Baldev Singh Manhas

Spectral and magnetic studies on normal cobalt(II) planar and cobalt(III) octahedral, spin-crossover cobalt(III) octahedral and planar-tetrahedral cobalt(II) carbodithioates

Abstract Five cobalt(II) complexes, a normal complex Co(4-PPipzcdt) 2 (4-PPipzcdt = 4-phenylpiperazine-1-carbodithioate), and four zwitterionic complexes, Co(4-PPipzcdtH) 2 X 2 and Co(4-MPipzcdtH) 2 X 2 (X = Cl, Br; 4-PPipzcdtH = 4-phenylpiperazine-1-carbodithioic acid, 4-MPipzcdtH = 4-methylpiperazine-1-carbodithioic acid), have been synthesized. Normal cobalt(III) complexes of the type Co(4-MPipzcdt) 3 and Co 2 {2-MPipz(cdt) 2 } 3 (2-MPipz(cdt) 2 = 2-methylpiperazine-1,4-dicarbodithioate) and two zwitterionic cobalt(III) complexes of the type Co(4-MPipzcdtH) 3 X 3 (X = Cl, Br) have also been obtained. In addition to the room temperature IR and electronic spectra and magnetic susceptibility studies, all the complexes, except the normal Co(4-MPipzcdt) 3 and Co(4-PPipzcdt) 2 and zwitterionic Co(4-MPipzcdtH) 3 Cl 3 , have been investigated by variable-temperature magnetic susceptibility measurements. The results of the variable-temperature magnetic susceptibility studies suggest that two cobalt(II) carbodithioates exhibit a square planar-tetrahedral equilibrium, while two cobalt(III) octahedral carbodithioates show a spin-crossover phenomenon.

Infrared spectral, variable-temperature magnetic susceptibility and Mössbauer spectral investigations on tris(carbodithioato) iron(III) complexes

Two types of iron(III) carbodithioate complexes, (i) normal complexes, Fe(R2NCS2)3 with R2N = 4-methyl-, 4-phenyl-, or 2-methyl-piperazyl, piperidyl and thiomorpholyl and (ii) zwitterionic complexes, Fe(R2NCS2H)3X3 with R2N = 4-methyl- or 4-phenyl-piperazyl and X = Cl or Br have been synthesized. The complexes have been characterized by elemental analyses, IR spectral studies, variable-temperature magnetic susceptibility and in three cases by variable-temperature Mossbauer spectral studies. All the complexes exhibit the 2T2 (low spin, S = 12) ⇌6 A1 (high spin, S = 52) spin equilibrium process. The zwitterionic carbodithioate ligands have a weaker ligand field strength than their normal ligand analogues.

Synthesis and characterization of uranium(iv) compounds with piperazines

Abstract Compounds of the empirical formula [UX 4 · n (L)· m THF] (where X = thiocyanate, perchlorate, bromide and iodide; n = 1-3; L = piperazine, 1-methyl-, 2-methyl-, 1-phenyl-, 1,4-dimethyl-, 2,5-dimethyl- and 2,6-dimethylpiperazine; m = 0 and 1) have been prepared and characterized by physical studies. IR spectra indicate the mode of coordination. Electronic spectral and variable-temperature magnetic data have been employed to ascertain the stereochemical environment of uranium. Except for the perchlorate compounds, which are 1:1 electrolytes, all other compounds are non-electrlytes.

Complexes of thorium tetranitrate with N-methylpiperazine, 2-methylpiperazine, N-phenylpiperazine and N, N′-dimethylpiperazine

Abstract Complexes of Th(NO 3 ) 4 with the title ligands have been synthesised and characterised on the basis of elemental analyses and IR spectral studies which indicate that the ligands in the complexes are in chair conformation and the nitrate group is bidentate. Coordination number is higher than ten in all the complexes.

Complexes of lanthanum(III) and cerium(III) with substituted piperazines

Abstract Complexes of LaCl 3 , CeCl 3 , La(NO 3 ) 3 and Ce(NO 3 ) 3 have been synthesized with N-methylpiperazine, 2-methylpiperazine, N-phenyl-piperazine and N,N′-dimethylpiperazine. These complexes, which are hygroscopic, were stored in vacuum-sealed ampoules and were prepared and handled in a dry bag. The complexes were characterized on the basis of elemental analyses, IR, electronic spectral data and magnetic susceptibility data. IR spectral data indicate that ligands probably coordinate in the chair form giving bridged polymeric complexes. The polymeric nature of the complexes is also suggested by the insolubility of the complexes in common organic solvents. It is possible that the coordination number of the lanthanide ion varies from six to nine in these complexes. An attempt has been made to assigny v (M-O) (in nitrate complexes) and v (M-N). The bidentate and monodentate nature of the coordinated nitrate ion is also discussed.

