Accepted Manuscript

Synthesis, Structural Characterization and Spectroscopy Studies of New Oxo-vanadium(IV, V) Complexes with Hydrazone Ligands

Patrycja Paciorek, Janusz Szklarzewicz, Anna Jasińska, Bartosz Trzewik,Wojciech Nitek, Maciej Hodorowicz

PII: S0277-5387(14)00725-6DOI: http://dx.doi.org/10.1016/j.poly.2014.11.018Reference: POLY 11066

To appear in: Polyhedron

Received Date: 11 September 2014Accepted Date: 6 November 2014

Please cite this article as: P. Paciorek, J. Szklarzewicz, A. Jasińska, B. Trzewik, W. Nitek, M. Hodorowicz, Synthesis,Structural Characterization and Spectroscopy Studies of New Oxovanadium(IV, V) Complexes with HydrazoneLigands, Polyhedron (2014), doi: http://dx.doi.org/10.1016/j.poly.2014.11.018

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customerswe are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, andreview of the resulting proof before it is published in its final form. Please note that during the production processerrors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Synthesis, Structural Characterization and Spectroscopy Studies of New Oxovanadium(IV, V)

Complexes with Hydrazone Ligands.

Patrycja Paciorek, Janusz Szklarzewicz*, Anna Jasińska, Bartosz Trzewik, Wojciech Nitek and Maciej

Hodorowicz

Faculty of Chemistry, Jagiellonian University, R. Ingardena 3, 30-060 Kraków, Poland

*Corresponding author. Tel: +4812-6632223, fax: +4812-6340515. E-mail address:

szklarze@chemia.uj.edu.pl (J. Szklarzewicz).

ABSTRACT

The reaction of vanadyl acetoacetonate, VO(acac)2, with 2-hydroxybenzaldehyde hydrazone in ethanol

gave the mononuclear oxovanadium(IV) complex [VO(salh1)2] (1). However, when the hydrazides 3-

hydroxy-2-naphthoic acid hydrazide (h2) and 5-phenylisoxazole-3-carboxylicacidhydrazide (h3) were

used, the mononuclear oxoethoxovanadium(V) complexes [VO(acanh2)(OEt)] (2) and

[VO(acanh3)(OEt)] (3) were isolated, respectively. The reaction with benzene-1,4-dicarbohydrazide

(h4) in a water-ethanol solution gave polynuclear [VO(µ-EtO)2](µ-acanh4) n (4). The complexes were

characterized by elemental analysis, IR, UV-Vis and 51V NMR spectra. Magnetic susceptibility

measurements indicated the +5 vanadium oxidation state in 2, 3 and 4 and +4 in 1. X-ray single crystal

diffraction studies revealed that the vanadium(V) center has a distorted square pyramidal geometry in

2 and 3, and a distorted octahedral geometry in 4, with an O3N coordination environment around the

V(V) acceptor center. Complex 4 is a polymeric compound with dihydrazide ligand as a linker and

each two vanadium ions are connected via two µ-ethoxo bridges.

Keywords: vanadium, crystal structures, hydrazone

INTRODUCTION

Oxovanadium complexes are very promising candidates for the treatment of type II diabetes by

reducing the necessary dose of medicines lowering blood glucose levels and allowing the delay or

even excluding the need to take exogenous insulin. Despite promising results for treatment with

inorganic vanadium compounds, such as vanadium sulfate, problems with toxicity, tolerability and

absorption have attracted growing attention to vanadium complexes with organic ligands. Among

them, bis(maltolato)oxovanadium(IV) (BMOV) and bis(ethylmaltolato)oxovanadium(IV) (BEOV)

have proven to be useful as insulin-mimetic agents1. Moreover, vanadium compounds have also found

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

application in preventing carcinogenesis2, as antileukemic, antiamoebic and spermicidal agents3, as

well as combating parasites in Chagas disease and leishmaniasis2. In recent years, in these fields there

has been a rapidly increasing interest in complexes of vanadium(IV, V) with Schiff bases, where the

most popular sources of vanadium in these syntheses are VOSO4 and VO(acac)2 (where Hacac =

acetylacetone) 2,3,4. However VOSO4 has several drawbacks: it delivers an unknown amount of

crystallization water that is almost impossible to remove without complex decomposition, so it is

difficult to get a proper metal-to-ligand stoichiometry; the solubility of VOSO4 in alcohols is lower

