Complexation between vanadium (V) and phenyllactate: Synthesis, spectral studies and crystal structure of (NEt4)(NH4) 3[V2O2(O2)2(R-3-phlact) 2][V2O2</

Article abstract of DOI:10.1016/j.ica.2005.06.039

The peroxo complexes formed by vanadium (V) in the presence of rac- or S-3-phenyllactic acid as heteroligand, M₂[V₂O ₂(O₂)₂(rac-3-phlact)₂] ? nH₂O (M⁺ = K⁺

Full text of DOI:10.1016/j.ica.2005.06.039

Inorganica Chimica Acta 358 (2005) 3572–3580
www.elsevier.com/locate/ica
Complexation between vanadium (V) and phenyllactate:
Synthesis, spectral studies and crystal structure of
(NEt4)(NH4)3[V2O2(O2)2(R-3-phlact)2]
[V2O2(O2)2(S-3-phlact)2] Æ 6H2O, [3-phlact = 3-phenyllactato(2ꢀ)]
a,
a
b
P. Schwendt *, M. Ahmed , J. Marek
a
Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska´ dolina, SK-84215 Bratislava, Slovak Republic
b
Laboratory of Functional Genomics and Proteomics, Faculty of Science, Masaryk University, Kotla´ˇrska´ 2, CZ-61137 Brno, Czech Republic
Received 4 October 2004; accepted 13 June 2005
Available online 19 August 2005
Abstract
The peroxo complexes formed by vanadium (V) in the presence of rac- or S-3-phenyllactic acid as heteroligand,
M2[V2O2(O2)2(racþ-3-phlact)2] ÆþnH2O (M+ = K+ (1), NMe4 (3), NBu4 (6)), M2[V2O2(O2)2(S-3-phlact)2] Æ nH2O (M+ = K+ (7),
þ
þ
þ
þ
þ
NH4 (8), NMe4 (9), NEt4 (10), NPr4 (11), NBu4 (12)), (NH4)4[V2O2(O2)2(R-3-phlact)2][V2O2(O2)2(S-3-phlact)2] Æ 2H2O Æ
2CH3OH Æ 2H2O2 (2), (NEt4)(NH4)3[V2O2(O2)2(R-3-phlact)2][V2O2(O2)2(S-3-phlact)2] Æ 6H2O (4) and (NPr4)(NH4)3[V2O2(O2)2-
(rac-3-phlact)2]2 Æ 7H2O (5) were isolated from H2O/methanol solutions. All complexes were characterized by elemental analysis,
IR, UV–Vis and 51V NMR spectroscopies. The molecular structure of (NEt4)(NH4)3[V2O2(O2)2(R-3-phlact)2][V2O2(O2)2(S-3-phl-
act)2] Æ 6H2O (4) was determined by X-ray crystallography. The complex crystallizes as racemic compound with alternating
[V2O2(O2)2(R-3-phlact)2]2ꢀ and [V2O2(O2)2(S-3-phlact)2]2ꢀ anions in the structure. Coordination geometry around the central vana-
dium atoms is pentagonal pyramidal, which is typical for hexacoordinate oxoperoxovanadium (V) complexes.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Crystal structure; Peroxo phenyllactato complexes of vanadium (V); IR spectra; 51V NMR spectra
1. Introduction
Vanadium (V) peroxo complexes have been the object
of intense investigations, due both to their biological rel-
evance (insulinmimetic and antitumour activities [6–10],
functional models for the haloperoxidase enzymes
[11–13]) and their application in oxidation of several
substrates, such as benzene and other aromatics, alkenes,
allylic alcohols, sulfides, halides and primary and sec-
ondary alcohols [14]. Peroxovanadium complexes with
a-hydroxycarboxylic acids have been the object of spe-
cial interest, since the anions of these acids are known
to exist in biological media and to be involved in many
basic biochemical processes (Krebs cycle, Cori cycle,
photorespiration, and others [15]). The monoperoxova-
nadium complexes of citric, malic, tartaric, glycolic,
The past decade has seen a vast increase in interest in
the biological influences of vanadium [1–3]. Much of the
impetus toward vanadium biochemical research derives
from the fact that a number of vanadium complexes
have insulin-mimetic or insulin-enhancing properties.
Since discovery of the insulin mimetic effect of vanadium
(V) compounds [4], the structure and reactivity of vana-
dium (V) complexes with biologically important ligands
have been intensively studied [5].
*
Corresponding author. Fax: +421 2 6029 6273.
E-mail address: peter.schwendt@fns.uniba.sk (P. Schwendt).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.06.039

P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
3573
UK) Mo Ka radiation using rotation method with
x-scan technique. Cell parameters and an orientation
matrix for data reduction were obtained from all strong
reflections. For data collection, cell refinement and data
reduction, we used the CrysAlis (Oxford Diffraction,
2002) software package. Data were not corrected for
absorption effects. All calculations for structure solution
and refinement were done using the SHELX-97 program
[30].
Scheme 1.
mandelic and a-hydroxyhippuric acids were isolated and
characterized [10,15–25].
2.3. Syntheses
3-Phenyllactic acid (Scheme 1) and its derivatives
have found broad application in the production of many
chiral pharmaceutical and agricultural products. 3-Phen-
yllactic acid has recently been found in the cultures of
Lactobacillus plantarum that show antifungal activity in
sourdough breads [26]. 3-Phenyllactic acid has also been
reported to be one of the most abundant aromatic acids
to which antibacterial properties have been attributed to
occur in several honeys with different geographical
origins [27,28].
2.3.1. K2 [V2O2(O2)2(rac-3-phlact)2] Æ 2H2O (1)1
A solution of KVO3 (0.138 g, 1 mmol) in 5 ml water
was mixed with a solution of rac-3-H2phlact acid (0.166
g, 1 mmol) in 5 ml methanol. After cooling (0 ꢁC) of the
resulting solution, H2O2 (30%, 0.1 ml) was added under
constant stirring. Light red crystals were isolated after 4
days standing at 5 ꢁC. Anal. Calc. for K2C18H20O14V2:
C, 33.8; H, 3.1; O22ꢀ, 10.0; V, 15.9. Found: C, 33.3;
H, 3.0; O22ꢀ, 10.2; V, 15.5%.
