Complexes of titanium(IV), vanadium(IV) and tin(IV) with schiff bases derived from 2-(2-aminophenyl)benzimidazole

Summary New titanium(IV), vanadium(IV) and tin(IV) complexes with Schiff bases derived from 2-(2-aminophenyl)benzimidazole with benzaldehyde (L₁) and salicylaldehyde (L₂) have been prepared and have the general formulae MX₄ · 2L (M = Ti, V or Sn; L = L₁ or L₂; X = Cl or Br).All the complexes have been characterized by elemental analyses, magnetic measurements, e.p.r., electronic and i.r. spectral studies. The results show that the Schiff bases act as monodentate ligands. Tentative structures for the complexes are suggested.     

Transition metal schiff base chelates as ligands for phenyltin(IV) chlorides

Summary Binuclear complexes of phenyltin(IV) chlorides with transition metal chelates of tetradentate Schiff bases derived from acetylacetone, benzoylacetone oro-hydroxyacetophenone and ethylenediamine or propylenediamine, of the general formula Ph_nSnCl₄-nML (where n = 1 or 2, M = Ni¹¹ or Cu¹¹ and L^2–= the Schiff base dianion), have been synthesised and characterized through elemental analysis, conductance and i.r. spectroscopic data. The coordination of metal chelates to tin involves two triply bonded oxygen atoms giving rise to an octahedral environment around Sn^IV. The molar conductance of the complexes in nitrobenzene shows the presence of the uncoordinated ML and phenyltin(IV) chloride moieties in solution.Author to whom all correspondence should be directed.     

Bioactive versatile azomethine complexes of organotin(IV) and organosilicon(IV)

Diorganotin(IV) and diorganosilicon(IV) derivatives of the types R₂MCl(TSCZ) and R₂M(TSCZ)₂ (where TSCZ is the anion of a thiosemicarbazone ligand, R=Ph or Me and M=Sn or Si) have been synthesized and characterized by elemental analyses, molecular weight determinations and conductivity measurements. The mode of bonding has been established on the basis of IR and ¹H, ¹³C ²⁹Si and ¹¹⁹Sn NMR spectroscopic studies. Some of the representative complexes have also been evaluated for their antimicrobial effects on different species of pathogenic fungi and bacteria in vivoas well as in vitro.The results of these investigations are reported. © 1998 John Wiley & Sons, Ltd.     

Syntheses,Spectral, and Biological Studies of New Imines Derived From 5-Bromothiophene-2-Carboxaldehyde and Their Si(IV), Sn(IV) Complexes

The Schiff bases (imines) HL¹ and HL² have been synthesized by the reaction of 5-bromothiophene-2-carboxaldehyde with 4-amino-5-mercapto-1,2,4-triazole and 4-amino-3-ethyl-5-mercapto-1,2,4-triazole, respectively. Organosilicon(IV) and organotin(IV) complexes having the general formulae R₂MCl(L¹), R₂MCl(L²), R₂M(L¹)₂, R₂M(L²)₂, (M = Si, Sn; R = CH₃) were synthesized by the reaction of R₂MCl₂ with these Schiff bases in 1:1 and 1:2 molar ratio. The Schiff bases and their metal complexes have been characterized with the aid of elemental analyses, molar conductance, and spectroscopic studies, including UV, IR, ¹H, ¹³C, MS, ²⁹Si, and ¹¹⁹Sn NMR spectroscopy. On the basis of these studies, the resulting complexes have been proposed to have trigonal bipyramidal and octahedral geometries. In vitro activities of the Schiff bases and their metal complexes against some Gram positive and Gram negative bacteria and fungi have been carried out and described.     

Titanium(IV) and zirconium(IV) derivatives of tetradentate schiff bases

Summary Titanium and zirconium isopropoxides react with the tetradentate Schiff bases, I)is-salicylaldehyde-o-phenylenediimine (SBH₂ ) and bis-salicylaldehyde-p-phenylencdiimine (SBH₂) in anhydrous benzene in 1: 1 and 1 :2 molar ratios to give almost quantitative yields of M(OPr-i)₂ (SB) and M(OPr-i)2(SB)(SBH), where M = Ti or Zr and [SB]² is the anion of the corresponding Schiff base, SBH₂. The i.r. spectra of the completes have been recorded and tentative assignments for C=N and C-O stretching frequencies made.     

