Difficulties in the interaction of the free electron pair in diacetophosphides and diacetamides

1968 ◽  
Vol 17 (2) ◽  
pp. 377-380
Author(s):  
R. G. Kostyanovskii ◽  
V. V. Yakshin ◽  
S. L. Zimont ◽  
I. I. Chervin
Keyword(s):  
Free Electron ◽  
Electron Pair ◽  
Free Electron Pair

scholarly journals Structure and hydrogen bonding of the hydrated selenite and selenate ions in aqueous solution

2014 ◽  
Vol 43 (17) ◽  
pp. 6315-6321 ◽  
Author(s):  
Lars Eklund ◽  
Ingmar Persson
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Free Electron ◽  
Electron Pair ◽  
Bound Water ◽  
Water Molecules ◽  
Hydration Sphere ◽  
Free Electron Pair

The selenite ion has an asymmetric hydration sphere with loosely electrostatically bound water molecules outside the free electron pair.

Organic Sulfur Mechanisms. 17. A Brief Study of the Photolysis of an Unsaturated Cyclic Sulfone

1975 ◽  
Vol 53 (23) ◽  
pp. 3656-3659 ◽  
Author(s):  
J. F. King ◽  
E. G. Lewars ◽  
D. R. K. Harding ◽  
R. M. Enanoza
Keyword(s):  
Free Electron ◽  
Ring Opening ◽  
Electron Pair ◽  
Heterocyclic Ring ◽  
Organic Sulfur ◽  
Free Electron Pair

Photolysis of 3-phenyl-2H-thiopyran 1,1-dioxide (3) in methanol gives a mixture of 3-phenyl-5-methoxy-5,6-dihydro-2H-thiopyran 1,1-dioxide (4) and methyl 4-phenyl-2,4-pentadiene-1-sulfonate (5). Formation of 5 shows that the photochemical ring opening of cyclohexadienic sulfonyl compounds (1) does not require an atom bearing a free electron pair in the heterocyclic ring, and therefore argues in favor of a mechanism involving cycloreversion to the sulfene (1 → 2).

Darstellung und Kristallstruktur von K2Sb4S7 · H2O / Preparation and Crystal Structure of K2Sb4S7 · H2O

1979 ◽  
Vol 34 (3) ◽  
pp. 383-385 ◽  
Author(s):  
Brigitte Eisenmann ◽  
Herbert Schäfer
Keyword(s):  
Crystal Structure ◽  
Free Electron ◽  
Electron Pair ◽  
Three Dimensional ◽  
The Other ◽  
Water Molecules ◽  
Triclinic System ◽  
Dimensional Network ◽  
Free Electron Pair

Abstract K2Sb4S7 · H2O crystallizes in the triclinic system with a = 1171.4(5) pm, b = 952.0(5) pm, c = 715.6(5) pm and α = 99.36(5)°, β = 86.80(5)°, γ= 103.48(5)°. One half of the Sb atoms has three sulfur neighbours forming with the free electron pair a ψ-ShS3 tetrahedron, while the other half is coordinated by four S atoms to build a ψ-trigonal SbS4 bipyramid. These polyhedra are connected by common edges and corners to a three-dimensional network with two types of channels, in which either K+ ions only or K+ ions and water molecules are located.

Zum Bindungszustand des fünf- und sechsbindigen Siliciums in kationischen und anionischen o-Arylendioxychelaten / (d ← n) π-Bonding in Anionic and Cationic o-Arylenedioxy Chelates of Hexacoordinate and Pentacoordinate Silicon Studied by Means of ESCA

1974 ◽  
Vol 29 (1-2) ◽  
pp. 72-74 ◽  
Author(s):  
Heinrich Meyer ◽  
Günter Nagorsen
Keyword(s):  
Linear Correlation ◽  
Free Electron ◽  
Linear Relation ◽  
Good Yield ◽  
Electron Pair ◽  
Binding Energies ◽  
Considerable Extent ◽  
Silicon Compounds ◽  
Back Donation ◽  
Free Electron Pair

The “Si-2s- and Si-2p-binding energies” of 5 o-arylenedioxy complexes containing penta- and hexacoordinate silicon have been obtained from their ESCA-spectra. The data have been compared to those of tetracovalent silicon compounds. A linear correlation between calculated Pauling charges and binding energies has been found for compounds where no (d ← n) -interaction should exist. Characteristic deviations from the linear relation were found both in tetravalent silicon compounds containing Si-O-bonds, the (d ← n)π-interaction of which is well established, and in the anionic tris(o-phenylenedioxy) siliconate and in the bis(o-phenylenedioxy) organosiliconates. No deviations were observed in case of the cationic 6-coordinate complexes of silicon with acetylacetone and 2-hydroxypyridine-N-oxide. We conclude that an additional back donation from the free electron pair (dSi ← nOo) only exists to a considerable extent in tetracovalent silicic ester derivatives, in the hexa- and pentacoordinate tris(o-phenylendioxy) siliconate and in the bis(o-phenylenedioxy) organosiliconates. A method is given to obtain crystalline tris(2-oxypyridine-N-oxy) siliconium chloride in good yield.