The present work deals with the synthesis, spectro-
scopic study and crystal structure of the peroxovana-
dium (V) complexes with 3-phenyllactic acid. To our
knowledge, only one crystal structure containing coordi-
nated 3-phenyllactato ligand has been reported yet,
namely (salen)Ti(R-3-phlact) (salen = N,N0-ethylene-
bis(salicylideneaminate)) [29]. The structural parameters
of a-hydroxycarboxylatoperoxovanadates are compared
and their characteristic structural features are discussed.
2.3.2. (NH4)4[V2O2(O2)2(R-3-phlact)2][V2O2(O2)2
(S-3-phlact)2] Æ 2H2O Æ 2CH3OH Æ 2H2O2 (2)2
NH4VO3 (0.117 g, 1 mmol) and rac-3-H2phlact acid
(0.166 g, 1 mmol) were dissolved in 5 ml water and 10
ml methanol. After cooling of the solution, H2O2
(30%, 0.1 ml) was added under continuous stirring.
The red crystals were isolated after 3 days standing at
5 ꢁC. Anal. Calc. for C19H32N2O16V2: C, 35.3; H, 5.0;
N, 4.3; O22ꢀ, 10.0; V, 15.8. Found: C, 37.2; H, 4.4; N,
4.2; O22ꢀ, 10.3; V, 16.1%.
2. Experimental
2.3.3. (NMe4)2[V2O2(O2)2(rac-3-phlact)2] Æ 1.5H2O
(3)
All chemicals were of analytical grade and used as
supplied by Aldrich.
NH4VO3 (0.117 g, 1 mmol) was dissolved under stir-
ring in a NMe4OH solution (25%, 0.36 ml, 1 mmol) and
5 ml water. NH3 was removed from the solution by boil-
ing. After cooling of the resulting solution, H2O (5 ml),
H2O2 (30%, 0.1 ml), rac-3-H2phlact acid (0.166 g, 1
mmol) and methanol (5 ml) were added. The red solu-
tion obtained was allowed to crystallize at 5 ꢁC. The
red crystals were isolated after few days. Anal. Calc.
2.1. Physical measurements and analytical methods
UV–Vis spectra were recorded using a JASCO V-530
spectrophotometer. FT-IR measurements were taken on
a Nicolet 750 Magna spectrometer using Nujol mulls.
51V NMR spectra were measured on a Varian Gemini
2000 spectrometer operating at 78.94 MHz, the chemical
shifts were referenced to VOCl3 as external standard.
Carbon, hydrogen and nitrogen were estimated on a
Carlo Erba CHN-analyser. Peroxidic oxygen was deter-
mined by titration with KMnO4. Vanadium (V) was
determined by titration with FeSO4.
2ꢀ
for C26H43N2O13.5V2: C, 44.5; H, 6.2; N, 4.0; O2
,
1
We use the rac-3-phlact formula, when racemic ligand was used in
the synthesis, but without knowledge what enantiomers are bound in
the structure.
2
˚
X-ray structure of this compound was solved: a = 17.3196(13) A,
˚
˚
b = 17.4775(7) A, c = 17.7981(14) A, b = 114.697(9)ꢁ, Z = 4, space
group P21/n, Dc = 1.600 g/cm3. Some of the solvent molecules were
found to be disordered with two main positions and occupancy factors
2.2. X-ray structure determination
around 0.5. Due to disorder, the final
R factors were high
Low-temperature X-ray measurements were made on
a KUMA KM4 + CCD diffractometer with monochro-
mated (monochromator Enhance, Oxford Diffraction,
(R1(I > 2r1) = 0.0787), nevertheless, the results confirmed the expected
connectivity, racemic character of the compound and the presence of
CH3OH, H2O2 and H2O molecules in the structure.

3574
P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
9.1; V, 14.5. Found: C, 44.6; H, 5.8; N, 3.8; O22ꢀ, 8.9; V,
14.8%.
bath, S-3-H2phlact acid (0.332 g, 2 mmol) was dissolved
in 5 ml H2O and 5 ml methanol and added under stirring
to the solution of peroxovanadate. The red crystals of 8
were crystallized within 3 days standing at 5 ꢁC. Anal.
Calc. for C18H25N2O12.5V2: C, 37.8; H, 4.4; N, 4.9;
2.3.4. (NEt4)(NH4)3[V2O2(O2)2(R-3-phlact)2][V2O2-
(O2)2(S-3-phlact)2] Æ 6H2O (4)
2ꢀ
To a solution of NH4VO3 (0.117 g, 1 mmol) in 5 ml
H2O, NEt4OH (35%, 0.42 ml, 1 mmol) was added.
The solution was heated for a short time, cooled and
then H2O2 (30%, 0.1 ml) was added. Finally, rac-3-
H2phlact acid (0.166 g, 1 mmol) in 5 ml methanol was
added under vigorous stirring. The obtained solution
was allowed to crystallize (5 ꢁC), the red crystals of 4
were isolated after 4 days. Anal. Calc. for C44H76N4-
O30V4: C, 39.3; H, 5.7; N, 4.2; O22ꢀ, 9.5; V, 15.1. Found:
C, 39.3; H, 5.4; N, 3.8; O22ꢀ, 9.2; V, 14.9%.
O2 , 11.2; V, 17.8. Found: C, 37.6; H, 4.5; N, 5.0;
O22ꢀ, 10.9; V, 17.4%.
2.3.9. (NMe4)2[V2O2(O2)2(S-3-phlact)2] Æ 3H2O (9)
NH4VO3 (0.234 g, 2 mmol) was dissolved under stir-
ring in a NMe4OH solution (25%, 0.72 ml, 2 mmol) and
NH3 was removed from the solution by brief boiling.
