A series of 3d metal complexes prepared by in situ reactions of a flexible diacylhydrazine ligand: synthesis, structures and magnetic properties

Article abstract of DOI:10.1007/s11243-016-0101-0

The coordination reactions of 3d metal salts with malonic acid N,N′-bis(salicyloyl) bishydrazide (H₆mbshz) afforded three complexes, namely [Cu₂(H₂bshz)(Py)₄Cl₂]·Py (1) (Py?=?pyridine), [Fe₂(bshz)(Py)₂] (2) and the known complex [Ni₄(aehba)₂(DMF)₂(H₂O)₂]·2DMF (3), where bshz?=?N,N′-bis(salicyloyl)hydrazine anion and aehba^4??=?azo-enolic-2-hydroxybenzamide anion. The X-ray crystal structures of all three complexes have been obtained. Complexes 1 and 2 are composed of N–N-bridged binuclear units, while complex 3 displays a planar tetranuclear structure in which four Ni(II) centers are linked together by N–N and N=N bonds. The bshz anions in 1 and 2 and aehba^4? anions in 3 were all generated in situ from H₆mbshz. A mechanism for these reactions is proposed, involving tandem C–N cleavage and C–N/N–N coupling processes via free radical intermediates. Magnetic investigations revealed dominant antiferromagnetic interactions between the metallic centers of each complex.

Full text of DOI:10.1007/s11243-016-0101-0

Transit Met Chem
DOI 10.1007/s11243-016-0101-0
A series of 3d metal complexes prepared by in situ reactions
of a flexible diacylhydrazine ligand: synthesis, structures
and magnetic properties
Kai Wang1 Zi-Lu Chen2 Hua-Hong Zou2 Yan Li1 Fu-Pei Liang1,2
•
•
•
•
Received: 18 July 2016 / Accepted: 7 October 2016
Ó Springer International Publishing Switzerland 2016
Abstract The coordination reactions of 3d metal salts with
malonic acid N,N0-bis(salicyloyl) bishydrazide (H6mbshz)
afforded three complexes, namely [Cu2(H2bshz)(Py)4Cl2]Á
Py (1) (Py = pyridine), [Fe2(bshz)(Py)2] (2) and the known
complex [Ni4(aehba)2(DMF)2(H2O)2]Á2DMF (3), where
Introduction
The reactions of metal ions with ligands formed in situ
from pro-ligands are effective in the synthesis of novel
complexes and serve as an alternative to the more generally
employed coordination reactions of metal ions with pre-
synthesized ligands [1, 2]. Although it is difficult to predict
the final structures of such products, a number of sophis-
ticated coordination assemblies which are difficult to syn-
thesize through routine methods can thus be made
accessible and some of these have been found to possess
interesting structures and promising properties [3, 4]. For
example, a rare pillar-layered homochiral metal organic
framework with X-shaped pillars and zinc paddle wheels
was obtained through the in situ reaction of D-camphorate
[4], while two Cu–Ln nanomagnets were synthesized via a
two-step in situ reaction of picolinaldehyde [5]. On the
other hand, such in situ reactions also open a new avenue
toward the discovery of novel organic reactions and facil-
itate the elucidation of reaction mechanisms, acting as a
bridge between coordination chemistry and organic
chemistry [6]. A variety of interesting organic reaction
processes have been observed during in situ reactions, such
as oxidative hydroxylation of aromatic rings [7, 8], dehy-
drogenative C–C couplings [9], cycloaddition of organic
nitriles with azides and ammonia [10–12] and the trans-
formation of inorganic and organic sulfur [13].
bshz = N,N0-bis(salicyloyl)hydrazine anion and aehba4-
=
azo-enolic-2-hydroxybenzamide anion. The X-ray crystal
structures of all three complexes have been obtained.
