A dimeric oxidovanadium(V) complex derived from a hydrazonate ligand with an unusual asymmetrically bridged μ-(oxido)μ-(H2O){oxidovanadium(V)}2 core European Journal of Chemistry 11 (1) (2020) 1-5 European Journal of Chemistry View Journal Online View Article Online A dimeric oxidovanadium(V) complex derived from a hydrazonate ligand with an unusual asymmetrically bridged μ-(oxido)μ-(H2O){oxidovanadium(V)}2 core Alice Prudente Borges 1, Claudia Cristina Gatto 2, Victor Marcelo Deflon 3 and Pedro Ivo da Silva Maia 1,* 1 Departamento de Quimica, Universidade Federal do Triangulo Mineiro, Av. Dr. Randolfo Borges 1400, 38025-440, Uberaba, MG, Brazil aliceborges98@hotmail.com (A.P.B.), pedro.maia@uftm.edu.br (P.I.S.M.) 2 Instituto de Quimica, Universidade de Brasilia, Brasilia, Distrito Federal, Brazil ccgatto@unb.br (C.C.G.) 3 Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Av. Trabalhador Sao Carlense, 400, 13566-590, Sao Carlos, SP, Brazil deflon@iqsc.usp.br (V.M.D.) * Corresponding author at: Departamento de Quimica, Universidade Federal do Triangulo Mineiro, Av. Dr. Randolfo Borges 1400, 38025-440, Uberaba, MG, Brazil. e-mail: pedro.maia@uftm.edu.br (P.I.S. Maia). 10.5155/eurjchem.11.1.1-5.1948 Received: 15 December 2019 Received in revised form: 15 January 2020 Accepted: 17 January 2020 Published online: 31 March 2020 Printed: 31 March 2020 The binuclear oxidovanadium(V) complex [{VO(L)}2(μ-O)(μ-H2O)]∙2CH3CN (1), where L2– is the dianion of the Schiff base 2-salicylaldehyde-2-hydroxybenzoylhydrazone, were prepared and characterized by elemental analysis, FTIR, 1H, 13C and 51V NMR. Furthermore, the crystal structure of the compound 1 was determined by single crystal X-ray diffractometry revealing a distorted octahedral O5N-coordination geometry around the V(V) acceptor centers. The vanadium ions are connected by the μ-O2– and the μ-H2O asymmetric bridges located in the edge between the two octahedrons which keeps a distance of 3.194 Å between the two vanadium centers. Crystal data for C32H28N6O10V2 (M =758.48 g/mol): orthorhombic, space group P212121 (no. 19), a = 12.9655(8) Å, b = 14.1902(9) Å, c = 18.4379(10) Å, V = 3392.3(4) Å3, Z = 4, T = 293(2) K, μ(MoKα) = 0.616 mm-1, Dcalc = 1.485 g/cm3, 18803 reflections measured (3.622° ≤ 2Θ ≤ 56.704°), 8263 unique (Rint = 0.0473, Rsigma = 0.1020) which were used in all calculations. The final R1 was 0.0509 (I > 2σ(I)) and wR2 was 0.1531 (all data). The (VO)2(μ-O)(μ-H2O) core in compound 1 represents a rare case and few examples of similar type have been structurally characterized. Vanadyl Hydrazones Insulin mimesis Crystal structure Vanadium complexes Coordination chemistry Cite this: Eur. J. Chem. 2020, 11(1), 1-5 Journal website: www.eurjchem.com 1. Introduction The coordination chemistry of vanadium with has received special attention recently due to its catalytic [1-8] and medicinal importance [9-16]. Further, vanadium(V) complexes with a mixed ON coordination sphere is of high interest because of the potential of these complexes as structural and/or functional models for vanadate-dependent halo- peroxidases [8,9,17,18]. On the other hand, hydrazones are one of the most important pharmacophoric cores of several antitumor [9], anti-inflammatory [19] and antibacterial [21,22] agents. Few oxidovanadium(V) complexes of the type μ-(oxido) bis{oxidovanadium(V)} with dianionic hydrazonate ligands had their structure determined by X-ray diffraction methods [8,23-26]. In addition, much less is known about complexes of the type μ-bis(oxido)bis{oxidovanadium(V)}, which are generally acetylpyridine derivatives with V=O units in trans configurations [19,27]. For the μ-(oxido)bis{oxidovanadium(V)} complexes the angle V–O–V were found to be in the range 101- 112°, while for the