Synthesis, characterization, and crystal structure of a metallamacrocycle

Article abstract of DOI:10.1002/zaac.201000459

The novel macrocyclic decanuclear manganese(III) 30-metallacrown-10 compound [Mn₁₀(RS-3-chmshz)₁₀(DMF)₁₀] ·9DMF (1) was synthesized by self-assembly and characterized (H ₃RS-3-chmshz = N-((R,S)-3-cyclohexenoyl)-

Full text of DOI:10.1002/zaac.201000459

SHORT COMMUNICATION
DOI: 10.1002/zaac.201000459
Synthesis, Characterization, and Crystal Structure of a Metallamacrocycle
Dingjun Zhang,*[a] Yuxian Chen,[a] Qiang Zhao,[a] and Youzhi Wu[a]
Keywords: Manganese; 30-Metallacrown-10; Pentadentate ligand; Magnetic properties; Antiferromagnetic exchange
Abstract. The novel macrocyclic decanuclear manganese(III) 30-me- figuration. The decanuclear systems measure ~2.6 nm in diameter and
tallacrown-10 compound [Mn10(RS-3-chmshz)10(DMF)10]·9DMF (1) ~1.1 nm in thickness. The racemic N-(R,S)-3-cyclohexenoyl group di-
was synthesized by self-assembly and characterized (H3RS-3-chmshz = recting into the cavity of the metallamacrocycle shows the alternate
N-((R,S)-3-cyclohexenoyl)-5-methylsalicylhydrazide). Compound 1 is R,S chiral configuration. Magnetic measurements on the title 30-metal-
a 30-membered decanuclear metallamacrocycle and crystallizes in tri- lacrown-10 compound show weak antiferromagnetic exchange interac-
clinic space group P21/c, in an alternating …ΔΛΔΛ…-type chiral con- tion.
Introduction
The field of metallamacrocycles has undergone explosive
growth over the past decades due to their potential technologi-
cal applications in many areas such as molecular recognition,
separation processes, and catalysis.[1] Much research work has
been devoted to control their size, nuclearity, and physio-
chemical properties.[2] Diaza-bridged metallamacrocycles,
termed metalladiazamacrocycles, have received considerable
interest because of their potential to be used as secondary
building blocks for the construction of two- or three-dimen-
sional network structures.[3] To prepare architectures with the
desired structures and properties, it is important to understand
the delicate factors that influence the formation of these sys-
tems. The nuclearity and the shape of the metallamacrocycles
could be modulated by controlling the steric interactions
caused by N-acyl tails of the ligands.[4] Recently, a novel diaza-
bridged metallamacrocycle was prepared by combination of a
distorted octahedral MnIII or FeIII ion and the asymmetrical
bridging ligand N-acyl salicylhydrazide, where the size and
Figure 1. Molecular structure of the title compound with manganese,
nuclearity of the metalladiazamacrocycle could be modulated
nitrogen, and oxygen atom labeling. Hydrogen atoms and free solvent
molecules are omitted for clarity.
by controlling the steric repulsions between the ligands in the
macrocyclic ring system.[5] We report here the synthesis and
characterization of a novel 30-Metallacrown-10 compound,
[Mn10(RS-3-chmshz)10(DMF)10]·9DMF (1) (Figure 1) (H3RS-
3-chmshz = N-((R,S)-3-cyclohexenoyl)-5-methylsalicylhydraz-
ide) (Scheme 1).
Results and Discussion
The IR spectrum of 1 shows that, in comparison with the
ligand, the C=O band is shifted to lower frequencies, which
Scheme 1. The ligand H3RS-3-chmshz and basic binding sites in the
* Prof. Dr. D. Zhang
complex.