than VO(acac)2; last but not least, VOSO4 delivers water to the reaction environment, causing

decomposition of the Schiff base ligands to their starting components. Thus, VO(acac)2 has started to

be the most widely used substrate for the synthesis of complexes with Schiff base ligands. During the

reaction, the acac– ligand normally acts as a deprotonating agent, and remains in solution after filtering

off the product. However, in some cases the acac- ligand remains in the complex and serves as a ligand

in the coordination sphere5. In our work, we describe examples of such reactions in which the acac–

ligand behaves as a ketone and forms a Schiff base ligand in the course of the reaction with salicylic

aldehyde hydrazone or selected hydrazides (3-hydroxy-2-naphthoic acid hydrazide, 5-phenylisoxazole-

3-carboxylicacidhydrazide and benzene-1,4-dicarbohydrazide) as sources of NH2 groups. We have

isolated four complexes and characterized them by elemental analysis, IR, UV-Vis, 51V NMR spectra

and magnetic susceptibility measurements. For three of them, we present single crystal X-ray

structures. Complex 4 seems to be the most interesting compound due to its polymeric structure, which

has not been synthesized previously.

EXPERIMENTAL SECTION

General information and physical measurements.

All chemicals were purchased from Aldrich and used without further purifications. Microanalyses on

carbon, hydrogen and nitrogen were performed using a Vario Micro Cube elemental analyzer. IR

spectra were recorded in the range 4000-550 cm-1 on a Nicolet iS5 FT-IR spectrophotometer.

Electronic absorption spectra were measured on a Shimadzu UV-Vis-NIR UV-3600

spectrophotometer. Diffuse reflectance spectra were measured in BaSO4 pellets with BaSO4 as

a reference using a Shimadzu UV-2101PC equipped with an ISR-260 attachment. Room temperature

magnetic susceptibilities of the complexes in the solid state were determined with a Sherwood

Scientific MK 1 Magnetic Susceptibility Balance, calibrated with Hg[Co(SCN)4]. 51V NMR spectra

were recorded on a Bruker Avance III 600 spectrometer. Chemical shifts are reported relative to neat

VOC13 as an external reference.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Syntheses.

Method A.

To 50 cm3 of ethanol, 2-hydroxybenzaldehyde (sal) and an excess of hydrazine monohydrate were

added. The mixture was refluxed for 15 minutes to form a light yellow solution. Vanadyl

acetylacetonate, VO(acac)2, was then added. The solution turned green and product 1, in the form of

small green needles, precipitated almost immediately. However, refluxing was continued for several

additional minutes and after that the solution was left to cool for a couple of hours. The final product

was then filtrated off, washed with ethanol and dried in air.

Method B.

To 50 cm3 of ethanol hydrazide, 3-hydroxy-2-naphthoic acid hydrazide (h2) or 5-phenylisoxazole-3-

carboxylicacidhydrazide (h3) (for complexes 2 and 3, respectively), and VO(acac)2 were added, and the

mixture was refluxed for 15 minutes. The solution changed its color from green to dark brown. The

mixture was left for crystallization. Slow evaporation of the solution in air for over two days produced

crystals of 2 or 3. The product was filtrated off, washed with ethanol and dried in air.

Method C.

To 80 cm3 of ethanol, benzene-1,4-dicarbohydrazide (h4), VO(acac)2 and acetoacetanilide were added,

and the mixture was refluxed for 15 minutes. The solution changed its color from green to dark brown,

then 10 cm3 of water was added and the mixture was refluxed for 35 minutes. Slow evaporation in air

over five days produced crystals of 4. The product was filtrated off, washed with ethanol and dried in

air.

The stoichiometry and amounts of the reagents used and the results obtained from measurements are

as follows:

[VO(salh1)2] (1), method A: 2-Hydroxybenzaldehyde (sal) (400 µl, 3.75 mmol), hydrazine

monohydrate, h1 (400 µl, 5.3 mmol), VO(acac)2 (0.535 g, 2.0 mmol). Green needles. Yield: 0.601 g,

95%. Anal. Calcd. for C14H14N4O3V (fw = 337.2): C, 49.9; H, 4.2; N, 16.6%. Found: C, 49.5; H, 4.3;

N, 16.6%. IR νmax/cm-1: 3344(vs) (N-H), 1593(vs) (C=N), 1301(vs) (C-O)enolic,1151(s) (N-N), 965(s)

(V=O). UV-Vis λmax(DMSO)/nm (ε/dm3 mol-1 cm-1): 286sh (64400), 346 (31000); (DMF) 340

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

(15100); Reflectance spectrum λmax/nm: 222sh, 250sh, 284, 321sh, 345sh, 375, 397sh, 505, 658.

