Kamalendu Dey

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

SummaryMany new oxomolybdenum(V) and dioxomolybdenum(VI) complexes have been synthesized with tri- and tetradentate Schiff bases derived by the condensation of salicylaldehyde, thiosalicylaldehyde,o-hydroxyacetophenone, 3-carboxysalicyclaldehyde or acetylacetone with aminoalcohols, polymethylenediamines ando-phenylenediamines. Mononuclear oxothiolato Schiff base complexes of molybdenum(V) have been prepared for the first time. Quadridentate Schiff bases derived from salicylaldehyde and substituted salicylaldehydes ando-phenylenediamine have also been successfully employed to isolate dioxomolybdenum(VI) complexes in the solid state, in which two oxygen atoms of the MoO2 group arecis- to each other, similar to the situation observed for other dioxomolybdenum(VI) complexes of salicylaldehyde-polymethylenediamine Schiff base ligands.Structures have been determined with the help of elemental analyses, magnetic susceptibilities, molar conductances, i.r., electronic and1H n.m.r. spectral data.

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.

NS and NSO-Donor ligands and their metal complexes. Synthesis and characterisation of a new low-spin iron(III) complex with 1,2-di(o-aminophenylthio)ethane and iron(III), cobalt(III) and manganese(III) complexes of 1,2-di(o-salicylaldiminophenylthio)ethane

SummaryIron(III) complexes of a quadridentate N2S2 donor ligand, 1,2-di(o-aminophenylthio)ethane (DAPTE) and its Schiff Base with salicylaldehyde, a hexadentate N2S2O2 donor ligand,viz. 1,2-di(o-salicylaldiminophenylthio)ethane (H2DSALPTE) have been synthesised and characterised.The Schiff base ligand (1 mol) gave a dark green tri-iron(III) [Fe3(DSALPTE)(HDSALPTE)Cl3]Cl2 complex when reacted with anhydrous iron(III) chloride (1 mol). The Mössbauer data of this complex suggest the presence of three iron sites, one of which is octahedral and the other two tetrahedral. On the other hand, Fe(ClO4)3 reacted smoothly with H2DSALPTE in ethanol to give a mononuclear pseudo-octahedral complex in which the ligand functions in a dibasic hexadentate fashion. Mössbauer data suggest the presence of a low-spin-high-spin equilibrium in the solid state. The manganese(III) and cobalt(III) complexes of the Schiff base, H2DSALPTE, are also studied for the sake of comparison with the corresponding iron(III) complex. The N2S2 ligand, however, formed a low-spin pseudo-octahedral iron(III) complex. The complexes have been characterised by elemental analysis, molar conductance values, cryomagnetic data and i.r., electronic and Mössbauer spectral data.

Reactions of metal β-diketonates. : IV. Reactions of bis(acetylacetonato)oxovanadium(IV) hydrate, VO(acac)2H2O, with chelating ligands

Abstract The reactions of bis(acetylacetonato)oxovanadium (IV) hydrate, VO(acac)2H2O, with different chelating ligands (containing at least one NH2 group) have been studied. In dry refluxing toluene, heterochelates of the type [VO(acac)(Lsbnd;L)]0(or+)·nH2O (where LL = neutral or monoanion of bidentate chelating ligands; n = 0–1) have been isolated. On the other hand, dibasic tridentate (LH2) or dibasic tetradentate (L′H2) Schiff bases replaced all the acetylacetonate anions from VO(acac)2H2O to produce VO(L)H2O or VO(L′) in refluxing toluene or ethanol. Analogous reactions of VO(acac)2H2O with aminoacids, aminoalcohols, semi- and thiosemi-carbazide in ethanol, methanol, water-ethanol or water-acetone mixture, produced a variety of mixed ligand complexes of oxovanadium(IV) ion involving Schiff bases, many of which show subnormal magnetic moments at room temperature. In the course of this study several mixed ligand oxovanadium(IV) complexes with neutral acetylacetone (or glycine) have also been isolated. The reactions of VO(acac)2H2O with chelating amino ligands in presence of even trace amount of water invariably result in the template syntheses of Schiff base chelates, which has been discussed qualitatively The electronic spectra of these chelates have been interpreted with the help of either C2V or C4V local symmetry. The elemental analyses, i.r. spectral data and cryomagnetic data have also been used to characterise the complexes.

