MnBr2 Research Articles

4-Cyanoaniline complexes with transition metal(II) halides

Coordination 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.

ChemInform Abstract: Interaction of Complexes Mn(PPhMe2)Br, and Mn(PEt3)Br2 with Sulfur Dioxide.

AbstractIR‐spektroskopische Untersuchungen bestätigen, daß die Reaktion der Titelkomplexe MnLBr2 (L: PPhMe2, PEt3) mit SO2 jeweils zwei unterschiedliche Produkte ergibt.

The spectral and magnetic properties of some chloro and bromo transition metal complexes of picolinic acid and a study of their performance as colouring materials for poly(vinyl chloride)

Complexes of picolinic acid with the chlorides and bromides of manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) have been prepared. Spectral and magnetic studies have shown that the iron complexes have discrete octahedral structures while the other complexes have polymeric octahedral structures. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis. The performance of the complexes as colouring materials for poly(vinyl chloride) has also been investigated.

SOME FIRST ROW TRANSITION METAL COMPLEXES OF ISONIAZID

Abstract Complexes of the chlorides and bromides of manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) with isoniazid (INH) have been prepared and studied by means of their magnetic susceptibilities, infrared and electronic spectra. All of the complexes have octahedral structures with the exception of the zinc complexes and the chloro- complexes of manganese and iron which are tetrahedral. The chloro- complex of copper is square planar.

Neutral Four-coordinate Tetrahedral Manganese(II) Species Involving Coordinated Chloro- and Thiocyanato-Groups

Abstract Although high-spin and some low-spin octahedrally coordinated anionic and neutral complexes of manganese(I1) are common, tetrahedral coordination manganese(11) is mainly exhibited' in anionic species [MnX4l2-, X =CI, Br, CN, NCO, NCS or NCSe. Whereas manganese(I1) bromide is known to form neutral four-coordinated structures1 MnL, Br, L =Me, NO, C5H5N0, Ph, PO or Ph3As0, four-coordinated tetrahedral manganese(II) complexes as neutral species involving coordinated chloro- and thiocyanato-groups, MnL2X2 (L =a monodentate ligand, and X =C1 or NCS) are rather unknown. We report the isolation of 1 : 2 manganese(I1) chloride and thiocyanate complexes with 4-cyanopyridine N-oxide (4-CPO) which are shown from room temperature magnetic moments, electronic spectral, ligand field parameters and i.r. spectral studies down to 200 cm-' as neutral species exhibiting four-coordinated high-spin, monomeric tetrahedral environments around manganese(II) containing coordinated chloro- and thiocyanato- groups in the solid state.

The preparation and thermal analysis studies on some first row transition metal complexes of 2-aminopyrimidine

Complexes of 2-aminopyrimidine with the chlorides, bromides and iodides of cobalt(II), zinc(II) and also with the chlorides and bromides of manganese(II), nickel(II) and copper(II) have been prepared. The chloride complex of iron(II) was also obtained. The stereochemical configurations of the complexes were deduced using spectral and magnetic properties. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis.

Molecular structure of monomeric manganese (II) bromide with evidence on the structure of the dimer from electron diffraction

An electron diffraction investigation (at 608° C) determined r g(Mn-Br) = 2.344 ± 0.006 Å in MnBr 2. Assuming a linear equilibrium configuration, the observed vibrational amplitudes and shrinkage effect allowed estimation of the vibrational frequencies. The dimer has a four-membered ring and a bridging bond longer than the bond of the monomer by 0.23 Å.

Some first row transition metal complexes of nicotinamide and nicotinic acid

Some complexes of the chlorides and bromides of manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) with nicotinamide and nicotinic acid have been prepared. These complexes have stoichiometryML 2X2 whereM is a metal ion,L is an organic ligand andX is a halide ion. Spectral and magnetic properties indicate that these compounds have octahedral polymeric structures. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis. In only one instance was a decomposition product of the formulaMLX2 obtained. Its structure was also octahedral.

The excitation spectra of tetrahedral complex compounds of manganese(II) bromide with hydrobromides of some derivatives of pyridine and pyperidine

The excitation spectra of complex compounds of magnanese (II) bromide with hydrobromides of some derivatives of pyridine and pyperidine have been studied at temperatures of 77 and 298 K. The character and arrangement bands of the excitation spectra as well as the green luminescence observed are indicative of tetrahedral structure of these compounds. The mechanism of production of the spectra has been explained in terms of ligand field theory. The Racah parameters calculated and the value of 10Dq was estimated to be about 3100 cm−1. In analyzing the excitation spectra an original method of computation was applied which gave very good results in resolving the bands.