Magnetic moment: 1.83 B.M.

[VO(acanh2)(OEt)] (2), method B: 3-Hydroxy-2-naphthoic acid hydrazide, (h2) (0.202 g, 1.00 mmol),

VO(acac)2 (0.264 g, 1.00 mmol). Brown crystals. Yield: 0.251 g, 64%. Anal. Calcd for C18H19N2O5V

(fw = 394.3): C, 54.8; H, 4.9; N, 7.1 %. Found: C, 54.5; H, 4.8; N, 7.0%. IR νmax/cm-1: 1582(s) (C=N),

1287(m) (C-O)enolic, 1144(m) (N-N), 997(s) (V=O). UV-Vis λmax(CH3CN)/nm (ε/dm3 mol-1 cm-1): 232

(333000), 262sh (250000), 304 (140000), 347 (9900), 398 (7200), 428sh (4600); Reflectance spectrum

λmax/nm: 247sh, 263, 321, 343, 365, 399, 622. 51V NMR: 520 ppm. Magnetic moment diamagnetic.

[VO(acanh3)(OEt)] (3), method B: 5-Phenylisoxazole-3-carboxylicacidhydrazide, (h3) (0.203 g, 1.00

mmol), VO(acac)2 (0.264 g, 1.00 mmol). Green crystals. Yield: 0.287 g, 73%. Anal. Calcd. for

C17H18N3O5V (fw = 395.3): C, 51.7; H, 4.6; N, 10.6 %. Found: C, 51.6; H, 4.6; N, 10.7 %. IR νmax/cm-

1: 1600(s) (C=N), 1286(m) (C-O)enolic, 1144(w) (N-N), 993(vs) (V=O). UV-Vis λmax(CH3CN)/nm

(ε/dm3 mol-1 cm-1): 265 (31200), 342 (10300), 397 (6500), 428sh (4200); Reflectance spectrum

λmax/nm: 275, 335sh, 349, 385, 636. 51V NMR: 506 ppm. Magnetic moment: diamagnetic.

[VO( µ-EtO)2](µ-acanh4) n (4), method C: Benzene-1,4-dicarbohydrazide, (h4) (0.195 g, 1.00 mmol),

VO(acac)2 (0.530 g, 2.00 mmol), acetoacetanilide (0.709 g, 4.00 mmol). Dark violet crystals. Yield:

0.130 g, 45%. Anal. Calcd for C11H14N2O4V (fw = 289.2): C, 46.6; H, 4.8; N, 9.7 %. Found: C, 46.7;

H, 5.1; N, 9.3 %. IR νmax/cm-1: 1596(vs) (C=N), 1279(s) (C-O)enolic, 1145(w) (N-N), 981(s) (V=O),

866(w) (V-O-V). UV-Vis λmax(CH3CN) (ε/dm3 mol-1 cm-1): 265 (31200), 342 (10300), 397 (6500),

428sh (4200); Reflectance spectrum λmax/nm: 251sh, 289, 373, 401, 455sh, 507sh, 539sh. Magnetic

moment: diamagnetic.

X-ray Crystallography.

Diffraction data for single crystals of 2, 3 and 4 were collected on an Oxford Diffraction SuperNova

four circle diffractometer, using Mo (0.71069 Å) (for 2 and 3) and Cu (1.5418 Å) (for 4) Kα radiation

sources and a graphite monochromator. Cell refinement and data reduction were performed using

firmware13. Positions of all of non-hydrogen atoms were determined by direct methods using SIR-9714.

All non-hydrogen atoms were refined anisotropically using weighted full-matrix least-squares on F2.

Refinement and further calculations were carried out using SHELXL-9715. All hydrogen atoms joined

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

to carbon atoms were positioned with an idealized geometries and refined using a riding model with

Uiso(H) fixed at 1.5 Ueq of C for methyl groups and 1.2 Ueq of C for other groups. The crystal data and

a summary of the data collection and structure refinement parameters for 2, 3 and 4 are given in Table

1.

RESULTS AND DISCUSSION

Vanadium complexes 1, 2 and 3 were synthesized using VO(acac)2 and hydrazides in one-step

reactions (Scheme 1).