Complexes of NS and NSO donor ligands. Nickel(II), copper(II) and cobalt(II) complexes of glyoxal bis(morpholineN-thiohydrazone) and diacetyl bis(morpholineN-thiohydrazone)

SummaryReactions of glyoxal bis(morpholineN-thiohydrazone), H2gbmth, with NiCl2·6H2O, Ni(OAc)2·4H2O, Ni(acac)2· H2O, CuCl2·2H2O, Cu(OAc)2·H2O, Cu(acac)2, CoCl2· 6H2O, Co(OAc)2·4H2O and Co(acac)2·2H2O yield complexes of the type [M(gbmth)], [M=NiII, CuII or CoII]. Diacetyl reacts with morpholineN-thiohydrazide in the presence of nickel salts to yield [NiII(dbmth)], [NiII(dmth)(OAc)]H2O and [NiII(Hdmth)(NH3)Cl2] involving N2S2 and NSO donor ligands. Copper and cobalt complexes of N2S2 and NSO donor ligands with compositions [CuII(dbmth)], [CoII(dbmth)]·4H2O and [CoII(H2dbmth)]Cl2, have been isolated. The compounds have been characterised by elemental analyses, magnetic moments, molar conductance values and spectroscopic (electronic and infrared) data.

Reactions of [Cp2MCl2-7 (M = Ti or Zr and Cp = η5-C5H5) with Multidentate Ligands and the Synthesis of New Cyclopentadienyl Derivatives of Titanium and Zirconium

Abstract The reactions of the dibasic tridentate hydrazones H2L1, H2L2, and H2L3; benzothiazolines HL4 and HL6; 1,2-di(o-aminophenylthio) ethane L8 and a dibasic hexadentate Schlff base H2L9 with [Cp2Ticl2-] and [Cp2ZrCl2-] are described. The reactions of [TiCpClL5], synthesised in this study, with MeSH, SiMe3(NMe2), Me3SiC [tbnd] CPh, Na[FeCp(CO)2-], and SnCl4 are also described. Structures for the compounds are proposed on the basis of elemental analyses, molar conductances, molecular weights, and i. r. uv-visible, 1H n. m. r. spectroscopic data.

COORDINATION BEHAVIOUR OF 2-(1-CARBOXYL-2-HYDROXYPHENYL)BENZOTHIAZOLINE

ABSTRACT Reaction of 3-formylsalicylic acid with 2-aminobenzenethiol yielded 2-(1-carboxyl-2-hydroxyphenyl)benzothiazoline, H 2chpbzn, rather than the corresponding Schiff base, 2-(2-mercaptophenyl)(3′-carboxy)salicylaldimine, H 3mpcsalim. The reaction of H 2chpbzn with (π-C5H5)2TiCl2, (π-C5H5)2ZrCl2, CrCl3·6H2O, FeCl3 (anhydrous), VOSO4, VOCl3, Ni(OAc)2·4H2O, Na2PdCl4, Me2TlCl, Ph2TlCl, BiCl3 and SbCl3, under varied reaction conditions, afforded the corresponding Schiff base complexes of the metal ions. For all of the complexes, except those of bismuth and antimony, the dianion of the Schiff base acts as a tridentate NSO donor ligand, while in the bismuth and antimony complexes the neutral benzothiazoline functions as a monodentate N donor ligand. Reactions of [(Hmpcsalim)Ti(π-C5H5)Cl], isolated in this study, with Me3SiE (where E stands for SMe, NMe2, N3 and C≡C‒Ph) have also been studied leading to the synthesis of many new organotitanium(IV) compounds. The prepared new compounds were characterized by elemental analyses, magnetic susceptibilities, molar conductance values, molecular weights and spectroscopic (UV-Vis, IR and 1H NMR) data.