Fax: +86-9312976378
E-Mail: zhangdjpublic@yahoo.cn
[a] State Key Laboratory of Gansu Advanced Non-ferrous Metal
Materials
suggests the coordination of a carbonyl oxygen atom to a Mn3+
ion. The stretching vibration band δ(N–H) is significantly
weakened in the spectrum of 1, which indicates deprotonation
Lanzhou University of Technology
Lanzhou 730050, P. R. China
Z. Anorg. Allg. Chem. 2011, 637, 1175–1177
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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D. Zhang, Y. Chen, Q. Zhao, Y. Wu
SHORT COMMUNICATION
of the group and coordination of the hydrazide nitrogen atom
to the Mn3+ ion. The C–N bands at 1307 and 1241 cm–1 are
shifted to 1555 cm–1 due to deprotonation of the NH group.
Compound 1 was obtained by reaction of manganese acetate
tetrahydrate with H3RS-3-chmshz in a metal to ligand molar
ratio of 1:1 in DMF.[6] Crystallographic analysis revealed that
compound 1 is a 30-membered decanuclear metallamacrocycle
of the formula [Mn10L10(DMF)10]·9DMF, which crystallizes in
triclinic space group P21/c in an alternating …ΔΛΔΛ…-type
chiral configuration similar to other decanuclear manganese or
iron metalladiazamacrocycles (Scheme 2). The deprotonated
pentadentate ligand, chmshz3– acts as a trianionic ditopic
bridging ligand and hence coordinates through three oxygen
atoms and two hydrazinic nitrogen atoms. A phenolate oxygen
atom (O1) a hydrazide nitrogen atom (N1) and a carbonyl oxy-
gen atom (O3) of the chosen ligand are each bound to a man-
ganese atom in tridentate chelating mode, the other carbonyl
oxygen atom (O2) and the other hydrazide nitrogen atom (N2)
are bound to the adjacent manganese atom in bidentate chelat-
ing mode (Figure 2). The metal atoms are connected through
a hydrazide N–N linkage as shortest path in this type of bind-
ing mode. Each Mn3+ ion in 1 is in a distorted octahedral
MnN2O4 environment with a very distinct Jahn–Teller exten-
sion. The Jahn–Teller distortion results in elongation of the
axial manganese–oxygen/nitrogen (Mn1–O2, O15, O16/N2,
N9) bond lengths by ~0.3 Å relative to the other Mn–O/N
bond lengths. The resulting decanuclear system measures ~2.6
nm in diameter and ~1.1 nm in thickness. The bond lengths for
Mn–N(diazine), Mn–O(phenolate), and Mn–O(carbonyl) are in
the ranges 1.928(2)–2.272(1) Å, 1.842(2)–1.870(1) Å, and
1.959(2)–1.999(2) Å, respectively. The successive manganese
atoms of the …ΔΛΔΛ… chiral squence lead to a small differ-
ence in Mn···Mn interatomic distances and Mn···Mn···Mn inter-
atomic angles. The neighboring Mn···Mn interatomic distances
in 1 alternate between 4.85 and 4.89 Å, whereas the
Mn···Mn···Mn angles are between 122.3° and 141.9°. The aver-
age value of 133.4° for the Mn···Mn···Mn angles is close to
that expected (144°) for a planar cyclodecane structure. The
terminal R,S-3-cyclohexenyl groups of the tails of five ligands
are directed upside the cyclic structure, whereas the rest of
them are directed down the cycle. Lah et al. reported 36-mem-
bered dodecanuclear manganese metalladiazamacrocycles, ob-
tained by using the ligand N-cyclohexanoylsalicylhydrazide.[7]
The introduction of a sterically demanding α-branched N-R,S-
3-cyclohexenoyl group did not expand the ring size of the met-
allamacrocycles, from an decanuclear to a dodecanuclear sys-
tem as we expected. The largest diameter of the inner cavity
measured between Mn1 and the symmetry-related Mn1A at the
opposite position is ~15.7 Å, the size of the accessible hydro-
phobic core is ~6.7 Å at the entrance.
Scheme 2. A schematic diagram showing the Δ and Λ configurations
of the metal atoms of the propeller like bidentate/tridentate binding
modes, observed in 1.
