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L.-F. Jin et al. / Journal of Organometallic Chemistry 691 (2006) 2909–2914
H, 3.71; N, 17.65%. IR (KBr pellet, cmꢀ1): mOAH, 3298
M
O
O
Mn
OH
O
O
N
O
vs; mNAH, 3103 vs, broad; mC@O, 1684 s; mC@N, 1624
vs; mC@NAC@N, 1604 vs; mNO2, 1574 vs; mNAC@O,
1525 vs; dNAH, 1488 vs; m(CAOH)al, 1293 vs;
m(CAOH)phenolic, 1235 s, 1126 s; dAr, 748 s. 1H NMR
(DMSO), dppm: 10.70 (s, 1H, ArACOANHA); 10.42 (s,
1H, MeACOANHA); 8.78 (s, 1H, o-ArH); 8.30 (d, 1H,
p-ArH); 7.18 (d, 1H, m-ArH); 1.99 (s, 3H, ACH3). 13C
NMR (DMSO), d ppm: 170.40 (MeACOA); 166.26 (o-
ArCAOH); 165.97 (ArACOA); 142.08 (m-ArCANO2);
131.38 (p-ArC); 128.32 (o-ArC); 120.76 (ArCA); 119.11
(m-ArC); 23.19 (ACH3).
O
M
H
N
N
O2N
N
O2N
N
H
O
O
Mn
(a)
(b)
(c)
Scheme 1. Basic biding sites of shi3ꢀ (a), ligand H3anshz (b), and basic
biding sites in compound 2 (c).
carboxylate complexes [16]. Taking into account that all
the metallacrowns relative to the studies are the type of
hydroxamic acids our interest was focused on the type of
salicylhydrazides [19].
In the present paper, we report a new potential pentad-
entate ligand N-acetyl-5-nitrosalicylhydrazidate (1) (H3
anshz, Scheme 1(b)) and a novel manganese(III) 18-metal-
lacrown-6 compound, [Mn6(H2O)6 (anshz)6] Æ 10DMF (2)
(Scheme 1(c), DMF = N,N-dimethylformamide). The
2.3. [Mn6(H2O)6 (anshz)6] Æ 10DMF (2)
H3anshz (0.24 g, 1.0 mmol) was dissolved in 40 mL of
3:1 ethanol + DMF, and 0.25 g (1.0 mmol) of Mn(A-
cO)2 Æ 4H2O was dissolved in 10 mL of ethanol in another
flask. The two solutions were mixed and stirred for 2 h
and the color of the mixture changed to dark brown, then
filtered. After slow evaporation of the mother liquid in two
weeks, dark brown block crystals were obtained from the
filtrate. Yield: 62%. Calc. for C84H118Mn6N28O46: C,
39.01; H, 4.61; N, 15.17; Mn, 12.75. Found: C, 39.16; H,
4.86; N, 15.38; Mn, 12.99%. IR (KBr pellet, cmꢀ1):
mHAOH, 3377 s, broad; mC@O, 1656 vs; mC@NAC@N,
1607 vs; mNO2, 1574 vs; mNAC@O, 1520 vs.
triply
deprotonated
N-acetyl-5-nitrosalicylhydrazide
(anshz3ꢀ) of the title compound 2 may bridge the neighbor-
ing ions through its hydrazide NAN group shown in
Scheme 1(c). In addition, the meridional coordination of
the anshz3ꢀ to the Mn3+ cation forces the neighboring
Mn3+ cations into a propeller configuration. The existence
of intermolecular hydrogen bonds makes the title com-
pound 2 more stable. Minimum inhibitory concentrations
(MIC) against four different bacteria species of the metalla-
crown complex were also measured.
2.4. Physical measurements
2. Experimental
Infrared spectra were measured on a Thermo Nicolet
Corporation NEXUS FT-IR spectrometer as KBr pellets
in the 4000–400 cmꢀ1 region. UV–Vis spectra were
recorded on a Shimadzu-UV-2501 PC recording spectro-
photometer. C, H and N elemental analysis were per-
2.1. Materials
Chemicals for the synthesis of the compounds were used
as purchased. Methanol, ethanol and N,N-dimethylform-
amide (DMF) were used without any further purification.
5-Nitrosalicylic acid, sulfuric acid, hydrazine hydrate, ace-
tic anhydride, diethyl ether, and Mn(AcO)2 Æ 4H2O were
purchased from China Sinopharm Group Chemical
Reagent Co., Ltd. All chemicals and solvents were reagent
grade. The Staphylococcus aureus, Escherichia coli, Bacillus
subtilis and Proteus vulgaris were purchased from China
Center for Type Culture Collection.
formed on
a
Perkin–Elmer 2400 CHN elemental
analytical instrument, Mn was determined by atomic
absorption spectroscopy on
spectrophotometer.
a Perkin–Elmer 1100B
2.5. Biological activity
The antimicrobial activity of the complexes was assessed
by their ability to inhibit the growth of S. aureus, E. coli, B.
subtilis and P. vulgaris in Mueller–Hinton broth medium.
The minimum inhibitory concentration in lg/mL against
the four bacteria species was measured. Bacteria concentra-
tion was 500–800 cfu/mL and concentrations of 1600, 800,
400, 200, 100, 50, 25 lg/mL of the complex in 4:1 etha-
nol + DMF were tested. The solvent showed no antimicro-
bial action.
2.2. Synthesis of the ligand H3anshz (1)
5-Nitrosalicylhydrazide was synthesized according to
the literature procedure [30]. Acetic anhydride (6.8 g,
66.8 mmol) and 5-nitrosalicylhydrazide (11.0 g, 56.0 mmol)
were added to 120 mL of chloroform at 0 ꢁC. The reaction
mixture was slowly warmed to room temperature and stir-
red for 8 h. After staying for overnight at refrigerator, the
resulting light-yellow precipitate was filtered and rinsed
with chloroform and diethyl ether. Yield: 12.2 g, 91.1%.
The determination of melting point of 1 shows the sublima-
tion and oxidation occurred at 310 ꢁC. Calc. for
C9H9N3O5: C, 45.19; H, 3.80; N, 17.57. Found: C, 45.50;
2.6. X-ray crystal structure determination
A crystal of the title compound 2 with dimensions of
0.40 · 0.30 · 0.20 mm was mounted in a glass capillary
with the mother liquor to prevent the loss of the structural