B. V. Agarwala

Physicochemical studies of (o-vanillin thiosemicarbazonato)-nickel(ii) chelate

SummaryFive- and six-membered rings result from the chelation of nickel(II) by the dibasic tridentate Schiff base ligand, o-vanillin thiosemicarbazone(o-VTSC), a new chelate prepared and characterized. The structural results are discussed in the light of spectroscopic and other data.

Coordinative Capabilities of Acido Anions in Metal Complexes of Isatin and Vanillin Derivatives

Abstract The synthesis and characterization of two Schiff base hydrazone ligands isatin isonicotinic acid hydrazone (HIINH) and vanillin isonicotinic acid hydrazone (VINH) and their metal complexes with various salts of Cu(II) and Ni(II) are reported. The complexes have the compositions [M(IINH)X] or [M(VINH)2X2], where X=C1, NO3 or ½SO4, which contain 4- or 6-coordinated metals. The complexation of the former ligand occurs in the deprotonated diol form of the ligand, via the azomethine nitrogen and the carbonyl oxygen. All complexes were characterized by elemental analysis, m. p., molar conductance measurements and infrared and electronic spectral data.

Stereochemical changes in anisaldehyde thiosemicarbazone complexes

SummaryIsolation of coloured metal complexes of anisaldehyde thiosemicarbazone (HATSC) and anisaldehyde-4-phenylthiosemicarbazone (HAPTSC) of general formula [M(ATSC)2] and [M(APTSC)2]·2H2O are described. The room-temperature magnetic moment, i.r. and u.v. spectra, ligand field parameters and thermal characteristics are reported. The complexation occurs through deportonated thiol form of thiosemicarbazone and its azomethine nitrogen to yield 4- and 6-coordinate complexes.

New Octahedral Complexes of Schiff Bases Derived from 2,3-Indolinedione

Abstract Three Schiff bases derived from 2,3-indolinedione (isatin) viz. isatinsemicarbazone (iscH), isatin thiosemicarbazone (itscH) and isatin-4-phenylthiosemi-carbazone (iptscH) were prepared. All the ligands are tridentate (ONO-, ONS-donor). The metal(II) complexes formed with Co, Ni, Cu, Zn and Cd, in 1:2 stoichio-metric ratio are octahedral and do not contain water molecules. From the results of chemical analysis, magnetic susceptibility measurements employing varying currents, ir, diffuse reflectance spectral and thermal studies, the coordinating properties of the ligands and structures of the complexes have been discussed.

Spectrophotometric determination of vanadium and niobium: Xylenol orange as a chromogenic reagent

SummaryThe formation of red coloured chelates of vanadium(V) and niobium(V) with xylenol orange (DCAC) having λmax at 490 nm (at pH 5.0) and 530 nm (at pH 5.5) have been reported. The colour formation has been applied to the spectrophotometric determination of metal ions. The colour has been found to be stable between pH 3.5–6.5 and 2.0–7.0 respectively. The sensitivity of the reagent is 0.051μg/cm2 of vanadium and 0.093μg/cm2 of niobium. Maximum colour intensity has been found for Nb-DCAC chelate at pH 5.5 whereas no appreciable change has been found for V-DCAC chelate between pH 4.5 and 6.5.ZusammenfassungÜber die Bildung rot gefärbter Chelate von Vanadin und Niob mit Xylenolorange wurde berichtet. Deren Absorptionsmaxima liegen bei 490 nm (pH 5,0) bzw. bei 530 nm (pH 5,5). Die Farbreaktion wurde für die Bestimmung der beiden Metalle verwendet. Die Farbe ist zwischen pH 3,5 und 6,5 bzw. zwischen pH 2,0 und 7,0 stabil. Die Empfindlichkeit für Vanadin beträgt 0,051μg/cm2, für Niob 0,093μg/cm2. Die Farbe des Niobchelates erreicht bei pH 5,5 ein Maximum, während die des Vanadinchelates zwischen pH 4,5 und 6,5 keine wesentlichen Änderungen erkennen läßt.

