Binding energies and structural effects in halide anion-ROH and -RCOOH complexes from gas-phase equilibria measurements

1984 ◽  
Vol 106 (4) ◽  
pp. 967-969 ◽  
Author(s):  
Gary Caldwell ◽  
Paul Kebarle
Keyword(s):  
Phase Equilibria ◽  
Gas Phase ◽  
Binding Energies ◽  
Structural Effects ◽  
Halide Anion

Binding energies and stabilities of potassium ion complexes with ethylene diamine and dimethoxyethane (glyme) from measurements of the complexing equilibria in the gas phase

1976 ◽  
Vol 54 (16) ◽  
pp. 2594-2599 ◽  
Author(s):  
W. R. Davidson ◽  
P. Kebarle
Keyword(s):  
Phase Equilibria ◽  
Gas Phase ◽  
Ion Source ◽  
Potassium Ion ◽  
Binding Energies ◽  
Ethylene Diamine ◽  
Bidentate Ligands ◽  
Source Pressure ◽  
The Third ◽  
Monodentate Ligands

The temperature dependence of the gas phase equilibria [Formula: see text] where en = ethylene diamine were measured for n = 1 to n = 3. The equilibrium K+ + dimethoxyethane [Formula: see text] K+(dimethoxyethane) was also determined. The measurements were made with a high ion source pressure mass spectrometer equipped with a thermionic potassium ion emitter. The resulting ΔH0, ΔG0, and ΔS0 values are compared with the corresponding values for monodentate ligands like H2O, NH3, CH3OCH3 etc. determined in earlier work. As expected, the bidentate ligands lead to considerably stronger (0,1) interactions. Dimethoxyethane leads to a stronger complex than ethylene diamine. The third molecule of ethylene diamine leads to much weaker binding than is observed for the first two molecules. Explanation of the observed effects is given on basis of electrostatic and steric arguments.

Reactions in solution

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Phase Equilibria ◽  
Gas Phase ◽  
First Principles ◽  
Unique Feature ◽  
Life Sciences ◽  
Equilibrium Mixture ◽  
Second Law ◽  
Ideal Solution ◽  
Coupled Reactions ◽  
Definition Of

Another key chapter, examining reactions in solution. Starting with the definition of an ideal solution, and then introducing Raoult’s law and Henry’s law, this chapter then draws on the results of Chapter 14 (gas phase equilibria) to derive the corresponding results for equilibria in an ideal solution. A unique feature of this chapter is the analysis of coupled reactions, once again using first principles to show how the coupling of an endergonic reaction to a suitable exergonic reaction results in an equilibrium mixture in which the products of the endergonic reaction are present in much higher quantity. This demonstrates how coupled reactions can cause entropy-reducing events to take place without breaking the Second Law, so setting the scene for the future chapters on applications of thermodynamics to the life sciences, especially chapter 24 on bioenergetics.

Structural effects on the iodine cation basicity of organic bases in the gas phase

1989 ◽  
Vol 111 (24) ◽  
pp. 8960-8961 ◽  
Author(s):  
Jose Luis M. Abboud ◽  
Rafael Notario ◽  
Lucia Santos ◽  
Carmen Lopez-Mardomingo
Keyword(s):  
Gas Phase ◽  
Structural Effects ◽  
Organic Bases

Serine–Ca2+ versus serine–Cu2+ complexes — A theoretical perspective

2010 ◽  
Vol 88 (8) ◽  
pp. 759-768 ◽  
Author(s):  
Al Mokhtar Lamsabhi ◽  
Otilia Mó ◽  
Manuel Yáñez
Keyword(s):  
Gas Phase ◽  
Electron Density ◽  
Potential Energy Surfaces ◽  
Metal Ion ◽  
Theoretical Perspective ◽  
Binding Energies ◽  
Interacting Systems ◽  
Intramolecular Hydrogen ◽  
Energy Surfaces ◽  
Doubly Charged

The association of Ca2+ and Cu2+ to serine was investigated by means of B3LYP DFT calculations. The [serine–M]2+ (M = Ca, Cu) potential energy surfaces include, as does the neutral serine, a large number of conformers, in which a drastic reorganization of the electron density of the serine moiety is observed. This leads to significant changes in the number and strength of the intramolecular hydrogen bonds existing in the neutral serine tautomers. In some cases, a proton is transferred from the carboxylic OH group to the amino group and accordingly, some of the more stable [serine–M]2+ complexes can be viewed as the result of the interaction of the zwiterionic form of serine with the doubly charged metal ion. Whereas the interaction between Ca2+ and serine is essentially electrostatic, that between Cu2+ and serine has a non-negligible covalent character, reflected in larger electron densities at the bond critical points between the metal and the base, in the negative values of the electron density between the two interacting systems, and in much larger Cu2+ than Ca2+ binding energies. More importantly, the interaction with Cu2+ is followed by a partial oxidation of the base, which is not observed when the metal ion is Ca2+. The main consequence is that in Cu2+ complexes a significant acidity enhancement of the serine moiety takes place, which strongly favors the deprotonation of the [serine–Cu]2+ complexes. This is not the case for Ca2+ complexes. Thus, [serine–Ca]2+ complexes, like those formed by urea, thiourea, selenourea, or glycine, should be detected in the gas phase. Conversely, the complexes with Cu2+ should deprotonate spontaneously and therefore only [(serine–H)–Cu]+ monocations should be experimentally accessible.

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