Complexes 1 and 2 are composed of N–N-bridged binu-
clear units, while complex 3 displays a planar tetranuclear
structure in which four Ni(II) centers are linked together
by N–N and N=N bonds. The bshz anions in 1 and 2
and aehba4- anions in 3 were all generated in situ from
H6mbshz. A mechanism for these reactions is proposed,
involving tandem C–N cleavage and C–N/N–N coupling
processes via free radical intermediates. Magnetic investi-
gations revealed dominant antiferromagnetic interactions
between the metallic centers of each complex.
Electronic supplementary material The online version of this
article (doi:10.1007/s11243-016-0101-0) contains supplementary
material, which is available to authorized users.
& Fu-Pei Liang
fliangoffice@yahoo.com
In recent years, our group has been interested in the
coordination chemistry of diacylhydrazine ligands [14–16].
These ligands take advantage of multiple chelating pockets
and variable coordination modes. In particular, we have
investigated the influence of their structures on the archi-
tectures and properties of the resulting complexes, obtained
by variations of the substituents and terminal groups on
their core structures. In continuation of our previous work,
1
Guangxi Key Laboratory of Electrochemical and
Magnetochemical Functional Materials, College of
Chemistry and Bioengineering, Guilin University of
Technology, Guilin 541004, China
2
State Key Laboratory for the Chemistry and Molecular
Engineering of Medicinal Resources, School of Chemistry
and Pharmacy, Guangxi Normal University, Guilin 541004,
China
123

Transit Met Chem
we have employed flexible malonic acid as a core scaffold
for the synthesis of a new pro-ligand, N,N0-bis(salicyloyl)
bishydrazide (H6mbshz), and set out to study its coordi-
nation chemistry with 3d metal ions. Interestingly, the
reactions of 3d metal salts with H6mbshz resulted in three
complexes, in which the H6mbshz was transformed to
N,N0-bis(salicyloyl)hydrazine (bshz) ligands in 1 and 2 and
azo-enolic-2-hydroxybenzamide (aehba4-) ligand in 3,
respectively. Herein, we report the synthesis and crystal
structures of all three complexes. A mechanism for the
in situ ligand formation reactions is proposed, and the
magnetic properties of the complexes are also described.
Table 1. Selected bond lengths and bond angles are given
in Table S1.
Synthesis of malonic acid N0,N0-bis(salicyloyl)
bishydrazide (H6mbshz)
A solution of malonyl dichloride (2 mL) in THF (15 mL)
was added slowly to a solution of triethylamine (2.8 mL) and
salicylhydrazide (7.2 g, 50 mmol) in THF (60 mL) at 0 °C.
The resulting mixture was slowly warmed to ambient tem-
perature and was further stirred for 24 h. A reddish brown oil
was obtained after filtration and concentration. The recrys-
tallization of the oil-like crude product in DMF-H2O gave
H6bsbhz as a yellow precipitate in 75 % yield. IR (KBr,
cm-1): 3453 (s, br), 3282 (vs), 1719 (m), 1662 (vs), 1640
(vs), 1604 (vs), 1552 (m), 1493 (vs), 1455 (m), 1351 (m),
1313 (m), 1245 (m), 1212 (m), 1164 (m), 756 (s), 735 (m),
526 (w). Elemental analysis (%) calcd.: C, 54.84; H, 4.33; N,
15.05; Found: C, 54.66; H, 4.70; N, 15.24. 1H NMR
(400 MHz, DMSO-d6): d = 11.88 (s, 2H), 10.72 (s, 2H),
10.51 (s, 2H), 7.91 (d, 2H, J = 7.9 Hz), 7.45 (m, 2H), 6.95
(m, 4H), 3.38 (s, 2H) ppm; 13C NMR (100 MHz, DMSO-d6):
d = 166.59, 164.94, 159.21, 134.56, 129.10, 119.63, 117.74,
115.18, 40.59 ppm. ESI–MS m/z: 373.15 [M ? H]?.
