Four polynuclear complexes based on a versatile salicylamide salen-like ligand: Synthesis, structural variations and magnetic properties

Article abstract of DOI:10.1016/j.ica.2015.09.022

Four new polynuclear complexes based on a versatile asymmetric ligand, [Cu₂(H₂L)₂Cl₂] (1), [Cu₄(H₂L)₂(L)₂]·4CH₃OH (2), [MnL]_n (3), [Er₂

Full text of DOI:10.1016/j.ica.2015.09.022

Inorganica Chimica Acta 438 (2015) 232–244
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Inorganica Chimica Acta
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Four polynuclear complexes based on a versatile salicylamide salen-like
ligand: Synthesis, structural variations and magnetic properties
⇑
Xue-Qin Song , Pan-Pan Liu, Zhou-Rong Xiao, Xia Li, Yuan-Ang Liu
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Four new polynuclear complexes based on
a versatile asymmetric ligand, [Cu2(H2L)2Cl2] (1),
Received 7 September 2015
Received in revised form 26 September 2015
Accepted 28 September 2015
Available online 9 October 2015
[Cu4(H2L)2(L)2]ꢀ4CH3OH (2), [MnL]n (3), [Er2(HL)2(NO3)4]ꢀ4CH3CN (4), H3L = 2-hydroxy-N-(2-((2-hydrox-
ybenzylidene)amino)ethyl)benzamide], were prepared and structurally characterized. The coordination
behavior as well as deprotonation of the H3L in the four complexes reveal considerable variations
depending on the metal ions as well as counter anion. The hydroxyl-bridged dinuclear complex 1 with
a Cu–O–Cu–O four-membered ring was obtained when copper chloride was used as metal source. The
tetranuclear complex 2 with two Cu–O–Cu–O four-membered rings which bridged both through hydroxy
and amide group was obtained using copper acetate instead. Reacting the ligand with manganese acetate
yielded complex 3 which exhibits 1-D zig–zag chains only bridged through amide group. While complex
4 which holds a dinuclear one by aid of hydroxyl-bridge without nitrogen atom participating in
coordination when erbium nitrate was introduced. The experimental magnetic susceptibilities indicate
1, 2 and 4 exhibit antiferromagnetic interactions through hydroxy bridge, while 3 exhibits dominant
antiferromagnetic interactions with spin canting through the amido bridge.
Keywords:
Multidentate ligand
Polynuclear complex
Crystal structure
Magnetic properties
Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
Multidentate organic ligands based on N- and O-donors have
been witnessed to be excellent structural constructors due to their
Polynuclear metal complexes exhibit a fascinating variety of
unusual symmetries and structural patterns [1]. The potentially
important functions in magnetic behavior [2], optical materials
[3], catalytic [4] and biological activities [5] add to their interest
and significance. The possibility of obtaining multifunctional mate-
rials comes from the structure and flexibility for structural design
of these compounds. However, the rational construction of desir-
able architectures remains a long-term challenge due to the wide
range of factors which may influence structures of coordination
compounds, including organic ligand, metal ion, solvent system,
pH value of the solution, the metal-to-ligand ratio, counter anions,
etc [6]. Among these, the organic ligand is an important factor
undoubtedly. On the other hand, metal ions, especially their radii
and coordination geometry, determine the extending directions
important for the structure of the complexes. Therefore, much
more work is required to establish proper synthetic strategies that
can lead to the desired species with predictable structures and
properties.
various coordination modes related to metal ions. Up to now, a
number of polynuclear compounds with chelating-bridging
organic ligands based on N- and O-donors have received consider-
able attention because they can incorporate virtues of different
functional groups and it is easier to get architecture controlled
by delicate modification [7–10]. In addition, salicylamide
salen-like ligands are alterative excellent ligands because of their
interesting features as follows: (a) they have multiple O- and
N-coordination sites together with hydrogen-bond acceptors as
well as hydrogen bond donors, which are good candidates for the
assembly of novel 3d, 4f or 3d–4f architectures; (b) they have
abstractable protons that allow various acidity dependant
coordination modes, and as a result different structures can be con-
structed via changing only the pH values while using the same
reagents; (c) This kind of ligands can be good choices to construct
coordination compounds because the flexible nature of spacers
between the amide and imine groups allow the ligands to bend
and rotate to adapt somewhat to the changing size of the host
metal ions. However, there are few reports on compounds base
on salicylamide salen-like ligands. To date, some Mn(III) CPs with
ligands incorporating salicylamide derivatives have been isolated
[11,8a], and the previously results showed that substituted groups
⇑
Corresponding author. Tel./fax: +86 931 4938755.
E-mail address: songxq@mail.lzjtu.cn (X.-Q. Song).
http://dx.doi.org/10.1016/j.ica.2015.09.022
0020-1693/Ó 2015 Elsevier B.V. All rights reserved.