Scheme 1. Synthesis reactions for 1-4.

In the case of complex 4, the acetoacetanilide, used as the amine component, was not incorporated into

the coordination sphere of vanadium. This was probably due to too weak competition between

acetylacetonate and acetoacetanilide. Acetylacetohydrazone was thus formed by condensation of

acetylacetone with hydrazide in situ. A similar reaction was observed in the literature, but they are

relatively rare5,6,7. Magnetic susceptibility measurements of complexes 1-4 indicates that the metal ion

in complex 1 is paramagnetic [d1 vanadium(IV)], while in complexes 2-4 it is diamagnetic [d0

vanadium(V)].

Description of the crystal structures.

Complex 1 was obtained in the form of small needles which were not suitable for X-ray diffraction

measurements. The molecular structures of [VO(acanh2)(OEt)] (2) and [VO(acanh3)(OEt)] (3) are

shown in Figures 1 and 2, respectively.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Table 1. Crystal data and structure refinement for 2, 3 and 4

2 3 4 temp (K) 293(2) 293(2) 130(2) formula C18H19N2O5V C17H18N3O5V C11H14N2O4V

Fw 394.29 395.28 289.18 crystallographic system Triclinic triclinic monoclinic

space group P1 P1 P21/c crystal size (mm) 0.96×0.61×0.16 0.54×0.51×0.10 0.22×0.17×0.05

a (Å) 7.3285(4) 7.2290(5) 8.4810(3) b(Å) 10.4232(4) 10.2290(6) 12.2555(3) c (Å) 13.3744(5) 13.7752(8) 14.4601(5) α (deg) 102.547(3) 68.401(5) 90.00 β (deg) 98.537(4) 80.437(5) 125.055(2) γ (deg) 110.109(4) 75.700(5) 90.00 V (Å3) 908.26(7) 914.54(11) 1230.33(7)

Z 2 2 4 dcalcd (Mg m-3) 1.442 1.435 1.561 μ (mm-1) 0.577 0.575 6.847 F(000) 408 408 596

Θ range for data collection (deg) 2.98 to 26.50 3.118 to 26.499 5.195 to 71.253 reflections collected/unique 11561/3748 12056/3782 18186/2376

R (int) 0.0258 0.0467 0.0525 data/restraints/parameters 3748 / 14 / 246 3782 / 2 / 256 2376/0/166

GoF on F2 1.077 1.053 1.018 R1/wR2 (I > 2σ(I)) 0.0385/0.1033 0.0568/0.1425 0.0466/0.1250 R1/wR2 (all data) 0. 0.0502/0.1154 0.0856/0.1655 0.0589/0.1350

largest diff. peak/hole (e Å-3) 0.486/-0.345 0.518/-0.345 0.501/-0.469

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Fig 1. The structure of 2, with 30% probability ellipsoids. Hydrogen atoms are omitted for clarity.

Fig 2. The structure of 3 and the coordination centre of 2 (inset 2a) with 30% probability ellipsoids. Hydrogen atoms are

omitted for clarity.

Fig. 3. The assembly of layers in 2 viewed along the [010] direction.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Fig. 4. The assembly of layers in 3 viewed along the [010] direction.

Table 2. Selected bond lengths (Å) and angles (deg) for 2-4.

bond lengths 2 3 4 V1-O01 1.5816(17) 1.582(2) 1.575(3) V1-O02 1.7484(16) 1.748(2) 1.817(2) V1-O05 1.8691(15) 1.861(2) 1.862(2) V1-O14 1.9211(14) 1.916(2) 1.923(2) V1-N11 2.0754(16) 2.063(3) 2.101(3) O05-C06 1.313(3) 1.322(4) 1.317(4) C06-C07 1.495(3) 1.480(5) 1.490(5) C06-C08 1.359(3) 1.348(5) 1.354(5) C08-C09 1.411(3) 1.404(5) 1.422(5) C09-C10 1.505(3) 1.498(5) 1.506(5) C09-N11 1.316(3) 1.324(4) 1.317(4) N11-N12 1.389(2) 1.396(3) 1.404(4) N12-C13 1.299(3) 1.294(4) 1.290(4) C13-O14 1.315(2) 1.310(3) 1.308(4)