After cooling of the resulting solution, H2O (5 ml),
H2O2 (30%, 0.2 ml), S-3-H2phlact acid (0.332 g, 2
mmol) and methanol (5 ml) were added. The red solu-
tion obtained was allowed to crystallize at 5 ꢁC. The
red crystals were isolated after few days. Anal. Calc.
for C26H46N2O15V2: C, 42.9; H, 6.4; N, 3.8; O22ꢀ, 8.8;
V, 14.0. Found: C, 42.4; H, 5.9; N, 4.4; O22ꢀ, 9.1; V,
14.2%.
2.3.5. (NPr4)(NH4)3[V2O2(O2)2(rac-3-phlact)2]2 Æ
7H2O (5)
NH4VO3 (0.234 g, 2 mmol) was dissolved in a stirred
NPr4OH (1 mol dmꢀ3, 2 ml)/H2O (5 ml) mixture. NH3
was partially removed from the solution by brief boiling.
After cooling to the room temperature, H2O2 (0.2 ml,
30%) and rac-3-H2phlact acid (0.332 g, 2 mmol) in meth-
anol (5 ml) were added. The red solution obtained was
allowed to crystallize at 5 ꢁC. The red crystals were iso-
lated after three days. Anal. Calc. for C48H86N4O31V4:
C, 40.6; H, 6.1; N, 3.9; O22ꢀ, 9.0; V, 14.4. Found: C,
40.5; H, 6.0; N, 3.5; O22ꢀ, 9.3; V, 14.1%.
2.3.10. (NEt4)2[V2O2(O2)2(S-3-phlact)2] Æ 0.5H2O
(10)
The same procedure was followed as for 9, except
that NEt4OH solution (35%, 0.84 ml, 2 mmol) was used
in place of the NMe4OH solution. Anal. Calc. for
C34H57N2O12.5V2: C, 51.3; H, 7.2; N, 3.5; O22ꢀ, 8.0; V,
12.8. Found: C, 51.9; H, 7.7; N, 3.8; O22ꢀ, 8.3; V, 13.1%.
2.3.6. (NBu4)2[V2O2(O2)2(rac-3-phlact)2] Æ H2O (6)
The compound was prepared by the same procedure
as for 3, but using NBu4OH solution (40%, 0.65 ml,
1 mmol). Anal. Calc. for C50H90N2O13V2: C, 58.3; H,
8.8; N, 2.7; O22ꢀ, 6.2; V, 10.0. Found: C, 58.1; H, 9.0;
N, 2.6; O22ꢀ, 6.4; V, 10.2%.
2.3.11. (NPr4)2[V2O2(O2)2(S-3-phlact)2] Æ 4H2O (11)
NPr4OH (1 mol dmꢀ3, 2 ml, 2 mmol) was added to a
solution of NH4VO3 (0.234 g, 2 mmol) in 5 ml H2O. The
ammonia was removed from the resulting solution by
boiling. The solution was cooled and added to a solution
of H2O2 (30%, 0.2 ml). A solution of S-3-H2phlact acid
(0.332 g, 2 mmol) in 5 ml methanol was then added un-
der vigorous stirring. The obtained solution was allowed
to crystallize, the red crystals of 11 were obtained within
a few days. Anal. Calc. for C42H80N2O16V2: C, 51.9; H,
8.3; N, 2.9; O22ꢀ, 6.6; V, 10.5. Found: C, 51.8; H, 8.5; N,
2.6; O22ꢀ, 6.9; V, 10.2%.
2.3.7. K2[V2O2(O2)2(S-3-phlact)2] Æ 5H2O (7)
Prepared by the same procedure as for 1, but using
S-3-H2phlact acid (0.166 g, 1 mmol). Anal. Calc. for
K2C27H36O20V2: C, 31.1; H, 3.8; O22ꢀ, 9.2; V, 14.7.
Found: C, 31.2; H, 3.4; O22ꢀ, 9.0; V, 14.8%.
2.3.8. (NH4)2[V2O2(O2)2(S-3-phlact)2] Æ 0.5H2O (8)
NH4VO3 (0.234 g, 2 mmol) was dissolved in diluted
H2O2 (0.5 ml 30% in 10 ml H2O) under cooling in ice
2.3.12. (NBu4)2[V2O2(O2)2(S-3-phlact)2] Æ 2H2O (12)
Prepared by the same procedure as for 11, but using
NBu4OH (40%, 1.3 ml, 2 mmol). Anal. Calc. for
Table 1
Characteristic IR bands (cmꢀ1) for the vanadium (V) oxo peroxo rac-3-phenyllactato complexes (1–6)
1
2
3
4
5
6
Assignment
3642 s
3553 m
1645 s, 1623 s
1394 s, 1377 s
980 vs
3469 b
3343 b
3235 sh
1662 vs
1380 m, 1360 s
982 s
3435 b
3520 m
3435 m
1633 vs
1377 vs
983 s
3527 s
3440 m, 3293 w
1634 vs
1379 vs
990 vs, 980 s
931 vs
m(H2O) or
m(NH)
3297 m, 3160 m
1645 vs
1376 s
982 s
923 s
1652 vs
1375 vs
982 s
929 s
575 m
mas(COOꢀ)
ms(COOꢀ)
m(V@O)
923 vs
562 s
954 m, 933 vs
576 m, 541 s
929 s
582 m
m(Op–Op)
m(V–Op)
567 m
581 s

P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
3575
Table 2
Characteristic IR bands (cmꢀ1) for the vanadium (V) oxo peroxo S-3-phenyllactato complexes (7–12)
7
8
9
10
11
12
Assignment
3641 s
3445 m
3480 w
3533 s, 3440 m
3289 sh
1635 vs
1378 vs
989 vs
3531 m
3438 m
1636 vs
1378 vs
988 s
3527 s
m(H2O) or
m(NH)
3550 m
1645 s, 1621 s
1377 vs
979 s
3439 m
1634 vs
1379 vs
990 vs
1667 m, 1614 vs
1378 vs
977 m
1661 vs
1375 s
983 s
mas(COOꢀ)
ms(COOꢀ)
m(V@O)
924 s
562 m
938 s, 927 s
545 s
954 m, 932 vs
579 m, 540 m
933 vs
582 m, 540 m
934 vs
580 m, 540 m
931 vs
583 s, 539 m
m(Op–Op)
m(V–Op)