X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
233
of this kind of ligands can impact the coordination structures as
well as the magnetic properties effectively. This observation
prompted us to extend the synthesis of this kind of ligands
together with their complexes.
give a yellow solid which was washed with diethyl ether and dried in
air. H3L: 2.16 g, Yield 76.0%. m.p. 135–136 °C. Anal. Calc. for
C
16H16N2O3: C, 67.59; H, 5.67; N, 9.85. Found: C, 67.81, H, 5.65, N,
9.87%; IR (KBr,
t
, cmꢁ1): 3381 (w), 1633 (s), 1594 (s), 1553 (s),
In the present work, two transition metal elements, MnII and CuII,
and one lanthanide element, ErIII, are selected to investigate metal
ion effects on the coordination ability of the ligand. As a result, four
new complexes which were determined by single-crystal X-ray
diffraction analyses and further characterized by elemental analysis,
infrared spectra (IR), thermogravimetric analysis (TGA) and powder
X-ray diffraction (PXRD) were obtained: [Cu2(H2L)2Cl2] (1),
[Cu4(H2L)2(L)2]ꢀ4CH3OH (2), [MnL]n (3), [Er2(HL)2(NO3)4]ꢀ4CH3OH
(4). Their magnetic properties were investigated and the results
indicate 1, 2 and 4 exhibit antiferromagnetic interactions through
hydroxy bridge, while 3 exhibits dominant antiferromagnetic
interactions with spin canting through the amido bridge.
1490 (m), 1449 (m), 1360 (m), 1276 (m), 1230(m), 823 (m), 781
(m), 753 (s). 1H NMR (CDCl3, 400 MHz): d: 3.80 (m, 2H, CH2), 3.85
(m, 2H, CH2), 6.71 (s, 1H, ArH), 6.80 (m, 1H, ArH), 6.88 (m, 1H,
ArH), 6.97 (m, 1H, ArH), 7.23(m, 1H, ArH), 7.35 (m, 3H, CH@N),
8.41 (t, 1H, NH, J = 4 Hz), 12.21(s, 2H, OH).
2.3. Synthesis of the complexes
To the acetonitrile solution of 0.1 mmol (0.028 g) H3L, 0.1 mmol
metal salt was added and the solution was stirred for another 4 h
to obtain a suspension. To this turbid solution 5 mL methanol
was add to obtain a clear solution. The mixture was filtered into
a
sealed 10–20 mL glass vial for crystallization at room
temperature. After about two weeks single crystals suitable for
crystal analysis were obtained.
2. Experimental
[Cu2(H2L)2Cl2] (1) The empirical formula and the molecular
2.1. Materials and instrumentation
weight is
C32H30Cl2Cu2N4O6 and 764.60 respectively. Yield:
22 mg, 58% based on CuCl2ꢀ2H2O). Anal. Calc. for C, 50.27; H,
All chemicals and solvents were obtained from commercial
sources and used as received. N-(2-aminoethyl)-2-hydroxybenzamide
was prepared according to the literature [12].
Carbon, nitrogen, and hydrogen analyses were performed using
an EL elemental analyzer. Melting points were determined on a
Kofler apparatus. Powder X-ray diffraction patterns (PXRD) were
determined with Rigaku-D/Max-II X-ray diffractometer with
3.95; N, 7.33. Found: C, 50.48; H, 3.96; N, 7.30%; IR (KBr,
m,
cmꢁ1): 3360(m), 1608 (s), 1533 (s), 1477(s), 1288 (s), 1209 (m),
1157 (m), 816 (w), 755 (s).
[Cu4(H2L)2L2]ꢀ4CH3OH (2) The empirical formula and the
molecular weight is C68H72Cu4N8O16 and 1511.50 respectively.
Yield: 26 mg, 68% based on Cu(OAc)2ꢀH2O). Anal. Calc. for C,
54.03; H, 4.80; N, 7.41. Found: C, 54.24; H, 4.78; N, 7.46; IR (KBr,
graphite-monochromatized Cu K
a radiation. Thermogravimetric
m
, cmꢁ1): 3455 (w), 2932(w), 2854 (w), 1635(s), 1600(s), 1525
analyses were carried out on a SDT Q600 thermogravimetric
analyzer from room temperature to 800 °C under N2 atmosphere.
A platinum pan was used for heating the sample with a heating
rate of 10 °C/min. Infrared spectra (4000–400 cmꢁ1) were obtained
(s), 1485 (s), 1449(s), 1387(m), 1293(s), 1262(m) 1127(m) 1052
(m), 847 (w), 757 (s).
[MnL]n (3) The empirical formula and the molecular weight is
C
16H12MnN2O3 and 335.22 respectively. Yield: 24.8 mg, 74% based
on Mn(OAc) 2ꢀ2H2O). Anal. Calc. for C, 57.33 H, 3.61; N, 8.36.
Found: C, 57.40; H, 3.60; N, 8.38%; IR (KBr,
, cmꢁ1): 3419(w),
with KBr discs on
a Nicolet FT-170SX instrument in the
wavenumber range of 4000ꢂ400 cmꢁ1 with an average of 128
scans and 4 cmꢁ1 of spectral resolution. 1H NMR spectra were
recorded in CDCl3 solution at room temperature on a Bruker 400
instrument operating at a frequency of 400 MHz and referenced
to tetramethylsilane (0.00 ppm) as an internal standard. Chemical
shift multiplicities are reported as s = singlet, d = doublet, t = triplet
and m = multiplet. The magnetic measurements were carried out
on polycrystalline samples using a Quantum Design MPMS SQUID
magnetometer.
m
3057(w), 2913(w), 1635(s), 1600(s), 1572(s), 1528(s), 1498
(s),1466(s), 1449(s), 1387(m), 1322(m), 1262(m), 1127(m), 901
(m), 854(m), 751(s), 621(s), 473(m).
[Er2(HL)2(NO3)4]ꢀ4CH3CN (4) The empirical formula and the
molecular weight is C40H42Er2N12O18 and 1313.38 respectively.
Yield: 37 mg, 57% based on Er(NO3)3ꢀ6H2O). Anal. Calc. for C,
36.58; H, 3.22; N, 12.80; Found: C, 36.49; H, 3.20; N, 12.84%; IR
(KBr, m
, cmꢁ1): 3358(m), 2927 (m), 2854 (w), 1655 (s), 1608 (s),
1594 (s), 1563 (m), 1477(s), 1309 (s), 1238 (m), 1024 (m), 768 (s).
2.2. Synthesis of the ligand
The synthetic route for 2-hydroxy-N-(2-((2-hydroxybenzylidene)
amino)ethyl)benzamide (H3L) is shown in Scheme 1. 10 mmol
(1.22 g) salicylaldehyde in 10 mL anhydrous ethanol was added
dropwise in 10 min to a 10 mL ethanol solution of 10 mmol
(1.80 g) N-(2-aminoethyl)-2-hydroxybenzamide. The resulted mix-
ture was stirred and heated at reflux for 4 h. Then the mixture was
allowed to stand overnight at room temperature. The crude product
was separated by filtration and further recrystallized withethanol to
2.4. X-ray single-crystal diffraction analysis
Single crystals of dimensions 0.26 ꢃ 0.22 ꢃ 0.16 mm3 for 1,
0.32 ꢃ 0.20 ꢃ 0.10 mm3 for 2, 0.32 ꢃ 0.28 ꢃ 0.26 mm3 for 1 and
0.16 ꢃ 0.06 ꢃ 0.04 mm3 for 4 was mounted on a glass rod. The
crystal data were collected with
diffractometer using monochromated Mo
a
Bruker SMART CCD
radiation
(k = 0.71073 Å) at 293 K. A hemisphere of data was collected in
Ka
Scheme 1. The synthetic route of the ligand.

