid compounds are closely related
to the metal centers and the coordinated multidentate ligands.
Schiff bases are a preferred ligand class for cluster synthesis,
since a) they are polydentate ligands with diverse N and O
donor sites, b) they exhibit various coordination modes, and c)
the multiple coordination/ ligation modes of these ligands eas-
ily lead to the synthesis of coordination complexes. For the
metal centers, much attention has been focused on the zinc(II)
and nickel(II) complexes. A number of studies concentrate on
zinc(II) Schiff base complexes in terms of luminescence[11]
and catalysis.[12] The design and synthesis of nickel(II) com-
pounds based on Schiff base chelates arouses continuous inter-
ests for their interesting magnetic properties.[13]
Scheme 1. Structure of Schiff base ligands in this paper.
Results and Discussion
Description of Crystal Structures
In this work, o-vanillin reacts with amino alcohol 2-amino-
2-methyl-1-propanol and 3-amino-1,2-propanediol to obtain
the Schiff base ligands H2L1[14] and H3L2, respectively (see
Structure of [Zn3(HL1)3(μ3-CH3O)]·(ClO4)2(H2O)3 (1)
X-ray crystallographic analysis shows that complex 1 crys-
¯
tallizes in the triclinic space group P1. The structure of 1 con-
sists of a [Zn3(HL1)3(μ3-CH3O)]2+ cation, two isolated per-
chlorate anions and three solvent water molecules. Selected
bond lengths and angles for complex 1 are presented in
Table 1. As shown in Figure 1, the trinuclear zinc(II) core of
complex 1 consists of three metal ions, one deprotonated meth-
anol group and three Schiff base ligands (HL1)–, which acts in
a tetradentate mode. The coordination environments of the
* Prof. Dr. Z. Liu
Fax: +86-471-4992147
E-Mail: cezlliu@imu.edu.cn
[a] College of Chemistry and Chemical Engineering
Inner Mongolia University
Hohhot, 010021, P. R. China
[b] Key Lab of Nanoscience and Nanotechnology
Inner Mongolia
Hohhot, 010021, P. R. China
462
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Z. Anorg. Allg. Chem. 2014, 640, (2), 462–468

ZnII and NiII Complexes Based on Schiff Base Ligands
Table 1. Selected bond lengths /Å and bond angles /° for complex 1.
bond lengths /Å
Zn1–N1
Zn1–O1
Zn1–O2
Zn1–O3
2.028(5)
2.130(4)
2.142(5)
2.013(4)
Zn1–O6
Zn2–N2
Zn2–O1
Zn2–O5
1.979(4)
2.026(5)
2.101(4)
2.101(6)
Zn2–O6
Zn2–O9
Zn3–N3
Zn3–O1
2.012(4)
1.989(4)
2.026(5)
2.097(4)
Zn3–O3
Zn3–O8
Zn3–O9
1.970(5)
2.124(6)
1.999(4)
bond angles /°
N1–Zn1–O1
N1–Zn1–O2
O1–Zn1–O2
O3–Zn1–N1
O3–Zn1–O1
O6–Zn1–O1
O6–Zn1–O2
131.60(18)
79.8(2)
O6–Zn1–O3
N2–Zn2–O1
N2–Zn2–O5
O5–Zn2–O1
O6–Zn2–N2
O6–Zn2–O1
O9–Zn2–N2
102.45(19)
136.7(2)
78.9(2)
95.5(2)
88.7(2)
O9–Zn2–O1
O9–Zn2–O5
O9–Zn2–O6
N3–Zn3–O1
N3–Zn3–O8
O1–Zn3–O8
81.03(17)
97.3(2)
104.6(2)
135.31(19)
78.5(2)
O3–Zn3–N3
O3–Zn3–O1
O3–Zn3–O8
O3–Zn3–O9
O9–Zn3–N3
O9–Zn3–O1
142.90(19)
81.32(17)
96.6(2)
104.4(2)
90.0(2)
93.37(19)
89.53(19)
79.54(18)
79.99(17)
96.4(2)
79.97(17)
142.2(2)
93.3(2)
80.88(17)
three metal atoms are similar; each of them is hexacoordinated Figure 2. Selected bond lengths and angles for complex 2 are
