Oxo-bridged bis oxo-vanadium(V) complexes with tridentate Schiff base ligands (VOL)2O (L = SAE, SAMP, SAP): Synthesis, structure and epoxidation catalysis under solvent-free conditions

Article abstract of DOI:10.1016/j.ica.2010.09.021

The dinuclear V(V) complexes (VOL)₂O (L = SAE (1), SAMP (2), SAP (3)) have been synthesized from VO(acac)₂ and the corresponding tridentate ligands LH₂ in methanol under reflux conditions and subsequent air oxidation in organic solvent. They have been characterized by IR and NMR spectroscopy, by thermogravimetric analysis, and by single crystal X-ray diffraction for 1 and 2. DFT calculations were carried out for a better understanding of the vibrational pattern, principally the V-O related vibrations. Complex [VO(SAP)]₂O (3) catalyzes the epoxidation of cyclooctene by TBHP in water in the absence of any added solvent with good selectivity.

Full text of DOI:10.1016/j.ica.2010.09.021

Inorganica Chimica Acta 364 (2010) 144–149
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Oxo-bridged bis oxo-vanadium(V) complexes with tridentate Schiff base ligands
(VOL)2O (L = SAE, SAMP, SAP): Synthesis, structure and epoxidation catalysis
under solvent-free conditions
a
a,c,
Cindy Cordelle a,b, Dominique Agustin a,b, , Jean-Claude Daran , Rinaldo Poli
⇑
⇑
a CNRS, LCC (Laboratoire de Chimie de Coordination), Université de Toulouse, UPS, INPT, 205, route de Narbonne, F-31077 Toulouse, France
b Université de Toulouse, Institut Universitaire de Technologie Paul Sabatier, Département de Chimie, Av. Georges Pompidou, BP 20258, F-81104 Castres Cedex, France
c Institut Universitaire de France, 103, bd Saint-Michel, 75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online 14 October 2010
The dinuclear V(V) complexes (VOL)2O (L = SAE (1), SAMP (2), SAP (3)) have been synthesized from
VO(acac)2 and the corresponding tridentate ligands LH2 in methanol under reflux conditions and subse-
quent air oxidation in organic solvent. They have been characterized by IR and NMR spectroscopy, by
thermogravimetric analysis, and by single crystal X-ray diffraction for 1 and 2. DFT calculations were car-
ried out for a better understanding of the vibrational pattern, principally the V–O related vibrations. Com-
plex [VO(SAP)]2O (3) catalyzes the epoxidation of cyclooctene by TBHP in water in the absence of any
added solvent with good selectivity.
Dedicated to Arnie Rheingold, in recognition
of a longlife service to the Inorganic
Chemistry.
Keywords:
Ó 2010 Elsevier B.V. All rights reserved.
Vanadium
Vanadyl complexes
Schiff base ligands
Epoxidation
Homogeneous catalysis
1. Introduction
are limited by hydrolytic stability. We have therefore set out to
examine the behavior of the related oxovanadium(V) systems.
High-oxidation state metal oxido complexes are among the
most interesting oxidation catalysts [1,2]. Among them, vanadium
complexes are used in processes of industrial interest [3,4] and are
present in several biological systems [5], for instance in bromoper-
oxidase [6,7]. The advantage of vanadium species is their ability to
activate smooth oxidants. Indeed, a variety of (ep)oxidation reac-
tions with smooth oxidants, including dioxygen, have been re-
ported with use of ‘‘V(O)L(OR)” complexes [8]. We have recently
become interested in oxidative processes catalyzed by oxomolyb-
denum complexes [9–12]. In particular, we have reported that
the dioxomolybdic complexes [MoO2L]2 and MoO2L(MeOH)
(L = tridentate Schiff base ligand) catalyze the epoxidation of cyclo-
octene by aqueous TBHP with better selectivities than the refer-
ence compound MoO2(acac)2 under the same experimental
conditions [12]. However, we found that some of these systems
Mimoun has already reported on the excellent catalytic activity
of mononuclear oxovanadium(V) complexes containing tridentate
ligands, outlining the role played by peroxo-substituted intermedi-
ates [13]. Dinuclear complexes with a [V2O3]2+ core and tridentate
ONO ligands have apparently been scarcely explored in catalysis.
Some articles relate highly enantioselective oxidative couplings
of 2-naphthols [14–17], others epoxidation or sulfoxidation catal-
ysis [18,19], but the majority of experiments have been performed
using organic chlorinated solvents. We have then decided to use
these species under solvent-free conditions.