μ-bis(oxido)bis{oxidovanadium(V)} comp- lexes this angle is of 101.78 ° and 102.41 ° for the hydrazones derived from of 2-acetylpyridine and nicotinic acid hydrazide [19] and 2-furoic acid hydrazide [27], respectively. Mononuclear oxidoalkoxidovanadium(V) complexes and monoanionic dioxidovanadium(V) complexes derived from H2L are already known, as well as 4,4’-bipyridine-bridged binuclear oxidovanadium(V) complexes [17]. We now report the syntheses and structural characterization of a neutral complex with an asymmetrically bridged μ-(oxido)μ-(H2O) {oxidovanadium(V)}2 core, where different characteristics from those observed for similar structures reported in the literature. 2. Experimental 2.1. Materials and physical methods ABSTRACT RESEARCH ARTICLE KEYWORDS European Journal of Chemistry ISSN 2153-2249 (Print) / ISSN 2153-2257 (Online) – Copyright © 2020 The Authors – Atlanta Publishing House LLC – Printed in the USA. This work is published and licensed by Atlanta Publishing House LLC – CC BY NC – Some Rights Reserved. http://dx.doi.org/10.5155/eurjchem.11.1.1-5.1948 http://dx.doi.org/10.5155/eurjchem.11.1.1-5.1948 https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.11.1.1-5.1948&domain=pdf&date_stamp=2020-03-31 http://www.eurjchem.com/ http://dx.doi.org/10.5155/eurjchem.11.1.1-5.1948 mailto:aliceborges98@hotmail.com mailto:pedro.maia@uftm.edu.br mailto:ccgatto@unb.br mailto:deflon@iqsc.usp.br mailto:pedro.maia@uftm.edu.br http://www.eurjchem.com/ https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.11.1.1-5.1948&domain=pdf&date_stamp=2020-03-31� 2 Borges et al. / European Journal of Chemistry 11 (1) (2020) 1-5 Table 1. X-ray structure data collection and refinement parameters for the complex [{VO(L)}2(μ-O)(μ-H2O)]∙2CH3CN (1). Parameters Compound 1 Empirical formula C32H28N6O10V2 Formula weight 758.48 Crystal system Orthorhombic Space group P212121 a, (Å) 12.9655(8) b, (Å) 14.1902(9) c, (Å) 18.4379(10) Volume (Å3) 3392.3(4) Z 4 ρcalc (Mg∙m–3) 1.476 μ (mm-1) 0.613 θ Range for data collection (o) 1.81 to 28.35 Index ranges -17 ≤ h ≤ 16 -18 ≤ k ≤ 17 -16 ≤ l ≤ 24 Reflections collected 18803 Reflections unique/ Rint 8263 / 0.0473 Data/restraints/param. 8263 / 0 / 453 Absorption correction Semi-empirical from equivalents Max/min. transmission 1.000 and 0.557 R1 [I > 2σ(I)] 0.0509 wR2 [I > 2σ(I)] 0.1168 GOF on F2, S 0.935 [VO(acac)2] and analytical reagents grade chemicals and solvents were obtained commercially and used without further purification. IR spectra were recorded as KBr pellets on a Shimadzu FTIR-spectrometer in the 4000-400 cm–1 region. Melting points were measured on a Melt-Temp II apparatus. 1H, 13C and 51V NMR spectra were acquired on a Varian MERCURY plus spectrometer operating at 300.07, 75.46 and 78.92 MHz for 1H and 51V, respectively. The 1H spectra were internally referenced to TMS. The 51V spectra was externally referenced to VOCl3 (δ = 0), checked against an aqueous (NH4)VO3 solution containing capillary (δ = -541.2 for VO43–). Elemental analyses (CHNS) were determined with FISONS EA-1108 analyzer. 2.2. Synthesis 2.2.1. Synthesis of the ligand H2L The Schiff base compound was prepared by an adaption of the method previously described [28]. 5 mmol (0.76 g) of 2- hydroxydebenzoylhydrazide and 5 mmol of salicylaldehyde (0.68 g) were refluxed methanol (15 mL) for 2 hours. 2-Hydroxy-N'-(2-hydroxybenzylidene)benzohydrazide (H2L): Color: White. Yield: 80 % (1.02 g). M.p.: 170-172 °C. FT-IR (KBr, ν, cm–1): 3200 ν(OH); 3075 ν(NH); 1661 ν(C=O); 1637, 1618, 1560 ν(C=C + C=N); 1231 ν(C–O); 1034 ν(N–N). 1H NMR (300 MHz, DMSO-d6, δ, ppm): 6.94-7.01 (m, 4H, C6H4), 7.33 (ddd, 3J = 8 Hz, 4J = 2 Hz, 1H), 7.46 (ddd, 3J = 8 Hz, 4J = 2 Hz, 1H), 7.58 (dd, 3J = 8 Hz, 4J = 2 Hz, 1H), 7.90 (dd, 3J = 8 Hz, 4J = 2 Hz, 1H), 8.69 (s, 1H, -CH=N), 11.22 (s, 1H, NH), 11.76 (s, 1H, OH), 12.02 (s, 1H, OH). 