Synthesis and crystal structures of dioxomolybdenum(VI) complexes with catalytic property

Article abstract of DOI:10.1080/15533174.2012.684230

Two new dioxomolybdenum(VI) complexes, [MoO₂L ¹(CH₃ OH)] (1) and [MoO₂L²(CH ₃OH)] (2), where L¹ and L² are the dianionic form of isonicotinic acid (1-methyl-3-oxobutyl

Full text of DOI:10.1080/15533174.2012.684230

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Synthesis and Crystal Structures of
Dioxomolybdenum(VI) Complexes With Catalytic
Property
a
a
Nan-Yan Jin & Wen-Hui Li
a
College of Chemical Engineering and Pharmacy , Jingchu University of Technology ,
Jingmen Hubei , P. R. China
Accepted author version posted online: 29 May 2012.Published online: 28 Aug 2012.
To cite this article: Nan-Yan Jin & Wen-Hui Li (2012) Synthesis and Crystal Structures of Dioxomolybdenum(VI) Complexes
With Catalytic Property, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:8, 1167-1171,
DOI: 10.1080/15533174.2012.684230
To link to this article: http://dx.doi.org/10.1080/15533174.2012.684230
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:1167–1171, 2012
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.684230
Synthesis and Crystal Structures of Dioxomolybdenum(VI)
Complexes With Catalytic Property
Nan-Yan Jin and Wen-Hui Li
College of Chemical Engineering and Pharmacy, Jingchu University of Technology, Jingmen Hubei,
P. R. China
reported. In the present article, two new dioxomolybdenum(VI)
1
1
2
Two new dioxomolybdenum(VI) complexes, [MoO
2
L (CH
3
complexes, [MoO2L (CH3OH)] (1) and [MoO2L (CH3OH)]
2
1
2
1
2
OH)] (1) and [MoO
2
L (CH
3
OH)] (2), where L and L are the (2), where L and L are the dianionic form of isonicotinic
dianionic form of isonicotinic acid (1-methyl-3-oxobutylidene)
hydrazide and nicotinic acid (1-methyl-3-oxobutylidene)hydra-
zide, respectively, were prepared and structurally characterized
by physicochemical and spectroscopic methods and single crystal
1
acid (1-methyl-3-oxobutylidene)hydrazide (H2L ; Scheme 1)
2
and nicotinic acid (1-methyl-3-oxobutylidene)hydrazide (H2L ;
Scheme 1), respectively, are reported. The catalytic property
X-ray determination. The complexes are mononuclear molybde- of the complexes indicates that they are effective catalysts for
num compounds. The Mo atom in each complex is in octahedral sulfoxidation.
coordination. The catalytic property of the complexes indicates
that they are effective catalyst for sulfoxidation.
EXPERIMENTAL
All chemicals and solvents were of analytical reagent grade,
and were purchased from Beijing Chemical Reagent Com-
Keywords catalytic property, crystal structure, hydrazone, molybde-
num complex, synthesis
pany (China). Microanalyses (C, H, N) were performed using
a Perkin-Elmer 2400 elemental analyzer (Shanghai, China). In-
frared spectra were carried out using the JASCO FT-IR model
INTRODUCTION
The mechanism of molybdenum oxotransferase has been
received considerable interest for a long time. The synthe-
sis, characterization, and reactivity studies of a number of
4
20 spectrophotometer (Japan) with KBr disk in the region
−1
4000–200 cm . Electronic spectra were recorded on a Shi-
madzu UV 3101 spectrophotometer (Japan).
dioxomolybdenum complexes with Schiff bases have been re-
ported.[
1–4]
Some of the complexes have been shown to possess
1
Syntheses of [MoO2L (CH3OH)] (1)
oxygen atom transfer properties as they were found to oxidize
thiols, hydrazine, polyketones, and tertiary phosphines.[ Sul-
foxidation activity has been reported for molybdenum salts,
composite metal oxides, molybdate doped porous carbons, and
molybdenum-containing molecular sieves.
ability of dioxomolybdenum(VI) complexes with hydrazone lig-
A hot methanol solution (15 mL) of MoO2(acac)2 (0.33 g,
5,6]
1
mmol) was added to a hot methanol solution (15 mL) of
isonicotinohydrazide (0.14 g, 1 mmol). The mixture was stirred
for 30 min at reflux, and then cooled to room temperature to give
yellow solution. Single crystals suitable for X-ray diffraction
were formed by slow evaporation of the methanol solution of
the complex in air for a few days. Yield: 45%. Anal. Calcd. for
C12H15MoN3O5: C, 38.2; H, 4.0; N, 11.1. Found: C, 38.0; H,
[
7–10]
The catalytic
ands toward the oxidation of sulfides has received satisfactory
results.[
11,12]
However, the number of documented dioxomolyb-
denum(VI) complexes catalyzing the peroxidic oxidation of sul-
fides is still very limited. The search in the Cambridge Crystal-
4.1; N, 11.2%.
lographic Database (version 5.31 with addenda up to August,
2
molybdenum(VI) complexes with hydrazone ligands have been
2
Syntheses of [MoO2L (CH3OH)] (2)
010)[ revealed that there were only 36 mono- and dinuclear
13]
A hot methanol solution (15 mL) of MoO2(acac)2 (0.33 g,
1
mmol) was added to a hot methanol solution (15 mL) of
nicotinohydrazide (0.14 g, 1 mmol). The mixture was stirred for
0 min at reflux, and then cooled to room temperature to give
3
Received 18 November 2011; accepted 8 April 2012.
The authors greatly acknowledge Jingchu University of Technology
for financial support.
Address correspondence to Wen-Hui Li, College of Chemical En-
gineering and Pharmacy, Jingchu University of Technology, Jingmen
Hubei 448000, P. R. China. E-mail: liwh066@163.com
yellow solution. Single crystals suitable for X-ray diffraction
were formed by slow evaporation of the methanol solution of
the complex in air for a few days. Yield: 61%. Anal. Calcd. for
C12H15MoN3O5: C, 38.2; H, 4.0; N, 11.1. Found: C, 38.1; H,
4.1; N, 11.2%.
1167