Chromium(III) complexes of Schiff bases

Abstract The preparation, electronic and infrared spectra, and magnetic moments of numerous solid complexes of chromium(III) of the type [Cr(SB)L 2 ]X·nH 2 O (L = NH 3 or H 2 O; X = SCN or Cl; n = 1 or O); K[Cr(SB)L 2 ]H 2 O (L′ = CN or ONO); [Cr(SB) (py)(Cl)]; [Cr(SB)(LL)] (LL = acetylacetonate anion); [Cr(SB)(LL)]X·nH 2 O (LL = dipyridyl; X = ClO 4 ; n = 1 or O); H[Cr(SB′) 2 ]; and [Cr (SB″) 2 ]X (X = ClO 4 ) (SB = dianions of the tetradentate Schiff bases derived from salicylaldehyde, orthohydroxyacetophenone, and acetylacetone with ethylenediamine or orthophenylenediamine; SB′ = dianions of the tridentate Schiff bases derived from salicylaldehyde with anthranilic acid, orthoaminophenol or glycine; and SB″ = monoanion of the Schiff base derived from salicylaldehyde and ethanolamine respectively) are reported. Bivalent quandridentate Schiff bases are presumably non planar in [Cr(SB)(LL)] species, while in other complexes they occur square-planar configuration. The nitrite ion in K[Cr(SB) (ONO) 2 ] is bound to the chromium(III) ion through the oxygen atom.

Synthesis, characterization, and density functional study of some manganese(III) Schiff-base complexes

Some Mn(III) complexes of N,N′-(2-hydroxy)propylenebis(acetylacetoneimine) (abbreviated to H2L1) and N,N′-(2-hydroxy)propylenebis(2-imino-3-oximino)butane (abbreviated to H2L2), [Mn(III)(Lig)(X)] (where Lig stands for the dianion of the Schiff-base ligands and X stands for CH3COO−, Cl−, Br−, I−) were synthesized. The complexes are characterized with the help of elemental analyses, magnetic moments, spectroscopic data (UV-Vis, infrared), and molecular weight determination (measured by Rasts method). The structures of the complexes were obtained using density functional theory (DFT). DFT calculation shows that 1–4 and 8 are trigonal-bipyramidal whereas 5–7 are square-pyramidal.

Synthesis and characterization of oxovanadium(IV), vanadium(IV) and oxovanadium(V) complexes of tetradentate Schiff bases. Attempted preparation of vanadium-carbon bonded compounds through desilylation

Condensation of 1,3-diaminopropane-2-ol with diacetylmonoxime, acetylacetone, salicylaldehyde and orthohydroxyacetophenone yielded the tetradentate Schiff bases N,N′-(2-hydroxy)propylenebis{(2-imino-3-oximino)butane} (H2dampnol), N,N′-(2-hydroxy)propylenebis(acetylacetoneimine) (H2acacpnol), N,N′-(2-hydroxy)propylenebis-(salicyalaldimine) (H2salpnol) and N,N′-(2-hydroxy)propylenebis(7-methylsalicylaldimine) (H2ohacpnol), respectively. The ligands form complexes with oxovanadium(IV), vanadium(IV) and oxovanadium(V) salts. Some mixed ligand complexes involving σ-bonded phenyl and benzyl radical along with tetradentate ligand, H2L (where, H2L stands for H2dampnol, H2acacpnol, H2salpnol or H2ohacpnol) of the types [(L)V(C6H5)2]CH3OH and [(L)V(CH2Ph)2]CH3OH have been synthesized, characterized and also provide the syntheses of some new organovanadium(IV) complexes. Silylation coupled with desilylation have been employed as a route to new organovanadium(IV) complexes. All the complexes have been characterized with the help of elemental analyses, molar conductance values, molecular weights, magnetic moments and spectroscopic (IR, UV-Vis, ESR) data.