Experimental
Materials and methods
All reagents were used as received without further purifi-
cation. IR spectra were recorded in the range of
4000–400 cm-1 on a Perkin-Elmer Spectrum One FT/IR
spectrometer using KBr pellets. Elemental analyses for C,
H and N were obtained on a Model 2400 II, Perkin-Elmer
1
elemental analyzer. H and 13C NMR spectra were recor-
ded on a Bruker AV 400 spectrometer at 400 and
100 MHz, respectively. The ESI mass spectra were
acquired using a Bruker Daltonics HCT mass spectrometer.
Magnetic susceptibility measurements were taken in the
temperature range of 300–2 K using a Quantum Design
MPMS SQUIDXL-5 magnetometer equipped with a 5-T
magnetic field. The diamagnetic corrections for the com-
plexes were estimated using Pascal’s constants, and mag-
netic data were corrected for diamagnetic contributions of
the sample holder.
Synthesis of complex 1
A mixture of H6mbshz (0.76 g, 0.2 mmol) and CuCl2-
6H2O (0.120 g, 0.6 mmol) in Py (10 mL) was refluxed at
70 °C for 6 h followed by filtration. The filtrate was left to
evaporate at ambient temperature, giving light blackish
green crystals of complex 1 [Cu2(H2bshz)(Py)4Cl2]ÁPy
suitable for X-ray analysis after 1 week. Yield: 35 %
(based on Cu2?). IR (KBr, cm-1): 3420 (m, br), 3069 (m),
1602 (s), 1553 (s), 1516 (m), 1463 (vs), 1397 (s), 1334 (m),
1255 (s), 1222 (m), 1145 (m), 1082 (m), 1040 (s), 913 (m),
853 (m). Elemental analysis (%) calcd.: C, 54.23; H, 4.08;
N, 11.35 %. Found: C, 54.43; H, 3.92; N, 11.29 %.
X-ray structure determinations
All the data for complexes 1–3 were collected with a
Bruker SMART CCD instrument using graphite
˚
monochromatic Mo-Ka radiation (k = 0.71073 A). The
Synthesis of complex 2
data were collected at 153.15 K for 1 and 3 and at 296.15
for 2. Absorption effects were corrected by semiempirical
methods. The structures were solved by direct methods and
were refined by full-matrix least-squares methods with the
SHELXL-2013 crystallographic software package [17–19]
and Olex2 [20]. The non-hydrogen atoms were refined
anisotropically. The aromatic hydrogen atoms were placed
in calculated positions and refined using a riding model,
while other hydrogen atoms were located in the last final
difference Fourier map. The final cycle of full-matrix least-
squares refinement was based on observed reflections and
variable parameters. A summary of crystal data and rele-
vant refinement parameters for these complexes is given in
A mixture of H6mbshz (0.19 g, 0.05 mmol) and FeCl3-
6H2O (0.540 g, 0.2 mmol) in a mixture of MeOH and Py
(2.0 mL, V/V = 1/1) was sealed in a Pyrex tube, heated to
80 °C for 72 h and then cooled to room temperature at a
rate of 0.5 °C min-1. Blackish rhombohedral crystals of
complex 2 [Fe2(dshz)2(Py)2] suitable for X-ray analysis
were obtained after one week. Yield: 39 % (based on
Fe3?). IR (KBr, cm-1): 3416 (m, br), 1638 (s), 1597 (s),
1561 (m), 1498 (vs), 1445 (s), 1403 (m), 1321 (s), 1261
(m), 1215 (m), 1152 (m), 1088 (s), 760 (m), 690 (m).
Elemental analysis (%) calcd.: C, 58.65; H, 4.05; N, 12.07;
Found: C, 58.39; H, 4.17; N, 12.14.
