A.N. Gusev, I. Nemec, R. Herchel et al.
Polyhedron 196 (2021) 115017
J = 2.9 Hz) 7.05 (H, m, J = 3.2 Hz) 7.11 (H, m, J = 2.7 Hz) 7.18 (H,
d, J = 2.9 Hz) 7.41 (2H, d, J = 2.5 Hz) 7.72 (H, d-d, J = 2.7 Hz),
H
7.99 (2H, d, J = 2.9 Hz), 8.70 (1H, d, J = 2.7 Hz, CH–NH), 10.53
(1H, s OH) 11.56 (1H, d, J = 2.7 Hz, CH–NH).
N
H
OH
H3C
N
O
2.2.2. Coordination compounds
N
Synthesis of (Et3NH)2[Ni4L4(CH3COO)2]∙ CH3COOHꢁ5H2O (1).
Ni(CH3COO)2ꢁ4H2O (0.248 g, 1 mmol) was added to 30 mL of a
MeOH solution of the Schiff base ligand H2L (0.293 g, 1 mmol). Et3N
(0.300 g, 2 mmol) was added to the resulting solution followed by
further addition of 5 mL of MeOH. The resulting greenish-brown
solution was stirred for 2 h and kept at room temperature for slow
evaporation. Greenish-brown colour crystals appeared after 7 days.
Compound 1. Yield 62 (%). Anal. Calc. for C86H106N14Ni4O20 (%):
C, 54.63; H, 5.65; N, 10.37. Found: C, 54.91; H, 5.58; N, 10.48%. IR
(cmꢀ1): 3326(br), 3056(w), 2979(w), 1723(m), 1625(s), 1597(m),
1567(m), 1524(s), 1494 (s), 1353(s), 1334(s), 1247(s). ESI-MS: m/
z 350.0450 [Ni(L)] + H+] (Calcd 350.0239), m/z 699.0846 [Ni2(L)2] +-
H+] (Calcd 699.0729).
H2L
Scheme 1. Structure of H2L.
Moreover, we present a detailed magnetic study explaining the
observed unexpected magnetic behavior of complexes in correla-
tion to their structures.
2. Experimental
Compounds (Et3NH)2[Ni4L4(Me3CCOO)2]∙4H2O, (2) and (Et3-
NH)2[Ni4L4(Cl3CCOO)2]∙2H2O, (3) were obtained in a similar man-
ner using nickel(II) pivalate and nickel(II) trichloroacetate,
respectively, instead of Ni(CH3COO)2ꢁ4H2O.
2.1. Materials and methods
All chemicals and solvents used for the synthesis were of ana-
lytical grade. 2-Aminophenol and Ni(CH3COO)2ꢁ4H2O were com-
mercially available and used as received without further
purification. The starting nickel pivalate and trichloroacetate were
synthesized according to known procedures [23]. The synthesis of
new compounds was carried out with the use of trimethylacetic
ant trichloracetic acid (Acros Organics). 3-methyl-1-phenyl-4-
formylpyrazol-5-one was synthesized as described in the literature
[24,25]. The purity and composition of the prepared complexes
were confirmed by means of elemental analysis, electrospray-ion-
ization mass-spectrometry (ESI–MS), and FT-IR spectroscopy, and
single-crystal X-ray structure analysis.
Compound 2. Yield 75 (%). Anal. Calc. for C90H110N14Ni4O16 (%):
C, 57.54; H, 5.90; N, 10.44. Found: C, 57.38; H, 5.77; N, 10.32%. IR
(cmꢀ1): 3310(br), 3056(w), 2980(w), 1626(s), 1599(m), 1522(m),
1500(s), 1352(s), 1331(s), 1246(s). ESI-MS: m/z 350.0438 [Ni
(L)] + H+] (Calcd 350.0239), m/z 699.0848 [Ni2(L)2] + H+] (Calcd
699.0729).