exhibiting considerably distorted octahedral geometry. The six presented in Table 2. The structure of 2 consists of a neutral,
coordination sites of Zn1 are occupied by phenolate oxygen well-separated binuclear unit [Ni2(HL1)2(μ1,1-N3)(o-vanillin)]
O3 and O6, hydroxyl oxygen O2, alkoxyl O7, imino N1 from and one crystallographic water molecule. The metal atoms of
two different Schiff base ligands and oxygen atom O1 of the the dinuclear compound are linked by one nitrogen atom N3
μ3-methanol oxygen atom. Three central metal ions intercon- from the azide group in end-on (EO) fashion and one phenolate
nect through two types of oxygen bridges afforded by the μ2- oxygen atom O1 from o-vanillin in a tridentate manner. Each
phenolate oxygen from Schiff base ligand and the μ3-oxygen nickel ion is coordinated to one Schiff base ligand (HL1)–,
from deprotonated methanol group, respectively, constituting which acts in a tridentate mode, with one hydroxy oxygen
an incomplete cubane-like [Zn3O4]2+ core with the Zn–O bond atom, one deprotonated phenolate oxygen atom and one imino
lengths in the range of 1.963(6)–2.137(7) Å. In the incomplete nitrogen atom coordinated. The NiII ions are hexacoordinated
cubane-like [Zn3O4]2+ core, the Zn–O–Zn’ angles are in the exhibiting slightly distorted octahedral coordination environ-
range of 94.962(2)–103.665(3)° and the O–Zn–O’ angles are ment. The equatorial plane for Ni1 consists of the imino N1,
in the range of 79.403(2)–81.230(2)°, which are in accordance phenolate oxygen O1, alkoxyl O3 and N3 from azide group.
with those in previously reported cubane-like complexes.[15]
The axial positions of Ni1 are occupied by phenolate oxygen
O5 and hydroxyl oxygen O4 both from Schiff base ligand.
The Ni2 ion shows similar coordination geometry except that
aldehyde oxygen instead of alkoxyl in the axial. The Ni–O
distances are in the range of 1.978(2)–2.300(3) Å and Ni–N
distances are in the range of 1.993(3)–2.150(2) Å. The Ni···Ni
distance between two central metal ions is 3.1822(7) Å. All
these distances are very close to those of the previously re-
ported Ni2 complexes.[16] Furthermore, intra- and inter- molec-
ular hydrogen bonding interactions existing in the complex as
Figure 1. Coordination environment for complex 1, the hydrogen
atoms, solvent molecules and perchlorate counterion are omitted for
clarity.
Structure of [Ni2(HL1)2(μ1,1-N3)(o-vanillin)]·H2O (2)
X-ray crystallographic analysis shows that complex 2 crys-
¯
tallizes in the triclinic space group P1. A perspective view
Figure 2. Coordination environment for complex 2, the hydrogen
of the molecule structure with atom numbering is depicted in atoms and solvent molecule are omitted for clarity.
Z. Anorg. Allg. Chem. 2014, 462–468
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X. Qin, Y. Ji, Y. Gao, L. Yan, S. Ding, Y. Wang, Z. Liu
ARTICLE
Table 2. Selected bond lengths /Å and bond angles /° for complex 2.
