Methyl group exchange reactions of trimethylaluminium dimer

1973 ◽  
Vol 26 (4) ◽  
pp. 749 ◽  
Author(s):  
EM Krankovits ◽  
RJ Magee ◽  
KS Murray ◽  
MJ O'Conner
Keyword(s):  
Liquid Helium ◽  
Low Temperatures ◽  
Variable Temperature ◽  
Magnetic Behaviour ◽  
Exchange Reactions ◽  
Methyl Group ◽  
Ferromagnetic Behaviour ◽  
Cluster Interaction ◽  
Square Planar ◽  
Temperature Susceptibility

Variable temperature susceptibility measurements have been made on a number of bis(N,N-dialkylmonothiocarbamato)nickel(II) complexes. The results are characteristic of ferromagnetically coupled NiII clusters. Within the range 300-80 K the susceptibilities can be fitted extremely well to a number of possible cluster models and it is not possible to distinguish the exact molecularity. ��� Measurements on one of the complexes down to liquid helium temperatures confirm the ferromagnetic behaviour and demonstrate inter- cluster interaction at very low temperatures. The magnetic behaviour of these complexes contrasts with the diamagnetism of the square planar bis(N,N-dialkyldithiocarbamato) analogues.

On the design and implementation of a novel impedance chamber based variable temperature regulator at liquid helium temperatures

2010 ◽  
Vol 81 (4) ◽  
pp. 045112 ◽  
Author(s):  
R. Nagendran ◽  
N. Thirumurugan ◽  
N. Chinnasamy ◽  
M. P. Janawadkar ◽  
C. S. Sundar
Keyword(s):  
Liquid Helium ◽  
Variable Temperature ◽  
Temperature Regulator ◽  
Design And Implementation

The magnetic behaviour of CePd3 at low temperatures

1985 ◽  
Vol 56 (7) ◽  
pp. 623-626 ◽  
Author(s):  
J. Aarts ◽  
F.R. de Boer ◽  
P.F. de Châtel ◽  
A. Menovsky
Keyword(s):  
Low Temperatures ◽  
Magnetic Behaviour

Synthesis, structural and magnetic properties of macrocyclic aza-amido binuclear copper(II) complexes

1989 ◽  
Vol 67 (4) ◽  
pp. 662-670 ◽  
Author(s):  
Sanat K. Mandal ◽  
Laurence K. Thompson ◽  
Michael J. Newlands ◽  
Amal K. Biswas ◽  
Bibhutosh Adhikary ◽  
...  
Keyword(s):  
Variable Temperature ◽  
Complex Iii ◽  
Azomethine Nitrogen ◽  
X Ray Diffraction ◽  
Binuclear Copper ◽  
Magnetic Studies ◽  
Monoclinic System ◽  
Space Group ◽  
Pyramidal Geometry ◽  
Square Planar

Binuclear, antiferromagnetically coupled, macrocyclic copper(II) complexes, [Cu2(C28H32N4O4)]•H2O (II) and [Cu2(C36H32N4O4)]•CH3CN•H2O (III), involving asymmetric ligands with two deprotonated amide, two azomethine nitrogen, and two phenoxide donors at the binuclear centre, have been synthesized and characterized by single-crystal X-ray diffraction and variable temperature magnetic studies. Complex II crystallizes in the monoclinic system, space group P21/n, with a = 16.4854(9) Å, b = 7.6005(13) Å, c = 21.1617(11) Å, β = 104.090(5)°, Z = 4, Rf = 0.068 for 2062 significant reflections. The two copper(II) centres have square planar N2O2 donor sets with two phenoxide oxygen atoms bridging the copper centres with a copper–copper separation of 2.898(2) Å. A long copper–oxygen (amide) contact (2.808(10) Å) forms a weak dimer association. Complex III crystallizes in the triclinic system, space group [Formula: see text], with a = 8.7771(9) Å, b = 12.3983(16) Å, c = 15.7299(16) Å, α = 85.003(11)°, β = 84.574(8)°, γ = 76.838(10)°, Z = 2, Rf = 0.041 for 2966 significant reflections. The two copper(II) centres have distorted square-pyramidal geometry involving an N2O2 in plane donor set and two phenoxide oxygen bridges with a copper–copper separation of 3.018(1) Å. The fifth coordination site at each copper centre involves an amide oxygen from a neighbouring molecule (Cu(1)—O 2.371(4), Cu(2)—O 2.413(3) Å) in a staggered intermolecular array. Very strong antiferromagnetic exchange is observed in both cases (−2J = 689 ± 7 cm−1 (II), −2J = 816 ± 8 cm−1 (III)). Keywords: macrocycles, binuclear copper(II) complexes.