Condensation polymerization of bis-(salicylaldehydo) metal(II) with diamines

SummaryCondensation of bis-(salicylaldehydo) metal (II) (metal = Be, Zn and Cd) and diamines (1,4-diaminobenzene or 4,4-diaminodiphenyl) yield polymeric complexes which have been investigated for their characteristics, composition, structure, thermal stability and polymeric nature. The stable, powdery solids obtained by refluxing 1∶1 bis-(salicylaldehydo) metal-chelate (in DMF) and the diamine (ethanolic) have the composition (-ML-)n and are insoluble in common organic solvents. I.R. study indicates that salicylaldehyde molecule is bonded to the metal ion through the oxygen atoms of phenolic and aldehydic groups in bis-(salicylaldehydo) metal-chelates. On interaction with the diamines, the polymeric complexes are formed, the nitrogen atoms of the amino groups replacing the aldehydic oxygens. The terminal nitrogens of the diamine, bridge two bis-(salicylaldehydo) metal-chelates, and the polymeric chain grows in a similar manner. The complexes obtained from 4, 4″-diaminodiphenyl are thermally more stable than those from 1,4-diaminobenzene. The order of thermal stability of the polymers is : Be ∽ Zn>Cd.

Spectrophotometric determination of palladium with 4-(2-pyridylazo)-resorcinol (PAR)

SummaryA spectrophotometric method for the determination of palladium is described using 4-(2-pyridylazo)-resorcinol as reagent. The method involves the formation of two red coloured chelates of palladium-PAR at pH 4.0 and 10.5 respectively. The colour reactions have sensitivity of 0.0085μg cm−2 and 0.0071μg cm−2 for logI0/I= 0.001. The effects of pH, time, order of addition of reagents, temperature etc. have been investigated. The composition of the complexes (metal∶reagent) have been confirmed by two methods as 1∶1 (at pH 4.0) and 3∶2 (at pH 10.5).ZusammenfassungEine spektrophotometrische Methode zur Palladiumbestimmung mit PAR [4-(2-Pyridylazo)-resorcin] wurde beschrieben. Zwei rotgefärbte Chelate werden bei pH 4,0 bzw. 10,5 gebildet. Die Empfindlichkeit der beiden Reaktionen beträgt 0,0085 bzw. 0,0071μg · cm−2. Der Einfluß von pH, Zeit, Reihenfolge der Reagenzien, Temperatur usw. wurde untersucht. Die Zusammensetzung der Komplexe entspricht dem Molverhältnis Pd: Reagens= =1∶1 bei pH 4,0 bzw. 3∶2 bei pH 10,5.

4-(2-Pyridylazo) resorcinol as a sensitive reagent for vanadium, niobium, and tantalum

Abstract The formation of red colored chelates between vanadium, niobium and tantalum with 4-(2-pyridylazo)resorcinol (PAR) has been reported. The λmax of the chelates are respectively 550 mμ (ph 5.0); 540 mμ (pH 6.0) and 500 mμ (pH 6.0). Adherence to Beers law is observed over a wide range of metal concentrations, the color intensities are also stable within a wide range of pH particularly in case of Nb-PAR chelate. The reagent is highly sensitive specially for vanadium. The effect of various conditions like pH, time, order of the addition of the reactants and interference due to various ions have been studied.

Spectral Studies of Some Pyridine and Bipyridine Complexes of Platinum(II)

Abstract The increasing importance of complexes of platunum(II) owing to their potential use as antitumour drugs has aroused interest1. Coordination compounds formed by nitrogen donor ligands have been found to be significant in this context. Some of the important cis-platinammine active antitumour drugs bind covalently to DNA under specific conditions, whereas the inactive trans-compound does not. Spectral studies of dichloro (2, 2′-bipyridine) platinum(II)2, cis- and trans-dichloro (dipyridine)platinum(II)3 have been undertaken anticipating that these platinum(II) compounds in coordination with a base would provide additional evidence on the electronic configuration of such complexes. cis-Pt(py)2cl2 has recently been found to be of biochemical importance and its antitumour and antimitogenic properties have been reported4–6. It is less toxic to mice and increases the survival time of mice affected by tumour. Pfeffer7 has studied the i.r. and Raman spectra of cis- and trans-Pt(py)2cl2 and coordinate bonding

ESR and magnetic properties of coppet(II)-hydroxycarboxylic acid complexes

Abstract Hydroxycarboxylatocopper(II) complexes of the type Cu(oca)2, (Cu(m-ca)2 and Cu(hna)2 [o-ca = o-cresotic acid, m-ca = m-cresotic acid, hna = 2-hydroxy-3-naphthoic acid] systhsized in aqueous and alcoholic medium were studied by ESR and magnetic susceptibility measurements. The ESR spectra of 0-ca complexes show three lines and anomalous low magnetic moment values are observed at varying temperature (295-85 K). The results indicate a binuclear bridged structure with exchange interaction between Cu2+ pairs. m-ca Complexes are magnetically dilute and μeff values are nearly temperature independent including those of hna complexes. ESR parameters g∥, g⊥, gav and D have also been calculated.