1168
N.-Y. JIN AND W.-H. LI
TABLE 1
Crystal data for the complexes
1
2
Chemical formula
Fw
C12H15MoN3O5
377.2
C12H15MoN3O5
377.2
1
2
SCH. 1. The hydrazone ligands H2L (left) and H2L (right).
Crystal shape/color
Crystal size (mm)
Block/yellow
0.32 × 0.30
Block/yellow
0.32 × 0.30
× 0.30
298(2)
0.71073
Monoclinic
P21/n
×
0.30
X-Ray Structure Determination
T (K)
298(2)
0.71073
Monoclinic
Cc
X-ray measurements were performed using a Bruker Smart
λ (MoKα) (Å)
Crystal system
Space group
1000 CCD diffractometer (Germany) with graphite monochro-
mated Mo Ka radiation (λ = 0.71073 Å) using the ω-scan tech-
nique. Determination of the Laue class, orientation matrix, and
cell dimensions was performed according to the established pro- a (Å)
cedures where Lorentz polarization and absorption corrections b (Å)
were applied. Absorption corrections were applied by fitting a c (Å)
14.279(2)
7.676(1)
14.087(2)
112.216(1)
1429.4(3)
4
7.847(1)
8.012(1)
23.477(2)
96.597(2)
1466.2(3)
4
◦
pseudoellipsoid to the ψ-scan data of selected strong reflections β ( )
over a wide range of 2θ angles. The positions of non-hydrogen V (Å )
atoms were located with direct methods. Subsequent Fourier
syntheses were used to locate the remaining non-hydrogen µ (MoKα) (cm )
atoms. All non-hydrogen atoms were refined anisotropically. T (min)
The methanol H atoms in both complexes were located from T (max)
3
Z
−1
0.943
0.752
0.765
1.753
0.919
0.852
0.859
1.709
−3
difference Fourier maps and refined isotropically, with O–H D (g cm )
c
distances restrained to 0.85(1) Å. The remaining hydrogen Reflections/parameters
atoms were placed in calculated positions and constrained to Restraints
ride on their parent atoms. The analyses were performed with Unique reflections
2532/196
3
2161
3161/196
1
2674
2
the aid of the SHELXS-97 and SHELXL-97 suite of codes Goodness of fit on F
1.034
1.108
14,15]
(
Germany).[
The crystallographic data for the complexes Rint
0.0163
0.0232
0.0547
0.0290
0.0585
0.0218
0.0325
0.0723
0.0419
0.0765
are summarized in Table 1. Selected bond lengths and angles R [I ≥ 2σ(I)]
1
are given in Table 2. Hydrogen bonds are listed in Table 3.
wR [I ≥ 2σ(I)]
2
R1 (all data)
wR2 (all data)
RESULTS AND DISCUSSION
The dioxomolybdenum(VI) complexes were synthesized by
the reaction of the MoO2(acac)2 with isonicotinohydrazide and
nicotinohydrazide, respectively, in methanol in a 1:1 mole pro-
plexes have been confirmed by elemental analyses, IR spectra,
and X-ray single-crystal structure determination.
1
2
portion at reflux. The ligands H2L and H2L were formed by
the condensation reaction of isonicotinohydrazide and nicoti-
nohydrazide with acetylacetone come from MoO2(acac)2, re- Structure Description of the Complexes
spectively. The reaction progress (Scheme 2) is accompanied
The molecular structures of the complexes are shown in Fig-
by a color change of the solution from colorless to yellow. We ures 1 and 2, respectively. The structures of the complexes are
attempted to prepare and grow diffraction quality crystals from very similar to each other. In each of the complexes, the co-
various solvents; however, good quality crystals were finally ordination geometry around the Mo atom can be described as
obtained from methanol. The chemical formulae of the com- slightly distorted octahedral, with one imino N and two enolic
SCH. 2. The preparation of the complexes. For 1, X = N, Y = C; for 2, X = C, Y = N.

