Synthesis, characterizations and crystal structures of antimony(III) complexes with nitrogen-containing ligands

Structures and Chemical Bonding in Antimony(III) Bromide Complexes with Pyridine

Weakly or "partially" bonded molecules are an important link between the chemical and van der Waals interactions. Molecular structures of six new SbBr₃ -Py complexes in the solid state have been determined by single-crystal X-ray diffraction analysis. In all complexes all Sb atoms adopt a pseudo-octahedral coordination geometry which is completed by additional Sb⋅⋅⋅Br contacts shorter than the sum of the van der Waals radii, with Br-Sb⋅⋅⋅Br angles close to 180°. To reveal the nature of Sb-Br and Sb-N interactions, the DFT calculations were performed followed by the analysis of the electrostatic potentials, the orbital interactions and the topological analysis. Based on Natural Bond Orbital (NBO) analysis, the Sb-Br interactions range from the covalent bonds to the pnictogen bonds. A simple structural parameter, non-covalence criterion (NCC) is defined as a ratio of the atom-atom distance to the linear combination of sums of covalent and van der Waals radii. NCC correlates with E(2) values for Sb-N, Sb-Cl and Sb-Br bonds, and appears to be useful criterion for a preliminary evaluation of the bonding situation.

Synthesis, Structural Characterization, and Antibacterial Activity of Novel Erbium(III) Complex Containing Antimony

The novel 3D edta-linked heterometallic complex [Sb₂Er(edta)₂(H₂O)₄]NO₃·4H₂O (H₄edta = ethylenediaminetetraacetic acid) was synthesized and characterized by elemental analyses, single-crystal X-ray diffraction, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermal analysis. The complex crystallizes in the monoclinic system with space group Pm. In the complex, each erbium(III) ion is connected with antimony(III) ions bridging by four carboxylic oxygen atoms, and in each [Sb(edta)]^- anion, the antimony(III) ion is hexacoordinated by two nitrogen atoms and four oxygen atoms from the edta^4- ions, together with a lone electron pair at the equatorial position. The erbium(III) ion is octacoordinated by four oxygen atoms from four different edta^4- ions and four oxygen atoms from the coordinated water molecules. The carboxylate bridges between antimony and erbium atoms form a planar array, parallel to the (1 0 0) plane. There is an obvious weak interaction between antimony atom and oxygen atom of the carboxyl group from the adjacent layer. The degradation of the complex proceeds in several steps and the water molecules and ligands are successively emitted, and the residues of the thermal decomposition are antimonous oxide and erbium(III) oxide. The complex was evaluated for its antimicrobial activities by agar diffusion method, and it has good activities against the test bacterial organisms.

Ordnung muss sein: heteroelement order and disorder in polyoxovanadates

Three new mixed antimonato–germanato polyoxovanadates exhibit different degrees of order of their unique crystallographic heterometal atom positions.

Covalent Co-O-V and Sb-N Bonds Enable Polyoxovanadate Charge Control

The formation of [{Co^II(teta)₂}{Co^II₂(tren)(teta)₂}V^IV₁₅Sb^III₆O₄₂(H₂O)]·ca.9H₂O [teta = triethylenetetraamine; tren = tris(2-aminoethyl)amine] illustrates a strategy toward reducing the molecular charge of polyoxovanadates, a key challenge in their use as components in single-molecule electronics. Here, a V–O–Co bond to a binuclear Co²⁺-centered complex and a Sb–N bond to the terminal N atom of a teta ligand of a mononuclear Co²⁺ complex allow for full charge compensation of the archetypal molecular magnet [V₁₅Sb₆O₄₂(H₂O)]^6–. Density functional theory based electron localization function analysis demonstrates that the Sb–N bond has an electron density similar to that of a Sb–O bond. Magnetic exchange coupling between the V^IV and Co^II spin centers mediated via the Sb–N bridge is comparably weakly antiferromagnetic.

Charge neutrality of the [V₁₅Sb₆O₄₂(H₂O)]⁶⁻ cluster anion is achieved by simultaneous Sb−N and V−O−Co bond formation. The Sb−N bond has an electron density similar to that of a Sb−O bond. Weak antiferromagnetic exchange interactions are observed between the V^IV and Co^II spin centers.

Molecular design of a novel ligand for Menshutkin complexation of Bi(iii) from aqueous acidic copper sulfate electrolyte solutions and experimental investigations

A novel silica functionalised phen–arene adsorbent exhibits reversible and highly selective adsorption of Bi(iii) over Cu(ii) ions by Menshutkin complexation from an aqueous acidic copper electrolyte solution.