O02-C03A 1.436(8) 1.37(2) 1.433(4)b O02-C03B 1.462(14) 1.455(13) -

C03A-C04A 1.438(8)a 1.427(17) 1.495(6)b C03B-C04B 1.398(11)a 1.414(14) - bond angles 2 3 4 O01-V1-O02 105.77(9) 106.64(14) 102.72(13) O01-V1-O05 105.08(8) 104.38(12) 98.79(12) O01-V1-N11 98.77(8) 101.98(11) 99.51(13) O01-V1-O14 107.61(8) 106.49(12) 98.32(12) O02-V1-O05 97.29(7) 96.83(12) 101.72(10) O02-V1-N11 154.24(8) 150.32(12) 155.99(11) O02-V1-O14 89.91(7) 88.93(10) 92.70(9) O05-V1-N11 83.55(6) 83.34(10) 83.58(10) O05-V1-O14 143.12(7) 145.45(11) 154.54(11) N11-V1-O14 75.09(6) 75.46(9) 75.10(10)

O02-C03A-C04A 109.8(6)a 111.9(18) 112.3(3)b O02-C03B-C04B 110.6(9)a 109.9(12) -

aC04 is not split into A and B bC03 and C04 are not split into A and B

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

A single crystal X-ray study reveals that the asymmetric part of the unit cells of complexes

have a similar stoichiometry, [V(C2H5O)

2-carbohydrazide (2) and N'-(3-hydroxybutyl)

asymmetric units of the complexes with the adopted atomic numbering scheme

1 and 2, respectively. The crystallographic data and detailed information on the structure so

refinement for 2 and 3 are given in Table 1. Selected bond distances and bond angles are listed in

Table 2. In both structures the [V(C2H

pyramidal with coordination number 5 (see Figure 2a)

of the square pyramid) is significantly closer to

complexes the V-Ooxo distance is equal

pentacoordinate oxovanadium(V) compounds

the vanadium atom in one of the equatorial positions and

of this molecule were refined in two complementary positio

oxygen atoms [O(05) and O(14)], the imine nitrogen

the ethoxide oxygen. The central vanadium

and 3, respectively, and is directed towards the oxo ligand [O(01)]. The tride

forms six-membered and five-membered chelate ring

corresponding bite angles being 83.53(7) and 75.07(6)

complexes 2 and 3, the four V-O bond lengths are unequal

the V-O(05) (enolate) bond the longest. The vanadium

(oxo) < V-O(02) (alkoxide) < V-O(14) (enolate) < V

binding of the alkoxo group compared to

Fig. 5. The intermolecular interactions in 3. Hydrogen bonds

ray study reveals that the asymmetric part of the unit cells of complexes

O)4O(L)] where L = 1-hydroxy-N'-(3-hydroxybutyl)naphthalene

hydroxybutyl)-5-phenyl-1,2-oxazole-3-carbohydrazide (

with the adopted atomic numbering schemes are shown in Figure

1 and 2, respectively. The crystallographic data and detailed information on the structure so

are given in Table 1. Selected bond distances and bond angles are listed in

H5O)4O(L)] system adopts the same conformation of square

with coordination number 5 (see Figure 2a). The oxo ligand in the axial position (the apex

square pyramid) is significantly closer to the V cation than the other groups,

distance is equal to 1.582(2) Å, which is in agreement with data for other

pentacoordinate oxovanadium(V) compounds8,9,10. The deprotonated ethanol ligand is coordinated to

the vanadium atom in one of the equatorial positions and shows a dynamic disorder. The carbon atoms

ecule were refined in two complementary positions. The basal plane is made of two enolic

the imine nitrogen N(11) from the tridentate ligand, and O(02) from

vanadium atom is above the basal plane by 0.472 and 0.486 Å for

vely, and is directed towards the oxo ligand [O(01)]. The tridentate Schiff base ligand

membered chelate rings at the V(V) acceptor center

corresponding bite angles being 83.53(7) and 75.07(6)° for 2, and 83.3(1) and 75.5(1)° for

O bond lengths are unequal, with the V=O bond being the shortest and

O(05) (enolate) bond the longest. The vanadium-oxygen bond lengths follow the order: V

O(14) (enolate) < V-O(05) (enolate). These data indicate stronger

binding of the alkoxo group compared to the enolate oxygen atoms.