Synthesis,characterization and biological studies of oxovanadium(IV) complexes with triazole‐derived Schiff bases

A series of triazole‐derived Schiff bases (L¹–L⁵) and their oxovanadium(IV) complexes have been synthesized. The chemical structures of Schiff bases were characterized by their analytical (CHN analysis) and spectral (IR, ¹H and ¹³C NMR and mass spectrometry) data, and oxovanadium(IV) complexes were elucidated by their physical (magnetic susceptibility and conductivity), analytical (CHN analysis), conductance measurements and electronic spectral data. The molar conductivity data indicate the oxovanadium(IV) complexes to be non‐electrolyte. The Schiff bases act as bidentate and coordinate with the oxovanadium(IV)‐forming stoichiometry of a complex as [M (L‐H)₂] where M = VO and L = L¹–L⁵ in a square‐pyramidal geometry. The agar well diffusion method was used for in vitro antibacterial screening against E. coli, S. flexenari, P. aeruginosa, S. typhi, S. aureus and B. subtilis and for antifungal activity against T. longifucus, C. albican, A. flavus, M. canis, F. solani and C. glaberata. The biological activity data show the oxovanadium(IV) complexes to be more antibacterial and antifungal than the parent Schiff bases against one or more bacterial and fungal strains. Copyright © 2009 John Wiley & Sons, Ltd.     

Schiff base supported mononuclear organotin(IV) complexes: Syntheses,structures and fluorescence cell imaging

Three mononuclear organotin(IV) complexes supported by Schiff bases have been synthesized. The complexes [(C₆H₅)₂Sn(L)] ( 1 ), [(t‐Bu)₂Sn(L)] ( 2 ) and [(t‐Bu)₂Sn(L')] ( 3 ) (L, L' = deprotonated Schiff bases) were obtained in good yield by the reaction of Schiff bases H ₂ L or H ₂ L′ with corresponding diorganotin dichlorides respectively. All newly synthesized complexes were characterized by means of FT‐IR spectroscopy, elemental analysis and multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR spectroscopy. In addition, single crystal X‐ray diffraction analyses were employed to establish the solid state molecular structures of these complexes. The structures of 1 – 3 reveal that all complexes are mononuclear with a five‐coordinated tin(IV) centre in it. The absorption and emission properties of all complexes have been investigated. Moreover, cytotoxicity and fluorescence cell imaging studies of theses complexes have been performed.     

Synthesis,electrochemical and antimicrobial studies of mono and binuclear iron(III) and oxovanadium(IV) complexes of [ONO] donor tridentate Schiff-base ligands

Tridentate Schiff bases (H₂L¹ or H₂L²) were derived from condensation of acetylacetone and 2-aminophenol or 2-aminobenzoic acid. Binuclear square pyramidal complexes of the type [M₂(L¹)₂]?·?nH₂O (M?=?Fe–Cl, n?=?0; M?=?VO, n?=?1) were accessed from interaction of H₂L¹ with anhydrous FeCl₃ and VOSO₄?·?5H₂O, respectively. A similar reaction with H₂L², however, produced mononuclear complexes [ML²(H₂O) _x ]?·?nH₂O (M=Fe–Cl, x?=?0, n?=?0; M=VO, x?=?1, n?=?1). The compounds were characterized using elemental analysis, FT-IR, UV-Vis, and NMR (for ligand only), and mass spectroscopies and solution electrical conductivity studies. Magnetic susceptibility measurements suggest antiferromagnetic exchange in binuclear Fe(III) and VO(IV) complexes. Thermo gravimetric analysis (TGA) provided unambiguous evidence for the presence of coordinated as well as lattice water in [VOL²(H₂O)]?·?H₂O. Cyclic voltammetric studies showed well-defined redox processes corresponding to Fe(III)/Fe(II) and VO(V)/VO(IV). In vitro antimicrobial activities of the compounds were investigated against Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeroginosa, Escherichia coli, Bacillus subtilis, and Proteus vulgaris. H₂L¹ and its binuclear complexes exhibited pronounced activity against all the microorganisms tested.     