DIOXOMOLYBDENUM(VI) COMPLEXES
1169
TABLE 2
Selected bond lengths (Å) and angles ( ) for the complexes
◦
1
Bond lengths
Mo1-O1
Mo1-O3
2.008(2)
2.351(3)
1.698(3)
Mo1-O2
Mo1-O4
Mo1-N3
1.958(3)
1.681(3)
2.214(3)
Mo1-O5
Bond angles
O4-Mo1-O5
O5-Mo1-O2
O5-Mo1-O1
O4-Mo1-N3
O2-Mo1-N3
O4-Mo1-O3
O2-Mo1-O3
N3-Mo1-O3
2
105.3(2)
O4-Mo1-O2
O4-Mo1-O1
O2-Mo1-O1
O5-Mo1-N3
O1-Mo1-N3
O5-Mo1-O3
O1-Mo1-O3
98.0(1)
97.6(1)
152.2(1)
155.7(1)
73.1(1)
81.6(1)
80.6(1)
101.4(1)
96.4(1)
97.8(1)
82.1(1)
173.0(1)
81.2(1)
75.2(1)
FIG. 1. Molecular structure of 1 with 30% probability thermal ellipsoids.
Bond lengths
Mo1-O1
Mo1-O3
2.000(2)
2.376(2)
1.704(2)
Mo1-O2
Mo1-O4
Mo1-N3
1.946(2)
1.694(3)
2.226(2)
from the equatorial mean planes toward the apical oxo atoms
O4 are 0.335(2) Å for 1 and 0.342(2) Å for 2. The hydrazone
ligands are coordinated in their dianionic enolic forms, which
are evident from the C6–O1, C6–N2, C8–C9, and C9–O2 bond
lengths (Table 2). The Mo–O, Mo–N, and Mo = O bonds are
within normal ranges and are similar to those observed in similar
dioxomolybdenum(VI) complexes.[
In the crystal structure of 1, the complex molecules are linked
through intermolecular O—H···N hydrogen bonds to form 1D
chains, as shown in Figure 3. In the crystal structure of 2, ad-
jacent two complex molecules are linked through intermolec-
ular O—H···N hydrogen bonds to form a dimer, as shown in
Figure 4.
Mo1-O5
Bond angles
O4-Mo1-O5
O5-Mo1-O2
O5-Mo1-O1
O4-Mo1-N3
O2-Mo1-N3
O4-Mo1-O3
O2-Mo1-O3
N3-Mo1-O3
105.7(1)
O4-Mo1-O2
O4-Mo1-O1
O2-Mo1-O1
O5-Mo1-N3
O1-Mo1-N3
O5-Mo1-O3
O1-Mo1-O3
97.9(1)
98.0(1)
151.5(1)
155.3(1)
72.6(1)
81.1(1)
81.3(1)
101.7(1)
96.6(1)
97.9(1)
81.9(1)
173.2(1)
80.2(1)
75.4(1)
16–20]
IR Spectra
TABLE 3
−1
The weak bands centered at about 3435 cm in the IR spec-
tra of the complexes can be assigned to the νOH vibrations of the
methanol ligands. For both complexes, the Mo O stretching
◦
Distances (Å) and angles ( ) involving hydrogen bonding of
the complexes
Angle
D−H···A
d(D−H) d(H···A) d(D···A) (D−H···A)
1
i
2O 3−H3···N1
O3−H3···N1
0.85(1)
0.85(1)
1.84(1) 2.676(4)
1.88(1) 2.724(3)
171(5)
178(4)
ii
Symmetry codes: i) 1/2 + x, –1/2 – y, 1/2 + z; ii) 1 – x, 1 – y, 1 – z.
O atoms of the dianionic hydrazone ligand, and with one oxo
O atom defining the equatorial plane, and with one O atom
of a methanol ligand and the other oxo O atom occupying the
axial positions. The hydrazone ligands coordinate to the Mo
atoms in meridional fashion forming five- and six-membered
◦
chelate rings with bite angles of 73.1(1) and 82.1(1) for 1, and
7
◦
FIG. 2. Molecular structure of 2 with 30% probability thermal ellipsoids.
2.6(1) and 81.9(1) for 2. The displacement of the Mo atoms