123

Transit Met Chem
Table 1 Crystal data and
structure refinement parameters
for 1–3
Identification code
1
2
3
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
C39H35Cl2N7O4Cu2
863.72
C68H56N12O8Fe4
1392.65
C40H48N12O14Ni4
1155.74
153.15
296.15
153.15
Monoclinic
P21/c
Monoclinic
P21/n
Monoclinic
P21/c
˚
a/A
17.9260(3)
10.8903(2)
19.7967(3)
98.3990(10)
3823.25(11)
4
16.8207(4)
11.4918(2)
17.6341(4)
114.036(3)
3113.11(12)
2
8.8437(18)
14.410(3)
19.982(6)
116.27(2)
2283.5(10)
2
˚
b/A
˚
c/A
b/°
3
˚
V/A
Z
Dc/g cm-3
1.501
1.486
1.681
l/mm-1
1.303
0.981
1.704
F(000)
1768
1432.0
1192.0
Reflections collected
Independent reflections
Data/restrains/parameters
Rint
16,166
22,482
16,545
6717
5377
4029
6717/3/499
0.0267
5377/1/415
0.0361
4029/6/350
0.0351
GOF
1.068
1.028
1.048
Final R indexes (I [ 2r(I))
R1 = 0.0639
wR2 = 0.1852
R1 = 0.0755
wR2 = 0.1970
R1 = 0.0604
wR2 = 0.1403
R1 = 0.0731
wR2 = 0.1509
R1 = 0.0309
wR2 = 0.0701
R1 = 0.0386
wR2 = 0.0752
Final R indexes (all data)
Synthesis of complex 3
pyridine solution of H6mbshz and CuCl2 at ambient tem-
perature. Its molecular structure contains two Cu(II) cen-
ters, a H2bshz2- ligand generated in situ, two coordinated
Cl- anions, plus two coordinated and one free Py (Fig. 1).
Atom Cu1 adopts a distorted octahedral CuN3O2Cl
geometry, whose four equatorial positions are occupied by
a phenolic oxygen atom (O1), an acyl oxygen atom (O3),
an acylhydrazine nitrogen atom (N1) and a chloride ligand
(Cl1), respectively. The axial positions are occupied by two
Py nitrogen atoms (N3 and N4). The geometry of Cu2 is
almost the same as that of Cu1, only differing in the bond
distances and angles. The H2bshz2- ligand is not com-
pletely deprotonated, carrying a charge of -2 according to
charge balance calculations. This result is further sup-
ported by the presence of a peak of 3069 cm-1 in the IR
spectrum of the complex, which can be ascribed to the O–
H stretching vibrations of the phenol groups (Fig. S1). The
H2bshz2- ligand adopts an g6-l2 coordination mode, in
which all of the available donors are used to provide two
chelating pockets around the Cu2? ions, such that an N–N
bond-bridged dinuclear structure is formed, as shown in
Fig. 1. The Cu–O and Cu–N bond distances fall in the
A mixture of H6mbshz (0.19 g, 0.05 mmol) and Ni(OAc)2-
H2O (0.250 g, 0.1 mmol) in a mixture of DMF, MeOH and
Py (4.5 mL, V/V = 7/1/1) was sealed in a stainless steel
vessel, heated to 80 °C for 72 h and then cooled to room
temperature at a rate of 0.5 °C min-1. The filtrate was left to
evaporate at ambient temperature, giving red brown crystals
of complex 3 [Ni4(aehba)2(DMF)2 (H2O)2]Á2DMF suit-
able for X-ray analysisafter one week. Yield: 27 % (based on
Ni2?). IR (KBr, cm-1): 3374 (m, br), 1659 (s), 1598 (s), 1551
(m), 1528 (vs), 1465 (s), 1360 (m), 1254 (s), 1152 (m), 1102
(m), 1033 (m), 1002 (s), 835 (m), 759 (m). Elemental anal-
ysis (%) calcd.: C, 41.57; H, 4.19; N, 14.54; Found: C, 41.60;
H, 4.26; N, 14.61.
