Thio derivatives of β-diketones and their metal chelates. X. The anomalous paramagnetism of some iron(III) chelates of monothio-β-diketones

1968 ◽  
Vol 21 (8) ◽  
pp. 1987 ◽  
Author(s):  
RKY Ho ◽  
SE Livingstone
Keyword(s):  
Iron Atom ◽  
Thermal Equilibrium ◽  
Room Temperature ◽  
Magnetic Behaviour ◽  
The Other ◽  
Ligand Field ◽  
Pairing Energy ◽  
Temperature Dependent ◽  
Magnetic Susceptibilities ◽  
Derivatives Of

The magnetic susceptibilities of the iron(111) chelates Fe(R1CS=CHCOR2)3 (R1 = Ph, p-MeC6H4, p-MeOC6H4, p-BrC6H4, 2-thienyl, 2-furyl, R2 = CF3; R1 = Ph, R2 = Ph, OEt) have been investigated over a temperature range. The iron(111) complex of ethyl thiobenzoylacetate (R1 = Ph, R2 = OEt) is of the high-spin type and obeys the Curie-Weiss law with θ =-8�k. The moments of the other complexes vary between 2.31 and 6.61 B.M. at room temperature and are temperature-dependent, ranging from 1.86 to 4.07 B.M. at 80�k, depending on the nature of R1 and R2 This behaviour is postulated to be due to a thermal equilibrium between the nearly equi-energetic spin-paired (t5/2g) and spin-free (t3/2ge2/g) configurations of the iron atom, resulting from the approximately equal magnitudes of the ligand field (Δ) and the pairing energy (π) in these complexes. The ligand field and consequently the magnetic behaviour are sensitive to the nature of R1 and R2: electron-withdrawing groups appear to be the most effective in increasing the population of the spin-paired configuration.

Sulphur-nitrogen chelating agents. VIII. Magnetic behaviour of some cobalt(II) complexes at the crossover region

1969 ◽  
Vol 22 (9) ◽  
pp. 1825 ◽  
Author(s):  
PSK Chia ◽  
SE Livingstone
Keyword(s):  
Field Strength ◽  
Thermal Equilibrium ◽  
Chelating Agents ◽  
Magnetic Behaviour ◽  
Ligand Field ◽  
Crossover Region ◽  
Methyl Group ◽  
Quantitative Treatment

The bis-ligand cobalt(II) complexes of 6-methylpyrid-2-yi-N-(2?- methylthio-phenyl)methyleneimine (SNNMe) are spin-free and the corresponding complexes of 2-pyridyl-N-(2?- methylthiophenyl)methyleneimine (SNN) are spin-paired. This difference in magnetic behaviour arises from a lower effective ligand field strength of SNNMe, presumably due to the steric inter-ligand interference introduced by the methyl group in the 6-position of SNNMe. The moments of the cobalt(II) complexes are dependent on temperature and the departures from the Curie-Weiss law are quite anomalous. No quantitative treatment is given for the anomalous magnetic behaviour; however, the results are best explained as a thermal equilibrium between the nearly equi-energetic spin-paired and spin-free states of the cobalt(II) atom.

The anomalous paramagnetism of iron(III) NN-dialkyldithiocarbamates

1964 ◽  
Vol 17 (3) ◽  
pp. 294 ◽  
Author(s):  
AH White ◽  
R Roper ◽  
E Kokot ◽  
H Waterman ◽  
RL Martin
Keyword(s):  
Molecular Weight ◽  
Thermal Equilibrium ◽  
Room Temperature ◽  
Chemical Nature ◽  
Magnetic Moments ◽  
Chloroform Solution ◽  
Exchange Interactions ◽  
Magnetic Behaviour ◽  
Antiferromagnetic Exchange ◽  
Molecular Type

The magnetic moments of a series of 19 NN-disubstituted dithiocarbamates of iron(III), [Fe(S2C.NR?R")3], are anomalous in that their behaviour is neither "high-" nor "low-spin". Values of μeff. at room temperature lie between 2.62 and 5.83 B.M., the datum for each compound depending on the chemical nature of the substituents R' and R". This anomalous situation persists in benzene or chloroform solution. Cryoscopic and ebullioscopic molecular weight determinations establish that all the compounds are monomeric, which excludes the possibility that the magnetic behaviour arises from the presence of antiferromagnetic exchange interactions of either the inter- or intra-molecular type. These observations strongly support the early and generally overlooked work of Cambi who in 1932 proposed a thermal equilibrium between "magnetic isomers" of spins S = � and S = 5/2 to account for the origin of the magnetic anomaly.