234
X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
Table 1
Crystal data and structure refinement parameters for 1, 2, 3 and 4.
Compound
1
2
3
4
Empirical formula
T (K)
C
16H15ClCuN2O3
C68H72Cu4N8O16
298(2)
C16H12MnN2O3
296(2)
C40H40Er2N12O18
293(2)
296(2)
M
764.60
1511.50
335.22
1311.36
Crystal system, Space group
a (Å)
b (Å)
c (Å)
monoclinic, P2(1)/c
10.5771(4)
16.609(2)
9.8455(14)
116.963(2)
1541.7(4), 2
0.26 ꢃ 0.22 ꢃ 0.16
1.647
monoclinic, P2(1)/c
13.0600(11)
16.2379(14)
16.6451(15)
109.807(2)
3321.0(5), 2
0.32 ꢃ 0.20 ꢃ 0.10
1.512
monoclinic, P2(1)/c
10.850(4)
8.263(3)
15.645(6)
91.995(4)
1401.8(9), 4
0.32 ꢃ 0.28 ꢃ 0.26
1.588
0.955
684
monoclinic, P2(1)/c
13.9131(10)
17.3702(10)
20.8947(15)
106.007(8)
4853.9(6), 4
0.14 ꢃ 0.06 ꢃ 0.05
1.794
b (°)
V (Å3), Z
Crystal size (mm)
Dcalcd (kg mꢁ3
)
l
(mmꢁ1
F(000)
)
1.606
780
1.338
1560
3.519
2576
h range for data collection (°)
Completeness to theta = 25.02 (%)
index ranges, hkl
2.01–25.00
99.9
ꢁ12 6 h 6 12
ꢁ19 6 k 6 19
ꢁ9 6 l 6 11
0.0196
2.51–25.02
99.8
ꢁ15 6 h 6 15
ꢁ16 6 k 6 19
ꢁ19 6 l 6 16
0.0594
2.61–25.49
99.8
ꢁ13 6 h 6 13
ꢁ9 6 k 6 10
ꢁ18 6 l 6 18
0.0278
3.66–26.02
99.7
ꢁ15 6 h 6 17
ꢁ21 6 k 6 19
ꢁ22 6 l 6 25
0.0634
Rint
Reflections collectedcted/unique
Data/restraints/parameters
Goodness-of-fit on F2
8259/2714
2714/0/213
1.189
16546/5857
5857/0/433
1.022
10279/2606
2606/0/199
1.025
11274/4778
4778/0/331
1.002
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0242, wR2 = 0.0294
R1 = 0.0719, wR2 = 0.0871
ꢁ0.262 and 0.682
R1 = 0.0461, wR2 = 0.1104
R1 = 0.0779, wR2 = 0.1178
ꢁ0.366 and 0.455
R1 = 0.0321, wR2 = 0.0411
R1 = 0.0837, wR2 = 0.0891
ꢁ0.258 and 0.669
R1 = 0.0443, wR2 = 0.0732
R1 = 0.0678, wR2 = 0.0810
ꢁ1.186 and 1.163
Largest diff. peak and hole (e Åꢁ3
)
Table 2
Selected bond lengths (Å) for 1, 2, 3 and 4.
[Cu2 (H2L)2Cl2] (1)
Cu1–N1 1.951(2)
Cu1–O2 1.9551(17)
N1–Cu1–O2 93.46(8)
O2–Cu–Cl1 136.99(6)
Cu1–O2 1.9785(16)
O2–Cu1–O2 77.40(7)
N1–Cu1–O1 85.84(8)
Cu1–Cl1 2.2804(7)
N1–Cu1–Cl1 92.94(7)
O2–Cu1–O1 88.97(7)
Cu1–O1 2.3132(18)
N1–Cu1–O2 168.76(8)
O2–Cu1–Cl1 98.20(5)
O2–Cu1–O1 98.19(7)
[Cu4L2(H2L)2]ꢀ4CH3OH (2)
Cu1–O3 1.908(3)
Cu2–O2 1.996(3)
Cu1–O2 1.915(3)
Cu2–O1 1.973(3)
Cu1–N1 1.916(4)
Cu2–N4 1.980(4)
Cu1–N2 1.926(4)
Cu2–O2 1.996(3)
Cu1–O4 2.485(4)
Cu2–O3 2.309(3)
O3–Cu1–N1 169.65(14)
O2–Cu1–N2 177.45(15)
N1–Cu1–O4 86.71(14)
O1#1–Cu2–N4 169.13(14)
O6–Cu2–O3 111.04(13)
O3–Cu1–O2 84.74(12)
N1–Cu1–N2 85.66(17)
N2–Cu1–O4 91.69(16)
O6–Cu2–O2 171.56(14)
O1#1–Cu2–O3 91.24(12)
O2–Cu1–N1 94.96(14)
O3–Cu1–O4 103.63(12)
O6–Cu2–O1#1 83.73(14)
O1#1–Cu2–O2 88.90(12)
N4–Cu2–O3 99.62(13)
O3–Cu1–N2 94.21(16)
O2–Cu1–O4 90.81(12)
O6–Cu2–N4 91.90(15)
N4–Cu2–O2 94.62(14)
O2–Cu2–O3 73.13(11)
[MnL]n (3)
Mn1–O3 1.8526(17)
O3–Mn1–O1 92.69(7)
O1–Mn1–N1 88.56(8)
N2–Mn1–O2 96.09(9)
Mn1–O1 1.8974(17)
O3–Mn1–N2 92.90(7)
N2–Mn1–N1 83.23(8)
N1–Mn1–O2 91.98(8)
Mn1–N2 1.941(2)
O1–Mn1–N2 166.35(8)
O3–Mn1–O2 100.88(7)
Mn1–N1 1.987(2)
O3–Mn1–N1 166.90(8)
O1–Mn1–O2 95.07(8)
Mn1–O2 2.1519(18)
Er1–O7 2.391(5)
[Er2(HL)2(NO3)4]ꢀ4CH3CN (4)
Er1–O3 2.210(4)
Er1–O2 2.276(4)
Er1–O1 2.278(4)
Er1–O1 2.312(4)
Er1–O9 2.396(5)
Er1–O4 2.411(5)
Er1–O5A 2.419(13)
O3–Er1–O2 74.66(15)
O2–Er1–O1 140.44(15)
O1–Er1–O7 149.39(16)
O1–Er1–O9 157.10(16)
O2–Er1–O4 76.30(16)
O9–Er1–O4 106.9(2)
O1–Er1–O5A 83.6(3)
O3–Er1–O1 99.54(15)
O1–Er1–O1 73.27(16)
O1–Er1–O7 137.29(16)
O1–Er1–O9 84.50(17)
O1–Er1–O4 81.38(19)
O3–Er1–O5A 153.3(3)
O7–Er1–O5A 84.4(4)
O2–Er1–O1 76.28(15)
O3–Er1–O7 86.64(17)
O3–Er–O9 84.02(19)
O7–Er1–O9 52.89(17)
O1–Er1–O4 122.38(17)
O2–Er1–O5A 127.023(3)
O9–Er1–O5A 70.115(4)
O3–Er1–O1 86.05(15)
O2–Er1–O7 76.58(17)
O2–Er1–O9 126.10(17)
O3–Er1–O4 149.79(17)
O7–Er1–O4 78.7(2)
O1–Er1–O5A 101.0(4)
O4–Er1–O5A 51.5(3)
the h range of 0.98–25.00° using a narrow-frame method with scan
widths of 0.30° in and an exposure time of 5 s/frame. The data
were integrated using the Siemens SAINT program, with the intensi-
ties corrected for Lorentz factor, polarization, air absorption, and
absorption due to variation in the path length through the detector
faceplate. Multiscan absorption corrections were applied. The
structure was solved by the Direct Method of SHELXS-97 [13] and
were placed in geometrically idealized positions (C–H = 0.96 Å for
methyl groups, C–H = 0.97 Å for CH2 groups, C–H = 0.93 Å for phe-
nyl groups and O–H = 0.82 Å for hydroxyl groups) and constrained
to ride on their parent atoms with Uiso(H) = 1.5 Ueq(C) for methyl
groups, 1.2 Ueq(C) for aromatic and CH2 groups, and 1.5 Ueq(O) for
hydroxyl groups. The detailed crystallographic data and structure
refinement parameters of compounds are summarized in Table 1.
Selected bond distances for these compounds are listed in and
Table 2. CCDC reference numbers: 1408852–1408855. Graphics
were drawn with DIAMOND (Version 3.2) [15].
x
refined by full-matrix least-squares techniques using the SHELXL
-
97 program [14]. Nonhydrogen atoms of the compounds were
refined with anisotropic temperature parameters. All H atoms