Results and discussion
X-ray crystal structures of the complexes
Single-crystal X-ray diffraction studies reveal that com-
plexes 1–3 all crystallize in the monoclinic space group
P21/c. Complex 1 was obtained from the evaporation of a
˚
ranges of 1.901(3)–2.041(3) and 2.061(4)–2.213(4) A,
respectively. The torsion angle Cu1–N–N–Cu2 is 179.0°,
123

Transit Met Chem
established by bond valence sum (BVS) calculations and
charge balance considerations. They both show five-coor-
dinated FeN3O2 geometries, in which the basal planes are
provided by a phenol oxygen atom (O1 or O3), an acyl
oxygen atom (O3 or O4), an acylhydrazine nitrogen atom
(N1 or N2) and a Py nitrogen atom (N3 or N5). The apical
position is occupied by another Py nitrogen atom (N4 or
N6). The geometrical parameter s = (b - a)/60 was cal-
culated to evaluate the coordination geometries of the
Fe(II) centers, where b and a represent the two largest
ligand–metal–ligand bond angles [24, 25]. The resulting s
values for Fe1 and Fe2 are 0.23 and 0.19, respectively,
indicating square pyramidal geometries in both cases. The
ranges of the Fe–O and Fe–N bond distances are 1.918(4)–
˚
1.949(4) and 1.913(4)–2.306(4) A, respectively. The Fe–
N–N–Fe torsion angles are both 180.0°, while the Fe1ÁÁÁFe1
˚
and Fe2ÁÁÁFe2 distances are 4.551 and 4.565 A, respec-
Fig. 1 Molecular structure of 1. Selected geometric data: Cu(1)–
Cl(1) 2.2886(13); Cu(1)–N(1) 2.061(4); Cu(2)–N(2) 2.062(4); Cu(1)–
N(3) 2.213(4); Cu(1)–N(4) 2.200(4); Cu(1)–O(1) 1.901(3); Cu(1)–
O(3) 2.019(3); Cu(2)–Cl(2) 2. 297(13); Cu(2)–N(5) 2.183(4); Cu(2)–
tively. These structural data are close to those of a previ-
ously reported {Cu2} complex [26], which was constructed
directly from H4bshz ligands.
˚
N(6) 2.206(4); Cu(2)–O(2) 2.041(3); Cu(2)–O(4) 1.909(3) A. O(1)–
Complex 3 was synthesized through the reaction of
H6mbshz with Ni(OAc)2 in the presence of Py in DMF–
methanol solvent mixture. Instead of formation of the
bshz ligand, H6mbshz was transformed to aehba4- in situ
in this experiment. As shown in Fig. 4, the molecule of
complex 3 possesses a planar tetranuclear {Ni4} structure
in which four Ni centers are linked together through N–N
and N=N bonds. Two g8-l3 aehba4- ligands are nearly
coplanar. Each of them chelates a Ni1 center and
employs their N=N bonds to bridge two Ni2 ions. The
Ni1 ions have square planar geometries, while the Ni2
atoms are distorted octahedral, with DMF and H2O as the
terminal ligands. Further inspection of the structural
parameters reveals that 3 is a known complex, previously
synthesized through the in situ reaction of Ni(OAc)2-
4H2O and salicylhydrazide ligands [27]. This {Ni4}
complex is a rare example of a structure containing –N–
N=N–N– bridges, which demonstrates the capacity of
in situ reactions of this type to construct complexes with
unusual structures.
Cu(1)–N(1) 85.52(15); O(3)–Cu(1)–N(1) 76.49(14); N(1)–Cu(1)–
Cl(1) 171.82(12); N(1)–Cu(1)–N(3) 88.66(15); N(1)–Cu(1)–N(4)
89.93(15); O(2)–Cu(2)–N(2) 76.44(14); O(4)–Cu(2)–N(2) 85.28(14);
N(2)–Cu(2)–Cl(2) 172.99(12); N(2)–Cu(2)–N(5) 89.29(15); N(2)–
Cu(2)–N(6) 88.58(15)°
˚
and the Cu1ÁÁÁCu2 distance is 4.874 A. All these structural
parameters are comparable to those of complexes with
similar structures [21–23]. A weak hydrogen bond (C28–
˚
H28ÁÁÁCl1: 2.810 A) exists between the neighboring {Cu2}
units, linking them to form supermolecular chains
expanding along the c-axis (Fig. 2).