Synthesis and antibacterial activity of some 1-(2-propynyl) and 1-propadienyl derivatives of 1,4-dihydro-4-oxoquinoline-3-carboxylic acids and similar heterocycles

1991 ◽  
Vol 56 (2) ◽  
pp. 439-448 ◽  
Author(s):  
Stanislav Rádl ◽  
Lenka Kovářová ◽  
Jiří Holoubek
Keyword(s):  
Antibacterial Activity ◽  
Dimethyl Sulfoxide ◽  
Carboxylic Acids ◽  
Potassium Carbonate ◽  
Potassium Hydroxide ◽  
Room Temperature ◽  
Ethyl Esters ◽  
The Other ◽  
Other Hand ◽  
Derivatives Of

N-Alkylation of IIIa, IIIb, IIId - IIIf and 9-acridanone with 3-bromopropyne in dimethyl sulfoxide in the presence of potassium carbonate yielded N-(2-propynyl) derivatives IVa - IVe and VIa, respectively. Ethyl esters IVa, IVb, and IVe were hydrolyzed to IVf - IVh, respectively. Compounds IVf, IVg, IVctreated with bases yielded N-propadienyl derivatives Va - Vc. On the other hand 2-substituted compounds IVd and IVh did not change under the same conditions. Compound VIa treated with powdered potassium hydroxide in dimethyl sulfoxide at room temperature yielded N-(1-propynyl) derivative VII.

Disubstituted derivatives of (L—L)Fe2(CO)6 (L—L = fluorocarbon bridged ligand)

1976 ◽  
Vol 54 (20) ◽  
pp. 3185-3191 ◽  
Author(s):  
Lian Sai Chia ◽  
William R. Cullen ◽  
John R. Sams ◽  
James C. Scott
Keyword(s):  
Iron Atom ◽  
Spectroscopic Studies ◽  
The Other ◽  
Bidentate Ligands ◽  
Mössbauer Measurements ◽  
Derivatives Of

The complexes (L—L)Fe2(CO)6 react with a range of bidentate ligands to give the complexes (L—L)′(L—L)Fe2(CO)4 ((L—L) = fluorocarbon-bridged ligand such as f4fars, f4AsP etc. (L—L)′ = fluorocarbon- and hydrocarbon-bridged ligands such as f4AsP diars etc.). Spectroscopic studies, in particular magnetically perturbed Mössbauer measurements, indicate that (L—L)′ in most complexes is chelated to one iron atom, FeA. This leaves one CO group on FeAcis to the FeA—FeB bond and three on FeB. A smaller class of derivatives appear to have (L—L)′ bridging the two iron atoms cis to the FeA—FeB bond. The sign of Vzz is positive at both iron sites in the bridged derivatives. It is negative at FeA and positive at FeB in the other complexes.

Is Free Thyroxine Accurately Measurable at Room Temperature?

1992 ◽  
Vol 38 (6) ◽  
pp. 880-886 ◽  
Author(s):  
H A Ross ◽  
T J Benraad
Keyword(s):  
Temperature Effect ◽  
Room Temperature ◽  
Free Thyroxine ◽  
The Other ◽  
Temperature Dependent ◽  
Thyroxine Binding Globulin ◽  
Total Binding ◽  
Relative Contribution ◽  
Back Titration ◽  
Titration Assay