1170
N.-Y. JIN AND W.-H. LI
Catalytic Property
The catalytic oxidation tests of the complexes on the oxida-
tion of sulfides under homogeneous conditions in solution using
methyl phenyl sulfide (thioanisol) as substrate were carried out
according to the literature method.[ As oxidant hydrogen per-
oxide was used in a slight excess of 1.25 equivalents based
on the sulfide substrate. Reactions were run with 1 mol% of
12]
◦
catalyst based on the substrate at a temperature of 10 C. The
reaction was started by the addition of hydrogen peroxide. A
control reaction under the same condition without any complex
present leads to less than 1% sulfide conversion within 4 h. In
the presence of the complexes conversions of about 76% for 1
and 73% for 2 of sulfide to the corresponding sulfoxide within
30 min reaction time were observed. After about 2 h in all cases
the conversions of total amount of sulfide were complete. Under
the given conditions no over oxidation to the sulfone could be
detected.
FIG. 3. Molecular packing of 1, viewed along the b axis. Hydrogen bonds are
drawn as thin dashed lines.
CONCLUSION
modes occur as a pair of sharp strong bands at about 940 and
−1
910 cm , assigned to the antisymmetric and symmetric stretch-
In summary, two new dioxomolydenum(VI) complexes
ing modes of the dioxomolybdenum(VI) moieties. The bands with similar hydrozone ligands isonicotinic acid (1-methyl-
due to the νC O and νNH were absent in the complexes, and 3-oxobutylidene)hydrazide and nicotinic acid (1-methyl-3-
−1
new C–O stretches appear at 1252–1260 cm . This suggests oxobutylidene)hydrazide, respectively, have been prepared and
occurrence of ketoimine tautomerization of the hydrazone lig- structurally characterized. The hydrazone ligands coordinate to
ands during the coordination. The strong bands indicative of the the Mo atoms through the imino N and ethanolic O atoms. The
−
1
C N–N C groups in the complexes are shifted to 1612 cm
for the complexes. The new weak peaks observed in the range complexes have effective catalytic property to the oxidation of
3
Mo atoms in the complexes are in octahedral coordination. The
−1
50–800 cm may be attributed to the Mo–O and Mo–N vi- sulfides. The position of the N atom in the pyridine ring plays
brations in the complexes. The IR spectra of the two com- no obvious role for the catalytic procedure.
plexes are similar to each other, indicating the complexes are of
the similar structures, as evidenced by the single crystal X-ray
SUPPLEMENTARY MATERIALS
determination.
CCDC 854396 (1) and 854397 (2) contain the
supplementary crystallographic data for the com-
plexes. These data can be obtained free of charge via
http://www.ccdc.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44)1223–336-033; or email:
deposit@ccdc.cam.ac.uk.
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