. Hydrogen bonds are coloured in black dashes and C-H...p interactions in bl

ray study reveals that the asymmetric part of the unit cells of complexes 2 and 3

hydroxybutyl)naphthalene-

carbohydrazide (3). The

shown in Figures

1 and 2, respectively. The crystallographic data and detailed information on the structure solution and

are given in Table 1. Selected bond distances and bond angles are listed in

)] system adopts the same conformation of square

the axial position (the apex

and for both

1.582(2) Å, which is in agreement with data for other

The deprotonated ethanol ligand is coordinated to

The carbon atoms

The basal plane is made of two enolic

N(11) from the tridentate ligand, and O(02) from

atom is above the basal plane by 0.472 and 0.486 Å for 2

ntate Schiff base ligand

at the V(V) acceptor center, with the

for 3. In both

V=O bond being the shortest and

oxygen bond lengths follow the order: V-O(01)

O(05) (enolate). These data indicate stronger

H...p interactions in blue.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Table 3. Hydrogen bond lengths [Å] and angles [deg] in

D-H...A d(D-H)

C(03A)-H(03A)...O(17) 0.97 C(03B)-H(03C)...O(17) 0.97

O(17)-H(17)...N(12) 0.74(3)

C(16)-H(16)...O(01) 0.93 C(10)-H(10B)...O(18) 0.96

C(03)-H(03A)...N(11) 0.99 C(04)-H(04C)...O(05) 0.98

Table 4. C-H...π contact distances in 2 and 3.

C-H...ππππ

C10-H10B… Cg3[1-X,1-Y,1-Z]

C07 -H07B…Cg4 [2-X,-Y,-Z]

C07 -H07C…Cg4 [1-X,-Y,-Z]

Analysis of the crystal structures of 2

molecules are held together by T-shape

(Figure 5), which are summarized in Table

classified by type IV, according to Malone

assembly of the complex molecules in layers (Figure 5) and stabilization of

Fig. 6. The structure of 4 with 30% probability ellipsoids. Hydrogen atoms are omitted for clarity.

Hydrogen bond lengths [Å] and angles [deg] in 2, 3 and 4.

d(H...A) d(D...A) <(DHA) 2 2.64 3.349(8) 129.8 2.59 3.511(13) 157.8

1.97(3) 2.603(2) 144(3) 3 2.53 3.344(4) 146.6 2.57 3.486(4) 159.7

4 2.63 3.259(5) 121.7 2.65 3.386(5) 131.9

H...Cg X-H...Cg X...Cg

2 2.68 142 3.483(3)

3 2.86 166 3.803(5)

2.99 122 3.588(5)

and 3 at the supramolecular level reveals that the complex

shaped hydrogen C-H...π interactions and several hydrogen bond

which are summarized in Tables 4 and 3, respectively. The C-H...π contact can be

classified by type IV, according to Malone11. All these interactions are responsible for

assembly of the complex molecules in layers (Figure 5) and stabilization of the 3D structure.

30% probability ellipsoids. Hydrogen atoms are omitted for clarity.

X...Cg

3.483(3)

3.803(5)

3.588(5)

at the supramolecular level reveals that the complex

ons and several hydrogen bonds

contact can be

. All these interactions are responsible for the self-

3D structure.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Fig. 7. The polymeric chain in 4.

Fig. 8. The assembly of layers in 4 viewed along

The X-ray diffraction study demonstrates that complex

P21/n and shows a 1-D polymeric coordination chain structure. The molecular structure of complex

is shown in Fig. 6. The crystal structure is built up of dinuclear centrosymmetric complex molecules,

[V2L(O)(µ2-EtOH)2], L = 4-[2-(3-hydroxybutyl)hydrazinyl]carbonylbenzamide. Each V(V) is hexa

coordinated by one tridentate ligand L, two bridging eth

coordination environment as shown in Fig. 7. The V(1) ion has an octahedr

plane consisting of one nitrogen and two ox

V(1)–O [O(05) and O(15)] distances of 1.862(2) and

the deprotonated ethanol molecules, with

occupied by the oxo [O(01)] and ethoxo atom

equatorial plane. The O(14)–V(1)–O(05), O(01)

along the [001] direction.

ay diffraction study demonstrates that complex 4 crystallizes in the monoclinic space group

D polymeric coordination chain structure. The molecular structure of complex

is shown in Fig. 6. The crystal structure is built up of dinuclear centrosymmetric complex molecules,

hydroxybutyl)hydrazinyl]carbonylbenzamide. Each V(V) is hexa

, two bridging ethoxo ions and an oxo ligand to form a VNO

coordination environment as shown in Fig. 7. The V(1) ion has an octahedral geometry with the basal

two oxygen atoms from the ligand L, [N(11), O(05), O(14)], with

nd O(15)] distances of 1.862(2) and 1.923(2) Å, respectively and one oxygen atom of

with a V(1)–O(02) distance of 1.817(2) Å. The axial positions are

occupied by the oxo [O(01)] and ethoxo atoms [O(02)]. V(1) is displaced by 0.3312(13)

