C.L. Yadava

STructural information on manganese(II), cobalt(II), nickeL(II), zinC(II) and cadmium(II) sulphate complexes with hexamethylenetetramine (a potentially tetradentate ligand) from their magnetic moments, electronic and infrared spectra

Abstract Coordination compounds formed by the interaction of hexamethylenetetramine (Hmta), a potentially tetradentate ligand, with manganese(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) sulphates have been prepared and characterized from their elemental analyses, magnetic susceptibilities and electronic and infrared spectral studies down to 200 cm −1 in the solid state. The compounds isolated are: Mn(Hmta)SO 4 , Co(Hmta)SO 4 , Ni(Hmta)SO 4 , Zn(Hmta)SO 4 , and Cd(Hmta)SO 4 . It is shown that Hmta, though a potentially tetradentate ligand, acts only as a bidentate ligand bridging between two metal ions retaining the chair configuration of the uncoordinated molecule in all these complexes. Tentative stereochemistries of the complexes in the solid state are discussed. The ligand field parameters 10 Dq , B ,β and λ calculated for the manganese(II), cobalt(II) and nickel(II) complexes are consistent with their proposed stereochemistries.

Hexamethylenetetramine complexes with manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) thiocyanates

Abstract Coordination compounds formed by the interaction of hexamethylenetetramine (Hmta), a potentially tetradentate ligand, with Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) thiocyanates have been prepared and characterized from their elemental analyses, magnetic susceptibilities, electronic and i.r. spectral studies down to 200 cm−1 as well as X-ray powder diffraction patterns in the solid state. The compounds isolated are: Mn(NCS)2(Hmta)2(EtOH)2, Mn(NCS)2(Hmta)2, Co(NCS)2(Hmta)2(EtOH)2, Co(NCS)2(Hmta)2, Ni(NCS)2(Hmta)2(EtOH)2, Ni(NCS)2(Hmta)2, Cu(NCS)2(Hmta)2, Zn(NCS)2(Hmta)2 and Cd(NCS)2(Hmta). It is shown that Hmta, though a potentially tetradentate ligand, acts only as a terminally bonded monodentate ligand or a bidentate ligand bridging between two metal atoms retaining the chair configuration of the uncoordinated molecule in all these complexes. The tentative stereochemistries of the complexes are discussed. The ligand field parameters 10 Dq, B, β, λ and ν2/ν1 calculated for the cobalt, nickel and copper complexes are consistent with their proposed stereochemistries.

Coordination polymers of cobalt (II) involving 4,4'-bipyridyl and its dioxide

SummaryAnalytical data, room temperature magnetic moment values, electronic and i.r. spectral measurements down to 200 cm−1 on the coordination compounds formed by the interaction of cobalt(II) chloride, bromide, thiocyanate, acetate and nitrate with 4,4′-bipyridyl and 4,4′-bipyridylN,N′-dioxide indicate that the isolated compounds are coordination polymers having tetrahedral or octahedral stereochemistry around cobalt(II) involving bridging 4,4′-bipyridyl/4,4′-bipyridylN,N′-dioxide molecules. Terminally bonded acetato- and nitrato-ligands and bridging or terminally bonded chloro-, bromo- and thiocyanato-groups in the solid state.

Electron spin resonance and optical absorption spectral studies on some manganese(II) complexes with 2,2′-bipyridyl, 4,4′-bipyridyl and their dioxides

Abstract Coordination compounds formed by the interaction of manganese(II) chloride, thiocyanate, acetate and sulphate with 2,2′-bipyridyl (2,2′-Bipy), 4,4′-bipyridyl (4,4′-Bipy) and their dioxides have been characterized by electron spin resonance and optical absorption spectral studies in solid and solution states to determine the spin-Hamiltonian constant for manganese(II), metal-ligand bond parameters and the tentative environments around manganese(II). The metal-ligand σ,-bond in the compounds studied herein in formamide solution is found to be moderately covalent. The compounds seem to have an essentially axial symmetry with g-value close to 2.0. The magnetic moments, electronic and photoacoustic spectra of these complexes are also recorded and interpreted in the solid state.

