Oxocation complexes, Part X. Oxomolybdenum(V) and dioxomolybdenum(VI) complexes with tri- and tetra-dentate Schiff bases

Syntheses, Characterization, and Biological Activities of Metal Complexes of N-(2-Carbamoylthienyl)-C-(3′-carboxy-2′-hydroxyphenyl) Azetidin-2-one with Some Di-, Tetra-, and Hexavalent Metal Ions

The cyclization of the Schiff base, N-(2-carbamoylthienyl)-3′-carboxy-2′-hydroxybenzylideneimine with ClCH2COCl in dioxane, in the presence of triethylamine (Et3N) forms N-(2-carbamoylthienyl)-C-(3′-carboxy-2′-hydroxyphenyl) azetidin-2-one, LH3(I). A methanolic solution ofIreacts with Co(II), Cu(II), Zn(II), Zr(OH)2(IV), and MoO2(VI) ions and forms the coordination compounds, [Co(LH)(MeOH)]2(II), [Cu(LH)]2(III), [Zn(LH)(MeOH)2] (IV), [Zr(OH)2(LH)(MeOH)] (V), and [MoO2(LH)(MeOH)2] (VI). The compounds have been characterized on the basis of elemental analyses, molar conductance, molecular weight, spectral (IR, NMR, reflectance, and ESR) studies, and magnetic susceptibility measurements. All the coordination compounds are nonelectrolytes (ΛM=3.1-9.2 mho cm2mol−1) in DMF.Ibehaves as a dibasic tridentate OON donor ligand inV; a dibasic tetradentate OONO donor ligand inII,III, andVI; and a dibasic tetradentate OONS donor ligand inIV.IIandIIIare dimers, while others are monomers in diphenyl.IIIexhibits subnormal magnetic moment (1.55 B.M.) and is involved in antiferromagnetic exchange, while the other complexes are magnetically dilute. A square-pyramidal structure forIIIand an octahedral structure forII,IV, andVare suggested.VIexhibits an eight-coordinate structure. The ligand (I) and its compounds show antibacterial activities towardsE. coli(gram negative) andS. aureus(gram positive).

New tetradentate Schiff bases of 2,2-dimethyl-1,3-diaminopropane and acetylacetone derivatives and their vanadyl complexes

A series of new VO(IV) complexes with two new tetradentate Schiff base of 4,4'-(2,2-dimethylpropane-1,3-diyl)-bis(azan-1-yl-1-yldene)dipent-2-en-2-ol) [H(2)L(1)] and 3,3'-(2,2-dimethylpropane-1,3-diyl)azan-1-yl-1-ylidene)-bis(1-phenylbut-1-en-1-ol) [H(2)L(2)] (which have been derived from 2,2-dimethyl-1,3-diaminopropan, and diketones of acetylacetone and benzoylacetone) were synthesized and characterized by (1)H NMR, (13)C NMR, FT-IR, mass and UV-Vis spectrophotometry. The electrochemical properties of the vanadyl complexes were investigated by means of cyclic voltammetry. The oxidation potentials are increased by increasing the electron-withdrawing properties of functional groups of the Schiff base ligands according to the trend of Me<Ph. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the VO(IV) complexes were carried out in the range of 20-700°C. The complexes were decomposed in two stages. Also, decomposition of the synthesized complexes is related to the Schiff base characteristics. The thermal decomposition of the studied reactions was first order. The kinetic parameters for the decomposition steps in vanadyl complexes thermograms have been calculated.

A series of transition and non-transition metal complexes from a N₄O₂ hexadentate Schiff base ligand: Synthesis, spectroscopic characterization and efficient antimicrobial activities

Some transition and non-transition metal complexes of the hexadentate N₄O₂ donor Schiff base ligand 1,8-N-bis(3-carboxy)disalicylidene-3,6-diazaoctane-1,8-diamine, abbreviated to H₄fsatrien, have been synthesized. All the 14 metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic (UV-Vis, IR, NMR, ESR) data. The analytical data helped to elucidate the structures of the metal complexes. The Schiff base, H₄fsatrien, is found to act as a dibasic hexadentate ligand using N₂N₂O₂ donor set of atoms (leaving the COOH group uncoordinated) leading to an octahedral geometry for the complexes around all the metal ions except VO²(+) and UO₂²(+). However, surprisingly the same ligand functions as a neutral hexadentate and neutral tetradentate one towards UO₂²(+) and VO²(+), respectively. In case of divalent metal complexes they have the general formula [M(H₂fsatrien)] (where M stands for Cu, Co, Hg and Zn); for trivalent metal complexes it is [M(H₂fsatrien)]X·nH₂O (where M stands for Cr, Mn, Fe, Co and X stands for CH₃COO, Cl, NO₃, ClO₄) and for the complexes of VO²(+) and UO₂²(+), [M(H₄fsatrien)]Y (where M=VO and Y=SO₄); M=UO₂ and Y=2 NO₃). The Schiff base ligand and most of the complexes have been screened in vitro to judge their antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Aspergillus niger and Pencillium chrysogenum) activities.

Synthesis and spectroscopic characterization of some transition metal complexes of a new hexadentate N(2)S(2)O(2) Schiff base ligand

A novel interesting hexadentate dibasic N(2)S(2)O(2) donor Schiff base ligand, H(4)dcsalpte, was synthesized by the condensation of 3-formylsalicylic acid and 1,2-di(o-aminophenylthio)ethane and characterized. The reactions of the ligand with different metal(II/III)salts under varied reaction conditions afforded a series of metal complexes. The ligand, H(4)dcsalpte, behaves either as a dibasic or neutral hexadentate one, depending on the reaction conditions. Structural investigations on the ligand and their complexes have been made based on elemental analyses, molar conductance values, magnetic moment values, cryomagnetic and spectral (UV-vis, IR, (1)H NMR, and Mössbauer) data. Based on magnetic susceptibility, Mössbauer and electronic spectral data the iron(III) complex [Fe(III)(H(2)dcsalpte)]ClO(4) (8), isolated in the present investigation, it is inferred that the spin states 5/2 and 1/2 are in equilibrium. Similarly a tri-iron(III) complex [Fe(III)(3)(H(2)dcsalpte)(H(3)dcsalpte)Cl(3)]Cl(3) (7), isolated in this study, has been inferred to contain two iron(III) sites in tetrahedral environment and one in the octahedral environment. The aerial oxidation of an equimolar mixture of H(4)dcsalpte and Co(CH(3)COO)(2).4H(2)O in ethanol under reflux gave two products, [Co(H(2)dcsalpte)]CH(3)COO (10) and [(Hbtcsaldm)Co(Hbvcsaldm)] (11), a cobalt(III) complex bound to two dissimilar tridentate NSO donor ligands formed as a result of the oxidative cleavage of the CS bond. In the complex 11, Hbtcsaldm stands for the dianion of the tridentate Schiff base ligand N-(2'-benzenethiol)-3-carboxysalicylaldimine and Hbvcsaldm stands for the mono anion of the tridentate Schiff base ligand N-(benzene-2'-S-vinyl)-3-carboxysalicylaldimine, both being formed as a result of the oxidative cleavage of H(4)dcsalpte.