Compound 3. Yield 58 (%). Anal. Calc. for C84H88Cl6N14Ni4O14
(%): C, 51.34; H, 4.51; N, 10.82. Found: C, 51.62; H, 4.26; N,
10.72%. IR (cmꢀ1):): 3302(br), 3057(w), 2980(w), 1621(s), 1595
(m), 1519(s), 1499(s), 1354(s), 1339(s), 1238(s). ESI-MS: m/z
350.0440 [Ni(L)] + H+] (Calcd 350.0239), m/z 699.0842 [Ni2(L)2] +-
H+] (Calcd 699.0729).
Elemental analyses of C, H, and N were performed with a Per-
kin–Elmer 240 C analyzer. 1H NMR spectra were recorded on a Bru-
ker VXR-400 spectrometer at 400 MHz from solutions in DMSO-d6.
IR spectra were measured with a Spectrum Two PerkinElmer Inc
spectrometer in the range 4000–400 cmꢀ1. Electrospray mass spec-
tra of complexes were measured with the Finnagan TSQ 700 mass
spectrometer in positive ion mode. Samples were prepared at a
concentration of ~2 mg/ml MeOH. The mass spectra were acquired
over the m/z range of 50–2000; several scans were averaged to pro-
vide the final spectrum.
2.3. X-ray crystallography
Diffraction data were collected using the standard rotational
method on a Bruker SMART APEX II automated diffractometer
equipped with a CCD detector and a monochromatic radiation
source (H2L, MoK
diffractometer equipped with a Photon 100 CMOS detector using
the Mo-K radiation (compounds 1–2) or a Super-Nova diffrac-
tometer equipped with a HyPix-3000 detector (Cu-K radiation
a radiation, k = 0.71073 Å) or a Bruker D8 Quest
a
a
Magnetic measurements were carried out on a SQUID MPMS 5S
Quantum Design magnetometer in the 2–300 K temperature range.
The diamagnetic contributions of the samples were estimated from
Pascal’s constants.
k = 1.54184 Å) (compound 3). Data collection, data reduction,
and cell parameters refinements were performed using the Bruker
Apex III software package [26]. The molecular structures were
solved by direct methods SHELXS-2014 and all non-hydrogen
atoms were refined anisotropically on F2 using full-matrix least-
squares procedure SHELXL-2014 [27]. All hydrogen atoms were
found in differential Fourier maps and their parameters were
refined using a riding model with Uiso(H) = 1.2(CH) or 1.5(CH3)
2.2. Synthesis
2.2.1. Syntheses of the Schiff base ligand
The ligand H2L 4-{[(2-hydroxyphenyl)amino]methylene}-5-
methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one was prepared by
the condensation of 2-aminophenol (0.546 g, 5 mmol) with 3-
methyl-1-phenyl-4-formylpyrazol-5-one (1.01 g, 5 mmol) in pres-
ence of a single drop of glacial acetic acid in methanol medium
(50 mL). On refluxing the methanolic solution for 5 h a light-yellow
solid was obtained. Precipitate was filtered off and recrystallized
from ethanol. Yield 1.55 g (87%).
Light-yellow crystals. Yield 84%. Anal. calc. for C17H15N3O2: C
69.61%, H 5.15%, N 14.33%. Found: C, 69.70; H, 5.22; N, 14.41%. IR
spectrum, selected bands, cmꢀ1: 1668, 1623, 1593, 1488, 1317,
1270, 758, 688. 1H NMR, d (ppm): 2.30 (3H, s, CH3), 6.93 (H, d,
Ueq. The crystallographic parameters and X-ray diffraction experi-
mental parameters are given in Table S1. Non-routine aspects of
refinement: The crystals of 2 and 3 suffer from solvent loss and
therefore, despite numerous attempts, we were not able to get
diffraction data of sufficient quality to reasonably model the elec-
tron density corresponding to triethylammonium cations and co-
crystallized solvent molecules. However, the positions of the Et3-
NH+ cations in 2 and 3 were localized and the figures of the (ap-
proximate) second coordination spheres in these compounds are
shown in supplementary. Prior the final refinement, a SQUEEZE
procedure incorporated to PLATON was used to subtract the elec-
tronic density corresponding to cations and solvent molecules [28].
2