Oxo-tricyano complexes of molybdenum(IV) and tungsten(IV) with bidentate Schiff bases

Summary The reaction of [M(CN)₄O(OH₂)]^2– (M = Mo or W) with 2-acetylpyridine and methyl-or butyl-amine in a water-MeOH mixture gave [M(CN)₃O(L-L)]^- (L-L= Schiff base ligand), isolated as [AsPh₄]⁺ salts. The complexes have been characterized by elemental analysis, and electronic, i.r. and¹H-n.m.r. spectroscopy. The Schiff base ligands complex in a bidentate manner through the two nitrogen atoms giving mixed-ligand compounds similarly to 2,2-bipyridyl or 1,10-phenanthroline.On leave from the Faculty of Chemistry, Jagiellonian University, Kraków.     

Hafnium(IV) complexes with Schiff bases

Summary Hafnium(IV) complexes have been prepared by the reactions of hafnium(IV) isopropoxide isopropanol with Schiff bases [bis(salicylaldehyde)hydrazine] (Sal-AH₂), (bis(o-hydroxyacetophenone)hydrazine] (Acp-AH₂), [bis(resacetophenone)hydrazine] (Res-AH₂), [bis(salicylaldehyde)ethylenediimine) (SaleneH₂), [bis(o-hydroxyacetophenone)ethylenediimine] (AcpeneH₂) and [bis(salicylaldehyde)o-phenylenediimine] (SalpheneH₂) (derived from salicylaldehyde,o-hydroxyacetophenone, resacetophenone and diamines) in appropriate molar ratios using benzene as solvent. The complexes [Hf(OPr-i)₂(SB)] and [Hf(SB)₂] (where SB^2– represents the dianion of the Schiff base) are reported. The complexes of Sal-A, Acp-A and Res-A are 5-and 6-coordinate while those of salene, acpene and salphene are 6-and 8-coordinate. The Schiff bases draw on Sal-A, Acp-A and Res-A are tridentate and salene, acpene and salphene are tetradentate. The mode of bonding through nitrogen and oxygen and the stereochemistry of the complexes are discussed in relation to the elemental analyses and spectra (electronic, infrared and nuclear magnetic resonance).     

Syntheses of new oxovanadium(IV) complexes with some new Schiff bases derived from salicylaldehyde or substituted salicylaldehyde and 3-aminothiophenol

Summary The syntheses of several new oxovanadium(IV) complexes of new Schiff bases derived from Salicylaldehyde, 5-ch orosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 4-methoxysalicylaldehyde, 2-hydroxy-l-naphthaldehyde and 3-aminothiophenol are described. The complexes, which are of the VOL₂ type, have been characterized on the basis of elemental analysis, i.r. and electronic absorption spectra, and magnetic susceptibility measurements. The Schiff bases behave as bidentate ligands and a five-coordinate square-pyramidal structure is suggested for the complexes which exhibit two or three spin-allowed d-d bands atca. 12000, 17000 and 22000 cm^–1. The v(V=0) vibration occurs in the 940–980 cm^–1. range. The complexes exhibit normal magnetic moments (µ_eff = 1.71-1.73 B.M.) at room temperature.     

Adducts of tellurium and organotellurium(IV) chlorides with transition metal chelates of tetradentate schiff bases

Summary Coordinative interaction between tellurium tetrachloride or aryltellurium trichloride and transition metal chelates of tetradentate Schiff bases has yielded bimetallic molecular adducts of the general formula R_nTeCl_4–n · ML [n = 0 or 1, R = Ph,p-MeOC₆H₄ orp-EtOC₆H₄, M = nickel(II) or copper(II) and L^2– dianion of the Schiff bases derived from salicylaldehyde oro-hydroxyacetophenone and ethylenediamine]. The i.r. spectral and magnetic measurements on the complexes in the solid state indicate coordination of the metal chelates to tellurium(IV)via two phenolic oxygens. Planarity about the transition metal ion is thus retained.     