Versatile structures of group 13 metal halide complexes with 4,4′-bipy: from 1D coordination polymers to 2D and 3D metal–organic frameworks

The nature of the group 13 metal halides strongly affects the structure of their complexes with 4,4′-bipy.

Syntheses, characterization, antimicrobial and cytotoxic activities of pyridine-2,5-dicarboxylate complexes with 1,10-phenanthroline

In this study, four mononuclear M(II)-pyridine-2,5-dicarboxylate (M = Co(II), Ni(II), Cu(II) and Zn(II) complexes with pyridine-2,5-dicarboxylic acid or isocinchomeronic acid, 1,10-phenanthroline (phen), [Co(Hpydc)(2)(phen)]·H(2)O (1), [Ni(pydc)(phen)(2)]·6.5H(2)O (2) [Cu(pydc)(phen)(H(2)O)(2)] (3) and [Zn(pydc)(phen)(H(2)O)(2)]·H(2)O (4) have been synthesized. Elemental, thermal and mass analyses, molar conductance, magnetic susceptibilities, IR and UV/vis spectroscopic studies have been performed to characterize the complexes. Subsequently, these ligands and complexes were tested for antimicrobial activity by disc diffusion method on Gram positive, negative bacteria and yeast. In addition, cytotoxic activity tests were performed on rat glioma (C6) cells by MTT viability assay for 24 and 48 h. Antimicrobial activity results demonstrated that when compared to the standard antibiotics, phen displayed the most effective antimicrobial effect. The effect of synthesized complexes was close to phen or less. Cytotoxic activity results showed that IC(50) value of phen was determined as 31 μM for 48 h. (1) and (2) compared to the alone ligand had less toxic activity. IC(50) values of (3) for 24 and 48 h treatments were 2.5 and 0.6 μM, respectively. IC(50) value of (4) for 48 h was 15 μM. In conclusion, phen, (3) and (4) may be useful as antibacterial and antiproliferative agents in the future.

Improved antileishmanial activity of Dppz through complexation with antimony(III) and bismuth(III): investigation of the role of the metal

Two novel trivalent antimony(III) and bismuth(III) complexes with the nitrogen-donor heterocyclic ligand dipyrido[3,2-a:2',3'-c]phenazine (dppz) were synthesized and characterized as [Sb(dppz)Cl₃]∙H₂O∙CH₃OH and [Bi(dppz)Cl₃]. The crystal structure of Sb(III) complex was determined by X-ray crystallography. These complexes were evaluated for their activity against the promastigote form of Sb(III)-sensitive and -resistant Leishmania infantum chagasi and Leishmania amazonensis strains. Both complexes were more effective than dppz alone in inhibiting the growth of Leishmania promastigotes and were at least 77 and 2,400 times more active than potassium antimonyl tartrate in Sb(III)-sensitive and -resistant Leishmania, respectively. The cytotoxicity of dppz and its complexes against mouse peritoneal macrophages occurred at dppz concentrations at least 6-fold greater than those found to be active against Leishmania promastigotes.To investigate the role of the metal in the improved antileishmanial activity of dppz, the activity of the Sb(III) complex was compared between the Sb-resistant mutants and their respective parental sensitive strains. The lack of cross-resistance to the Sb(III)-dppz complex together with the much lower activity of antimonyl tartrate, SbCl₃ and BiCl₃ strongly support the model that the metal is not active by itself but improves the activity of dppz through complexation.

Investigation on the pharmacological profile of antimony(III) complexes with hydroxyquinoline derivatives: anti-trypanosomal activity and cytotoxicity against human leukemia cell lines

Complexes [Sb(QN)(2)Cl] (1), [Sb(QC)(2)Cl] (2) and [Sb(QI)(2)Cl] (3) were obtained with 8-hydroxyquinoline (HQN), 5-chloro-8-hydroxyquinoline (HQC) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol, HQI). The quinoline derivatives and their antimony(III) complexes were evaluated for their anti-trypanosomal activity as well as for their cytotoxicity against HL-60 and Jurkat human leukemia cell lines. Upon coordination to antimony(III) the anti-trypanosomal activity of HQC and HQI increases, the highest improvement being observed for complex (3), which was the most active among all studied compounds against both epimastigote and trypomastigote forms of Trypanosoma cruzi. All quinoline derivatives proved to be cytotoxic against both leukemia cell lineages. Upon coordination to antimony(III) the cytotoxicity of HQN improved against Jurkat leukemia cells. While SbCl(3) proved to be cytotoxic against HL-60 cells, it was not active against Jurkat cells. However, its coordination to the quinoline derivatives resulted in complexes with significant cytotoxicity against Jurkat cells.