bond lengths /Å
Ni1–O1
Ni1–O5
Ni1–N1
2.008(2)
1.978(2)
1.993(3)
Ni1–O4
Ni1–N3
Ni1–O3
2.101(2)
2.101(3)
2.300(3)
Ni2–O1
Ni2–O8
Ni2–N2
2.005(2)
1.970(2)
1.996(3)
Ni2–O7
Ni2–N3
Ni2–O2
2.093(2)
2.150(2)
2.087(2)
bond angles /°
O1–Ni1–O4
O1–Ni1–N3
O1–Ni1–O3
O5–Ni1–O1
O5–Ni1–N1
O5–Ni1–N3
86.78(9)
77.80(9)
73.67(9)
99.84(9)
92.63(10)
97.37(10)
O5–Ni1–O3
N1–Ni1–O4
N1–Ni1–N3
N1–Ni1–O3
O4–Ni1–O3
N3–Ni1–O4
84.43(10)
80.32(10)
104.60(10)
103.94(10)
89.48(10)
92.18(10)
O1–Ni2–O7
O1–Ni2–N3
O1–Ni2–O2
O8–Ni2–O1
O8–Ni2–N2
O8–Ni2–N3
94.22(9)
76.72(9)
87.52(9)
92.57(9)
92.39(10)
91.03(10)
O8–Ni2–O2
N2–Ni2–O7
N2–Ni2–N3
N2–Ni2–O2
O7–Ni2–N3
O2–Ni2–O7
93.10(10)
80.86(10)
101.87(10)
93.52(10)
92.24(10)
85.44(10)
listed in Table 3. As shown in Figure 3, hydroxyl group – Figure 4, this compound contains three hexacoordinate nickel
O4H4 is hydrogen bonded to the alkoxyl oxygen atom O9 and ions which are bonded to two Schiff base ligands, two ethanol
the phenolate oxygen atom O8. Two hydrogen atoms H10D, molecules and four benzoates with two different types of coor-
H10E of the lattice water molecular are engaged in two hydro- dination of carboxylic groups. The Schiff base ligand acts in a
gen bonding, respectively. And the oxygen atom O10 of the tetradentate mode. The metal atoms Ni1 and Ni2 are connected
lattice water molecular is hydrogen bonded to the hydroxyl through one deprotonated μ2-phenolate oxygen atom of ligand
group –O7H7 to result in an H-bonded dimeric entity.
(HL2)2– and one μ2-carboxyl group of benzoate ion. Finally,
there are two monocoordinated PhCOOH molecules to com-
plete the coordination sphere of Ni2 and Ni2A. The central
metal Ni1 atom is bonded to six oxygen atoms in a slightly
distorted octahedral coordination environment with the Ni1–O
distances in a range of 2.023(3)–2.088(3) Å, and the O–Ni1–
O’ angles in a range of 78.15(12)–102.51(12)°. The other two
metallic atoms Ni2 and Ni2A are surrounded by five oxygen
atoms and one nitrogen atom with slightly distorted octahedral
arrangement. The Ni2–O distances are in the range of
2.029(3)–2.129(3) Å and Ni2–N distance is 2.014(4) Å. The
Ni···Ni distance between two adjacent nickel atoms is
3.4841(12) Å, the Ni2···Ni1···Ni2A angle is 146.247(14)°. All
of them are within the normal range as reported in other litera-
ture.[17]
Table 3. Hydrogen bond lengths /Å and bond angles /° for complex 2.
D–H···A
d(D–H)
d(H···A)
d(D···A)
DHA
O7–H7···O101
O4–H4···O8
0.840(10)
0.849(10)
0.849(10)
0.844(10)
0.844(10)
0.846(10)
0.846(10)
2.107(13)
1.775(18)
2.56(4)
2.59(5)
1.88(3)
2.10(5)
2.50(6)
2.888(5)
2.593(3)
3.118(4)
3.128(4)
2.664(4)
2.756(3)
2.960(4)
155(2)
161(4)
125(3)
123(5)
154(6)
133(6)
115(5)
O4–H4···O9
O10–H10D···O12
O10–H10D···O72
O10–H10E···O52
O10–H10E···O62
1
Symmetry transformations used to generate equivalent atoms: 1–x,
2
2–y, –z; –1+x, +y, +z.