13C NMR (75 MHz, DMSO-d6, δ, ppm): 115.6, 116.4, 117.2, 118.5, 119.0, 119.3, 128.5, 129.4, 131.6, 133.9, 148.9, 157.4, 158.9, 164.4. 2.2.2. Preparation of [{VO(L)}2(μ-O)(μ-H2O)]∙2CH3CN (1) To a hot solution of H2L (0.064 g, 0.25 mmol) in acetonitrile (10 mL) was added a solution of [VO(acac)2] (0.066 g, 0.25 mmol) in acetonitrile (10 mL). A dark solution was immediately formed. The reaction mixture was kept under constant stirring for 2 hours and then deposited at –15 °C for one day for obtaining dark crystals of compound 1. The dark crystals were filtered off and dried in air. Some crystals, suitable for diffraction analysis, were kept in the solution. μ-Oxido-μ-aqua-bis(((1Z, N'E)-2-hydroxy-N'-(2-oxidobenzyli dene)benzohydrazonate)oxidovanadium(V)) diacetonitrile solvate (1): Yield: 55 % (0.104 g). The substance suffers a continuous darkening without melting up to 300 °C. FT-IR (KBr, ν, cm–1): 1621, 1597, 1550, 1523 ν(C=C + C=N), 1270, 1250 ν(C–O, phenolate and enolate), 997 ν(V=O), 909 ν(V–O– V). 1H NMR (300 MHz, DMSO-d6, δ, ppm): 6.60-7.40 (m, 8H, C6H4), 7.75-7.82 (m, 8H, C6H4), 9.19 (s, 1H, CH), 9.07 (s, 1H, CH), 11.35 (s, 2H, OH). 13C NMR (75 MHz, DMSO-d6, δ, ppm): 113.7; 115.5; 116.7; 119.1; 119.9; 120.6; 129.2; 133.0; 133.6; 134.6; 152.1; 158.3; 163.3; 170.3. 51V NMR (79 MHz, DMSO-d6, δ, ppm): -542.9 (25.7 %), -575.1 (74.3 %). Anal. calcd. for C32H28N6O10V2: C, 50.67; H, 3.72; N, 11.08. Found: C, 50.66; H, 3.49; N, 10.86%. 2.3. Crystal structure determination Dark crystals of the complex 1 were obtained as described above. The data collections were performed with Mo-Kα radiation (λ = 71.073 pm) on a Bruker KAPPA APEX II CCD diffractometer. The structure was solved by direct methods using SHELXS-97 [29] and refined by full-matrix least-squares methods against F2 (SHELXL2016) [30]. All non-hydrogen atoms were refined with anisotropic displacement parameters with SHELXL2016 [30]. The hydrogen atoms positions were found in Fourier map or calculated in the idealized positions. Crystallographic data and experimental details for structural analysis are summarized in Table 1. 3. Results and discussion 3.1. Synthesis and spectroscopic characterization The complex 1 was obtained in satisfactory yield from 1:1 reaction mixtures of [VO(acac)2] and the free H2L hydrazone ligand (Scheme 1) by a similar procedure to that described in reference [17]. Microanalyses and spectroscopic results are consistent with the formation of the complex 1. The FTIR spectroscopy provides some information about the coordination modes of the H2L to the vanadium central atoms. The spectrum of the complex 1 does not present the bands at 3200 cm–1 [ν(NH)] and 1661 cm–1 [ν(C=O)], observed in the spectrum of the free ligand. The absence of these bands in the spectrum of the complex is consistent with the enolisation of the amide functional group and subsequent proton replacement by the metal ion. A new band appearing at 1251 cm–1 is assigned to the ν(C–O)(enolic) mode [19, 23, 31]. 2020 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.11.1.1-5.1948 Borges et al. / European Journal of Chemistry 11 (1) (2020) 1-5 3 N H NH O OH OH N H N O O OH N H N O O OH V V O O O O HH [VO(acac)2]+ MeCN Stirring 2 hours Scheme 1. Synthesis of the complex 1. (a) (b) Figure 1. Crystal and molecular structure of [{VO(L)}2(μ-O)(μ-H2O)]∙2CH3CN (1) with labeling scheme (a). Space filling of the dinuclear oxidovanadium(V) hydrazonate complex (b). The bands related to the ν(C=N) and ν(C=C) stretching modes are found shifted in comparison to the spectrum of the free ligand. One strong band observed at 997 cm–1 is attributed to the terminal ν(V=O) stretching. Another band moderately strong observed at 909 cm–1, asymmetric bridge ν(V–O–V) vibrations. The