X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
235
phenoxy oxygen(O2) from another monoanion ligand occupying
the axial site. The CuII atom strays from the equatorial plane
0.045 Å. As illustrated in Table 2, The Cu–O bond distances in equa-
torial plane are 1.9551(2) and 1.9785(2) Å and Cu–Cl distances is
2.2804(7) Å that are comparable to those found in the basal plane
[17]. The Cu atom is shifted by about 0.045 Å from the least-square
3. Results and discussion
3.1. Synthesis and physical measurement
H3L was synthesized in good yield by condensation of
N-(2-aminoethyl)-2-hydroxybenzamide with salicylaldehyde in
1:1 M ratios according to a literature procedure [12] with minor
modification as depicted in Scheme 1. The four compounds which
were found to be rather insoluble in most solvents other than
methanol, acetonitrile, DMSO and DMF were obtained by solvent
evaporation method with metal:ligand molar ratio of 1:1 in a
methanol and acetonitrile mixture. The elemental analysis were
consistent with their chemical formulas. The manganese oxidation
states in compound 3 were established as +3 by bond-valence sum
(BVS) calculations. It is well established that MnII can readily be
oxidized by atmospheric oxygen to MnIII and stabilized by complex
formation on reacting with ligands involving imine group, as can
be inferred from numerous reports in this field [16].
basal planes toward the apical imine N atoms. The Addison
s
parameter for the CuII centers is 0.20, highlighting a slight tbp
(trigonal-bipyramid) distortion from ideal spy geometry [18].
Notably, the one deprotonated ligand anion H2Lꢁ in cis-configura-
tion adopts tetradentate coordination modes with one phenolic
oxygen atom and one Schiff base nitrogen atom and one amide
oxygen atom chelating to one copper ion as well as one phenolic
oxygen atom bridging another copper ion. As shown in Fig. 1c,
two crystallographically equivalent CuII ions are bridged by two
l2-O (O2) to give a dinuclear building block possessing a
Cu–O–Cu–O four membered ring with Cuꢀ ꢀ ꢀCu distance of
3.070 Å and Cu–O–Cu angle of 102.5°. Upon careful investigation
of the structure, it can be seen that two neighboring dinuclear units
are held together to a puckered two-dimensional(2D) supramolec-
ular network via O–Hꢀ ꢀ ꢀCl hydrogen bonding with phenolic oxygen
atom from salicylamide as donor and chloride from adjacent units
as acceptor (Fig. 2). The O3ꢀ ꢀ ꢀO1 distance (3.110(2) Å), as well as
O3–H3Aꢀ ꢀ ꢀC1 angle (168°), are all within the ranges of those
reported O–Hꢀ ꢀ ꢀC1 hydrogen bonds [19].
In the infrared spectra of H3L, the characteristic sharp NH
stretching of the amide function are present at 3381 cmꢁ1 with
the carbonyl(C@O) and imine(C@N) stretch appears at 1633 and
1594 cmꢁ1 as the strongest bands. Upon ligation to CuII, the C@O
group splits to two bands at 1632 and 1608 cmꢁ1, and C@N group
hypochromatic shift of 60–70 cmꢁ1 with obvious difference above
3000 cmꢁ1 compared to the free ligand, clearly indicating CuII ion
in complex 1 and 2 is coordinated to amide oxygen and imine
nitrogen atom. While the absence of characteristic sharp NH band
in the MnIII complex IR spectra indicates the deprotonation of the
amide group. The appearance of a broad band at 3419 cmꢁ1, the
3.2.2. Crystal structure of [Cu4(H2L)2(L)2]ꢀ4CH3OH (2)
To investigate the influence of the counter anion on the struc-
ture of the CuII complex, the acetate analogue was used to perform
the same reaction. Owing to the weaker coordination ability of
acetate compared to that of chloride ion, the coordination behavior
of the ligand changed dramatically which acts both as a tridentate
and pentadentate coordination mode. The X-ray diffraction study
performed on 2 reveals that the asymmetric unit contains two
crystallographically unique CuII ion, one fully deprotonated ligand
anion L3ꢁ, one partly deprotonated ligand anion H2Lꢁ and two lat-
tice methanol molecules. As shown in Fig. 3a, Cu1 atom is coordi-
nated by two phenoxy oxygen atoms (O2, O3), two nitrogen atoms
(N1 and N2) from one fully deprotonated ligand anion L3ꢁ, one
oxygen atom of amide group (O4) from one partly deprotonated
ligand anion H2Lꢁ. While the coordination of Cu2 is completed
by one imine nitrogen atom(N4), one phenoxy oxygen atom (O6)
from the partly deprotonated ligand anion H2Lꢁ, two phenoxy oxy-
gen atoms (O2, O3) and one oxygen atom of amide group (O1) from
the fully deprotonated ligand anion L3ꢁ. As shown in Fig. 3b, both
Cu1 and Cu2 exhibit slightly distorted square pyramid. The O2, O3,
N1 and N2 atoms from the same ligand anion consist of the equa-
torial plane with O4 occupying the axial position and Cu1 atom
straying from the equatorial plane 0.107 Å; while Cu2 atom strays
from the equatorial plane consisted of O1, O2, O6 and N4 atoms
0.128 Å with the axial site occupied by O3 atom. As shown in
Table 2, the Cu–N bond lengths vary from 1.916(4) Å to 1.980
(4) Å, and Cu–O bond lengths vary from 1.908(3) Å to 2.309(4) Å
with the Cu–Ocarbonyl bond length of 2.485(4) Å which are
longer due to the Jahn–Teller effect. The angles of N2–Cu1–O2,
N1–Cu1–N3 N4–Cu2–O1 and O2–Cu2–O6 are 177.44(11)°, 169.64
(11)°, 171.56(11)° and 169.10(9)°, respectively, which are deviated
from the theoretical value of 180°. Therefore, the local coordination
geometry around the CuII center can be described as distorted
splitting of the C@O group to two bands at 1635 and 1600 cmꢁ1
,
as well as 22 cmꢁ1 hypochromatic shift of C@N group of the MnIII
complex compared to the free ligand, clearly indicates MnIII ion
of the complex 3 is coordinated to the amido and imine nitrogens
and the two phenoxo oxygen atoms as well as amide oxygen atom
which are very similar to our previously reported MnIII complex
[8a]. The imine C@N stretch remained at 1594 cmꢁ1 in
compound 4, suggesting that the C@N group does not take part
in coordination when erbium was introduced to the reaction
system. These IR spectra analysis were further validated by the
structural analysis as follows.
PXRD experiments were also carried out for 1–4 to confirm
whether the crystal structures are truly representative of the bulk
materials (Figs. S1–S4). By comparison, the experimental patterns
and the simulated ones are in good agreement with each other,
which confirms the phase purity of the as-synthesized products.
3.2. Crystal structure descriptions
3.2.1. Crystal structure of [Cu2(H2L)2Cl2] (1)
A single-crystal X-ray diffraction study reveals that compound 1
crystallizes in the monoclinic space group P21/c with a crystallo-
graphic inversion center, implying that the asymmetric unit con-
tains half of
a dinuclear molecule. The asymmetric unit is
composed of one crystallographically unique CuII ions, one chloride
and one partly deprotonated H2Lꢁ ligand. It is worth noting that
the ligand in compound 1 is tetradentate without coordination of
both nitrogen atom from amide and phenolic oxygen atom from
salicylamide. As shown in Fig. 1a, CuII ion is five-coordinated to
one carbonyl oxygen atom, two phenoxy oxygen atoms and one
Schiff base nitrogen atom that come from two different one depro-
tonated ligands and one chloride anion. As depicted in Fig. 1b, Cu1
exhibits a slightly distorted trigonal bipyramidal configuration
with phenoxy oxygen(O1), amide oxygen atom (O2) from the same
monoanion ligand, chloride ion consisting of the equatorial plane
and Schiff base nitrogen atom from the same monoanion ligand,
square pyramids. Addison
s
parameter for the CuII centers in 2
are 0.01 and 0.045, highlighting a slight distortion from ideal spy
geometry. As shown in Fig. 3c, Cu1 and Cu2 are bridged by two
phenolic
l2-O (O2 and O3) to give a dinuclear building block
possessing a Cu–O–Cu–O four membered rings with Cu1ꢀ ꢀ ꢀCu2
separations of 3.126 Å and Cu–O–Cu angle of 95.2° and 106.1°
respectively. On the other hand, the two crystallographically