Abstract Two recently developed two-step, or "back-titration" assay kits for free thyroxine (FT4)--one based on a europium-labeled derivative of T4, the other on conventional radiolabeled T4--were compared with both symmetrical dialysis and an indirect FT4 radioimmunoassay. Discrepancies between the two-step and the other two methods were observed, particularly in samples that had very low to zero thyroxine-binding globulin (TBG) content. In those instances the two-step methods gave values almost twice as high as the other methods. This effect could be largely reversed in one of the two-step assays and completely reversed in the other by performing the first incubation step at 37 degrees C rather than at room temperature, as prescribed by the manufacturers. When symmetrical dialysis is performed at both temperatures, FT4 at room temperature is about 40% of the amount determined at 37 degrees C, except in zero-TBG samples, where it averages almost 80% of the value at 37 degrees C. Moreover, we demonstrated that the affinity of TBG for T4 is much more temperature-dependent than the affinity of transthyretin and albumin for T4, so that the net temperature effect on the FT4 in a sample depends on the relative contribution of TBG to total binding. We conclude that performing FT4 assays at room temperature is principally incorrect and leads to falsely increased values when samples with very low TBG concentrations are analyzed.

The magnetic properties of the Tris(2-methyl-1,10-phenanthroline)iron(II) ion

1968 ◽  
Vol 21 (1) ◽  
pp. 83 ◽  
Author(s):  
HA Goodwin ◽  
RN Sylva
Keyword(s):  
Magnetic Properties ◽  
Thermal Equilibrium ◽  
Magnetic Moments ◽  
Anomalous Behaviour ◽  
Ligand Field ◽  
Temperature Dependent ◽  
Methyl Group ◽  
Temperature Range ◽  
Effective Strength

The magnetism of the salts [Fe mephen3]X2 (X = I-, ClO4-, BF4-, PF6-; mephen = 2-methyl- 1,l0-phenanthroline) has been investigated over the temperature range c. 100-300�K. The compounds exhibit anomalous behaviour, and this has been qualitatively interpreted as being the result of the presence of nearly equi-energetic ground terms 1A1 and 5T2 of the complexed iron(11) ion, a thermal equilibrium between these terms causing the magnetic moments to be markedly temperature dependent. This behaviour is apparently the result of the sterie hindrance to the coordination of an iron(11) ion induced by the presence of the methyl group in the ligand and the consequent lowering of the effective strength of the ligand field. The colour of the salts varies with temperature, and this has been discussed in terms of π-bonding between the iron(11) ion and the ligand.

PD Fluids Contain High Concentrations of Cytotoxic GDPs Directly after Sterilization

2004 ◽  
Vol 24 (4) ◽  
pp. 392-398 ◽  
Author(s):  
Martin Erixon ◽  
Torbjörn Lindén ◽  
Per Kjellstrand ◽  
Ola Carlsson ◽  
Malin Ernebrant ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Main Part ◽  
Room Temperature ◽  
Degradation Products ◽  
The Other ◽  
Dependent Manner ◽  
Peritoneal Membrane ◽  
Temperature Dependent ◽  
Different Temperatures ◽  
High Concentrations

Objective Glucose degradation products (GDPs) in peritoneal dialysis (PD) fluids are cytotoxic and affect the survival of the peritoneal membrane. One of the most reactive GDPs in PD fluids is 3,4-dideoxyglucosone-3-ene (3,4-DGE). 3,4-DGE has been reported as an intermediate between 3-deoxyglucosone (3-DG) and 5-hydroxymethyl furaldehyde (5-HMF) during degradation of glucose. In PD fluids, 3,4-DGE exists in a temperature-dependent equilibrium with a pool of unidentified substances. The aim of this study was to explore this equilibrium and its temperature dependence during the first months of storage after the sterilization procedure. Methods GDPs and inhibition of cell growth (ICG) were measured directly after sterilization of the PD fluid and during storage at different temperatures for 60 days. The following GDPs were analyzed: 3-DG, 3,4-DGE, 5-HMF, formaldehyde, acetaldehyde, glyoxal, and methylglyoxal. Results Immediately after sterilization, the concentration of 3,4-DGE was 125 μmol/L. During the first weeks of storage, it decreased by about 80%. At the same time, the 3-DG concentration increased. None of the other GDPs were significantly affected. Cytotoxicity correlated well with the concentration of 3,4-DGE. When pure 3,4-DGE was substituted for the lost amount of 3,4-DGE after 30 days of storage, the initial ICG was almost completely regained. Conclusions Heat sterilization of PD fluids promotes the formation of large quantities of 3,4-DGE, rendering the fluid highly cytotoxic. During storage, the main part of 3,4-DGE is reversibly converted in a temperature-dependent manner to a less cytotoxic pool, consisting mainly of 3-DG. Cytotoxicity seems to be dependent exclusively on 3,4-DGE. In order to avoid higher levels of 3,4-DGE concentrations, PD fluids should not be used too soon after sterilization and should not be stored at temperatures above room temperature.