C50H92N2O14V2: C, 57.3; H, 8.9; N, 2.7; O22ꢀ, 6.1; V,
9.7. Found: C, 57.0; H, 8.8; N, 2.5; O22ꢀ, 6.4; V, 10.1%.
3. Results and discussion
3.1. Syntheses
The red or light red peroxo complexes of vanadium
(V) of composition M2[V2O2(O2)2(rac-3-phlact)2] Æ nH2O
(M+ = K+ (1), NMe4þ (3), NBu4þ (6)),þM2[V2O2(O2)2(S-
3-phlþact)2] Æ nH2O (M+ = K+ (7),þNH (8), NMe4 (9),
þ
4
þ
NEt4 (10), NPr4 (11), NBu4 (12)), (NH4)4[V2O2-
(O2)2(R-3-phlact)2][V2O2(O2)2(S-3-phlact)2] Æ 2H2O Æ 2CH3-
OH Æ 2H2O2 (2), (NEt4)(NH4)3[V2O2(O2)2(R-3-phlact)2]-
[V2O2(O2)2(S-3-phlact)2] Æ 6H2O (4) and (NPr4)(NH4)3-
[V2O2(O2)2(rac-3-phlact)2]2 Æ 7H2O (5) were obtained by
crystallization from the MVO3–H2phlact–H2O2–H2O–
CH3OH and NH4VO3–H2phlact–NR4OH–H2O2–H2O–
CH3OH systems (R = Et, Me, Bu, Pr). The complexes
decompose slowly at room temperature both in the solid
state and solution.
Fig. 1. The structure of the [V2O2(O2)2(S-3-phlact)2]2ꢀ anion in 4 at
the 50% probability level.
Table 3
Crystal data and structure refinement for (NEt4)(NH4)3[V2O2(O2)2-
(R-3-phlact)2][V2O2(O2)2(S-3-phlact)2] Æ 6H2O (4)
Formula
C44H76N4O30V4
Crystal system
Space group
T (K)
orthorhombic
Pbcn
3.2. Infrared spectroscopy
120(2)
10.0312(4)
29.4515(11)
19.7814(8)
90
90
90
5844.1(4)
The infrared spectra for complexes 1–12 are listed in
Tables 1 and 2. The spectra exhibit strong absorptions
for the carbonyl of the carboxylate group in both the
asymmetric and symmetric vibration regions. Asymmet-
ric stretching vibrations mas(COOꢀ) appeared in the
region from 1667 to 1614 cmꢀ1, whereas the correspond-
ing symmetric stretches ms(COOꢀ) were present in the
range 1394–1360 cmꢀ1. For all of the complexes studied
here, the difference between the asymmetric and symmet-
ric stretches, D = mas(COOꢀ) ꢀ ms(COOꢀ), was greater
than 200 cmꢀ1, indicating that the carboxylate group in
the phenyllactate ligand was coordinated to vanadium
in a monodentate fashion [31]. This was further confirmed
by the X-raycrystal structure of 4. The spectra also exhibit
characteristic bands of the VO(O2) group [32,33]. The
bands at 990–977 cmꢀ1 were assigned to V@O stretches,
in agreement with a double bond character of this bond,
the bands at 954–923 cmꢀ1 were assigned to the peroxo
Op–Op stretches and the V–Op stretching vibrations were
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
4
Dcalc (g/cm3)
1.524
0.71073
˚
k (A)
Crystal size (mm)
h Range (ꢁ)
0.30 · 0.20 · 0.20
2.90–25.00
ꢀ11 6 h 6 11, ꢀ35 6 k 6 34,
ꢀ23 6 l 6 19
29340
5127 [0.0683]
1.223
R1 = 0.0631, Rw2 = 0.1084
R1 = 0.0838, Rw2 = 0.1170
0.307 and ꢀ0.250
Index ranges
Reflections collected
Independent reflections [Rint
Goodness-of-fit on F2
Final R indices (I > 2r1)
R indices (all data)
]
Largest difference in peak and
ꢀ3
˚
hole (e A
)
Refinement method
Data/restraints/parameters
full-matrix least-squares on F2
5127/9/411
observed at 583–539 cmꢀ1
.

3576
P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
3.3. Crystal structure
monodentate carboxylate and another to the adjacent
deprotonated alcoholic group. The latter donor behaves
as a monoatomic bridge and coordinates simultaneously
to two metal centres, giving a central V2O2 rhomboid
ring. The V2O2 core is nonplanar and the V@O groups
are cis-oriented in relation to the V2O2 core [15] (vide
infra). The coordination environment around each
vanadium can be described as a distorted pentagonal
pyramid. The equatorial planes are occupied by the
peroxo groups (O(2), O(3), O(8), O(9)), both bridging
hydroxyl oxygen atoms (O(6), O(12)), and the oxygen
atoms (O(4), O(10)) from the monodentate carboxylic
The ORTEP diagram of the anion in 4 is shown in
Fig. 1. Crystal data and structure refinement for
(NEt4)(NH4)3[V2O2(O2)2(R-3-phlact)2][V2O2(O2)2(S-3-
phlact)2] Æ 6H2O are shown in Table 3. The selected
interatomic distances and angles, listed in Table 4, are
in the expected ranges. The structure of the anion can
be described as a dimer of two oxoperoxovanadium
(V) units with two R (or S)-3-phenyllactate ligands.