Figure 2. O1, N1, and O3 atoms bound to one manganese atom,
whereas O2 and N2 atoms are bound to the adjacent manganese atom
in a back-to-back fashion.
to the typical value for magnetically dilute. The value of χMT
increases gradually to approximately 2.48 cm3·K·mol–1 at 50
K, then decreases sharply to a value of approximately
0.25 cm3·K·mol–1 at 2K.
A magnetic study carried out on 1 is shown in in Figure 3.
The magnetic susceptibilities of 1 were measured on crystal-
line samples in the temperature range of 2 K to 300 K under
1000 Oe to confirm the charge value of the manganese atoms.
The plot of χMT and the inverse magnetic susceptibility (χ–1)
of vs. T shows a typical weakly coupled antiferromagnetic be-
Figure 3. Plots of χMT and χ–1 vs. T of a polycrystalline sample of 1.
The solid line corresponds to the best fit.
Conclusions
We were able to accomplish the synthesis of the
havior. The χMT product of 3.40 cm3·K·mol–1 at 300 K is close novel
30-Metallacrown-10
compound
[Mn10(RS-3-
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© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 1175–1177

Synthesis and Crystal Structure of a Metallamacrocycle
(m), 1014 (s), 959 (s), 918 (s), 900 (s), 875 (s), 835 (s), 821 (s), 789
(s), 764 (s), 748 (s), 699 (m), 677 (s), 628 (s), 592 (s), 566 (m), 545
(m), 503 (m), 472 (s), 442 (s) cm–1.
chmshz)10(DMF)10]·9DMF. The minimal modification in the
bridging domain of the potential pentadentate ligand, whereas
all remaining parts of the ligand were kept the same, led to
different chelation modes around the macrocyclic ring metal
atoms. This work may provide useful information for investi-
gations on metallamacrocycles.
The IR spectrum of 1 shows that the C=O band is shifted to lower
frequencies compared to the ligand, which suggests the coordination
of a carbonyl oxygen atom to a Mn3+ ion. The stretching vibration
band δ(N–H) disappears in the spectrum of 1, which indicates deproto-
nation of the group and coordination of the hydrazide nitrogen atom
to the Mn3+ ion. The bands of C–N at 1307 and 1241 cm–1 are shifted
to 1555 cm–1 due to the deprotonation of the NH group.
Experimental Section
All reagents not specifically listed below were obtained from commer-
cial sources and were used as received. Carbon, nitrogen and hydrogen
analyses were determined using a Vario EL elemental analyzer. IR
spectra were recorded with a Nicolet Avatar 360 FT-IR instrument
CCDC-750878 contains the supplementary crystallographic data for (1).
These data can be obtained free of charge from The Cambridge Crystal-
lographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
1
using KBr discs in the 400–4000 cm–1 region. H NMR spectra were
measured with a FT-400A spectrometer in [D6]DMSO solution, with
TMS as internal standard. Temperature-dependent magnetic suscepti-
bility measurements were carried out on powdered samples between 2
and 300 K using a Quantum Design MPMS-7XL SQUID magnetome-
ter. Field-cooled magnetization data were collected at H = 1000 Oe.
The diamagnetic correction for each complex was calculated using
Pascal’s constants. The intensity data were collected at 296 K with a
Bruker Smart APEX II diffractometer with graphite-monochromatized
Mo-Kα radiation (λ = 0.71073 Å). The structure was solved by direct
methods and refined by full-matrix least-squares techniques on F2 with
all non-hydrogen atoms treated anisotropically. All calculations were
performed with the program package SHELXTL. Non-hydrogen atoms
with geometrical rigidity were refined anisotropically, but non-hydro-
gen atoms with geometrical flexibility were refined isotropically; hy-
drogen atoms attached to the nondisordered part were assigned iso-
tropic displacement coefficients U(H) = 1.2 U(C) or 1.5 U(Cmethyl),
and their coordinates were allowed to ride on their respective atoms.
Acknowledgement
The financial support of the study project of State Key Laboratory of
Gansu Advanced Non-ferrous Metal Materials and Lanzhou University
of Technology is gratefully acknowledged.