coordination modes of the ligand were further confirmed by recording 1H and 13C NMR spectra of the ligand and complex in DMSO-d6 solutions. The free H2L ligand exhibit a signal at δ 11.22 ppm due to the NH proton of the hydrazone moiety. The absence of this signal in the spectrum of complex 1 suggests the deprotonation of the ligand upon coordination, enolisation of the of the amide functional group as observed in the FTIR spectrum. Similarly, the absence of the signal for the phenolic OH (ca. δ 12.02 ppm in the ligand) indicates coordination of phenolate oxygen. The signals due to the azomethine protons (–CH=N), are downfield shifted to the δ 9.01-9.25 ppm region with respect to the signal of the free ligand, observed at δ 8.69 ppm, which confirms the coordination of the azomethine nitrogen. The aromatic protons of the ligand as well as complex appear within the expected range, but in the spectrum of the complex the signals are overloaded by each other, making attributions difficult. The 13C NMR spectra of both ligand and complex present all expected signals. There are both downfield and upfield shifts by comparing the spectrum of the complex in relation to the spectrum of the free ligand. Assignments of the peaks are based on the chemical shift and intensity patterns. Large displacements observed for carbon atoms in the vicinity of the phenolate (δligand/complex = 148.9/152.1), azomethine (δligand/ complex = 158.9/163.3) and enolate (δligand/complex = 164.4/170.3) groups suggest their involvement in coordination. The appearance of two signals at δ -542.9 and -575.1 ppm for complex 1 in the spectrum of 51V NMR, approximately in the ratio of 3:1, indicates the presence of two species. The major signal (δ -575.1 ppm) is assigned to complex 1. The nature of the minor, down-field signal is proposed to be from the corresponding square pyramidal dimeric complex without the water and acetonitrile molecules. 3.2. Structure description A single crystal of complex 1, obtained from a CH3CN solution, was analyzed by X-ray diffraction methods. The structure of the dimeric oxidovanadium complex with atomic labels as well as a space filling model representation are depicted in Figure 1. Selected bond lengths and angles for complex 1 are shown in Table 2. The L2– ligand coordinates in O,N,O-tridentate mode forming one five- and one six-membered chelate ring around each V(V) center. The two vanadium centers are not equivalent in relation to the V–O–V bridges, which are slightly asymmetric in relation to the μ-O2– bridge, but considerably asymmetric for the μ-H2O bridge (see Figure 2) and there are significant metric differences for the bonding parameters in the two parts of the molecule (see the caption to Figure 1). The interatomic distances for the terminal vanadyl groups, V(1)– O(13) and V(2)–O(23), correspond to double bonds, being in the normal bond length range [19,23-25,27]. It is to note that the V–O bond involving the phenolate oxygen, V(1)– O(11)/V(2)–O(21) 1.818(3)/1.824(3) Å, is shorter than the corresponding bond involving the enolate oxygen atom, V(1)– O(12)/V(2)–O(22) 1.934(3)/1.922(3) Å, showing the greater ability of the first to act as donor to the vanadium center. 