Luminescent Properties
The fluorescence properties of the Schiff base ligand H2L1
and its ZnII complex 1 were investigated at room temperature
(298 K) in the solid state (see Figure 5). Upon the irradiation
of ultraviolet light, the emission maximum wavelength for
complex 1 is 483 nm upon excitation 395nm, and the emission
maximum wavelength for the H2L1 ligand is 540 nm upon
excitation 468 nm. The emission spectrum shows that the ZnII
complex 1 displays much stronger emission intensity than that
of Schiff base ligand H2L1 with a slightly blue-shift. The
weaker fluorescence of the ligand is related to the occurrence
of a photoinduced electron transfer (PET) process due to the
presence of a lone pair of electrons of the donor atoms in the
ligand (N, O-donor).[18] Complex 1 exhibits stronger emission
fluorescence tentatively attributable to the PET process is pre-
Figure 3. Hydrogen bonding interactions of complex 2.
Structure of [Ni3(HL2)2(PhCOO)2(PhCOOH)2(EtOH)2] (3)
X-ray crystallographic analysis shows that complex 3 crys- vented by the complexation of ligand with metal ions. Further-
tallizes in the monoclinic space group C2/c. Half of the neutral more, the fluorescence intensity may be greatly enhanced by
compound 3 is contained in the asymmetric unit, with the other the ligation between the ligand and the stable d10 zinc metal
half generated by a twofold axis. Selected bond lengths and centers which effectively increases the rigidity of the ligand
angles for complex 3 are presented in Table 4. As shown in and reduces the loss of energy by nonradioactive decay.[19]
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ZnII and NiII Complexes Based on Schiff Base Ligands
Table 4. Selected bond lengths /Å and bond angles /° for complex 3.
bond lengths /Å
Ni1–O1
Ni1–O6
Ni1–O7
2.024(3)
2.033(3)
2.086(3)
Ni2–O2
Ni2–O3
2.028(3)
2.053(4)
Ni2–O5
Ni2–O6
2.122(3)
2.029(3)
Ni2–O8
Ni2–N1
2.129(3)
2.009(4)
bond angles /°
O1–Ni1–O11
O11–Ni1–O61
O1–Ni1–O61
O11–Ni1–O7
O6–Ni1–O7
88.86(17)
102.36(11)
85.67(11)
91.29(13)
78.25(11)
O6–Ni1–O71
O71–Ni1–O7
N1–Ni2–O3
N1–Ni2–O5
N1–Ni2–O6
93.71(11)
88.56(19)
89.55(18)
81.49(14)
91.81(14)
N1–Ni2–O8
O2–Ni2–O3
O2–Ni2–O5
O2–Ni2–O6
O2–Ni2–O8
90.91(17)
89.79(13)
88.18(12)
98.55(12)
90.11(12)
O3–Ni2–O5
O5–Ni2–O8
O6–Ni2–O3
O6–Ni2–O8
90.47(13)
91.46(12)
93.22(13)
84.89(12)
1
Symmetry transformations used to generate equivalent atoms: 1–x, +y, 1/2–z.
Figure 4. Coordination environment for complex 3, the hydrogen
atoms are omitted for clarity.
Figure 6. Plots of χM and χMT vs. T for complex 2. The solid lines
represent the best fits.
Figure 7. Plots of χM and χMT vs. T for complex 3. The solid lines
represent the best fits.
Figure 5. Normalized emission spectra of Schiff base ligand H2L1 and
complex 1 in the solid state at room temperature.
At room temperature, magnetic susceptibility data per
[Ni2ON] entity for 2 shows a χMT value of 2.13 cm3 mol–1
(see Figure 6) which is very close to the spin only value of
K
Magnetic Properties
The magnetic properties of complexes 2 and 3 were studied two NiII ions (2 cm3 mol–1 K). Plots of χMT vs. T increase
to evaluate the magnetic interactions between the metallic ion with decreasing temperature and reach a maximum at 20 K
centers. Variable temperature magnetic susceptibility measure- then follows by a rapidly decrease until 2 K. This behavior
ments from 2 to 300 K under a constant magnetic field of 1 indicates a characteristic feature of intramolecular ferromag-
kOe were carried out. The χMT and χM vs. T plots are shown netic interactions between metal centers of 2. The sharp de-
in Figure 6 and Figure 7 for compound 2 and 3, respectively.