2. Results and discussion
2.1. Synthesis and characterization of (VOL)2O complexes
The LH2 ligands salicylideneaminoethanol (SAEH2), salicylid-
eneaminomethylpropanol (SAMPH2) and salicylideneaminophe-
nol, SAPH2) have been obtained as described recently using
salicylaldehyde and the corresponding aminoalcohols in water
[10]. The syntheses of the dinuclear vanadium complexes occur
in a ‘‘one pot” procedure, through two consecutive reactions steps
(see Scheme 1).
⇑
Corresponding authors. Addresses: Université de Toulouse, Institut Universi-
taire de Technologie Paul Sabatier, Département de Chimie, Av. Georges Pompidou,
BP 20258, F-81104 Castres Cedex, France. Fax: +33 563356388 (D. Agustin); CNRS,
LCC (Laboratoire de Chimie de Coordination), Université de Toulouse, UPS, INPT,
205, route de Narbonne, F-31077 Toulouse, France. Fax: + 33 561553003 (R. Poli).
E-mail addresses: dominique.agustin@iut-tlse3.fr (D. Agustin), rinaldo.poli@
lcc-toulouse.fr (R. Poli).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.09.021

C. Cordelle et al. / Inorganica Chimica Acta 364 (2010) 144–149
145
H
O
V
N
O
O
O
H
H
O
O
V
N
O
O
O
N
OH
O
N
air
+ O=V(acac)2
- 2 acacH
V
V
O
N
solvent
OH
O
O
H
H
LH2
(VOL)2
(VOL)2O
=
N
O
N
L = SAP
O
N
O
N
O
L = SAE
L = SAMP
Scheme 1. Synthetic procedure for the synthesis of (VOL)2O complexes.
In the first reaction step, V(O)(acac)2 and one equivalent of the
tridentate LH2 ligand lead to a [VIV(O)L]2 intermediate complex as
described elsewhere for a procedure carried out under anaerobic
conditions [20,21]. Transformation into the corresponding dinucle-
ar [LV(O)]2O complex occurred by simple air oxidation. The com-
pounds gave dark solids, in sufficiently good crystalline state for
1 and 2 to perform an X-ray structural determination (see below).
The ÀIR1 spectra of these species show absorption bands around
980 cm , attributable to V@O vibrations, one broad band around
760 cmÀ1 for the V–O–V moiety, as well as the imino vibration
around 1630 cmÀ1 (see Table 1) [22–26].
The thermal behavior in the 20–650 °C range is similar to those
observed with [MoO2L]2 complexes [10]. Ligand loss and concur-
rent oxygen uptake occur to yield the final vanadium oxide V2O5
(see Scheme 2 and Table 2). The thermograms of the three com-
pounds are shown in the Supporting Information.
low-temperature measurement. A view of the molecular geometry
is shown in Fig. 1, with selected distances and angles listed in Table
3. The molecular unit is composed of two [(SAE)V@O] moieties
asymmetrically linked together through the bridging O(3) atom
[V–O bond lengths of 1.770(2) and 1.866(2) Å for V(2)–O(3) and
V(1)–O(3), respectively]. The V@O bonds lengths are in the range
1.59–1.60 Å, conform to those found in the literature for related
terminal VV@O bonds. Each vanadium atom is located at the center
of a O3N base in a square pyramidal geometry, a terminal oxido li-
gand being situated at the top of the pyramid. The structures of 1,
2, and that previously reported for 3 [20], are very close to each
other in terms of length of the covalent and coordinative bonds
and coordination geometries (bond angles). An interesting feature
that has been observed earlier in other related structures is the
presence of a loose intramolecular OÁÁÁV interaction between an
oxygen atom of one [OV(SAE)] unit and the vanadium center of
the second [OV(SAE)] unit (V(1)–O(23), 2.401(2) Å). This distance
is at the short end of the range observed for this class of com-
pounds, the shortest being 2.380(2) Å for compound 2 (our low-
temperature structure; 2.404(2) Å in the literature report [20]).
Others are 2.403(9) Å for compound 3 [27], 2.459 Å for [(ONpAE)-
VO]2O [ONpAE = N-(2-oxyethyl)-2-oxidonaphthaliden-iminato]
[22] and the longest one is 2.684 Å for [(SABH)VO]2O SABH =
salicylaldehydebenzoylhydrazonato [28]. However, the dioxane
adduct of compound 3 does not show this type of interaction
[29]. The V(2)ÁÁÁO(11) distance is even longer (>2.8 Å), making
the coordination geometry around V(2) more typical of a square
pyramid, but the geometry is strongly distorted in both cases
2.2. X-ray characterization of (VOL)2O complexes
Single crystals suitable for X-ray analysis could be obtained for
compounds 1 and 2. The structure of compound 2 (and also that of
3) had already been reported in the literature [20], but was deter-
mined at a higher level of precision in our case, certainly due to the
Table 1
Main IR vibration for compounds 1–3.