MAGNETIC BEHAVIOUR OF UPdAl, UCuGa AND UCuSn

1993 ◽  
Vol 07 (01n03) ◽  
pp. 850-854 ◽  
Author(s):  
V.H. TRAN ◽  
R. TROĆ
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Low Temperatures ◽  
Magnetic Behaviour ◽  
Type Structure ◽  
Complex Structures ◽  
Temperature Dependent ◽  
Antiferromagnetic Ordering

Magnetic susceptibility and electrical resistivity have been measured on UCuGa, UCu1+xSn1−x, (x=0 and 0.1), and UPdAl. The first two compounds, crystallizing in the hexagonal CaIn2-type structure, show at low temperatures an antiferromagnetic ordering probably with complex structures. UPdAl, which adopts the orthorhombic TiNiSi-type structure, was found to be a weakly temperature-dependent paramagnet down to 4.2 K.

scholarly journals Experiments at very low temperatures obtained by the magnetic method I—The production of the low temperatures

1935 ◽  
Vol 149 (866) ◽  
pp. 152-176 ◽  
Keyword(s):  
Liquid Helium ◽  
Vapour Pressure ◽  
Low Temperatures ◽  
Usual Method ◽  
Magnetic Method ◽  
Isothermal Magnetization

The lowest limit of temperature obtainable by the hitherto usual method of evaporating liquid helium lies at about 0⋅7º. At this temperature the vapour pressure of helium is already so small that it does not seem possible to proceed to appreciably lower temperatures in this way. In the course of last year the first successful experiments in attaining still lower temperatures were carried out using the magnetic method proposed by Debye and Giauque. This method is based on the possibility of diminishing considerably the entropy of some paramagnetic salts by isothermal magnetization. The subsequent demagnetization, if carried out adiabatically, then results in a lowering of the temperature.

Versatile Cryostated Optically Transparent Thin-Layer Electrochemical (OTTLE) Cell for Variable-Temperature UV-Vis/IR Spectroelectrochemical Studies

1994 ◽  
Vol 48 (12) ◽  
pp. 1522-1528 ◽  
Author(s):  
F. Hartl ◽  
H. Luyten ◽  
H. A. Nieuwenhuis ◽  
G. C. Schoemaker
Keyword(s):  
Thin Layer ◽  
Low Temperatures ◽  
Variable Temperature ◽  
Experimental Setup ◽  
Strictly Anaerobic ◽  
Carbonyl Complexes ◽  
Anaerobic Conditions ◽  
Optically Transparent ◽  
Solution Layer ◽  
Preset Temperature

This article describes the construction of a novel optically transparent thin-layer electrochemical (OTTLE) cell for IR and UV-Vis spectroelectrochemical experiments at variable temperature. The cell has a three-electrode set melt-sealed into a smooth polyethylene spacer which is sandwiched between two CaF2 windows. The width of this spacer (0.18–0.20 mm) defines the thickness of the thin solution layer. The whole electrode assembly is housed in a thermostated Cu block of the OTTLE cell which fits into a double-walled nitrogen-bath cryostat. The experimental setup permits relatively fast electrolysis within the tested temperature range of 295 to 173 K under strictly anaerobic conditions and protection of light-sensitive compounds. Other important merits of the cell design include lack of leakage, facile cleaning, almost negligible variation of the preset temperature, and facile manipulation in the course of the experiments. The applicability of the variable-temperature IR/UV-Vis OTTLE cell is demonstrated by stabilization of a few electrogenerated carbonyl complexes of Mn(I) and Ru(II) with 3,5-di- tert. butyl-1,2-benzo(semi)quinone (DB(S)Q) and N, N′-diisopropyl-1,4-diaza-1,3-butadiene (iPr-DAB) ligands, respectively, at appropriately low temperatures.

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