2020 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.11.1.1-5.1948 4 Borges et al. / European Journal of Chemistry 11 (1) (2020) 1-5 Table 2. Selected bond lengths (Å) and angles (°) refined from X-ray data and calculated for [{VO(L)}2(μ-O)(μ-H2O)]∙2CH3CN (1). V(1)-O(10) 1.578(3) V(2)-O(20) 1.588(3) V(1)-O(30) 1.799(3) V(2)-O(30) 1.801(3) V(1)-O(1) 1.818(3) V(2)-O(4) 1.824(3) V(1)-O(2) 1.934(3) V(2)-O(40) 2.397(3) V(1)-O(40) 2.491(3) V(2)-O(5) 1.922(3) V(1)-N(1) 2.095(4) V(2)-N(3) 2.104(3) O(30)-V(1)-O(40) 75.33(11) O(20)-V(2)-O(4) 101.68(16) O(30)-V(1)-O(10) 106.74(14) O(20)-V(2)-O(30) 103.35(14) O(10)-V(1)-O(40) 174.40(15) O(20)-V(2)-O(40) 177.93(14) O(30)-V(1)-O(2) 92.42(14) O(5)-V(2)-N(3) 74.25(13) O(10)-V(1)-O(2) 96.76(16) O(40)-V(2)-N(3) 82.91(11) O(40)-V(1)-N(1) 78.07(12) O(20)-V(2)-N(3) 95.64(14) O(10)-V(1)-N(1) 99.09(14) O(4)-V(2)-O(5) 150.52(13) O(2)-V(1)-N(1) 74.61(14) O(20)-V(2)-O(5) 99.52(15) V(1)-O(40)-V(2) 81.59(9) V(1)-O(30)-V(2) 125.09(15) (a) (b) Figure 2. Perspective view from the direction [010] with the principal bond distances (Å) on left and of the environment around the two vanadium centers forming the coordination polyhedrons connected by one edge on the right. The distances from the vanadium centers to the oxygen of the μ-O bridge, V(1)–O(12) and V(2)–O(22), are considerably shorter than the distances to the oxygen of the μ-H2O bridge, V(1)–O(13) and V(2)–O(23), indicating a trans effect caused by the vanadyl groups (see Figure 2). The angles between the two vanadium atoms (i.e. the angles formed by the vanadium atoms and the bridges), V(1)–O(4)–V(2) and V(1)–O(5)–V(2), differ significantly, with values of 125.09(15) and 81.59(9)°, respectively. The value of 125.09(15)° for the V–(μ-O)–V is intermediate among the observed for similar compounds, 112.06° [19], 151.5° [20], 102.41(4)° [22] and 101.78° [27]. Each vanadium center is six-coordinated, with the axial angles O(13)–V(1)–O(5)/O(23)–V(2)–O(5), forming the almost linear axis, with values of 174.40(15)° and 177.93(14)°, respectively. The vanadium centers are almost in the same plane spanned by the O,N,O-tridentate ligands and the μ-O bridging oxygen, 0.301 Å and 0.272 Å toward de oxido ligands for V(1) and V(2), respectively. The V–V distance [3.194(0) Å] is higher than those of other reported complexes [23,32]. The environments around the two vanadium atoms may be considered as two octahedrons attached by one edge, formed by the μ-O2– and the μ-H2O bridges (see Figure 2). The compound is stabilized by two molecules of aceto- nitrile. The acetonitrile molecules are in H-bonding contact with the hydrogen atoms from the μ-(H2O) bridge: O(5)– H(52)∙∙∙N(4) [O(5)∙∙∙N(4) = 280.3(6) pm, O(5)–H(52)∙∙∙N(4) = 171.4°] and O(5)–H(51)∙∙∙N(3) [O(5)∙∙∙N(3) = 281.7(6) pm, O(5)–H(51)∙∙∙N(3) = 171.5 °]. Intramolecular hydrogen bonds of the type O–H∙∙∙N, formed by the hydroxide groups with the nitrogen atoms N(12) and N(21) are also found: O(16)– H(16)∙∙∙N(12) [O(16)∙∙∙N(12) = 261.9(5) pm, O(16)–H(16)∙∙∙ N(12) = 147.0°] and O(26)–H(26)∙∙∙N(22) [O(26)∙∙∙N(22) = 261.6(5) pm, O(26)–H(26)∙∙∙N(22) = 146.7°]. These hydrogen bonds can be observed in Figure 1. 4. Conclusion A dimeric oxidovanadium(V) complex with a hydrazonate ligand has been synthesized and its structure was elucidated with various modalities. The ligand is able to coordinate in a dianionic NOO-tridentate mode. The metal centers are connected by asymmetric oxido and aqua bridges, forming an octahedral geometry with the V=O units in a syn configuration. Further studies regarding the biological applications of the complex are now ongoing. Acknowledgements This work was supported by Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (Grants: 305432/ 2017-6, 424095/2018-1 and 307443/2015-9), Fundacao de Amparo a Pesquisa de Sao Paulo (Grant 2009/54011-8) and Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (Grants: APQ-03174-18, APQ-01988-14, APQ-00583-13 and APQ-03017-16). This work is also a collaboration research project of members of the Rede Mineira de Quimica and of the Grupo de Materiais Inorganicos do Triangulo-GMIT, research groups supported by Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (Grants: CEX-RED-00010-14 and APQ- 00330-14). Supporting information CCDC-1972103 contains the supplementary crystallo- graphic data for this paper. These data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/, or by e- mailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)1223-336033. 