scholarly journals Thermochromism of Metal Complexes of Cresolphthalein Dye. Solvent Effect on Temperature-Dependence and Reversibility

1991 ◽  
Vol 64 (2) ◽  
pp. 705-707 ◽  
Author(s):  
Masato Nanasawa ◽  
Mitsuo Wada ◽  
Hiroyoshi Kamogawa
Keyword(s):  
Metal Complexes ◽  
Solvent Effect ◽  
Temperature Dependence

Intramolecular reorientation, an electron spin relaxation process in solutions of discrete paramagnetic transition-metal complexes

1978 ◽  
Vol 31 (11) ◽  
pp. 2355 ◽  
Author(s):  
DM Doddrell ◽  
DT Pegg ◽  
MR Bendall ◽  
AK Gregson
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Temperature Dependence ◽  
Transition Metal Complexes ◽  
Spin Relaxation ◽  
Electron Spin ◽  
Potential Energy Profile ◽  
Methyl Proton ◽  
Electron Spin Relaxation ◽  
Time Modulation

Time modulation of the g-tensor by intramolecular reorientation between structurally equivalent molecular arrangements is postulated to dominate electron spin relaxation in solutions of some paramagnetic transition-metal complexes. The process is treated theoretically and it is shown that the resulting electron spin relaxation time depends on the correlation time for intramolecular reorientation. The temperature dependence of the nuclear T1 thus yields information concerning the potential energy profile for intramolecular reorientation. Experimental results on the field dependence of the temperature dependence of T1 of the methyl proton in Ru(acac)3 are in accord with the theory.

Reaction of 1,3-diphenyltriazene with phenyl isocyanate. Solvent effect, activation parameters and kinetic isotopic effect

1981 ◽  
Vol 46 (6) ◽  
pp. 1376-1382
Author(s):  
Erhard Lejdar ◽  
Oldřich Pytela ◽  
Miroslav Večeřa ◽  
Pavel Vetešník
Keyword(s):  
Hydrogen Atom ◽  
Solvent Effect ◽  
Temperature Dependence ◽  
Activation Parameters ◽  
Phenyl Isocyanate ◽  
Isotopic Effect ◽  
Imino Group ◽  
Reaction Velocity ◽  
Kinetic Isotopic Effect ◽  
Previous Communication

Effect of 14 solvents has been studied on the reaction of phenyl isocyanate with 1,3-diphenyltriazene. For ten of these solvents temperature dependence of the reaction velocity has been determined and the respective activation parameters calculated. Hydrogen atom of the triazene imino group has been replaced by deuterium, and the deuterium kinetic isotopic effect has been studied in seven solvents. The results confirm the mechanism suggested in a previous communication.

Metal complexes of 1,10-phenanthroline derivatives. X. 5T2 ↔ 1A1 transitions in iron(II) complexes of 2-(1,10-Phenanthrolin-2-yl)imidazole derivatives

1975 ◽  
Vol 28 (3) ◽  
pp. 505 ◽  
Author(s):  
DW Mather ◽  
HA Goodwin
Keyword(s):  
Metal Complexes ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Chelating Agents ◽  
Elevated Temperatures ◽  
Magnetic Moments ◽  
Spin Transition ◽  
Benzimidazole Derivative ◽  
Crossover Region ◽  
Experimental Temperature Range

The preparation of the tridentate chelating agents 2-(1,10- phenanthrolin-2-yl)imidazoline and 2-(1,10-phenanthrolin-2- yl)benzimidazole and their bis-ligand complexes with iron(II) and nickel(II) is described. The latter ligand coordinates as either a neutral or anionic tridentate. Data from the spectra of the nickel(II) complexes indicate that the ligands have field strengths in the iron(II) crossover region. The temperature dependence of the magnetism of the imidazoline iron(II) complex reveals a gradual, temperature- induced 5T2 ↔ 1A1 transition which is not complete within the experimental temperature range (83-363 K). Both the cationic and neutral iron(II) complexes of the benzimidazole derivative are essentially low-spin at room temperature but a significant increase in their magnetic moments at elevated temperatures indicates that a spin transition may be occurring in these compounds too.

Luminescence and photochemistry of transition metal complexes. I. Studies of temperature dependence of tervalent chromium complexes with oxygen-, nitrogen-, and carbon-coordinated ligands

1971 ◽  
Vol 24 (9) ◽  
pp. 1807 ◽  
Author(s):  
JL Laver ◽  
PW Smith
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Temperature Dependence ◽  
Transition Metal Complexes ◽  
Energy Interval ◽  
Experimental Investigations ◽  
Chromium Complexes ◽  
Radiative Processes

Experimental investigations of the luminescence exhibited by a range of tervalent chromium complexes are reported. The effects of the coordinated ligand on the temperature dependence of phosphorescence are examined and rationalized in terms of the 4T2-2E energy interval. In the case of hexaureachromium complexes which emit both phosphorescence and fluorescence the varying emission intensities observed for compounds with a variety of anions are interpreted in terms of competition between the non-radiative thermal repopulation process 2E ~~→ 4T2 and the radiative processes 2E → 4A2, 4T2 → 4A2.

Metal complexes of 1,10-phenanthroline derivatives. I. Bis complexes of 2-Carboxy-1,10-phenanthroline with first row transition metal ions

1967 ◽  
Vol 20 (2) ◽  
pp. 217 ◽  
Author(s):  
HA Goodwin ◽  
RN Sylva
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Complexes ◽  
Temperature Dependence ◽  
Spectral Properties ◽  
Acidic Solution ◽  
Chelating Agent ◽  
Transition Metal Ions

2-Carboxy-1,10-phenanthroline has been prepared by brominating 2- methyl-phenanthroline and then hydrolysing in acidic solution the resultant 2-tribromomethyl derivative. The acid acts as a tridentate chelating agent and six-coordinate inner complexes of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II) as well as a complex of iron(III) are described. The formulation of the complexes as six-coordinate is supported by their magnetic and spectral properties. The temperature dependence of the magnetism of the iron(II) complex indicates that the complex is a simple paramagnetic.

A Thermodynamic Study of The Association of K+ And Rb+ Cations with 1,3-Bis(Benzyloxy)-p-tert-butylcalix[4]crown-5 in a CHCl3–Methanol Mixture

2005 ◽  
Vol 60 (6) ◽  
pp. 424-428
Author(s):  
Shehadeh A. Mizyed ◽  
Muhammad Ashram
Keyword(s):  
Computer Program ◽  
Solvent Effect ◽  
Temperature Dependence ◽  
Stability Constants ◽  
Thermodynamic Study ◽  
Complexation Reaction ◽  
Conductivity Data ◽  
Complexation Constants ◽  
Methanol Mixture ◽  
The Stability

The conductivity during the complexation reaction between K+ or Rb+ and 1,3-bis(benzyloxy)- p-tert-butylcalix[4]crown-5 in a CHCl3-methanol mixture at 288 - 303 K has been measured. The conductivity data were analyzed using a computer program based on 1 : 1 stoichiometry. The stability constants of the resulting complexes were determined, indicating that K+ is more stable than Rb+ in the solvents used. The ΔH and Δ S values for the complexation processes were determined from the temperature dependence of the complexation constants. Their significance as well as the solvent effect is discussed.

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