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X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
Fig. 1. (a) Coordination environment of CuII ion in compound 1 with 30% probability thermal ellipsoids, all hydrogen atoms are omitted for clarity. (b) Coordination
polyhedron of CuII in compound 1. (c) View of the dinuclear structure of compound 1 with a Cu–O–Cu–O four-membered ring.
Fig. 2. The 2D supramolecular structure of compound 1 with OꢁHꢀ ꢀ ꢀCl hydrogen bond which are indicated with dashed lines (hydrogen atoms, except those forming
hydrogen bonds, are omitted for clarity).
Fig. 3. (a) Coordination environment of CuII ion in compound 2 with 30% probability thermal ellipsoids (all hydrogen atoms as well as crystalline methanol molecules are
omitted for clarity). (b) Coordination polyhedron of Cu1 and Cu2 in compound 2. (c) View of the tetranuclear structure of compound 2 with two Cu–O–Cu–O four-membered
rings.
equivalent dinuclear CuII units are syn-syn amido bridged by two
amide from the fully deprotonated ligand anion L3ꢁ to give a
tetranuclear parallelogram building block with separations of
Cu1ꢀ ꢀ ꢀCu2 (5.222 Å) which is greatly longer than that between
Cu1 and Cu2 bridged by two phenolic oxygen atoms.
quintuple cooperative hydrogen bonds among two crystalline
methanol molecules which acted both as hydrogen bonding donor
and acceptor, oxygen atom of amide group of one fully deproto-
nated ligand anion L3ꢁ (O1) and phenoxy oxygen atom (O6) from
the partly deprotonated ligand anion H2Lꢁ which acted as hydro-
gen bonding acceptor, and CH groups of phenyl ring (H21 and
H23) acted as hydrogen bonding donor, are formed among six
Notably, significant intermolecular hydrogen bonding
interactions exist between the tetranuclear units. Intermolecular

X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
237
Fig. 4. The 2D supramolecular structure of compound 1 with quintuple OꢁHꢀ ꢀ ꢀO and CꢁHꢀ ꢀ ꢀO hydrogen bond which are indicated with dashed lines (hydrogen atoms, except
those forming hydrogen bonds, are omitted for clarity).
neighbouring tetranuclear units. As a result, the supramolecular
tetranuclear units are held together into 2D puckered
supramolecular architecture as shown in Fig. 4. The Oꢀ ꢀ ꢀO distance
(2.800(7)–2.856(5) Å), Cꢀ ꢀ ꢀO distance (3.239(8)–3.404(7)) Å) and
O–Hꢀ ꢀ ꢀO angle (138–170°), C–Hꢀ ꢀ ꢀO angle (151–160°) are all
within the ranges of those reported hydrogen bonds [20].
similar to our previously reported [8a]. As shown in Fig. 5a. The
asymmetric unit of MnIII complex contains one independent MnIII
ions and one trianion L3ꢁ with MnIII ion unusually five-
coordinating to one carbonyl oxygen atom, two hydroxy oxygen
atoms and two nitrogen atoms that come from two different
fully deprotonated ligands. As shown in Fig. 5b, Mn1 exhibits a
slightly distorted square pyramidal configuration with O1, O3, N1
and N2 atoms from the same ligand trianion consisting of the
equatorial plane and an amide oxygen atom from another ligand
trianion occupying the apical site. The MnIII atom strays from the
equatorial plane of 0.205 Å. The axial position is occupied by O2
from another ligand anion with the longer bond length of 2.1519
(18) Å. The angles of O1–Mn1–N2, and O3–Mn1–N2 are 166.35
(8)° and 166.90(8)° respectively, which are deviated from the
theoretical value of 180°. Therefore, the local coordination
geometry around the MnIII center can be described as a slightly
a
3.2.3. Crystal structure of [MnL]n (3)
The introduction of MnII during the synthesis results in quite a
different product. In contrast to the tetradentate chelating-bridg-
ing coordination mode in compound 1 and both tridentate and
pentadentate coordination mode in compound 2 observed for CuII
complexes, the ligand coordinates to MnIII in a pentadentate
chelating-bridging mode, A single-crystal X-ray diffraction study
revealed that MnIII complex of the ligand is a 1D polymeric chain
crystallized in the monoclinic space group P21/c which is very
Fig. 5. (a) View of the coordination environment of Mn1 centre with thermal ellipsoids at 30% probability with a labelling scheme for compound 3 (All hydrogen atoms are
omitted for clarity). (b) The coordination polyhedron of Mn1. (c) 1D zig-zag MnIII coordination chain view along c-axis.