The electronic spectra and magnetic behaviour of some dithiocacodylate complexes

1971 ◽  
Vol 24 (8) ◽  
pp. 1587 ◽  
Author(s):  
AT Casey ◽  
DJ Mackey ◽  
RL Martin
Keyword(s):  
Field Strength ◽  
Electronic Spectrum ◽  
Electronic Spectra ◽  
Magnetic Behaviour ◽  
The Other ◽  
Ligand Field ◽  
Ionic Character ◽  
Nephelauxetic Effect ◽  
Other Hand ◽  
Square Planar

The large nephelauxetic effect and low ligand field strength produced by the dithiocacodylate group [(CH3)2AsS2-] in complexes with Ni2+, Co2+, and Cr3+ is explained in terms of significant covalency of the metal- sulphur bonds. The Mn2+ compound, however, has properties consistent with considerable ionic character. ��� The electronic spectrum and magnetic behaviour of bisdithiocacodylato-cobalt(II) can be better interpreted in terms of tetrahedral rather than octahedral CoSx microsymmetry. On the other hand, the Ni2+ compound is square-planar and both the Mn2+ and Cr3+ compounds appear to be octahedrally coordinated by sulphur atoms.

CO-ORDINATION COMPOUNDS OF NICKEL(II): PART I. THE SPECTRA OF SALICYLALDIMINE DERIVATIVES OF NICKEL(II) IN SOME ORGANIC SOLVENTS

1959 ◽  
Vol 37 (2) ◽  
pp. 436-443 ◽  
Author(s):  
H. C. Clark ◽  
R. J. O'Brien
Keyword(s):  
Field Theory ◽  
Carbon Tetrachloride ◽  
Absorption Spectra ◽  
Organic Solvents ◽  
Ligand Field ◽  
Temperature Dependent ◽  
Visible Absorption ◽  
Ligand Field Theory ◽  
Recent Developments ◽  
Derivatives Of

Measurements of the ultraviolet and visible absorption spectra of bis-N-methyl-salicylaldimine nickel(II) and its 5-chloro and 5-bromo derivatives in benzene, chloroform, carbon tetrachloride, and cyclohexane solutions at temperatures between 15° and 45 °C are reported. The results confirm the occurrence of a temperature dependent equilibrium between dia- and para-magnetic forms. The nature of the paramagnetic form is discussed in terms of the recent developments of the ligand field theory. The effect on the equilibrium of substitution of chlorine or bromine in the five position of the salicylaldehyde molecule is also discussed.

Complexes of Some Platinum Metals with p-Diethylamino Anil of Phenyl Glyoxal

1978 ◽  
Vol 33 (9) ◽  
pp. 1001-1004 ◽  
Author(s):  
H. S. Verma ◽  
R. C. Saxena
Keyword(s):  
Schiff Base ◽  
Room Temperature ◽  
Complex Compounds ◽  
The Other ◽  
Spectral Studies ◽  
Ligand Field ◽  
Octahedral Structure ◽  
Platinum Metals ◽  
Bidentate Schiff Base Ligand ◽  
Ligand Field Parameters

Complex compounds of platinum metals Ru(III), Rh(III), Os(IV), Ir(IlI) and Pt(IV) with the bidentate Schiff base ligand derived by the condensation of phenyl glyoxal with p-diethylamino aniline have been prepared and characterized. All the complexes are stable at room temperature. The complexes of Ru(III) and Os(IV) are Paramagnetic and the other complexes of Rh(III), Ir(III) and Pt(IV) are diamagnetic. The spectral studies and the calculation of ligand field parameters clearly indicate the octahedral structure of these complexes.

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