TWO MONONUCLEAR MOLYBDENUM(VI) OXO COMPLEXES
89
Synthesis of H2L1. 3ꢀEthoxysalicylaldehyde
(1.0 mmol, 0.166 g) and (4ꢀnitrophenoxy)acetic acid
hydrazide (1.0 mmol, 0.211 g) were dissolved in methꢀ
anol (30 mL) with stirring. The mixture was stirred for
about 30 min at room temperature to give a yellow soꢀ
lution. The solvent was evaporated to give yellow crysꢀ
talline product of H2L1. The yield was 91%.
times with cold methanol and dried in a vacuum over
anhydrous CaCl2. The yield was 73%.
For C16H14N3O8BrMo
anal. calcd., %: C, 34.80;
Found, %: C, 34.67;
H, 2.56;
H, 2.50;
N, 7.61.
N, 7.73.
Xꢀray structure determination. Diffraction intensiꢀ
ties for the complexes were collected at 298(2) K using
a Bruker D8 VENTURE PHOTON diffractometer
For C17H17N3O6
anal. calcd., %: C, 56.82;
Found, %: C, 56.65;
H, 4.77;
H, 4.68;
N, 11.69.
N, 11.57.
with MoKα radiation (λ = 0.71073 Å). The collected
data were reduced using the SAINT program [11], and
multiꢀscan absorption corrections were performed usꢀ
ing the SADABS program [12]. The structures were
solved by direct methods and refined against F2
by fullꢀmatrix leastꢀsquares methods using the
SHELXTL [13]. All nonꢀhydrogen atoms were refined
anisotropically. The methanol H atoms in the comꢀ
plexes were located in difference Fourier maps and reꢀ
fined isotropically with O–H distances restrained to
Synthesis of H2L2. 5ꢀBromosalicylaldehyde
(1.0 mmol, 0.201 g) and (4ꢀnitrophenoxy)acetic acid
hydrazide (1.0 mmol, 0.211 g) were dissolved in methꢀ
anol (30 mL) with stirring. The mixture was stirred for
about 30 min at room temperature to give a yellow soꢀ
lution. The solvent was evaporated to give yellow crysꢀ
talline product of H2L2. The yield was 94%.
0.85(1) Å. All other H atoms were placed in idealized
positions and constrained to ride on their parent atꢀ
oms. The crystallographic data for the complexes are
summarized in Table 1. Selected bond lengths and anꢀ
gles are given in Table 2.
For C15H12N3O5Br
anal. calcd., %: C, 45.71;
Found, %: C, 45.59;
H, 3.07;
H, 3.16;
N, 10.66.
N, 10.53.
Supplementary material for structures
deposited with the Cambridge Crystallographic Data
Centre (nos. 897243 ( ), 897244 (II); deposit@ccdc.
I and II has
Synthesis of [MoO2(L1)(CH3OH)] (I). A methanꢀ
olic solution (10 mL) of [MoO2(Acac)2] (0.1 mmol,
32.6 mg) was added to a methanolic solution (10 mL)
of H2L1 (0.1 mmol, 35.9 mg) with stirring. The mixꢀ
ture was stirred for 20 min to give an orange solution.
The resulting solution was allowed to stand in air for a
few days. Orange blockꢀshaped crystals suitable for
Xꢀray single crystal analysis were formed at the bottom
of the vessel. The isolated product was washed three
times with cold methanol and dried in a vacuum over
anhydrous CaCl2. The yield was 62%.
I
RESULTS AND DISCUSSION
Replacement of two acetylacetonate ligands in
[MoO2(Acac)2] by hydrazone ligands resulted in the
formation of mononuclear molybdenum(VI) oxoꢀ
complexes. In both complexes, the dinegative ligands
are coordinated to the cisꢀMoO2 cores via the phenoꢀ
lateꢀoxygen, iminoꢀnitrogen, and enolateꢀoxygen atꢀ
oms. The sixth coordination site is occupied by the oxyꢀ
gen atom from the methanol solvent. The complexes are
soluble in methanol, ethanol, and acetonitrile. The moꢀ
For C18H19N3O9Mo
anal. calcd., %: C, 41.79;
Found, %: C, 41.95;
H, 3.70;
H, 3.77;
N, 8.12.
N, 8.20.
lar conductance of the complexes I and II at the concenꢀ
trations of 10–4 mol/L are 8 and 11 Ω–1 cm2 mol–1, reꢀ
spectively, indicating they are nonꢀelectrolytes.
Synthesis of [MoO2(L2)(CH3OH)] (II). A methanꢀ
olic solution (10 mL) of [MoO2(Аcac)2] (0.1 mmol,
32.6 mg) was added to a methanolic solution (10 mL)
of H2L2 (0.1 mmol, 39.4 mg) with stirring. The mixꢀ
ture was stirred for 20 min to give an orange solution.
The resulting solution was allowed to stand in air for a
few days. Orange blockꢀshaped crystals suitable for
Xꢀray single crystal analysis were formed at the bottom
The molecular structures and the atom numbering
schemes of the complexes I and II are shown in Fig. 1.
The coordination geometry around each Mo atom is
highly distorted octahedral. In each complex, the hyꢀ
drazone ligand behaves in a tridentate manner in
which the phenolate O, imino N, and enolate O atoms
occupy a meridonial plane. The coordination geomeꢀ
try around molybdenum can be described as distorted
octahedral in the complexes. The dianionic hydrazone
of the vessel. The isolated product was washed three ligands act in planar tridentate manner, forming one
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 40
No. 2
2014
Qian