crease of χMT value at very low temperature region may be
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X. Qin, Y. Ji, Y. Gao, L. Yan, S. Ding, Y. Wang, Z. Liu
ARTICLE
attributed to zero-field splitting phenomenon. According to the atom from Schiff base ligands. The solid state luminescent
structure of complex 2, two central ions are bridged through spectra demonstrates complex 1 displays much stronger emis-
nitrogen atom of EO azide group and phenolate oxygen atom sion intensity than that of Schiff base ligand H2L1 with a
from Schiff base ligand H2L1. According to the literature, the slightly blue-shift. The fitting magnetic results confirm that
ferromagnetic interaction between NiII ions has been observed complex 2 exhibits ferromagnetic coupling whereas complex
in μ2-phenolate oxygen bridged[20] and EO azide bridged[21] 3 exhibits antiferromagnetic coupling between the NiII ions.
binuclear nickel complexes. Actually, in the case of EO-azide The next work to design and synthesize nickel and zinc com-
bridging mode, the coupling between the bridged paramagnetic plexes with various nuclear numbers which may exhibit inter-
metal ions is ferromagnetic for a wide range of M–N–M esting properties and applications is under investigation in our
angles.[22]
lab.
For the theoretical analysis of the magnetic behavior of
compound 2, the analytical expression based upon the Hamil-
tonian[23] was used.
Experimental Section
General: o-Vanillin, 2-amino-2-methyl-1-propanol, 3-amino-1,2-pro-
panediol were obtained from Aldrich. The other reagents were all labo-
ratory originally. All the starting reagents were of A.R. grade and were
used as purchased. Elemental analyses for carbon, hydrogen and nitro-
gen were carried out with a Perkin–Elmer 2400 Elemental Analyzer.
Fourier transform infrared (FTIR) spectra were recorded with a Bruker
Tensor 27 spectrophotometer using the reflectance technique (4000–
400 cm–1). Samples were prepared as KBr disks. The luminescence
spectra for the powdered solid samples were measured at room tem-
perature on a FLS920 fluorescence spectrophotometer. The excitation
slit and the emission slit were 0.5 nm. Variable temperature magnetic
susceptibility measurements were performed in the temperature range
2–300 K using a Quantum Design MPMS XL-7 SQUID magnetometer
at a magnetic field of 1000 Oe. The diamagnetic corrections for the
compounds were estimated using Pascal’s constants, and magnetic data
were corrected for diamagnetic contributions of the sample holder.
Accordingly, the temperature dependence of the magnetic
susceptibility of compound 2 was fitted, in which J is the usual
intramolecular exchange parameter, D is the zero-field splitting
term of the 3A2 ground state. The best fit using the above
equation was obtained with values of J = 6.69 cm–1,
D = –11.68 cm–1, g = 2.01 and the agreement factor R =
Σ[(χM)obs–(χM)calc]2/Σ [(χM)obs]2 = 7.55ϫ 10–4. This result in-
dicates that the complex 2 undergoes a ferromagnetic spin-
exchange interaction between the metal ions. The coupling in-
teractions in the binuclear magnetic entity are relatively strong,
which is consistent with the reported binuclear NiII complex
in literature.[24]
As shown in Figure 7, the χMT value of 2.98 cm3 mol–1
K
at room temperature for complex 3 is slightly lower than the
Synthesis of Schiff Base Ligands: The Schiff base ligand H2L1 was
prepared as described elsewhere.[14] The Schiff base ligand H3L2 was
synthesized by a reflux reaction between o-vanillin (760 mg, 5 mmol)
and 3-amino-1,2-propanediol (455 mg, 5 mmol) in methanol (10 mL).
The resulting orange yellow solution containing the required product
was used without further purification. The concentration of both li-
gands solution is 0.5 mmol mL–1.