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X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
distorted square pyramid which is very rare for MnIII. As a whole,
the ligand is distorted with two phenyl rings deviating from the
N2O2 equatorial coordination plane of 2.51° and 21.58°
respectively. Similar to our previous report, the fully
deprotonated ligand anion L3ꢁ in cis-configuration adopts
pentadentate coordination modes with two phenolic oxygen
atoms and two nitrogen atoms chelating to one manganese as
well as one carbonyl oxygen atom of amide group bridging
another manganese. As shown in Fig. 5c, the amido oxygen
atoms are involved in the coordination process as well as the
related nitrogen atom, allowing the amido function with a head
to tail arrangement to actually bridge adjacent MnIII ions in a
syn-anti mode, thus leading to a one-dimensional zig-zag chain
running along the crystallographic c-axis. It is important to note
that the adjacent MnN2O2 equatorial coordination planes in the
chain are nearly perpendicular and the corresponding dihedral
angle is 88.40°, larger than that of previously reported MnIII
analogues [8a]. The amido oxygen atom coordinates to MnIII with
the slight longer bond length of 2.1519 (18) Å than those
previously reported [8a]. The amido-bridged Mnꢀ ꢀ ꢀMn distance is
6.032(2) Å with the C–O–Mn bond angle is 165.7(2)° and the
torsion of Mn–amide–Mn of 159.57°, which is slight longer than
that of 1D MnIII coordination polymer previously reported
[8b,11]. Quite different from the CuII analogue of the H3L and the
MnIII coordination polymer of the similar ligand [8a], there is no
intermolecular hydrogen bond between the neighbouring chains.
monoclinic I2/c space group. A view of the molecular structure,
together with its numbering scheme, is depicted in Fig. 6a. The
erbium atom is in a distorted [NdO8] dodecahedron coordination
geometry (Fig. 6b), of which the coordination sphere for ErIII is
defined by three oxygens (O1, O2, O3) from the same partly
deprotonated HL2ꢁ ligand, one oxygen(O1) from another partly
deprotonated HL2ꢁ ligand and the remaining four oxygen atoms
from two bidentate nitrates (O4, O5A, O7, O9). Quite different from
compound 1, 2 and 3, the ligand adopts tridentate coordination
modes with two phenolic oxygen atoms and one amide oxygen
atom chelating to one erbium ion as well as one phenolic oxygen
atom bridging another erbium ion. As shown in Fig. 6c, two
crystallographically equivalent ErIII ions are bridged by two
l2-O
(O1) to give a dinuclear building block with shorter separations
of Erꢀ ꢀ ꢀEr of 3.644 Å, in which there is only one inversion center
(i) without any crystallographically imposed symmetry for the
ligands or the metal centers. Furthermore, two neighboring
dinuclear units are held together to a one-dimensional (1D)
supramolecular chain via C–Hꢀ ꢀ ꢀO hydrogen bonding with methy-
lene carbon atoms as donor and nitrate oxygen atoms of adjacent
units as acceptor (Fig. 6d). The C9ꢀ ꢀ ꢀO4 distance (3.109(9) Å), as
well as C9–H9Bꢀ ꢀ ꢀO4 angle (131°), are all within the ranges of
those reported C–Hꢀ ꢀ ꢀO hydrogen bonds [21].
3.3. Effect of the reaction system on structural diversity
As shown in Fig. 7, the coordination behavior and deprotonation
of the ligand presented in the four compounds are significantly
different and reveal a much stronger dependence on the nature
of the metal ions as well as counter anion. The complexes 1–4
were obtained from the same starting materials and similar exper-
imental method, however, four structural types were obtained as
follows. The one deprotonated H2Lꢁ ligand adopts tridentate
3.2.4. Crystal structure of [Er2(HL)2(NO3)4]ꢀ2CH3OH (4)
To study the influence of lanthanide element on the coordina-
tion behavior of the ligand, erbium nitrate was selected in place
of transition element under similar synthetic conditions and a
new dinuclear complex 4 was obtained. Single-crystal X-ray
diffraction analysis reveals that compound 4 crystallizes in the
Fig. 6. (a) Coordination environment of ErIII ion in compound 4 with 30% probability thermal ellipsoids (All hydrogen atoms as well as crystalline acetonitrile molecules are
omitted forclarity). (b) Coordination polyhedron of Er(III) in compound 4. (c) View of the dinuclear structure of compound 4 with a Er–O–Er–O four-membered ring. (d) The
2D supramolecular structure of compound 4 with CꢁHꢀ ꢀ ꢀO hydrogen bond which are indicated with dashed lines (hydrogen atoms, except those forming hydrogen bonds, are
omitted for clarity).