Synthesis and characterization of di- and triorganotin(IV) complexes of 2-tert-butyl-4-methyl phenol

The di- and trialkyltin(IV) complexes of composition R₂SnCl_2−x (OAr), and n-Bu₃Sn(OAr) (R = n-Bu and Me; x = 1 and 2; OAr = OC₆H₃Bu ^t -2-Me-4) have been synthesized by the reactions of di-n-butyl and dimethyltin dichlorides and tri-n-butyltin(IV) chloride with 2-tert-butyl-4-methylphenol and triethylamine in tetrahydrofuran. The reaction of triphenyltin chloride with trimethylsilyl-2-t-butyl-4-methylphenoxide in the same solvent however, gives a complex of composition Ph₃Sn(OAr). The complexes have been characterized by microanalyses, molar conductance measurements, molecular weight determinations and IR and ¹H, ¹³C and ¹¹⁹Sn NMR and mass spectral studies. Thermal behaviour of the complexes has been studied by TGA and DTA techniques. From the non-isothermal TG data, the kinetic and thermodynamic parameters have been calculated employing Coats-Redfern equation and the mechanism of decomposition has been computed using non-isothermal kinetic method. Thermal investigations on the blends of poly(methylmethacrylate). PMMA, with organotin(IV)-2-tert-butyl-4-methylphenoxides have shown increased thermal stability compared to pure PMMA suggesting thereby their potential as additives towards PMMA.     

Ruthenium(II) unsymmetrical N2O2 tetradentate Schiff-base complexes: synthesis,characterization, and catalytic studies

A series of six-coordinate ruthenium(II) complexes [Ru(CO)(L ^x )(B)] (B = PPh₃, AsPh₃ or Py; L ^x = unsymmetrical tetradentate Schiff base, x = 5–8; L⁵= salen-2-hyna, L⁶= Cl-salen-2-hyna, L⁷= valen-2-hyna, L⁸= o-hyac-2-hyna) have been prepared by reacting [RuHCl(CO)(EPh₃)₂(B)] (E = P or As) with unsymmetrical Schiff bases in benzene under reflux. The new complexes have been characterized by analytical and spectroscopic (infrared, electronic, ¹H, ³¹P, and ¹³C NMR) data. An octahedral structure has been assigned for all the complexes. The new complexes are efficient catalysts for the transfer hydrogenation of ketones and also exhibit catalytic activity for the carbon–carbon coupling reactions.     

Synthesis and spectroscopic studies of homo- and heteroleptic N-arylsalicylaldiminates of titanium(IV), zirconium(IV) and chromium(III)

Homo- and heteroleptic N-arylsalicylaldiminate derivatives of Ti^IV and Zr^IV of the type, MX_4–x (OC₆H₄CH=NAr) _x (X = OPrⁱ, x = 2,3; X = Cl, x = 1,2,3,4; Ar = C₆H₃Me₂-2,6, C₆H₃Et₂-2,6) have been prepared by reactions in the desired molar ratios of: (i) Ti(OPrⁱ)₄/Zr(OPrⁱ)₄·PrⁱOH with N-arylsalicylaldimines in benzene, and (ii) MCl₄ (M = Ti, Zr) with Me₃SiOC₆H₄CH=NAr or HOC₆H₄CH=NAr in the presence of Et₃N as a base or the potassium salt of N-arylsalicylaldimines in benzene. The three homoleptic derivatives of Cr^III, Cr(OC₆H₄CH=NAr)₃ (Ar = C₆H₂Me₃-2,4,6, C₆H₃Et₂-2,6, C₆H₃Prⁱ ₂-2,6) have also been prepared by salt-elimination. All of these new derivatives have been characterized by elemental analyses, spectroscopic [i.r., ¹H and ¹³C-n.m.r. (Ti and Zr complexes), and electronic (for Cr complexes)] studies, as well as molecular weight measurements.     

Synthesis and spectral studies of copper(II), nickel(II), cobalt(II) and vanadyl(II) complexes of tridentate Schiff bases of 1,2,3,5,6,7,8,8a-octahydro-3-oxo-N,1-diphenyl-5-(phenylmethylene)-2-naphthalenecarboxamide

Summary Metal(II) chelates of Schiff bases derived from the condensation of 1,2,3,5,6,7,8,8a-octahydro-3-oxo-N,1-diphenyl-5-(phenylmethylene)-2-naphthalenecarboxamide with o-aminophenol (KAAP), o-aminothiophenol (KAAT) or o-aminobenzoic acid (KAAB) have been prepared and characterized. The complexes are of the type [M(N₂X)]₂ for M = Cu^II and M(NX)₂·nH₂O for M = Ni^II, Co^II and VO^II (X = phenolic oxygen, thiophenolic sulphur or carboxylic oxygen; n = 0 or 2). Conductivity data indicate that the complexes are non-ionic. The Schiff bases behave as dibasic tridentate ligands in their copper(II) complexes and as monobasic bidentate ligands in their nickel(II), cobalt(II) and vanadyl(II) complexes. The subnormal magnetic moments of the copper(II) complexes are ascribed to an antiferromagnetic exchange interaction arising from dimerization. Nickel(II) and cobalt(II) complexes are trans octahedral whereas vanadyl(II) complexes are square pyramidal     