II
spin-only (g = 2) value of 3 cm3 mol–1 K expected for a Ni3
unit. As the temperature decreases, χMT decreases smoothly
until 50 K, on further cooling the χMT value starts decreasing
abruptly to 1.01 cm3 mol–1 K at 2.0 K. This behavior indicates
the typical antiferromagnetic interactions between the mag-
netic centers. According to the trinuclear nickel core structure
of complex 3, the coupling mode can be expressed as the spin
[Zn3(HL1)3(μ3-CH3O)]·(ClO4)2(H2O)3 (1): Zn(ClO4)2·6H2O (186 mg,
0.5 mmol) was added to a solution of H2L1 (1 mL, 0.5 mmol) in meth-
anol/dichloromethane (24 mL, 1:2 v/v). The mixture was filtered after
further stirring for 20 min and a light yellow solution was obtained.
After several days standing at room temperature, yellow crystals suit-
able for X-ray diffraction analysis were collected. Yield: ca. 54%
based on Zn(ClO4)2·6H2O. Elemental analysis: C37H51Cl2N3O21Zn3
(1140.82): C 54.54 (calcd. 54.01); H 4.68(calcd. 4.88), N 2.37(calcd.
2.36)%. IR (KBr, selected data): v = 3421 (m), 3157 (m), 2972 (m),
2835 (w), 1629 (s), 1562 (w), 1467 (s), 1400 (s), 1305 (m), 1247 (s),
1107 (s), 968 (m), 858 (w), 736 (s), 624 (s), 567 (w), 470 (w) cm–1.
Hamiltonian[25] H = –2J (S1S2 + S2S3). Thus, the temperature
dependence of χM was modeled. Least-squares best-fit param-
eters are J = –1.28 cm–1, g = 2.01 and R = 2.34 ϫ 10–4 (R =
Σ[(χM)obs–(χM)calc]2/Σ[(χM)obs]2). The above model provides a
good fit over the temperature range 2–300 K. This result indi-
cates that the complex 3 undergoes a weak antiferromagnetic
spin-exchange interaction between the metal ions. The cou-
pling interactions in the trinuclear magnetic entity are weak,
which is consistent with the reported trinuclear NiII complex
in former literature.[26]
ˆ
ˆ ˆ
ˆ ˆ
[Ni2(HL1)2(μ1,1-N3)(o-vanillin)]·H2O (2): Ni(ClO4)2·6H2O (176 mg,
0.5 mmol) was dissolved in a solution of H2L1 (1 mL, 0.5 mmol) in
methanol/dichloromethane (24 mL, 1:2 v/v). Afterwards, NaN3
(65 mg, 1 mmol) in 1 mL aqueous solution was added dropwise with
stirring. The mixture was filtered after further 20 min stirring, the re-
sulting dark green solution was obtained. After several days standing
at room temperature, diamond-shaped dark green crystals that suitable
for X-ray diffraction analysis were collected. Yield: ca. 61% based
on Ni(ClO4)2·6H2O. Elemental analysis: C32H41N5Ni2O10 (773.12): C
49.21 (calcd. 49.59), H 5.14 (calcd. 5.59), N 9.54 (calcd. 9.04)%. IR
Conclusions
One novel zinc(II) complex [Zn3(HL1)3(μ3-CH3O)]·
(ClO4)2(H2O)3 (1) and two new nickel(II) complexes
[Ni2(HL1)2(μ1,1-N3)(o-vanillin)]·H2O (2), [Ni3(HL2)2(PhCO O)2-
(PhCOOH)2·(EtOH)2] (3) have been synthesized by using
metal ions and potentially multidentate Schiff base ligands.
Single crystal X-ray diffraction reveal that central metal ions
in complexes 1, 2 and 3 are all bridged by phenolate oxygen (KBr, selected data): v = 3427 (m), 3159 (m), 1633 (m), 1556 (m),
466 www.zaac.wiley-vch.de
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2014, 462–468

ZnII and NiII Complexes Based on Schiff Base Ligands
Table 5. Crystallographic data and structure refinements for complexes 1–3.