Substituent Effect on Carbodithioate Ligand Field Strength in Iron(III) Carbodithioates: Synthesis and Characterization

Abstract New iron(III) carbodithioate complexes of the general formulae Fe(Lcdt)3 [(where L is the anion of an heterocyclic amine and Lcdt are the following anions: 4-methylpiperazine-l-carbodithioate (4-MPipzcdt), 4-phenylpiperazine-l-carbodithioate (4-PPipzcdt), piperidinecarbodithioate (Pipdcdt), 2-methylpiperidine-carbodithioate (2-MPipdcdt), 4-methylpiperidine carbodithioate (4-MPipdcdt), morpholinecarbodithioate (Morphcdt), 2,6-dimethylmorpholinecarbodithioate (2,6-M2Morphcdt), 2,5-dimethylpyrrolecarbodithioate (2,5-M2Pyrrcdt)] and Fe2[2-MPipz(cdt)2]3 [(2-MPipz(cdt)2 = 2-methylpiperazine-l, 4-dicarbodithioate dianion)] have been synthesized. These compounds have been characterized by elemental analyses, infrared spectral and magnetic susceptibility measurements and in some cases by electron paramagnetic resonance studies. The room temperature magnetic moments of the complexes are indicative of a trigonally distorted octahedral geometry around iron(III) observing a 6A1 ↔ 2T2 spin croosover phenomenon. The EPR studies give the gav values 4.4960-4.9962.

Synthesis and Characterisation of Some Uranium(VI) Complexes with Heterocyclic Bases

Abstract The synthesis of forty complexes of uranium(VI) of the general formula UO2X2. nL.mC2H5 OH where X = Br, I, NCS and C104; n = 0.5, 1 and 2; L = piperazine, 1-methylpiperazine, 2-methyl-piperazine, 1-phenylpiperazine, 2,5-dimethylpiperazine, 2,6-dimethylpiperazine, 1,4-dimethylpiperazine, 2-methylpiperidine, 3-methylpiperidine and 4-methylpiperidine and m = 0, 0.5, 1 and 2 is described. Elemental analyses, infrared spectra, molar conductance and thermogravimetric analysis (for some of the complexes only) have been used to characterise the complexes. The infrared spectral data show that the piperazines are coordinated in the chair form in all the complexes thus excluding the possibility of monomoric chelated complexes. The piperidines are coordinated in all the cases. The coordination of various anions and ethanol molecules have been discussed on the basis of infrared spectral studies and molar conductance measurements. Most complexes are insoluble in common organic solvents. They do not melt but de...

COMPLEXES OF URANIUM TETRACHLORIDE AND THORIUM TETRACHLORIDE WITH N‐METHYLPIPERAZINE, 2‐METHYLPIPERAZINE, N‐PHENYLPIPERAZINE, N,N′‐DIMETHYLPIPERAZINE, AND PYRAZINE

Abstract Stable complexes of uranium tetrachloride and thorium tetrachloride with the title ligands have been synthesised and characterised on the basis of elemental analyses, IR and electronic reflectance spectral studies and magnetic susceptibility measurements. The ligands probably coordinate in the chair conformation bridging the metal ions as indicated by IR spectral studies and insolubility of these complexes in common organic solvents. A coordination number of six for uranium (IV) is suggested by the electronic reflectance spectral and magnetic susceptibility data.

Carbodithioates of Oxozirconium(IV) and Dioxourantum(VI) Ions

Abstract New carbudithioate conplexes of the oxozirconium(IV) and dioxouranium(VI) ions of the general formulae MOx(L)2.(H2O)n (NaL = sodium 4-MPipzcdt and sodium 4-PPipzcdt and x = 2 and n = 0 for M = U(VI); NaL = sodium 4-MPipzcdt and x=1 and n = 2 for Zr(IV)) have been prepated and studied by elemental analyses, IR spectral and magnetic susceptibility measurements. The carbcdithiaate ligands, 4-methylpigerazine 1-carbodithioate (4-MPipzcdtH) and 4-phenylpiperazine-1-carbodithioate (4-PPipzcdtH), were derived from saturated heterocyclic secondary amines. The complexes exhibit diamagnetic behaviour.

Magnetic and spectroscopic characterization of copper(II) toluate adducts with substituted piperidines

New copper(II) toluate complexes with saturated monoheterocyclic bases, substituted piperidines, of the type Cu(OOCR)2L (where R = 2‐, 3‐, or 4‐CH3C6H4 and L = 1‐methyl‐, 1‐ethyl‐ or 2,6‐dimethylpiperidine) have been synthesized and characterized by elemental analyses, IR, electronic reflectance and EPR spectral and magnetic susceptibility measurement studies. All of these complexes show antiferromagnetic behaviour. The spin exchange parameter, − 2J, for three of these complexes has been evaluated from EPR measurements at different temperatures, which corresponds to axial binuclear copper(II) complexes with S = 1.