O(05), O(01)–V(1)–O(02) and N(11)–V(1)–O(02) bond ang

crystallizes in the monoclinic space group

D polymeric coordination chain structure. The molecular structure of complex 4

is shown in Fig. 6. The crystal structure is built up of dinuclear centrosymmetric complex molecules,

hydroxybutyl)hydrazinyl]carbonylbenzamide. Each V(V) is hexa-

oxo ligand to form a VNO5

al geometry with the basal

O(05), O(14)], with

Å, respectively and one oxygen atom of

O(02) distance of 1.817(2) Å. The axial positions are

[O(02)]. V(1) is displaced by 0.3312(13) Å from the

bond angles are

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

154.5(1), 174.7(2) and 156.0(1)°, respectively. This indicates that the coordination sphere of the V(1)

ion is a slightly distorted octahedron. In complex 4, the ligand L shows very interesting bridging with a

bis-tridentate coordination mode, join neighboring V(V) centers into an infinite zigzag chain along the

[101] direction, as depicted in Fig. 8, within which the adjacent V···V separation is 11.838(5) Å and

the V–V–V angle is 163.2(2)°. Intramolecular C–H···N and C–H···O interactions stabilize such a 1-D

coordination motif. No aromatic rings stacking has been found in the crystal lattice of compound 4. In

the binuclear unit, the two V(V) ions are connected by two oxygen atoms from two bridging ethoxy

molecules to define a centrosymmetric dimeric unit, in such a way a planar asymmetric bridge between

the V ions is formed. Each bridging oxygen atom is more closely associated with a single V(V) center,

with V(1)–O(02) and V1–O(02)' bond lengths of 1.817(2) and 2.398(2) Å, respectively. A V(1)–

O(02)–V(1) bond angle of 107.9(1)° and a V⋯V distance of 3.425 Å are observed in the complex.

IR spectroscopy. Selected IR bands are given in the Experimental section. The IR spectra show characteristic V=O

stretching bands at 965, 997, 993 and 981 cm-1 for complexes 1, 2, 3 and 4, respectively. A new band

at 866 cm-1 for complex 4 is assigned to an asymmetric V-O-V bridge vibration8,9 (Fig. 9). New bands

in the range 1599-1557 cm-1 are assigned to the stretching vibrations of the C=N group present in all

the studied complexes.

Fig. 9. IR spectrum of complex 4.

UV-Vis spectra.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

In the reflectance spectrum of 1, a band at 658 nm can be attributed to the d-d transition in d1 V(IV).

This band, due to its very low intensity, is not very visible in the spectrum measured in solution due to

the low solubility of the complex. For complexes 2-4 (Fig. 10) in the 200-450 nm range, bands

connected with the ligand (< 350 nm) and with the metal to ligand charge transfer (at ca 397 and 428

nm) are observed. Lack of a d-d transition band for complexes 2-4 is in agreement with the

vanadium(V) oxidation state.

Fig. 10. UV-Vis reflectance spectra of compounds 2-4.

CONCLUSIONS

It was found that the reaction of vanadyl acetoacetonate, [VO(acac)2], in ethanol with 2-

hydroxybenzaldehyde hydrazone or hydrazides: 3-hydroxy-2-naphthoic acid hydrazide (h2) and 5-

phenylisoxazole-3-carboxylicacidhydrazide (h3) gave mononuclear oxoethoxovanadium complexes 1,

2 and 3, respectively. Magnetic susceptibility measurements indicated the +5 vanadium oxidation state

in 2, 3 and 4, and +4 in 1. The difference in oxidation states is a result of complex properties. Complex

1 precipitated almost immediately with two salh1- ligands. Change of the V:salhy1

- stoichiometry

results only in a change in the yield of the synthesis. The long time required for the precipitation of 2,

3 and 4 caused oxidation of V(IV) to V(V), but only under aerobic conditions could crystals be

isolated.