Compound
V@O
V–O–V
CH@N
[(SAE)VO]2O (1)
[(SAMP)VO]2O (2)
[(SAP)VO]2O (3)
979
977
990
756
757
753
1630
1628
1602
Δ
(LVO)2O
V2O5
- 2 L + 2 O
Scheme 2. General scheme of the thermal degradation behavior.
Table 2
Experimental and theoretical mass losses observed in TG analysis for complexes 1–3
within the range 20–650 °C.
Compound
Experimental loss
Theoretical
[(SAE)VO]2O (1)
[(SAMP)VO]2O (2)
[(SAP)VO]2O (3)
61.4
66.2
68.3
61.8
65.8
68.2
Fig. 1. Molecular structure of [VO(SAE)]2O, 1.

146
C. Cordelle et al. / Inorganica Chimica Acta 364 (2010) 144–149
Table 3
Table 4
Bond lengths [Å] and angles [°] for 1.
Comparison of experimental and theoretical bond lengths (Å) for compound 1.
Bond
Distance
Observed
Calculated (B3LYP/
6-31 G*)
Calculated B3LYP/
6-31 G** + SDD for V
V(1)–O(14)
V(1)–O(13)
V(1)–O(12)
V(1)–O(11)
V(1)–N(11)
V(1)–O(23)
V(2)–O(22)
V(2)–O(12)
V(2)–O(21)
V(2)–O(22)
V(2)–N(21)
V(1)–V(2)
1.590(2)
1.811(2)
1.866(2)
1.899(2)
2.101(2)
2.401(2)
1.597(2)
1.770(2)
1.840(2)
1.893(2)
2.112(2)
2.9422(7)
V1–O11
V1–O12
V1–O13
V1–O14
V1–N11
V1–O23
V2–O12
V2–O21
V2–O22
V2–O23
V2–N21
1.899(2)
1.866(2)
1.811(2)
1.590(2)
2.101(2)
2.401(2)
1.770(2)
1.840(2)
1.597(2)
1.893(2)
2.112(2)
1.908
1.810
1.811
1.564
2.167
2.662
1.759
1.840
1.568
1.880
2.160
1.892
1.801
1.809
1.570
2.165
2.847
1.767
1.851
1.574
1.861
2.162
Bonds
Angle
O(14)–V(1)–O(13)
O(14)–V(1)–O(12)
O(13)–V(1)–O(12)
O(14)–V(1)–O(11)
O(13)–V(1)–O(11)
O(12)–V(1)–O(11)
O(14)–V(1)–N(11)
O(13)–V(1)–N(11)
O(12)–V(1)–N(11)
O(11)–V(1)–N(11)
O(14)–V(1)–O(23)
O(13)–V(1)–O(22)
O(12)–V(1)–O(23)
O(11)–V(1)–O(23)
N(11)–V(1)–O(22)
O(1)–V(1)–V(2)
100.43(11)
102.90(10)
100.67(9)
98.39(11)
155.99(10)
89.45(9)
101.97(10)
78.25(9)
154.86(9)
83.39(9)
172.04(9)
83.98(9)
69.61(7)
79.21(8)
85.36(8)
132.14(8)
107.62(7)
34.90(6)
107.21(10)
104.52(10)
99.98(9)
108.72(10)
84.94(9)
143.24(9)
96.43(10)
154.06(9)
83.83(9)
77.35(9)
132.54(8)
37.10(6)
110.85(7)
54.45(6)
117.54(7)
69.15(6)
1900
1700
1500
1300
1100
900
700
500
Wavenumber/cm-1
O(12)–V(1)–V(2)
O(3)–V(1)–V(2)
Fig. 2. Comparison between experimental and calculated vibrational spectra of
compound 1: bottom: experimental; middle: computed with the 6-31 G* basis set
for all atoms; top: computed with the SDD basis set for the V atom and the 6-31 G**
basis set for other atoms.