X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
239
Fig. 7. The coordination mode and conformation of the ligand presented in compound 1, 2, 3 and 4.
chelating-bridging coordination mode to obtain a dinuclear com-
pound 1 exempting amide nitrogen atom and salicylamide pheno-
lic oxygen atom from coordination to Cu2+ ion on the condition
that CuCl2 was used to carry out the reaction (Type 3). When Cu
(Ac)2 rather than CuCl2 was introduced to the reaction system,
obvious counter anion effect was observed. As a result, we
obtained a novel tetranuclear compound 2, where the ligand
adopts two kind of coordination mode, one is the fully deproto-
nated L3ꢁ anion acted as pentadentate ligand with all its three oxy-
gen atoms and two nitrogen atom binding three Cu2+ ions (Type 1),
the other is the one deprotonated H2Lꢁ anion employing tridentate
chelating-bridging coordination to bind to two Cu2+ ions without
amide nitrogen atom and salicylamide phenolic oxygen atom par-
ticipating in coordination which is quite different from Type 3
(Type 2). While manganese acetate was adopted, 1D zigzag coordi-
nation polymer was obtained, where the fully deprotonated L3ꢁ
anion take the role of pentadentate ligand chelating one man-
ganese ion with its two phenol oxygen atoms and two nitrogen
atoms from imine and amide group and bridging another man-
ganese with amide oxygen atom (Type 4). However, upon erbium
nitrate was incorporated to perform the reaction, the dinuclear
rare earth complex was obtained, where the one deprotonated
HL2ꢁ anion coordinated to erbium ion as tridentate ligand with
all its three oxygen rather than nitrogen atom taking part in coor-
dination (Type 5). During this work we realized not only that the
metal ion was important but also that the counter anions used in
the synthesis were not-innocent for the construction of diverse
metal complexes of H3L.
spin dimers with only one exchange parameter, denoted as J. The
magnetic susceptibility has thus been calculated from the follow-
ing isotropic spin Heisenberg–Hamiltonian: H = ꢁ2J{SCu,1ꢀSCu,2
}
where Si are the spin operators for each center with S = 1/2. Appli-
cation of the van Vleck equation [22] allows the determination of
the low-field analytical expression of the magnetic susceptibility
[23] taking into account the presence of a residual extrinsic para-
magnetic contribution:
2Ng2b2
kT
1
Ng2b2
2kT
vM ¼ ð1 ꢁ
qÞ
ꢃ
þ
q
3 þ eꢁ2J=kT
As shown in Fig. 8, the above expression of the magnetic
susceptibility reproduces almost perfectly the experimental MT
v
versus T data at 1 KOe. The best sets of parameters obtained are
given as g = 2.00, J = ꢁ55.73 cmꢁ1
, q = 3%, with an agreement factor
P
P
2
R = [
(v
MT)obsd ꢁ (
v
MT)calcd]2/ [(
vMT)obsd
]
of 4.0 ꢃ 10ꢁ4 (solid
line in Fig. 8). The negative sign of the magnetic interaction implies
that the CuII dimer unit possess an ST = 0 spin ground state, i.e., a
diamagnetic ground state. The
q values indicate that a very small
amount of residual paramagnetic contribution is present in the
measured samples of 1, as it is seen for materials displaying a
diamagnetic ground state. Taking into account that the impurity
possesses a Curie S = 1/2 paramagnetic behavior and the same
molecular weight as the major complex, the amount is about 3%
for 1.
The
vM and vMT versus T plots for 2 is shown in Fig. 9. On cooling,
the MT value decreases gradually indicating an antiferromagnetic
v
coupling between the CuII ions. The room temperature effective
magnetic moment of 1.35 cm3 K molꢁ1 per Cu4 unit is lower than
expected for four uncoupled CuII ions (1.5 cm3 K molꢁ1, S = 1/2,
g = 2.0). Considering the magneto-structural remarks, the magnetic
exchange in 2 can be modeled as depicted in Fig. S5 (Supporting
Information). A appropriate fit can be obtained by the Hamiltonian
derived from the parallelogram model Cu1(S1)–J1–Cu2(S2)–J2–
Cu1A(S3)–J1–Cu2A(S4)–J2–Cu1(S1), Cu1(S1)–J3–Cu1A(S3) and Cu2
(S2)–J4–Cu2A(S4). Considering these four different exchange param-
eters, the distance of Cu1ꢀ ꢀ ꢀCu2A, Cu1ꢀ ꢀ ꢀCu1A and Cu2ꢀ ꢀ ꢀCu2A are
5.031 Å, 5.222 Å and 6.985 Å, therefore the value of J3 and J4 are con-
sidered as negligible. Thus, the Hamiltonian can be performed using
the following expression: H = ꢁ2J1(S1S2 + S3S4) ꢁ 2J2(S2S3 + S4S1)
[24]. The CuI4I expression of the magnetic susceptibility can be per-
3.4. Magnetic properties
The temperature-dependent molar magnetic susceptibilities of
1, 2, 3 and 4 were measured at 1 kOe in the temperature range
2–300 K. The
vMT and vM versus T plots for 1 are shown in
Fig. 8. On cooling, the
vMT value decreases gradually indicating
an antiferromagnetic coupling between the CuII ions. The room
temperature effective magnetic moment of 0.751 cm3 K molꢁ1
per Cu2 is close to the expected spin only value for spin S = 1/2
(0.750 cm3 K molꢁ1). The plots of vM versus T shows the typical
signature for a strongly coupled binuclear CuII complex: there is
a maximum close to 98–100 K which then decreases to, theoreti-
cally, 0 cm3 molꢁ1. However, at very low temperature there is an
increasing, typical of these strongly coupled systems, that indicates
the presence of small amount of paramagnetic impurities.
formed:
v
M = (Ng2b2/3kT) [A/B], where A = [30exp(6J1/kT) + 6exp
(4J1/kT) + 6exp(2J1/kT) + 6exp((2J2 ꢁ 4J1)/kT)] and B = [5exp (6J1/kT)
+ 3exp(4J1/kT) + 3exp(2J1/kT) + 4exp((2J2 ꢁ 4J1)/kT) + 1]. As shown
in Fig. 9, the above expression of the magnetic susceptibility
Considering the magneto-structural remarks, the magnetic
properties of the compound can be analyzed in a first approxima-
tion with the same magnetic model including two identical S = 1/2
reproduces almost perfectly the experimental
vMT versus T data at
1 KOe. The best sets of parameters obtained are given as g = 2.11(2),