References
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[6] Crystal data for [Mn10(RS-3-chmshz)10(DMF)10]·9DMF (1):
C207H281Mn10N39O49, M = 4649.12 g·mol–1, monoclinic, space
group P21/c, a = 13.019(3), b = 28.230(6), c = 34.679(7) Å, β =
99.76(3)°, V = 12561(4) Å3, T = 296(2) K, Z = 2, μ = 0.559 mm–
1, GOF = 1.109, 22010 reflections measured (0.994 ≤ θ ≤ 25.00°),
final R1 = 0.1093 [I > 2σ(I)], wR2 = 0.3020, CCDC-750878.
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The
ligand
N-((R,S)-3-cyclohexenoyl)-5-methylsalicylhydrazide
(H3RS-3-chmshz) was synthesized by reaction of 2-hydroxy-4-methyl-
benzohydrazide (1.66 g, 10 mmol) with (R,S)-3-cyclohexenecarboxy-
lic anhydride (2.81 g, 12 mmol) in chloroform (25 mL) at 5 °C, after-
wards the mixture was slowly warmed to room temperature and stirred
for 3h. The resulting colorless precipitate was filtered and rinsed with
chloroform and diethyl ether to give the colorless solid product N-
((R,S)-3-cyclohexenyl)-5-methylsalicylhydrazide. It was then dried in
vacuo over P2O5. Yield: 1.67 g, 60.9 %. . C15H18N2O3 Calc: C 65.68,
1
H 6.61, N 10.21 %; Found: C 65.75, H 6.51, N 10.37 %. H NMR
(400 MHz, [D6]DMSO): δ = 11.97 (s, 1 H, –Ph–OH); 10.48 (s, 1 H,
–NH–); 10.10 (s, 1 H, –NH–); 7.78–7.76 (d, 1 H, –Ph); 6.77–6.74 (t,
2 H, –Ph); 5.69 (s, 2 H, –CH=CH–); 3.35 (s, 1 H, –CO–CH–); 2.53–
2.46 (p, 3 H, –Ph–CH3); 2.29–1.84 (p, 6 H, –CH2–CH2–CH2–). IR
(KBr pellet): ν = 3332 cm–1 (s), 3296 (s), 3064 (br), 1653 (s), 1636
˜
(s), 1622 (s), 1616 (s), 1607 (m), 1602 (m), 1575 (s), 1569 (s), 1558
(s), 1539 (s), 1520 (s), 1506 (s), 1495 (s), 1488 (s), 1472 (s), 1464
(m), 1457 (s), 1436 (s), 1418 (s), 1394 (m), 1386 (m), 1374 (m), 1362
(m), 1339 (s), 1307 (s), 1241 (s), 1200 (m), 1180 (m), 1117 (m), 1029
(m), 950 (m), 891 (m), 864 (m), 825 (m), 779 (w), 736 (m), 720 (m),
668 (s), 648 (m), 592 (m), 516 (m) cm–1.
The dark brown block crystals of 1 were grown and recrystallized from
DMF with slow evaporation at room temperature over a period
of 30 days (H3RS-3-chmshz:Mn(OAC)2·4H2O = 1:1). Yield: 47 %.
C207H281Mn10N39O49 Calc: C 55.48, H 6.32, N 8.44 %; Found: C
55.34, H 6.41, N 8.57 %. IR (KBr pellet): ν = 3440 cm–1 (br), 3070
˜
(w), 1657 (s), 1610 (s), 1572 (s), 1563 (s), 1555 (s), 1495 (s), 1429
(s), 1390 (s), 1364 (m), 1344 (m), 1324 (m), 1291 (w), 1277 (w), 1245
(s), 1209 (m), 1177 (s), 1161 (m), 1138 (w), 1119(s), 1104 (s), 1066
Received: December 31, 2010
Published Online: June 6, 2011
Z. Anorg. Allg. Chem. 2011, 1175–1177
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1177