The solvothermal reaction between H6mbshz and FeCl3
in methanol–pyridine mixed solvent gave complex 2, in
which the bshz4- ligand generated in situ shows the same
g6-l2 mode as that of H2bshz2- in 1. However, the
molecular structure of complex 2 contains two very similar
but discrete dinuclear units, both of which are composed of
a bshz4- ligand, two Fe centers and four Py ligands
(Fig. 3). Both Fe centers are in the ?2 oxidation state, as
Fig. 2 Supermolecular chain of 1 expanding along c-axis direction
123

Transit Met Chem
Fig. 3 Molecular structure of 2. Selected geometric data: Fe(1)–N(1)
1.913(4); Fe(1)–N(3) 2.306(4); Fe(1)–N(4) 2.014(4); Fe(2)–N(5)
2.022(4); Fe(2)–N(6) 2.287(4); Fe(1)–O(1) 1.925(3); Fe(1)–O(2a)
1.929(4); Fe(2)–N(2) 1.916(4); Fe(2)–O(3) 1.918(4); Fe(2)–O(4b)
N(1)–Fe(1)–N(3) 105.76(16); N(1)–Fe(1)–N(4) 158.44(17); N(2)–
Fe(2)–O(3) 91.63(15); N(2)–Fe(2)–O(4b) 81.26(15); N(2)–Fe(2)–N(5)
159.71(17); N(2)–Fe(2)–N(6) 106.58(16)°. Symmetry codes: (a) -x,
-y, 1 - z; (b) 1 - x, 1 - y, 1 - z
˚
1.949(4) A. N(1)–Fe(1)–O(1) 91.59(15); N(1)–Fe(1)–O(2a) 81.83(15);
are broken during the reactions, affording intermediates of
salicylhydrazide, malonic dihydrazide, malonyl and phe-
noxyl free radicals. These free radicals further couple
together in different combinations, along with coordination
of the 3d metal ions, finally resulting in the formation of
the complexes (Scheme 1). It is worth noting that these
in situ reactions might include tandem C–N cleavages and
C–N/N–N coupling processes, which has been rarely
observed in previous studies. Furthermore, these observa-
tions provide insights that could be used to develop the
syntheses of novel organic compounds.
Magnetic properties of the complexes
Variable-temperature magnetic susceptibility measure-
ments for all three complexes were taken at a direct current
field of 1000 Oe in the temperature range of 300–2 K. The
vmT values of complexes 1 and 2 at room temperature are
0.72 and 11.81 cm3 K mol-1, respectively, which are close
to the expected values of 0.75 and 12 cm3 K mol-1 for
non-interacting two Cu(II) ions (g = 2, S = 1/2) and four
Fe(II) ions (g = 2, S = 2), respectively (Figs. 5, 6). The
value for complex 3 (2.49 cm3 K mol-1) is lower than the
expected value for four magnetically isolated Ni(II) centers
(4.84 cm3 K mol-1, g = 2.2, S = 1; Fig. 7). Upon cool-
ing, complexes 1–3 all show a steady decrease in vm-
T values, reaching minima at 2 K of 0.20, 0.06 and
0.05 cm3 K mol-1, respectively. Their magnetic suscepti-
bilities all obey the Curie–Weiss law in the range of
100–300 K. The Curie constant C values are 0.75, 14.05
and 3.19 cm3 K mol-1 and Weiss constant h values are
-11.72, -58.41 and -84.19 K, respectively (Figs. S4–S6).