Electronic effects on enol acidity and keto-enol equilibrium constants for ring-substituted 2-tetralones

1999 ◽  
Vol 77 (5-6) ◽  
pp. 634-638 ◽  
Author(s):  
Xudong Yao ◽  
Ralph M Pollack
Keyword(s):  
Aqueous Solution ◽  
Charge Transfer ◽  
Systematic Study ◽  
Free Electron ◽  
Electron Pair ◽  
Equilibrium Constants ◽  
Hydroxyl Group ◽  
Negative Deviation ◽  
Electronic Effects ◽  
Free Electron Pair

Equilibrium constants for the ionization of a variety of phenyl-substituted 2-tetralones (pKaK), for the ionization of their enols (pKaE), and for keto-enol tautomerization (pKE) were determined. Hammett plots of pKaK and pKaE vs. σ- are linear with slopes (-ρ) of -1.66 ± 0.06 and -0.90 ± 0.03, respectively, except for deviations of the points corresponding to 6-nitro-2-tetralone (1b) and its enol. We have previously attributed the negative deviation of 1b from the correlation for the acidities of the ketones obtained with the more limited set of data to the lack of a free electron pair on C-1 of the free tetralone (Nevy et al.). The negative deviation of the point for 1b from the correlation for the acidities of the enols suggests that charge transfer from the hydroxyl group of the enol to the nitro group is less important than it is for phenols. This study represents the first systematic study of electronic effects on equilibria among ketone, enol, and enolate in aqueous solution. Key words: enol, acidity, equilibrium, substituent, conjugation.

Eine pentagonal pyramidale Koordination des Bismuts. Kristallstruktur von Methylbismutbis( diethyldithiocarbamat) / A Pentagonal Pyramidal Coordination of Bismut. Crystal Structure of Methylbismuthbis( diethyldithiocarbamate)

1979 ◽  
Vol 34 (7) ◽  
pp. 1037-1039 ◽  
Author(s):  
Christian Burschka ◽  
Markus Wieber
Keyword(s):  
Crystal Structure ◽  
Free Electron ◽  
Title Compound ◽  
Crystalline State ◽  
Electron Pair ◽  
Benzene Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Free Electron Pair

Abstract Methylbismuth-bis(diethyldithiocarbamate), X-ray The crystal structure of the title compound, recrystallized from ethanol, was solved by means of X-ray diffraction methods and could be refined to an i?-value of 0.050 with 2126 reflections observed. In contrast to its behaviour in benzene solution, where the compound is monomeric, in the crystalline state dimeric units are formed by intermolecular Bi-S-interactions. The bismuth atoms are coordinated in form of a slightly distorted pentagonal pyramid with the free electron pair presumably directed opposite the apical C-atom.

scholarly journals Theoretical Study of the Coordination of Semicarbazone and Its Methylated Derivatives

2018 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Urbain A. Kuevi ◽  
Gaston A. Kpotin ◽  
Guy S. Y. Atohoun ◽  
Jean-Baptiste Mensah
Keyword(s):  
Nitrogen Atom ◽  
Oxygen Atom ◽  
Transition Metal Complexes ◽  
Free Electron ◽  
Electron Pair ◽  
Theoretical Study ◽  
Electron Pairs ◽  
Chemical Structures ◽  
Physiological Properties ◽  
Free Electron Pair

Semicarbazone is a molecule with a group R1R2C=N-NR3-C(=O)-NR4R5.The oxygen atom has two free electron pairs; each nitrogen atom has one free electron pair. These free electron pairs are potential sites of coordination. The simplest molecule in this series is the semicarbazone which the formula is H2C=N-NH-C(=O)NH2. By replacing the oxygen atom by a sulfur atom is obtained a thiosemicarbazone. Some semicarbazones, such as nitrofurazone, and some thiosemicarbazones are known to have many properties: antiviral, antibacterial, antitrypanosomal, anticonvulsant, antitumor, anticancer. They are usually mediated by an association with copper or iron.Indeed transition metal complexes with given chemical structures are useful alternatives in the treatment of certain diseases since coordination of active ingredients deeply modifies both the physiological properties of metals and ligands in the meaning of overall improvement of these properties.The present work focuses on quantum study of the complexation of semicarbazone and its methylated derivatives. The purpose of this study is to determine the most favorable coordination site of each of these ligands. It was found that the oxygen atom appears more favorable to the coordination of semicarbazones.Complexes of these ligands with the Zn (II) were modeled. The calculations were made by the method DFT / B3LYP with the orbital basis 6-31G (d, p).

Possible ferromagnetism of a free-electron pair

1979 ◽  
Vol 57 (2) ◽  
pp. 243-252
Author(s):  
S. Olszewski
Keyword(s):  
Triplet State ◽  
Magnetic Moment ◽  
Free Electron ◽  
Electron Pair ◽  
Singlet State ◽  
A Priori ◽  
Wave Functions ◽  
Mutual Position ◽  
Spin Magnetic Moment ◽  
Free Electron Pair

It is pointed out that the relation E(ΦA) < E(ΦS) holds for a free-electron pair within a potential box on condition that the assumptions of (i) the continuity of wave functions and their derivatives, (ii) very thin potential box, and (iii) weak Coulomb interaction between the electrons, are satisfied; E(ΦA) denotes the lowest energy of the triplet state of the pair with which a net spin magnetic moment may be associated E(ΦS) is the lowest energy of the nonmagnetic singlet state of the pair. Mutual position of E(ΦA) and E(ΦS) cannot be predicted a priori, as wave functions ΦA and ΦS fulfill different boundary conditions.

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