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X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
Fig. 8. The
vMT and vM vs. T plot for 1 collected in an applied dc field of 0.1 T. The solid line shows the best fit to the magnetic model.
Fig. 9. The
v
MT and vM vs. T plot for 2 collected in an applied dc field of 0.1 T. The solid line shows the best fit to the magnetic model.
J1 = –40.66(8) cmꢁ1 and J2 = 0 cmꢁ1
,
with an agreement factor
For compound 3, the room temperature magnetic moment per
Mn (2.84 cm3 K molꢁ1
is slight lower than the spin-only
value expected for a high-spin MnIII ions with S = 2 and g = 2
P
P
2
R = [
line in Fig. 9).
(
v
MT)obsd ꢁ (
v
MT)calcd]2/ [(
v
MT)obsd
]
of 1.93 ꢃ 10ꢁ4 (solid
)
It is well known that comparing the
bridges such as O–C–N play a negligible role in propagating the
magnetic exchanges. According to the structure of compound 2,
the magnetic exchanges within the (Cu2(l-O)2} unit is dominant.
l
-O bridge, three-atom
(3.00 cm3 K molꢁ1). Upon cooling,
vMT decreases smoothly from
2.84 cm3 K molꢁ1 at 300 K to a minimum of 1.83 cm3 molꢁ1 K at
ca. 11 K, suggesting a dominant antiferromagnetic interaction.
Below 11 K, a maximum of 17.13 cm3 molꢁ1 K is observed at
4.5 K which is much larger than its room-temperature value. Below
Merz and Haase [25] found an almost linear correlation between
the magnitude of the exchange interaction and the Cu–O–Cu
bridging angle within the symmetric Cu2O2 core of dimeric
alkoxobridged copper(II) complexes. They concluded that when
the Cu–O–Cu angle is greater than 95.8°, the overall magnetic
behavior is antiferromagnetic. Otherwise ferromagnetic coupling
is observed. In the case of compound 1 and 2, the Cu(1)–O(2)–Cu
(1), Cu(1)–O(2)–Cu(2) and Cu(1)–O(3)–Cu(2) bond angles are
102.16 106.1(2) and 95.2(4)°, respectively. Thus the exchange
across the hydroxy group in the two complexes are
antiferromagnetic.
4.5 K, the
v
MT drops abruptly again and approaches to a value of
magnetic phase transition
9.85 cm3 molꢁ1 K, indicating
a
(Fig. 10). The susceptibility data of the compound above 22 K
follow the Curie–Weiss law, with C = 3.05 cm3 K molꢁ1 and
h = ꢁ8.10 K indicating antiferromagnetic interactions predominate
between Mn(III) ions at 22–300 K. The C value is close to the spin-
only value of 3.0 cm3 K molꢁ1 expected from two high-spin d4
(S = 2) species. The nearest-neighbor interaction can be attributed
to the through bond Mn3+–Mn3+ coupling across the amido-
bridges. Fig. 11 shows the isothermal magnetization vs. field plot

X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
241
Fig. 10. The plot of
v
MT and vꢁM1 vs. T (inset) for 3 collected in an applied dc field of 0.1 T.
Fig. 11. Magnetization–magnetic field strength (M–H) curves for polycrystalline of 3 measured at 2 K with sweep rates of 100 Oe/min from 0–80 KOe (inset: plot of the
hysteresis loop at 2 K).
at 2 K. The magnetization at 80 kOe (1.78 Nb) is far below the sat-
uration value of 4.0 Nb expected for an S = 2 system, consistent
with a canted antiferromagnetism. The magnetizations measured
at 2 K show hysteresis loops. Extrapolating the linear part of the
magnetization curve at high fields to H = 0 gives a magnetization
value of 0.037 Nb. If we assume this to be the uncompensated
magnetization, the canting angle is estimated to be 5.3° [26]. The
coercive field (Hc) and the remnant magnetization (Mr) at 2 K
are 24.4 Oe and 0.0028 Nb, respectively (Fig. 11, inset).
due to the depopulation of the Stark sublevels and the probable
weak magnetic interactions between the metal centers [27]. The
latter contribution is not readily extracted from the magnetic data
because of the orbital angular moment arising from ErIII ions. The
data between 2 K and 300 K are fitted by the Curie–Weiss law
and affords h = ꢁ6.78 cm3 K molꢁ1, C = 24.48 K, the negative value
of
h confirms the presence of antiferromagnetic interaction
between ErIII ions.
For 4, the value of
v
MT is 24.14 cm3 K molꢁ1 at 300 K as shown
3.5. Thermogravimetric analyses
in Fig. 12, which is greater than the spin-only value of two
uncoupled ErIII ions (4I15/2, 11.48 cm3 K molꢁ1, S = 3/2, g = 6/5). As
The thermal study, both Thermogravimetric Analysis (TGA) and
Differential Scanning Calorimetry (DSC), was carried out for the
four compounds to examine their thermal stabilities (Fig. 13).
the temperature is lowered,
vMT undergoes a gradual reduction
and then a more abrupt decrease below 64 K. This behavior is

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X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
Fig. 12. The plot of
v
MT and vꢁM1 vs. T (inset) for 4 collected in an applied dc field of 0.1 T.
Fig. 13. Weight loss (TG thermograms) and DSC thermograms at high temperature for compound 1–4. The observed and theoretical values of the weight loss and the
estimated intermediate products are indicated.

X.-Q. Song et al. / Inorganica Chimica Acta 438 (2015) 232–244
243
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There is no solvent molecule in compound 1, and it began to lose
weight above 191 °C with two endothermic peaks observed by
DSC at 210 and 400 °C to producing a residue of CuO around
850 K. All uncoordinated solvent molecules in complexes 2 and 4
were lost at the first weight loss. For complex 2, the TG curve
shows that the first weight loss of 8.55% (Calc. 8.48%) from 46 to
184 °C corresponds to the loss of four lattice methanol molecules.
Increasing temperature led to the further decomposition of com-
plex 2 at 254 °C. The final pyrolysis was completed at 674 °C, as
indicated by a significant weight loss 73.4%, giving the powder of
CuO (Calc. 73.7%).There is no solvent molecule in compound 3,
and it began to lose weight above 345 °C, this shows that the ther-
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thermal behavior presents two features: the acetonitrile loss and
the final decomposition producing Er2O3. Loss of four crystalline
acetonitrile molecules take place from 61 °C to 145 °C. Up to a tem-
perature of around 333 °C, it starts to decompose with several
exothermic peaks observed and the decomposition finishes at
around 865 °C.
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Four new metal complexes with diverse structures of a asym-
metric amide-imine multidentate ligand were prepared and struc-
turally characterized. This investigation demonstrates that the
nature of the metal ion as well as counter anions have significant
effects both on coordination behavior of the ligand as well as mag-
netic properties of the resulted complexes. The thermogravimetric
analyses show that complexes 1–4 exhibit high thermal stability.
The experimental magnetic susceptibilities indicate 1, 2 and 4
exhibit antiferromagnetic interactions through hydroxy bridge,
while 3 exhibits dominant antiferromagnetic interactions with
spin canting through the amido bridge. Our current studies of
metal ions effects both on structures and magnetic properties are
helpful in achieving further insights into the rational design and
construction of functional complexes through the selection of the
ligands and metal ions under corresponding conditions. We are
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formation of hetero-polynuclear metallic complexes of this ligand.
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This work was supported by the National Natural Science
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CCDC 1408852–1408855 contains the supplementary crystallo-
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