Fig. 4 Molecular structure of 3. Ni(1)–N(1) 1.820(2); Ni(1)–N(4)
1.813(2); Ni(1)–O(1) 1.827(2); Ni(1)–O(4) 1.834(2); Ni(2)–O(6)
2.052(2); Ni(2)–N(2) 2.044(2); Ni(2)–N(3a) 2.041(2); Ni(2)–O(2)
˚
2.0404(19); Ni(2)–O(3a) 2.0539(19); Ni(2)–O(5) 2.072(2) A. N(1)–
Ni(1)–O(1) 94.31(9); N(1)–Ni(1)–O(4) 176.79(9); N(4)–Ni(1)–O(1)
176.58(9); N(4)–Ni(1)–O(4) 94.43(9); N(4)–Ni(1)–N(1) 82.40(10);
O(2)–Ni(2)–N(2) 77.19(8); O(2)–Ni(2)–N(3a) 174.78(8); N(2)–
Ni(2)–O(3a) 174.57(8); N(2)–Ni(2)–O(5) 88.40(8); N(2)–Ni(2)–O(6)
96.01(9); N(3a)–Ni(2)–O(3a) 77.13(8); N(3a)–Ni(2)–O(5) 88.00(8);
N(3a)–Ni(2)–O(6) 90.10(9); N(3a)–Ni(2)–N(2) 98.27(9)°. Symmetry
codes: (a) –x - 2, -y ? 1, -z - 1
A tentative mechanism can be suggested for the in situ
generation of dshz anions in complexes 1 and 2 and
aehba4- in 3. The H6mbshz contains four C–N bonds. As
indicated by previous researchers, these acylhydrazine C–
N bonds can undergo cleavage to generate formyl radicals
under the catalysis of some transition metal salts [28, 29].
Given this observation, together with the structural analy-
ses of 1–3, we speculate that four C–N bonds in H6mbshz
123

Transit Met Chem
Scheme 1 Possible in situ formation mechanism for ligands in 1–3
0.12
0.75
2.5
2.0
1.5
1.0
0.5
0.0
1
3
0.024
0.020
0.016
0.09
0.60
mT
0.06
m
0.45
Best fitting
m
T
0.03
0.00
m
T
mT
0.30
0.15
m
0.012
m
m
Best fitting
0.008
300
0
50
100
150
200
250
0
50
100
150
200
250
300
T
/ K
T / K
Fig. 7 vmT - T and vm - T curves recorded under a 1000 Oe for 3.
The red lines represent the best fitting. Inset magnetic exchange
pathways for 3 with a 2J model. (Color figure online)
Fig. 5 vmT - T and vm - T curves recorded under a 1000 Oe for 1.
The red lines represent the best fitting. (Color figure online)
0.14
12
2
To further explore their intramolecular magnetic inter-
actions, the variable-temperature magnetic susceptibility
data of complexes 1–3 were fitted using the Magpack
Program [30, 31]. The fitting of 1 and 2 is based upon the
0.12
9
0.10
mT
m
6
0.08
Best fitting
ˆ ˆ
ˆ
Hamiltonian H = –2JS1ÁS2. The magnetic interactions of 3
T
m
can be simplified as a Hamilton operator, as follows [32]:
0.06
0.04
0.02
3
0
m
h
X
i
^
^
^
^
^ ^
^
H ¼ À2J1S1 Á S2 À 2J2
Si Á S3 À Si Á S4
i¼1;2
in which the terms J1 and J2 represent the magnetic
interactions between Ni1 and Ni2 (or Ni2a), and Ni2 and
Ni2a, respectively (Fig. 7 inset). The fitting results for all
three complexes all agree well with their experimental data
(Figs. 5, 6, 7). The best fit parameters are as follows:
g = 2.1 and J = -23.2 cm-1 for 1, g = 2.0 and
J = -4.3 cm-1 for 2, and g = 2.2, J1 = -11.5 cm-1 and
J2 = -0.2 cm-1 for 3. The strengths of these antiferro-
magnetic interactions are comparable to those of
0
50
100
150
T / K
200
250
300
Fig. 6 vmT - T and vm - T curves recorded under a 1000 Oe for 2.