Reaction with benzene-1,4-dicarbohydrazide (h4) in water-ethanol solution gave, however, the

polynuclear compound [VO(µ-EtO)2](µ-acanh4) n (4). The use of acetoacetanilide in the reaction

resulted in a higher yield and crystals suitable for X-ray structure measurements. However,

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

acetoacetanilide itself does not participate in the reaction, probably due to its lower stability in

comparison to the acetyloacetonate ligand. As found by X-ray crystal structure measurements, the

metal environments in 2, 3 and 4 are almost identical, suggesting that the polymeric form of 4 has to

be caused by a change in the synthetic procedure and not in the type of ligand used. The only

difference in the structure of 4 compared to 2 and 3 is that the ethoxy groups form bridges between the

V centers; the stoichiometry V:EtO- remains unaltered. The only explanation is addition of water in the

synthesis of 4. Similar but dimeric complexes with no linker between the dimeric vanadium units were

recently reported in the literature5,17,18,19. The change in solvent polarity has to be responsible for the

polymer formation.

ACKNOWLEDGEMENTS

This research was carried out with the equipment purchased thanks to the

financial support of the European Regional Development Fund in the

framework of the Polish Innovation Economy Operational Program (contract

no. POIG.02.01.00-12-023/08).

Appendix A. Supplementary data

CCDC 1013003, 1013004 and 1013005 contain the crystallographic data for 2, 3 and 4, respectively.

These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or

from the Cambridge Crystallographic Data Center, 12 Union Road, Cambridge CB2 1EZ, UK, fax:

(+44) 1223-336-033, or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data associated with this

article can be found in the online version.

REFERENCES

1. K. H. Thompson, J. Lichter, C. LeBel, M. C. Scaife, J. H. McNeil, C. Orvig, J. Inorg. Biochem.

2009, 103, 554-558

2. G. Romanowski, J. Kira, M. Wera, Polyhedron, 2014, 67, 529-539

3. S. H. Sumrra, Z. H. Chohan, Spectrochim. Acta Part A, 2012, 98, 53-61

4. Q. Guo, L. Li, J. Dong, Liu H., J. Dong, T. Xu, J. Li, Spectrochim. Acta Part A, 2013, 106, 155-162

5. M. Sutradhar, A.J.L. Pombeiro, Coord. Chem. Rev., 2014, 265, 89-124

6. M. Moon, M. Pyo, Y. C. Myoung, C. I. Ahn, M. S. Lah, Inorg. Chem. 2001, 40, 554-557

7. Y. Jin, M. S. Lah, Eur. J. Inorg. Chem. 2005, 4944-4952

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

8. C. Tsiamis, B. Voulgaropoulos, D. Charistos, G. P. Voutsas, C. Kavounis, Polyhedron 2000, 19,

2003-2010

9. A. A. Diamantis, J. M. Frederiksen, M. A. Salam, M. R. Snow, E. R. T. Tiekink, Aust. J. Chem.

1986, 39,1081.

10. W. Wang, X. Wang, H. X. Liu, M. Y. Tan, J. Coord. Chem. 1995, 36, 49-55.

11. J. F. Malone, C. M. Murray, M. H. Charlton, R. Docherty, A. J. Lavery, J. Chem. Soc., Faraday

Trans. 93. 1997, 19, 3429-3436.

12. R. Dinda, P. Sengupta, S. Ghosh, T. C. W. Mak, Inorg. Chem. 2002, 41, 1984

13. R. Dinda, P. Sengupta, M. Sutradhar, S. Ghosh, T. C. W. Mak, Inorg. Chem. 2008, 47, 5634

14. Oxford Diffraction (2010). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England

15. SIR97 - A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giacovazzo, A. Guagliardi, A.

G. G. Moliterni, G. Polidori, R. Spagna, J Appl. Cryst., 1999, 32, 115-119.

16. G.M. Sheldrick, Acta Cryst. 2008, A64, 112-122

17. H. W. Wong, K. M. Lo, S. W. Ng, Acta Cryst., 2011, E67, m90

18. A. Sakar, S. Pal, Inorg. Chim. Acta, 2009, 362, 3807-3812

19. H.H. Monfared, S. Kheirabadi, N.A. Lalami, P. Mayer, Polyhedron, 2011, 30, 1375

http://ees.elsevier.com/poly/download.aspx?id=455618&guid=6b75f6bb-602d-45eb-b686-51adb4fe31c6&scheme=1

Four vanadium complexes with hydrazone ligands were characterized by IR, UV-Vis, NMR,

cyclic voltammetry and magnetic susceptibility measurements. X-ray crystal structures of two

monomeric and one polymeric compound are described.