O(22)–V(2)–O(12)
O(22)–V(2)–O(21)
O(12)–V(2)–O(21)
O(22)–V(2)–O(23)
O(12)–V(2)–O(23)
O(21)–V(2)–O(23)
O(22)–V(2)–N(21)
O(12)–V(2)–N(21)
O(21)–V(2)–N(21)
O(23)–V(2)–N(21)
O(22)–V(2)–V(1)
O(12)–V(2)–V(1)
O(21)–V(2)–V(1)
O(23)–V(2)–V(1)
N(21)–V(2)–V(1)
O(11)-V(1)–V(2)
N(11)–V(1)–V(2)
O(23)–V(1)-V(2)
expected, all computed frequencies are slightly shifted to higher
frequencies relative to those observed experimentally (see Fig. 2).
The use of the better basis set for the V atom causes little changes
to the calculated spectrum. Greater shifts are noted for the vibra-
tions of doubly bonded moieties, whereas a closer agreement is
found for the V–O–V vibration. The same trend has been observed
for higher nuclearity tungsten and molybdenum polyoxometalates
[30]. This phenomenon is probably related to the greater discrep-
ancy between calculated and observed bond distances for the
bonds of higher multiplicity.
120.99(7)
39.90(5)
2.4. Epoxidation of cyclooctene with TBHP in water using [VO(SAP)]2O
complex
[displacements from the mean plane of atoms O(12), O(21),
O(23) and N(21): V(2), 0.469(1) Å; O(11), 2.322(2) Å; displace-
ments from the mean plane of atoms O(11), O(12), O(13) and
N(11): V(1), 0.365(1) Å; O(23), 2.015(2) Å].
Complex 3 has been tested as cyclooctene epoxidation pre-cat-
alyst using aqueous TBHP or aqueous H2O2 (30% wt) as oxidant,
without organic solvents, at 80 °C (3/oxidant/cyclooctene = 1/200/
100). Under these conditions, 94% of the cyclooctene was con-
verted in 5.5 h with an epoxide selectivity of 83% when using TBHP
as oxidant, whereas no reaction occurred with H2O2. This may be
related to the inability of the H2O2 reagent to mix with the organic
substrate phase. A control experiment carried out under the same
condition with the equivalent amount of H2SAP ligand instead of
complex 3 gave no conversion, confirming the catalytic role of
the vanadium atom. In another control reaction, the oxidation
was carried out under the same conditions with the precursor
complex VO(acac)2, without the SAP ligand. The conversion was
still quite high (74% after 5.5 h), but the selectivity was completely
different (only 13% of epoxide). This result confirmed the impor-
tant role of the ligand SAP associated to vanadium. Finally, the
same experiment was carried out in the presence of TEMPO in or-
der to test whether radicals may be involved, yielding identical
2.3. DFT calculations for complex 1
The structure of 1 was optimized by DFT using the experimen-
tally determined structure as input and included the calculation of
the normal mode frequencies on the geometry minimum. The
agreement between experimental and calculated structure is
excellent (see Table 4). Note that the computed V@O bonds are
shorter relative to the experiment, whereas the V–N and the loose
VÁÁÁO bonds are longer. The use of a better basis set for the V atom
yields a slightly better agreement fore the covalent V–O bonds but
a greeter disagreement for the loose VÁÁÁO bond. A comparison be-
tween computed and observed IR absorptions is shown in Fig. 2.
The three most relevant vibrations are those associated with the
C@N, V@O and asymmetric V–O–V stretching motions. As

C. Cordelle et al. / Inorganica Chimica Acta 364 (2010) 144–149
147
results. Compared to previous studies, carried out in solution of or-
ganic solvents ranging from aromatic to chlorinated ones, the
activity is very good as well as the selectivity. Bellemin et al. indi-
cated a conversion of just 50% of 1-hexene to the corresponding
using TBHP and the [(2,6-bis{(À)-menthyl}pyridine)VO]2O dimeric
complex [19] as pre-catalyst, the nature of which is similar to that
of compound 3. Other contributions relate the epoxidation of
cyclooctene with V(IV) complexes in a N2O2 tetradentate coordina-
tion environment. A few of these systems displayed moderate
cyclooctene epoxidation activity with TBHP in acetonitrile (88–
96% selectivity but only 46–75% conversion in 6 h and at reflux)
[31]. The solvent influence (dichloromethane, acetonitrile or chlo-
roform) was investigated, the highest conversion (94%) being ob-
tained with VO{salnptn(3-OMe)2} and VO{hnaphnptn} in
chloroform after 6 h [32]. Similar complexes have been used in
combination with greener oxidants, i.e. dioxygen, again for cyclo-
octene epoxidation by THBP, leading to conversion (selectivity) in
the range 25–91% (30–60%) in acetonitrile or in DMF [33,34]. An-
other [VOL]2 complex containing vanadium(V) atoms and NNO
Schiff base ligands has shown good epoxidation activity (94% after
4 h) but in chloroform [35]. Although all these systems are catalyt-
ically efficient, organic solvents were needed in the experimental
procedures. We have shown here for the first time that a vanadyl
complex is also catalytically efficient in the absence of organic sol-
vent and by using an aqueous oxidant.
4.72 (s, 2H), 6.4–8.0 (m, 4H), 8.44 (s, 1H). 13C{1H} NMR (DMSO-
d6): 59.0 (CH2N), 67.8 (CH2O), 118.4 (CAr), 120.4 (CAr), 120.5 (CAr),
135.4 (CAr), 136.3 (CAr), 165.4 (CAr–O) 168.7 (CH@N). UV–Vis
(DMSO; nm (e
in molÀ1 L cmÀ1)): 262 nm (32 000), 355 (8500).
TGA: Exp (theor) mass loss of 61.4% (61.8) – 2 (L-O).
4.2. Synthesis of [VO(SAMP)]2O (2)
This procedure follows previously reported protocols using eth-
anol instead of dichloromethane [20] or acetone [22]. To a solution
of SAMPH2 (583 mg, 3.02 mmol) in methanol (10 mL) was added a
methanol solution of VO(acac)2 (796 mg, 3.00 mmol, in 15 ml). The
mixture was then refluxed for four hours. The solution was then
concentrated under vacuum to a dark pasty residue. Addition of
acetonitrile led to a red-blood solution, which yielded a few crys-
tals upon standing for three days. The partial evaporation of the
solution led to a solid has been separated from the solution by fil-
tration and washed with diethylether. The solid was recrystallized
by dissolution in the minimum amount of acetonitrile and dark
crystals suitable for X-ray crystallography were obtained after slow
evaporation (yield 0.520 g, 68%). 1H NMR (DMSO-d6) 1.00–1.80 (m,
6H), 4.51 (s, 2H), 6.4–8.0 (m, 8H), 8.89 (s, 1H). 13C{1H} NMR
(DMSO-d6): 26.6, 76.4, 89.1, 118.1, 120.6, 121.5, 135.2, 137.2,
163.4, 163.9. UV–Vis (DMSO; nm (e
in molÀ1 L cmÀ1)): 264 nm
(39 000), 356 (7900). TGA: Exp (theor) mass loss of 66.2% (65.8)
– 2 (L-O).
3. Conclusion
4.3. Synthesis of [VO(SAP)]2O (3)
The synthesis of bis(vanadyl) complexes of general formula
[VO(L)]2O with tridentate ligands (L = SAE, SAMP, SAMP) has been
revisited here. The synthetic procedure makes use of easily acces-
sible ligands. The crystallographic structure of [VO(SAE)]2O has
been determined here for the first time. Compound [VO(SAP)]2O
exhibited good catalytic activity in cyclooctene epoxidation using
aqueous TBHP as oxidant and no organic solvent. These results
are of interest for the development of greener oxidation protocols.
Further mechanistic and experimental studies under solvent-free
conditions are in progress and will be described in due course.
This procedure follows previously reported protocols using eth-
anol instead of dichloromethane [20] or acetone [22]. To a solution
of SAPH2 (641.7 mg, 3.0 mmol) in MeOH (10 mL) was added drop-
wise a MeOH solution of VO(acac)2 (795.6 mg, 2.36 mmol, in
15 mL). The resulting mixture was refluxed for four hours and left
cooling at room temperature, leading to crystals after one night.
The rest of the pastry solution was slowly evaporated, washed with
diethyl ether. (Yield 715 mg 84%). 1H NMR (DMSO-d6): 6.4–8.0 (m,
8H), 9.40 (s, 1H). 13C{1H} NMR (DMSO-d6): 118.2, 120.7, 123.3,
130.6, 133.6, 137.7, 149.9, 161.9, 193.1. UV–Vis (DMF; nm (e in
molÀ1 L cmÀ1)) 275 nm (46 000), 382 (15 500) 427 (20 500). TGA:
Exp (theor) mass loss 68.3% (68.2) – 2 (L-O).
4. Experimental section
Compound VO(acac)2 (Aldrich), MeOH and acetonitrile (Aldrich,
technical grade) were used as received. The ligands SAEH2,
SAMPH2 and SAPH2 were synthesized using previously described
methods [10]. Infrared spectra were recorded on KBr pellets at
room temperature with a Mattson Genesis II FTIR spectrometer.
Thermogravimetric analyses were performed with a SETARAM
TGA 92-16.18 thermal analyzer. The samples were placed into
nickel/platinum alloy crucibles and heated at 0.83 K sÀ1 in recon-
stituted air flow from 20 °C to 650 °C. An empty crucible was used
as a reference. 1H and 13C{1H} NMR measurements were carried
out with a Bruker Avance DPX 200 spectrometer.
4.4. Catalytic tests
In a round flask was added 3 (52.4 mg, 0.091 mmol), dodecane
(internal reference, 42.0 mg, 0.246 mmol) and cyclooctene
(1.07 g, 9.68 mmol). The magnetically stirred mixture was heated
to 80 °C and the reaction was started by the addition of aqueous
TBHP (2.5 mL, 70% wt, 18.06 mmol). Stirring was stopped after
5.5 h, leading to the appearance of two phases. A 0.1 ml sample
of the organic phase was withdrawn, mixed with Et2O (2 mL)
and a small quantity of MnO2 to destroy the residual peroxide.
The mixture was then filtered through silica and analyzed by GC
equipped with FID. GC parameters were quantified with authentic
samples of products prior to the analysis. Conversion of cis-cyclooct-
1-ene and the formation of the cyclooctene oxide were calculated
from calculation curves (r2 = 0.999) relatively to dodecane prior to
the reaction. Other reactions were analyzed by 1H NMR using ace-
tophenone as internal standard.
4.1. Synthesis of [VO(SAE)]2O (1)
This procedure follows previously reported protocols using eth-
anol instead of dichloromethane [20] or acetone [22]. In a 100 mL
flask, SAEH2 (497.6 mg, 3.01 mmol) was dissolved in methanol
(10 mL) and a MeOH solution of VO(acac)2 (795.6 mg, 3.00 mmol,
in 15 mL) was then added dropwise. The mixture was then re-
fluxed for four hours. Volatiles were eliminated by evaporation
and the pasty brown residue was recrystallized from hot acetoni-
trile to afford dark crystals suitable for X-ray crystallography,
which were finally washed with a minimum of diethyl ether (yield
330 mg, 48.6%). 1H NMR (DMSO-d6): 3.66 (m, 2H), 3.76 (m, 2H),
4.5. X-ray crystallography
Single crystals of compounds 1 and 2 were mounted under
inert perfluoropolyether on the tip of a glass fiber and cooled in
the cryostream of a Bruker APEXII-II diffractometer. Data were
collected using the monochromatic Mo Ka radiation (k = 0.71073).

148
C. Cordelle et al. / Inorganica Chimica Acta 364 (2010) 144–149
Table 5
Appendix A. Supplementary material
Crystal data and structure refinement for 1.
1 – [VO(SAE)]2O
18H18N2O7V2
476.22
110(2)
0.71073
monoclinic
P21/n
2 – [VO(SAMP)]2O
CCDC 775912 and 775913 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associ-
ated with this article can be found, in the online version, at
doi:10.1016/j.ica.2010.09.021.
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å) (Mo K
Crystal system
C
C22H26N2O7V2
532.33
293(2)
0.71073
monoclinic
C2/c
a)
Space group
Unit cell dimensions
a = 6.6299(3) Å
b = 16.9926(8) Å
c = 16.7975(7) Å
a = 33.758(2)
b = 7.1777(6)
c = 19.4965(15)
Reference
a
=
c
= 90°,
a = c = 90°,
b = 99.474(2)°
1866.58(14)
4
b = 99.363(5)
4661.2(6)
8
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1.695
1.517
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Absorption coefficient
1.047
0.847
(mmÀ1
)
F(0 0 0)
968
2192
Crystal size (mm3)
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0.131 Â 0.066 Â 0.03
h Range for data collection 1.72–25.23
(°)
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À7 6 h 6 7,
À39 6 h 6 37
–8 6 k 6 8
–24 6 l 6 24
19 486
4365 [R(int) = 0.1091]
94.9
Semi-empirical from
equivalents
Full-matrix least-
squares on F2
4365/0/302
1.012
R1 = 0.0492
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R1 = 0.0927
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Semi-empirical from
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r
(I)]
R
1 = 0.0548
wR2 = 0.0823
Largest difference peak and 0.490 and À0.383
hole (e ÅÀ3
wR2 = 0.1184
0.352 and À0.356
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