The red lines represent the best fitting. (Color figure online)
Both the profiles of vmT - T curves and the negative h
values suggest that antiferromagnetic interactions dominate
between the metal ions in these complexes.
123

Transit Met Chem
6. Zhao H, Qu ZR, Ye HY, Xiong RG (2008) Chem Soc Rev 37:84
7. Zheng YZ, Tong ML, Chen XM (2004) New J Chem 28:1412
8. Zhang XM, Tong ML, Chen XM (2002) Angew Chem Int Ed
41:1029
previously reported complexes with similar magnetic
exchange pathways [33, 34].
9. Hu S, Chen JC, Tong ML, Wang B, Yan YX, Batten SR (2005)
Angew Chem Int Ed 44:5471
10. Zheng N, Bu X, Feng PJ (2002) Am Chem Soc 124:9688
11. Xiong RG, Xue X, Zhao H, You XZ (2002) Angew Chem Int Ed
41:3800
12. Zhang JP, Zheng SL, Huang XC, Chen XM (2004) Angew Chem
Int Ed 43:206
13. Wang J, Lin ZJ, Ou YC, Yang NL, Zhang YH, Tong ML (2008)
Inorg Chem 47:190
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Chem 36:653
16. Qin SN, Chen ZL, Liu DC, Huang WY, Liang FP (2011) Inorg
Chem Commun 14:784
Conclusion
In conclusion, three complexes were obtained through
coordination reactions between Cu, Fe and Ni salts and the
diacylhydrazine ligand H6mbshz. The in situ formations of
bshz anions in 1 and 2 and aehba4- in 3 are thought to
involve tandem C–N cleavage and C–N/N–N coupling
processes via free radicals intermediates. All three com-
plexes show dominant antiferromagnetic interactions. This
work affords interesting and unusual examples of in situ
ligand formation reactions and may provide insights that
will prove to be of use in organic synthesis.
17. Sheldrick GM (2008) Acta Crystallogr A 64:112
18. Sheldrick GM (2015) Acta Crystallogr C 71:3
19. Sheldrick GM (2015) Acta Crystallogr A 71:3
20. Dolomanov OV, Bourthis LJ, Gildea RL, Howard JAK, Pusch-
mann HJ (2009) Appl Crystallogr 42:339
Supplementary material
21. Chen XH, Liu SX (2005) Chin J Inorg Chem 21:15
22. Chen YT, Dou JM, Li DC, Wang DQ, Zhu YH (2007) Acta Cryst
E63:m2118
23. Chen YT, Dou JM, Li DC, Wang DQ, Zhu YH (2007) Acta Cryst
E63:m3129
CCDC 1478797, 1478796 and 1503067 contain the sup-
plementary crystallographic data for 1–3 in this paper.
These data can be obtained free of charge via http://www.
ccdc.cam.ac.uk/conts/retrieving.html or from the Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (?44) 1223 336 33; or
e-mail: deposit@ccdc.cam.ac.uk.
24. Addison AW, Rao TN, Reedijk J, van Rijn J, Verschoor GC
(1984) J Chem Soc Dalton Trans 1349
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AS, Ovcharenko VI, Minin VV (2012) Russ J Coord Chem 38:44
27. Chen SL, Liu Z, Han GC (2012) Chin J Struct Chem 11:1641
28. Braslau R, Anderson MO, Rivera R, Jimenez A, Haddad T, Axon
JR (2002) Tetrahedron 58:5513
Acknowledgments This work was supported by the National Natural
Science Foundation of China (Nos. 51572050, 21271050 and 21261004)
and the Guangxi Natural Science Foundation (Nos. 2015GXNSFDA
139007, 2014GXNSFBA118055 and 2013GXNSFGA019008).
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