2020 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.11.1.1-5.1948 https://www.ccdc.cam.ac.uk/structures/ mailto:data_request@ccdc.cam.ac.uk Borges et al. / European Journal of Chemistry 11 (1) (2020) 1-5 5 Disclosure statement Conflict of interests: The authors declare that they have no conflict of interest. Author contributions: All authors contributed equally to this work. Ethical approval: All ethical guidelines have been adhered. Sample availability: Samples of the compounds are available from the author. Funding Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) http://www.cnpq.br Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) https://fapemig.br/pt/ Fundacao de Amparo a Pesquisa de Sso Paulo (FAPESP) http://www.fapesp.br/ ORCID Alice Prudente Borges http://orcid.org/0000-0002-6525-1260 Claudia Cristina Gatto http://orcid.org/0000-0002-3736-6861 Victor Marcelo Deflon http://orcid.org/0000-0002-5368-6486 Pedro Ivo da Silva Maia http://orcid.org/0000-0003-4699-9481 References [1]. Belokon, Y. N.; Clegg, W.; Harrington, R. W.; Young, C.; North, M. Tetrahedron 2007, 63, 5287-5299. [2]. Kwiatkowski, E.; Romanowski, G.; Nowicki, W.; Kwiatkowski, M.; Suwinska, K. Polyhedron 2007, 26, 2559-2568. [3]. Alvarez, H. M.; Andrade, J. L.; Pereira, N.; Muri, E. M. F.; Horn, A.; Barbosa, D. P.; Antunes, O. A. C. Catal. Commun. 2007, 8, 1336-1340. [4]. Langeslay, R. R.; Kaphan, D. M.; Marshall, C. L.; Stair, P. C.; Sattelberger, A. P.; Delferro, M. Chem. 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Chem. 2017, 8(4), 328-332. [32]. Souza, P. C.; Maia, P. I. S.; Barros, H. B.; Leite, C. Q. F.; Deflon, V. M.; Pavan, F. R. Curr. Clin. Pharmacol. 2015, 10(1), 66-72. Copyright © 2020 by Authors. This work is published and licensed by Atlanta Publishing House LLC, Atlanta, GA, USA. The full terms of this license are available at http://www.eurjchem.com/index.php/eurjchem/pages/view/terms and incorporate the Creative Commons Attribution-Non Commercial (CC BY NC) (International, v4.0) License (http://creativecommons.org/licenses/by-nc/4.0). By accessing the work, you hereby accept the Terms. This is an open access article distributed under the terms and conditions of the CC BY NC License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited without any further permission from Atlanta Publishing House LLC (European Journal of Chemistry). No use, distribution or reproduction is permitted which does not comply with these terms. Permissions for commercial use of this work beyond the scope of the License (http://www.eurjchem.com/index.php/eurjchem/pages/view/terms) are administered by Atlanta Publishing House LLC (European Journal of Chemistry). 2020 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.11.1.1-5.1948 http://www.cnpq.br/ http://www.fapesp.br/ http://orcid.org/0000-0002-6525-1260 http://orcid.org/0000-0002-3736-6861 http://orcid.org/0000-0002-5368-6486 http://orcid.org/0000-0003-4699-9481 http://www.eurjchem.com/index.php/eurjchem/pages/view/terms http://creativecommons.org/licenses/by-nc/4.0 http://www.eurjchem.com/index.php/eurjchem/pages/view/terms 1. Introduction 2. Experimental 2.1. Materials and physical methods 2.2. Synthesis 2.2.1. Synthesis of the ligand H2L 2.2.2. Preparation of [{VO(L)}2(μ-O)(μ-H2O)]∙2CH3CN (1) 2.3. Crystal structure determination 3. Results and discussion 3.1. Synthesis and spectroscopic characterization 3.2. Structure description 4. Conclusion Acknowledgements Supporting information Disclosure statement Funding ORCID References PrintField10: PrintField11: PrintField12: PrintField13: PrintField14: PrintField20: PrintField21: PrintField22: PrintField23: PrintField24: