Synthesis and Characterization of Vanadium(IV) and (V) Complexes with 2-Hydroxy-acetophenone-semicarbazone (H2hasc) as Ligand. X-Ray Crystal Structures of [VO2(H2hasc)] and [VO2(Hhasc)]

Autor: Sebastia–o S. Lemos, Alzir A. Batista, Otaciro R. Nascimento, Gerimário F. de Sousa, Elke Niquet, Victor M. Deflon, Pedro I. S. Maia
Rok vydání: 2007
Předmět:
Zdroj: Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual)
Universidade de São Paulo (USP)
instacron:USP
ISSN: 1521-3749
0044-2313
Popis: Three novel vanadium complexes with pharmacologically active ligands were synthesized and characterized: [VIVO(acac)(Hhasc)], [VIVO2(H2hasc)], and [VVO2(Hhasc)], where H2hasc = 2-Hydroxy-acetophenone-semicarbazone. The analytical methods used included FTIR, 1H-, 13C-, 51V-NMR and EPR spectroscopies, elemental analysis and X-ray diffractometry from single crystals. The crystal and molecular structures of [VIVO2(H2hasc)] and [VVO2(Hhasc)] were determined. [VIVO2(H2hasc)] crystallizes monoclinic [P21/c, Z = 4, a = 783.4(2), b = 1024.9(2), c = 1365.5(3) pm, β = 99.506(14)°]. The (VO2)2+ core is coordinated to a neutral O,N,O-tridentate unit of the H2hasc ligand, with the vanadium atom showing a square pyramidal coordination sphere. In the crystal of [VVO2(Hhasc)], triclinic [, Z = 4, a = 858.73(11), b = 967.39(5), c = 1318.63(12) pm, α = 97.423(5), β = 101.590(6), γ = 98.144(5)°], two symmetry independent (VO2)+ cores are observed. Each of them coordinates to a monodeprotonated Hhasc− unit, in a O,N,O-tridentate mode. One assumes a square pyramidal geometry for the pentacoordinate vanadium(V) center. An additional interaction is observed for the other one, involving the phenolate oxygen atom from a symmetry related unit, resulting in a [5+1]-coordination number for the transition metal atom.
Databáze: OpenAIRE
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