The 3-phenyllactate(2ꢀ) anion exhibits a chelating
bonding mode via two oxygens, one belonging to a
Table 4
˚
Selected bond lengths (A) and angles (ꢁ) for (NEt4)(NH4)3
[V2O2(O2)2(R-3-phlact)2][V2O2(O2)2(S-3-phlact)2] Æ 6H2O (4)
V(1)–O(1)
V(1)–O(3)
V(1)–O(2)
V(1)–O(6)
V(1)–O(12)
V(1)–O(4)
V(2)–O(7)
V(2)–O(8)
V(2)–O(9)
V(2)–O(12)
V(2)–O(10)
V(2)–O(6)
O(2)–O(3)
O(8)–O(9)
1.590(3)
1.863(3)
1.885(3)
1.964(3)
1.998(2)
2.016(3)
1.583(3)
1.863(3)
1.880(3)
1.983(3)
2.019(3)
2.020(2)
1.428(4)
1.433(4)
Fig. 2. UV–Vis spectra of 10ꢀ3 mol dmꢀ3 (NMe4)2[V2O2(O2)2
(S-3-phlact)2] Æ 3H2O (9) in MeCN at T = 278 K and 30 min (a), 1 d
(b), 2 d (c), 4 d (d), 5 d (e), 6 d (f), 10 d (g) after dissolution.
O(1)–V(1)–O(3)
O(1)–V(1)–O(2)
O(3)–V(1)–O(2)
O(1)–V(1)–O(6)
O(3)–V(1)–O(6)
O(2)–V(1)–O(6)
O(1)–V(1)–O(12)
O(3)–V(1)–O(12)
O(2)–V(1)–O(12)
O(6)–V(1)–O(12)
O(1)–V(1)–O(4)
O(2)–V(1)–O(4)
O(6)–V(1)–O(4)
O(12)–V(1)–O(4)
O(7)–V(2)–O(12)
O(8)–V(2)–O(12)
O(9)–V(2)–O(12)
O(7)–V(2)–O(10)
O(8)–V(2)–O(10)
O(9)–V(2)–O(10)
O(12)–V(2)–O(10)
O(7)–V(2)–O(6)
O(8)–V(2)–O(6)
O(9)–V(2)–O(6)
O(12)–V(2)–O(6)
O(10)–V(2)–O(6)
O(3)–O(2)–V(1)
O(2)–O(3)–V(1)
V(1)–O(6)–V(2)
O(9)–O(8)–V(2)
O(8)–O(9)–V(2)
V(2)–O(12)–V(1)
106.69(15)
100.85(14)
44.80(11)
106.54(14)
138.77(12)
145.59(12)
95.59(12)
82.62(11)
127.38(11)
70.50(10)
96.78(13)
79.13(12)
77.34(11)
147.65(11)
103.89(12)
145.06(11)
142.82(11)
97.80(13)
78.21(11)
122.30(11)
77.23(10)
98.35(12)
126.20(12)
82.35(11)
69.67(10)
145.76(11)
66.77(16)
68.43(16)
107.68(12)
68.12(15)
66.86(15)
107.81(12)
Fig. 3. Time dependence of the 51V NMR spectra of the aqueous
solutions of vanadium (V) peroxo rac-3-phenyllactato complexes.
Solution prepared by mixing of aqueous NH4VO3, rac-3-phlact and
H2O2 [c(V) = c(rac-3-phlact) = c(H2O2) = 0.02 mol dm3] at T = 278
K. 1, 40 min; 2, 8 h; 3, 24 h; 4, 2 days after preparation; 5, solution
prepared by mixing of aqueous NH4VO3 and rac-3-phlact
[c(V) = c(rac-3-phlact) = 0.02 mol dmꢀ3], 30 min after preparation.
For A–F see text.

P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
3577
group. The axial positions are taken by the double
bonded oxygen atoms (O(1), O(7)). The length of the
VO (alcoholate) bonds (2.000, 1.967, 2.026 and 1.988
signal at ꢀ604 ppm. The complex A converts into an
oxovanadium complex of rac-3-phlact acid E [V2O4-
(rac-3-phlact)2]2ꢀ (ꢀ537 ppm) by release of the second
active oxygen atom. The identity of the E species was
˚
A) supports the view that the hydroxyl groups are
deprotonated. Formation of the [V2O2(O2)2(R-3-phl-
act)(S-3-phlact)]2ꢀ stereoisomer was not observed, the
complex crystallizes as a racemic compound.
confirmed by the in situ measurement (Fig. 3, spectrum
51
5). The
HxV10O28
V NMR spectra also exhibit peaks of
ð6ꢀxÞꢀ
(F) at about ꢀ521, ꢀ506 and ꢀ427
ppm and [VO(O2)2(H2O)]ꢀ (D) at about ꢀ697 ppm.
3.4. Solution spectra
3.5. Characteristic features of the crystal structures of
a-hydroxycarboxylatooxoperoxovanadates
The UV–Vis spectra of 9 (and similarly of other pre-
pared complexes) in MeCN solution (Fig. 2) exhibit a
LMCT band at 424 nm, which is characteristic for the
vanadium (V) monoperoxo complexes [34,35].
The structure of all structurally characterized
a-hydroxycarboxylatooxoperoxovanadates (V) listed in
Table 5 consists of dinuclear anions and counter cations.
The characteristic structural feature of anions is the
central rhombic V2O2 core. All a-hydroxycarboxylato
ligands are coordinated to the central atom via monod-
entate carboxylic and hydroxylic groups, the latter
forming a bridge between two vanadium centres. The
citrato, malato and a-hydroxyhippurato ligands are
coordinated to the vanadium atom as tridentate ligands
using the oxygen atoms of carboxylic groups (from
COOH or CO) as the third donor atom.
The coordination number of the central atom varies
between 6 (pentagonal pyramidal geometry) and 7 (pen-
tagonal bipyramidal structure). With exception of the
citrato, malato and a-hydroxyhippurato complexes
mentioned above, the pentagonal bipyramidal arrange-
ment is achieved by bonding of a water molecule or
exceptionally by bonding of a molecule of a-hydroxy-
carboxylic acid. The geometric parameters of the V2O2
core in various compounds are similar (Table 6).
The 51V NMR spectra of oxo peroxo complexes of
vanadium (V) with a-hydroxycarboxylates and other
ligands have been currently studied [20,21,36–45]. In
the presence of hydrogen peroxide and rac-3-phenyllac-
tic acid in aqueous solution, vanadium (V) can form
several complexes (Fig. 3, spectra 1–4). The chemical
shift d = ꢀ604 ppm can be assigned to the dinuclear
monoperoxo vanadium complex C, [V2O2(O2)2(rac-3-
phlact)2]2ꢀ, which is probably the species with the same
structure as found in the solid state. We tentatively
assign the signal B at ꢀ552 ppm to a monomeric mono-
peroxo species [VO(O2)(rac-3-phlact)(H2O)]ꢀ [38,39].
The species A is attributed to the intermediate decompo-
sition product [V2O3(O2)(rac-3-phlact)2]2ꢀ (resulting
from the decomposition of C by release of one oxygen
atom from the two peroxo groups). For the [V2O3(O2)-
(rac-3-phlact)2]2ꢀ ion, we should expect two 51V NMR
signals: one for the vanadium atom in the dioxo moiety,
observed at ꢀ524 ppm, and the second one for the vana-
dium atom in the intact VO(O2) moiety. The latter sig-
nal, lacking in the spectra, is probably hidden in the
The V2O2 core is planar or nonplanar in dependence
on the type of the a-hydroxycarboxylato ligands (chiral
Table 5
Structurally characterized a-hydroxycarboxylatooxoperoxovanadates (V)
No.
Complexa
Ref.
1
2
3
4
5
(NBu4)2[V2O2(O2)2(S-lact)2] Æ 2H2O
(NBu4)2[V2O2(O2)2(R-lact)(S-lact)] Æ 2H2O
(NH4)2[V2O2(O2)2(H2cit)2] Æ 2H2O
K4[V2O2(O2)2(R-mal)(S-mal)] Æ 4H2O
(NH4)4[V2O2(O2)2(R-mal)(S-mal)] Æ 3H2O
K2[V2O2(O2)2(R-Hmal)(S-Hmal)] Æ 2H2O
[15]
[15]
[23]
[24]
[24]
[24]
6
7
8
(NBu4)4[V2O2(O2)2(S-mand)2][V2O2(O2)2(R-mand)2] Æ (R-H2mand)(S-H2mand)
K4[V2O2(O2)2(R-lact)2][V2O2(O2)2(S-lact)2]
[18]
[19]
9
K2[{VO(O2)(RR-H2tart)}2(l-H2O)] Æ 5H2O
[17]
10
11
12
13
14
15
16
17
a
(NBu4)2[V2O2(O2)2(glyc)2] Æ H2O
[20]
[21]
[21]
[21]
[22]
[41]
this work
[25]
(NMe4)4[V2O2(O2)2(R-mand)2][V2O2(O2)2(S-mand)2] Æ 13H2O
(NMe4)2(NH4)2[V2O2(O2)2(R-mand)2(H2O)][V2O2(O2)2(S-mand)2(H2O)] Æ 4H2O
(NEt4)2[V2O2(O2)2(R-mand)2]
(NPr4)2[V2O2(O2)2(R-a-hhip)(S-a-hhip)] Æ 5H2O
(NBu4)2[V2O2(O2)2(R-a-hhip)(S-a-hhip)] Æ 5H2O
(NEt4)(NH4)3[V2O2(O2)2(R-3-phlact)2][V2O2(O2)2(S-3-phlact)2] Æ 6H2O
(NH4)6[V2O2(O2)2(cit)2] Æ 4.5H2O
glyc = glycolato (C2H2O3)2ꢀ, cit = citrato (C6H4O7)4ꢀ, mal = malato (C4H3O5)3ꢀ, lact = lactato (C3H4O3)2ꢀ, mand = mandelato (C8H6O3)2ꢀ
,
tart = tartrato (C4H2O6)4ꢀ, a-hhip = a-hydroxyhippurato (C9H7NO4)2ꢀ, 3-phlact=3-phenyllactato (C9H8O3)2ꢀ
.

3578
P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
Table 6
Geometric parameters of the V2O2 core in a-hydroxycarboxylatooxoperoxo-vanadates (V)
Complex no.a
Space group
d(V–O) (A)
\OVO (ꢁ)
\VOV (ꢁ)
Geometryb
NP
Chiralityc
Td
B
CNe
6
˚
1
P21
1.918(6)
2.037(5)
1.927(6)
2.049(6)
69.8(3)
69.3(2)
109.4(3)
109.3(3)
CH (SS)
2
3
4
5
P21/n
P21/n
P21/c
2.025(6)
1.927(6)
70.0(3)
72.45(8)
72.30(8)
71.6(2)
110.0(3)
107.15f
107.70f
108.4f
P
P
P
P
CH (RS)
ACH
A
A
A
A
6
6
7
7
1.992(2)
2.034(2)
2.005(2)
2.025(2)
CH (RS)
CH (RS)
ꢀ
P1
1.987(3)
2.026(3)
6
7
8
9
P21/c
Pbcn
C2/c
1.986(2)
2.021(2)
71.43(9)
69.57(10)
70.0(1)
108.57f
P
CH (RS)
A
B
B
B
6
6
6
7
1.979(2)
2.000(2)
105.58(10)
109.9(1)
NP
NP
NP
CH (SS)
(RR)
1.957(3)
2.000(3)
CH (SS)
(RR)
C2221
2.010(5)
2.015(5)
2.026(5)
2.003(5)
70.3(2)
69.9(2)
101.0(2)
101.6(2)
CH
(RRRR)g
10
11
P21/n
C2/c
1.923(4)
2.011(4)
69.7(2)
110.3(2)
P
ACH
A
B
6
6
1.975(4)
2.035(3)
1.967(3)
1.990(4)
69.25(14)
70.32(14)
109.92(16)
108.44(15)
NP
CH (SS)
(RR)
12
P21/c
1.9747(19)
2.0004(19)
1.9871(19)
2.0211(19)
1.9979(19)
2.006(2)
70.04(8)
69.38(8)
70.31(8)
70.33(8)
109.39(9)
109.73(9)
103.16(8)
103.75(8)
NP
CH (SS)
(RR)
B
6, 7
1.9977(19)
2.0056(19)
13
14
P212121
1.975(2)
2.018(19)
1.954(2)
2.042(2)
68.44(8)
68.35(8)
108.59(9)
110.44(10)
NP
CH (RR)
CH (RS)
B
6
7
ꢀ
P1
2.032(4)
2.037(4)
2.032(4)
2.042(4)
2.289(4)
2.292(4)
70.98(14)
70.89(14)
108.79(19)
109.34(19)
P
A
15
P21/c
2.0330(15)
2.0403(15)
2.0244(14)
2.0301(15)
70.54(7)
72.05(7)
109.46(7)
107.95(7)
P
CH (RS)
A
7
(continued on next page)

P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
3579
Table 6 (continued)
Complex No.a
16
Geometryb
NP
Chiralityc
Td
B
CNe
6
˚
Space group
d(V–O) (A)
\OVO (ꢁ)
\VOV (ꢁ)
Pbcn
1.967(3)
2.000(3)
2.026(3)
1.988(3)
1.968(3)
2.002(3)
2.023(3)
1.986(3)
70.55(11)
69.61(11)
70.53(11)
69.73(11)
107.63(12)
107.87(12)
107.68(12)
107.79(12)
CH (SS) (RR)
17
C2/c
2.013(3)
2.055(3)
73.44(11)
106.56(11)
P
ACH
A
7
a
Numbering according to Table 5.
b
c
d
e
f
Planarity of the V2O2 core: P, planar; NP, nonplanar.
Chirality of the ligands: ACH, achiral ligand; CH, chiral ligand with combination of enantiomers in the anion in parentheses.
Types according to Fig. 4.
Coordination number.
Calculated value.
g
Two chiral centres in one ligand, i.e., four chiral centres in a dinuclear anion.
or achiral) and on the combination of ligand enantio-
mers in the dinuclear anion (RR, SS or RS) (Fig. 4).
For all complexes given in Table 5, the previously for-
mulated rule on the geometry of the V2O2 core [15]
(Fig. 4, Table 6) is valid. The different arrangement of
the [V2O2(O2)2(ligand)2]nꢀ anions in dependence on the
enantiomers of a ligand present in the dinuclear anion
can be attributed in large part to the steric demands of
the ligand. With ligands containing the bulky benzene
ring in the proximity of the OH group, in spite of
racemic ligand used in the synthesis, the [V2O2(O2)2-
(R-ligand)2]nꢀ and [V2O2(O2)2(S-ligand)2]nꢀ isomers can
only be obtained. This is the case of mandelic acid
(one C atom between benzene ring and the donor
oxygen atom of the hydroxylic group) and 3-phenyllac-
tic acid (two C atoms – Scheme 2). On the other hand,
with a-hydroxyhippuric acid, in which the aromatic ring
is relatively distant from the hydroxylic group, [V2O2-
(O2)2(R-ligand)(S-ligand)]2ꢀ isomer was formed. Using
lactic acid as a heteroligand, both isomers M2[V2O2-
(O2)2(S-lact)2] and M2[V2O2(O2)2(R-lact)(S-lact)] were
prepared [15].
Scheme 2.
Table 7
The deviations of the vanadium atoms from the least squares
pentagonal plane in complexes 9 and 12–15
Complex no.
V1
V2
V3
V4
9
12
13
14
15
16
0.3688
0.4588
0.4302
0.2720
0.2423
0.3745
0.3501
0.3166
0.4858
0.2879
0.2462
0.3845
0.3383
0.2850
0.3744
0.3464
0.2612
0.3859
The deviation of the vanadium atoms from the least
squares pentagonal plane (Table 7) depends on the
structural type (A and B) and on the coordination num-
ber of vanadium. The deviation is smallest for the seven
coordinated vanadium atoms in the structures with a
˚
planar V2O2 core (ꢁ0.24–0.29 A) and largest for the
six coordinated vanadium atoms in mandelato com-
˚
plexes (ꢁ0.31–0.49 A, the V2O2 core is nonplanar).
4. Supplementary material
Fig. 4. Structural types of the a-hydroxycarboxylatooxoperoxovana-
dates. A (left) – planar V2O2 group for RS combination of a chiral
ligand or some achiral ligands (glycolato-, citrato-), B (right) – for RR
or SS combination of the chiral ligand.
Supplementary data are available from CCDC 12
Union Road, Cambridge, CB 2 1EZ, UK on request
quoting the deposition number CCDC 247261.

3580
P. Schwendt et al. / Inorganica Chimica Acta 358 (2005) 3572–3580
[19] F. Demartin, M. Biagioli, L. Strinna-Erre, A. Panzanelli, G.
Micera, Inorg. Chim. Acta 299 (2000) 123.
Acknowledgement
ˇ
´
´
[20] P. Svancˇarek, P. Schwendt, J. Tatiersky, I. Smatanova, J. Marek,
This work was supported by the Ministry of Educa-
tion of the Slovak Republic (Grant 1/1375/04) and the
Czech Republic (Grant 143100008).
Monatsh. Chem. 131 (2000) 145.
[21] M. Ahmed, P. Schwendt, J. Marek, M. Sivak, Polyhedron 23
´
(2004) 655.
[22] P. Schwendt, M. Ahmed, J. Marek, Inorg. Chem. Commun. 7
(2004) 631.
[23] M. Tsaramyrsi, D. Kavousanaki, C.P. Raptopoulou, A. Terzis,
A. Salifoglou, Inorg. Chim. Acta 320 (2001) 47.
[24] M. Kaliva, T. Giannadaki, C.P. Raptopoulou, A. Terzis, Inorg.
Chem. 40 (2001) 3711.
[25] M. Kaliva, C.P. Raptopoulou, A. Terzis, A. Salifoglou, Inorg.
Chem. 43 (2004) 2895.
[26] P. Lavermicocca, F. Valerio, A. Visconti, J. Appl. Environ.
Microbiol. 69 (2003) 634.
[27] E. Steeg, A. Montag, Z. Lebensm.- Unters. Forsch. 184 (1987) 17.
[28] R.J. Weston, K.R. Mitchell, K.L. Allen, Food Chem. 64 (1999)
295.
References
[1] A.S. Tracey, D.C. Crans (Eds.), Vanadium Compounds: Chem-
istry, Biochemistry and Therapeutic Applications, ACS Sympo-
sium Series, vol. 711, ACS Books, Washington, 1998.
[2] H. Sigel, A. Sigel (Eds.), Vanadium and its Role in Life, Metal
Ions in Biological Systems, vol. 31, Marcel Dekker, New York,
1995.
[3] D. Rehder, Inorg. Chem. Commun. 6 (2003) 604.
[4] J. Shechter, S.J.D. Karlish, Nature 284 (1980) 556.
[5] D.C. Crans, in: H. Sigel, A. Sigel (Eds.), Vanadium and its Role
in Life, Metal Ions in Biological Systems, vol. 31, Marcel Dekker,
New York, 1995, p. 147.
[29] K.M. Caroll, J. Schwartz, D.M. Ho, Inorg. Chem. 33 (1994) 2707.
[30] G.M. Sheldrick, SHELX-97 Program, Dept. Inorg. Chem., Univer-
sity of Go¨ttingen, Germany.
[6] K.H. Thompson, J.H. McNeill, C. Orvig, Chem. Rev. 99 (1999)
2561.
[7] A. Shaver, J.B. Ng, D.A. Hall, B.S. Lum, B.I. Posner, Inorg.
Chem. 32 (1993) 3109.
[31] K. Nakamoto, Infrared and Raman Spectra of Inorganic
and Coordination Compounds, fourth ed., Wiley and Sons,
New York, Chichester, Brisbane, Toronto, Singapore, 1990,
p. 253.
[8] B.I. Posner, R. Faure, J.W. Burgess, A.P. Bevan, D. Lachance,
G. Zhang-Sun, I.G. Fantus, J.B. Ng, D.A. Hall, B.S. Lum, A.
Shaver, J. Biol. Chem. 269 (1994) 4596.
[9] A.P. Bevan, J.W. Burgess, J.F. Yale, P.G. Drake, D. Lachance, G.
Baquiran, A. Shaver, B.I. Posner, Am. J. Physiol. 268 (1995) E60.
[10] C. Djordjevic, M. Lee, E. Sinn, Inorg. Chem. 28 (1989) 719 (and
references cited therein).
[11] G.J. Colpas, B.J. Hamstra, J.W. Kampf, V.L. Pecoraro, J. Am.
Chem. Soc. 116 (1994) 3627.
[12] G.J. Colpas, B.J. Hamstra, J.W. Kampf, V.L. Pecoraro, J. Am.
Chem. Soc. 118 (1996) 3469.
[32] H. Mimoun, L. Saussine, E. Daire, M. Postel, J. Fischer, R.
Weiss, J. Am. Chem. Soc. 105 (1983) 3101.
[33] P. Schwendt, Collect. Czech. Chem. Commun. 48 (1983) 248.
[34] M. Orhanovic, R.G. Wilkins, J. Am. Chem. Soc. 89 (1967) 278.
´
[35] M. Sivak, Chem. Papers 41 (1987) 311.
[36] V. Conte, F. Di Furia, S. Moro, J. Mol. Catal. 104 (1995) 159.
[37] S. Hati, R.J. Batchelor, F.W.B. Einstein, A.S. Tracey, Inorg.
Chem. 40 (2001) 6258.
[38] L.L.G. Justino, M.L. Ramos, M.M. Caldeira, V.M.S. Gil, Inorg.
Chim. Acta 311 (2000) 119.
[39] L.L.G. Justino, M.L. Ramos, M.M. Caldeira, V.M.S. Gil, Eur. J.
Inorg. Chem. (2000) 1617.
[13] K. Kanamori, K. Nishida, N. Miyata, K. Okamoto, Chem. Lett.
(1998) 1267.
´
[40] A. Gorzsas, I. Andersson, L. Pettersson, Dalton Trans. (2003)
[14] A. Butler, M.J. Clague, G.E. Meister, Chem. Rev. 94 (1994) 625.
2503.
ˇ
´
´
[41] M. Ahmed, P. Schwendt, J. Marek, M. Siva´k, Trans. Met. Chem
29 (2004) 675.
[15] P. Schwendt, P. Svancˇarek, I. Smatanova, J. Marek, J. Inorg.
Biochem. 80 (2000) 59.
[16] C. Djordjevic, M. Lee-Renslo, E. Sinn, Inorg. Chim. Acta 233
(1995) 97.
[42] C. Slebodnick, V.L. Pecoraro, Inorg. Chim. Acta 283 (1998) 37.
[43] I. Andersson, A. Gorzsa
´s, L. Pettersson, Dalton Trans. (2004)
ˇ
´
839.
[17] P. Schwendt, P. Svancˇarek, L. Kuchta, J. Marek, Polyhedron 17
(1998) 2161.
ˇ
[44] M. Casny
´, D. Rehder, Dalton Trans. (2004) 839.
ˇ
´
´
ˇ´
[45] M. Vennat, J.-M. Bregeault, P. Hersoan, Dalton Trans. (2004)
908.
[18] I. Kuta Smatanova, J. Marek, P. Svancarek, P. Schwendt, Acta
Crystallogr. C56 (2000) 154.