Ultraviolet Absorption of Transition Metal Halides

The fundamental absorption spectra of the chlorides and the bromides of manganese, iron, cobalt, and nickel have been measured over the range from 2 to 40 eV. Fine structures occurring below 10 eV very as the transition metal changes. Spectral profiles 10 eV are simple and alike among the halides of different transition metals. Peaks located at the absorption edge shift systematically toward high energy from nickel halides to manganese halides, and are ascribed to the charge transfer transition from the outermost p orbitals of halogen to the unoccupied 3d orbitals of the transition metal. Comparison with soft X-ray absorption spectra suggests that the transitions from the outermost p orbitals of halogen to the 4 s orbitals of the transition metals produce peaks around 8 eV. Some of the other structures in the spectra are discussed.

X-Ray Photoemission Spectra of the Valance Electrons in Transition Metal Halides

The energy spectra of valance electrons photoemitted by excitation with X-rays have been measured on the chlorides and the bromides of nickel, cobalt, iron, and manganese. The profiles of the spectra obtained by deconvoluting raw data with a measured instrumental response function show structures representing the energy dependence of the state-densities of 3d electrons of metal ions. The structures in the spectra are qualitatively in terms of the molecular orbital energy levels. Variations in the spectral among different materials are discussed in connection with the fundamental optical absorption spectra.

Temperature dependence and angular variation of ESR line widths in two-dimensional manganese(II) bromide salts

Angular and temperature dependence of the ESR line widths of (RNH 3) 2MnBr 4 salts give evidence for exchange coupling and the two-dimensional nature of the systems.

Photoluminescence of manganese bromide compounds with different methyl- and dimethylquinoline hydrobromides

Photoluminescent properties of manganese bromide compounds with different methyl- and dimenthylquinoline hydrobromide were investigated. These compounds in solid state show green fluorescence with spectral distribution which may be represented by a function which is close to the Gaussian distribution. Aqueous and ethanol solutions of the investigated substance show violet-blue fluorescence which comes from the emission processes in the quinolinium ion. In solid state the luminophor is the manganese ion.

Crystal structure of a molecular complex of acetylacetone with manganese(II) bromide, MnBr2(C5H8O2)2

The crystal structure of a molecular complex of acetylacetone with MnBr2 has been determined by an X-ray diffraction analysis: the manganese and bromine atoms constitute an infinite chain (MnBr2)∞ and two enolic acetylacetone molecules are linked to each metal atom as unidentate ligands, thus constructing the octahedral arrangement of [MnBr4O2].

Stability constants of manganese(II) bromide complexes

Manganese-54 has been used as a tracer in an investigation of solutions containing manganese(II) bromide complexes. By a cation-exchange method values have been obtained for the stability constants beta(j) = [MnBr((2-j)+)(j)]/[Mn(2+)][Br(-)](j), valid for 20 degrees and ionic strength 0.691M maintained with perchloric acid.

Complexes of tri-(2-pyridyl)amine. Part II. Some complexes with metal halides. The ligand field strength of terdentate tri-(2-pyridyl)amine

The structure of some new complexes of tri-(2-pyridyl)amine with the chlorides and bromides of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), palladium(III), rhodium(III), and iridium(II) are discussed. Terdentate tri-(2-pyridyl)amine is recognised as a strong-field ligand (Δ= 12,820 cm.–1 with respect to NiII) thus indicating that strong conjugation between the aromatic centres in polypyridyl ligands is not a prerequisite for high ligand field strength.

Replacement of polydentate ligands in Mn(II) complexes by ammonia

The synthesis and characterization of complexes of manganese (II) bromide with ethylenediamine, diethylenetriamine and triethylenetetramine are described. It is shown that, under appropriate conditions, these complexes are converted to hexamminemanganese (II) bromide by treatment with liquid ammonia.

The kinetics and mechanism of the auto-oxidation of p-toluic acid in acetic acid solution catalyzed by cobalt and manganese bromides

The kinetics and mechanism of the auto-oxidation of p-toluic acid in acetic acid solution catalyzed by cobalt and manganese bromides