Some Neutral Three-Coordinate Complexes of Mercury(II)

Abstract The preparation of 1:2 and 1:1 mercury(II) chloride and bromide complexes with 2- and 4- cyanoanilines is described. These compounds are freely soluble in ethanol in which they behave as non-electrolytes. Molecular weight measurements in molten camphor indicate the 1:1 complexes as monomeric structures. Based on molar conductance values, molecular weight determinations and infrared spectral features down to 200 cm−1, the 1:2 (metal:ligand) complexes are considered as neutral 4-coordinated tetrahedral structures while the 1:1 complexes appear to be neutral species having monomeric, three-coordinated environments around mercury(II).

Synthesis and Characterization of Bis(2-Pyridyl-N-Oxide)Disulphide Complexes with Some Uranyl Salts

Abstract Coordination compounds formed by uranyl chloride, thiocyanate, nitrate, sulphate and acetate with bis(2-pyridyl-N-oxide)di-sulphide have been prepared and characterized on the basis of analytical data, molar conductance, electronic and infrared spectral measurements down to 200 om−1. Bis(2-pyridyl-N-oride)disulphide acts as a bidentate ligand through its oxygen atoms resulting in 9-membered rings. Coordination numbers and stereochemical environments around uranium(VI) are proposed.

4-Cyanoaniline complexes with transition metal(II) halides

SummaryCoordination compounds formed by the interaction of manganese(II), cobalt(II), nickel(II) and copper(II) chloride and bromide with 4-cyanoaniline (4-CA) have been prepared and characterized by molar conductance, magnetic susceptibilities, electronic and i.r. spectral measurements down to 200 cm−1 in the solid state. The isolated complexes are M(4-CA)2X2 except for nickel(II) bromide which is NI(4-CA)4Br2. I.r. spectra, indicate that 4-CA, though a potentially bidentate ligand, nevertheless acts only as a terminally aniline (NH2) bonded monodentate ligand in all the complexes. Tentative stereochemistries of the complexes have been suggested in the solid state.

Neutral Three-Coordinate Complexes of Mercury(II) Involving Coordinated Thiocyanato Groups

Abstract The preparation of 1:1 (metal:ligand) complexes of mercury(II) thiocyanate with several substituted pyridines — 4-benzyl-pyridine, 3- and 4- benzoylpyridines, nicotinamide and N-methyl-nicotinamide — is described. All the complexes are soluble in dimethylformamide or methanol in which they behave as non-electrolytes. Based on molar conductance values and infrared spectral features down to 200 cm−1, the complexes described herein are considered as neutral species exhibiting coordination number three around mercury(II) in the solid state.

Some neutral three-coordinate complexes of mercury(II) halides and pseudohalides with N-methylnicotinamide

Coordination compounds of mercury(II) chloride, bromide, cyanide and thiocyanate with N-methylnicotinamide, a potentially bidentate ligand, have been prepared. The complexesisolated have 1∶1 (metal:ligand)stoichiometry. Molecular weight measurements in molten camphor indicate that the mercury (II) chloride and bromide complexes are monomeric. Based on conductance values, molecular weight determinations and infrared spectral data, it is inferred that in the solid state in all these complexes the metal ion has a coordination number three and is bonded to the N-methylnicotinamide via its pyridine ring nitrogen, and is terminally bonded to the halogen/pseudohalogens.

Some Tetrahedral Coordination Polymers of Zinc(II), Cadmium(II), and Mercury(II) Involving 4-Aminomethylpyridine

Abstract Analytical data and infrared spectral measurements down to 200 cm−1 on the 1:1 compounds formed by the interaction of zinc(II) and cadmium(II) thiocyanates and mercury(II) chloride and bromide with 4-aminomethylpyridine indicate that the compounds are coordination polymers having tetrahedral stereochemistry with bidentate bridging 4-aminomethylpyridine molecules and terminally bonded halogen/pseudohalogen groups in the solid state.