1
2
3
Empirical formula
Formula weight
Temperature /K
Crystal system
Space group
a /Å
b /Å
c /Å
α /°
β /°
Zn3C37H57Cl2N3O21
1146.92
293(2)
Ni2C32H43N5O10
776.12
296(2)
Ni3C54H58N2O18
1199
293(2)
monoclinic
C2/c
21.551(4)
9.2719(19)
29.551(6)
90.00
triclinic
triclinic
¯
¯
P1
P1
13.420(2)
13.617(2)
17.866(2)
69.577(13)
82.469(12)
60.492(16)
2659.4(7)
10.1165(16)
12.5769(19)
14.218(2)
74.4670(10)
84.084(2)
83.050(2)
1725.4(5)
2
103.47(3)
90.00
5742(2)
γ /°
Volume /Å3
Z
2
4
ρcalc /mg·mm–3
1.430
1.514
1.488
1.154
1.387
1.044
μ /mm–1
F(000)
1180.0
812.0
2496.0
Theta range/°
Index ranges (h, k, l)
5.86 to 50.04°
–14 Յ h Յ 15
–15 Յ k Յ 16
–21 Յ l Յ 21
17215
4.86 to 50°
–12 Յ h Յ 11
–14 Յ k Յ 14
–16 Յ l Յ 16
11852
4.8 to 50.02°
–24 Յ h Յ 25
–11 Յ k Յ 11
–34 Յ l Յ 33
22229
Reflections collected
Data/restraints/parameters
9348/260/715
1.054
5970/7/461
1.041
5007/1146/367
1.102
Goodness-of-fit on F2
Final R indexes [I Ն 2σ (I)]
Final R indexes [all data]
R1 = 0.0751, wR2 = 0.2180
R1 = 0.0978, wR2 = 0.2446
R1 = 0.0374, wR2 = 0.0929
R1 = 0.0520, wR2 = 0.1037
R1 = 0.0845, wR2 = 0.1954
R1 = 0.0969, wR2 = 0.2031
2
2 2
2 2
a) R = Σ||Fo|–|Fc||/Σ|Fo|, b) wR = [Σ[w(Fo – Fc ) ]/Σ[(wF0 ) ]]1/2
.
1465 (s), 1404 (s), 1303 (m), 1218 (s), 1105 (s), 972 (w), 860 (w), 738 the data can be obtained free of charge on quoting the depository
(m), 626 (m), 470 (w) cm–1.
numbers CCDC-942647, CCDC-942648, and CCDC-942649
(Fax: +44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk,
http://www.ccdc.cam.ac.uk).
[Ni3(HL2)2(PhCOO)2(PhCOOH)2(EtOH)2] (3): NiCl2·6H2O (238 mg,
1 mmol) was added to a solution of H3L2 (2 mL, 1 mmol) in ethanol
(20 mL), afterwards Et3N (200 mg, 2 mmol) and formic acid (92 mg,
2 mmol) were added to the mixture. The solution was stirred for Acknowledgments
30 min, and afterwards sodium benzoate (144 mg, 1 mmol) was added
with stirring. The resulting dark green solution was filtered after being
stirred for another 30 minutes at room temperature. Upon slow evapo-
ration of the solvents, dark green crystals formed from the filtrate in
a few days. Yield: ca. 58% based on NiCl2·6H2O. Elemental analysis:
Ni3C54H58N2O18 (1199): C 53.98 (calcd. 54.09) H 4.90 (calcd. 4.87)
N 2.45 (calcd. 2.34). IR (KBr, selected data): v = 3787 (w), 3413 (s),
2942 (m), 2047 (w), 1658 (s), 1600 (s), 1550 (s), 1398 (s), 1288 (m),
1217 (s), 1078 (m), 848 (w), 724 (m), 681 (m) cm–1.
Financial support by the National Natural Science Foundation of China
(21061009) and Inner Mongolia Autonomous Region Fund for Natural
Science (2013ZD09) are kindly acknowledged.
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Z. Anorg. Allg. Chem. 2014, 462–468