Zur chemie des tris(cyclopentadienyl)uran(IV)-kations in wässriger lösung : II. Oligomere metallorganische tetracyanometallat-komplexe des uran(IV): Bis(tris(pentahapto-cyclopentadienyl)uran(IV))-tetracyanonickolat(II) bzw. -platinat(II)

Novel organometallic uranium(IV) complexes of the composition [(η⁵-Cp)₃U^IV]₂[Mn^II(CN)₄] Cp = C₅H₅, M = Ni or Pt) have been prepared from Cp₃UCl and K₂[M(CN)₄] in aqueous solution. On the basis of their properties they are characterized as layered oligomeric structures involving squared arrays of both the U and M atoms within the same plane, and a presumably trigonal bipyramidal coordination of the uranium(IV) ion.     

Studies in nickel(IV) chemistry. Kinetics of electron transfer from dimethyl sulfoxide to oxohydroxonickel(IV) in aqueous acid medium

The kinetics of decomposition of “oxohydroxonickel(IV)” [Ni(IV)] with concomitant intramolecular electron transfer to produce hexaaquanickel(II) and dioxygen in aqueous acid solutions show pseudo-first-order dissappearance of the Ni(IV). The pseudo-first-order rate constants for the acid decomposition (k_ad) satisfy where K_MH and k_d refer to the equilibrium protonation constant and the decomposition constant of the protonated species of the Ni(IV) respectively. The values of K_MH and k_d in aqueous medium at 45°C and μ = 2.0M are 25.5 ± 1M^?1 and (1.7 ± 0.1) × 10^?5 s^?1, respectively. The kinetics of the intermolecular electron transfer from dimethyl sulfoxide (DMSO) to the Ni(IV), producing Ni(H₂O)₆²⁺ and dimethyl sulfone as products, have been investigated by monitoring the formation of Ni(H₂O)₆²⁺. The pseudo-first-order rate constants for the electron transfer k_obs are linearly dependent on [DMSO]₀ or [H⁺], attaining limiting values at higher relative [DMSO]₀ or [H⁺], in accordance with where K_1c and K_2c represent the formation constants of the precursors involving DMSO and the unprotonated and one-protonated Ni(IV) species, respectively, and k_1x and k_2x are the corresponding decomposition rate constants of the precursors. The values of K_2c and k_2x are (2.3 ± 0.1) × 10⁴M^?1 and 19 ± 1 s^?1, respectively, at 45°C and μ = 1.0M. Results are interpreted in terms of probable mechanisms involving (1) a rate-determining decomposition of the protonated Ni(IV) followed by rapid product formation steps, and (2) precursor complex formation between DMSO and the unprotonated or the protonated species of the Ni(IV) followed by rate-determining decomposition with electron transfer.     

Differential pulse polarographic determination of some organotin(IV) compounds in dimethyl sulfoxide

The differential pulse polarographic behavior of two series of organotin(IV) compounds having the general formula R_xSnCl_{4 − x} (R = Me, Ph; x = 1, 2, 3, 4) has been investigated in DMSO. The peaks obtained are recommended for the trace determination of these compounds. Linear calibration curves are obtained over the concentration range 10⁻⁴ –10⁻⁶ M.     

Oxovanadium(IV) Complexes of tetradentate SCHIFF Bases

The oxovanadium(IV) complexes of the Schiff bases derived from 1,3-diamino-propane-2-ol and salicylaldehyde, 3-aldehydosalicylic acid, 5-chloro-salicylaldehyde, acetyl acetone, and also of the Schiff base derived from 1.3-diaminopropane and salicylaldehyde have been isolated in the pure state and characterized. The structure of these complexes is discussed on the basis of elemental analyses, electronic spectra and magnetic moment values. These complexes are characterized as five co-ordinate compounds having the general formula [VO](L), where, LH₂ = a molecule of dibasic, tetradentate Schiff base. Electronic spectra of the complexes are found to be solvent independent. The compounds are paramagnetic (μ_eff. = 1.76–1.79 B. M.), and are very stable in air.