Neutral hyperconjugation and one-bond couplings between heavy atoms

2000 ◽  
Vol 78 (11) ◽  
pp. 1441-1444 ◽  
Author(s):  
Joseph B Lambert ◽  
Catherine E Shawl ◽  
Ernani Basso
Keyword(s):  
Double Bond ◽  
Aromatic Ring ◽  
Bond Order ◽  
Coupling Constant ◽  
Heavy Atoms ◽  
Two Systems ◽  
The Relationship

The relationship has been examined between bond order and one-bond couplings involving heavy atoms, as modulated by neutral hyperconjugation. Two systems have been studied in which either an aromatic ring or a double bond can influence, through hyperconjugation, the α and β bonds (respectively, Ci—C and Ci—M in =C-C-M). Hyperconjugation may be modulated by substituents on the aromatic ring or double bond or by placement of different atoms (M = C, Si, Ge, or Sn) at the β position. The α bond exhibits no relationship between coupling constant and neutral hyperconjugation, but the β bond shows a strong relationship.Key words: hyperconjugation, germanium, σ-π conjugation, silicon, tin.

The chemistry of pyrrolic compounds. LII. The preferred pathway of electron delocalization in metalloporphyrins

1982 ◽  
Vol 35 (11) ◽  
pp. 2315 ◽  
Author(s):  
S Chakraborty ◽  
PS Clezy ◽  
S Sternhell ◽  
Thuc L van
Keyword(s):  
Double Bond ◽  
Bond Order ◽  
Electron Delocalization ◽  
Similar Data ◽  
Coupling Constant ◽  
Metal Free ◽  
Proton Coupling ◽  
Synthetic Approaches

Measurement of the proton coupling constant in the allylic unit, CH3-C=C-H, of the zinc(II), nickel(II) and magnesium(II) chelates of the deuteroporphyrin isomer (3a) points in each case to the double bond of this system having a significantly diminished bond order. Similar data have been obtained for the dication derivative of (3a). These findings are in accord with the view that the π-electron delocalization pathway in porphyrin dications and metalloporphyrins involves the periphery of the molecule as was previously shown for the metal-free porphyrin. New synthetic approaches to the porphyrin (3a) have been studied.

The chemistry of pyrrolic compounds. XL. A new synthesis of protoporphyrins III and XIII and a 1H N.M.R. study of the preferred pathway of electron delocalization in the porphyrin macrocycle

1978 ◽  
Vol 31 (3) ◽  
pp. 639 ◽  
Author(s):  
PS Clezy ◽  
CJR Fookes ◽  
S Sternhell
Keyword(s):  
Double Bond ◽  
Bond Order ◽  
Oxidative Cyclization ◽  
Electron Delocalization ◽  
Coupling Constant ◽  
Proton Coupling ◽  
Porphyrin Macrocycle ◽  
New Synthesis

The synthesis of protoporphyrins III and XIII as the dimethyl esters has been completed by an oxidative cyclization of biladiene-ac intermediates. Protoporphyrin III has been converted into deuteroporphyrin III and measurements of the proton coupling constant in the allylic unit, CH3-C=C-H, of this latter porphyrin point to the double bond of this system having a significantly diminished bond order. This finding is in accord with the view that the π-electron delocalization pathway in the porphyrin macrocycle involves the periphery of the molecule.

Dissecting the Effects of Water Guest Adsorption and Framework Breathing on the AlO4(OH)2 Centers of Metal-Organic Framework MIL-53 (Al) by Solid State NMR and Structural Analysis

2021 ◽  
Author(s):  
Alexander G. Stepanov ◽  
Alexander E. Khudozhitkov ◽  
Sergei S. Arzumanov ◽  
Alexander V. Toktarev ◽  
Svetlana Cherepanova ◽  
...  
Keyword(s):  
Solid State Nmr ◽  
Metal Organic Framework ◽  
Structural Phase ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Aluminium Atom ◽  
Quadrupole Coupling ◽  
Adsorption Of Water ◽  
Metal Organic ◽  
The Relationship

The relationship between the adsorption of water on MIL-53 (Al) MOF, the structural phase of MIL-53 (Al), and quadrupole coupling constant of 27Al framework aluminium atom (QCC) of the MOF...

A Comparison of Activity-Based Costing and Time-Driven Activity-Based Costing

2017 ◽  
Vol 30 (1) ◽  
pp. 143-167 ◽  
Author(s):  
Sophie Hoozée ◽  
Stephen C. Hansen
Keyword(s):  
Numerical Experiment ◽  
Data Availability ◽  
Activity Based Costing ◽  
Analytical Comparison ◽  
Resource Information ◽  
Two Systems ◽  
System Maps ◽  
The Impact ◽  
The Relationship ◽  
Activity Information

ABSTRACT The relationship between activity-based costing (ABC) and time-driven activity-based costing (TDABC) has not been systematically investigated. We compare the two systems analytically and via a numerical experiment. Our analytical comparison generates formulas that describe how each system maps resources to activities and finally to products. We demonstrate that ABC aggregates resource-to-activity information by resources (columns), while TDABC selects partitions of activity-by-resource information. Our numerical experiment shows that TDABC is more accurate than ABC when traceability of resources to activities is high and activity traceability to products is low, while ABC is more accurate when activities are more traceable to products, irrespective of the level of resource traceability to activities. Finally, we examine the impact of hybridizing an ABC (TDABC) system with TDABC (ABC). We find that adding one ABC element into a TDABC system usually improves accuracy. However, adding one TDABC element into an ABC system usually substantially degrades accuracy. Data Availability: The simulated datasets are available from the first author on request.

Das ν1/ν3-Frequenzen-Verhältnis bei tetraedrischen Oxoanionen der Hauptgruppen- elemente und die Schwingungseigenschaften von Xenon-Tetroxid / The ν1/ν3 Frequency Ratio in Tetrahedral Oxoanions of The Main Group Elements and the Vibrational Properties of Xenon-Tetroxid

1972 ◽  
Vol 27 (6) ◽  
pp. 1000-1004 ◽  
Author(s):  
Enrique J. Baran
Keyword(s):  
Periodic System ◽  
Related Species ◽  
Frequency Ratio ◽  
Bond Order ◽  
Main Group ◽  
Vibrational Properties ◽  
Coriolis Coupling ◽  
Coupling Constant ◽  
Main Group Elements ◽  
Mean Amplitudes Of Vibration

AbstractIn an earlier work we have theoretically derived and explained certain rules relating the ν1/v3 frequency ratio of tetrahedral oxoanions of the transition metals with some basic properties of the anions. It is now demonstrated that these rules are also valid for oxoanions of the main group elements of the periodic system. Applying these and other relations it was possible to predict the value of the symmetric stretching frequency ν1(A1) of xenon tetroxide. Some vibrational properties of XeO4 (force constants, mean amplitudes of vibration, the Coriolis coupling constant and the bond order) are also calculated and compared with those of related species.

The chemistry of Eremophila spp. VIII. A cembrenetriol from E. clarkei

1977 ◽  
Vol 30 (12) ◽  
pp. 2717 ◽  
Author(s):  
P Coates ◽  
EL Ghisalberti ◽  
PR Jefferies
Keyword(s):  
Double Bond ◽  
Relationship Of ◽  
The Relationship

The isolation of a triol (1) from the title plant is described. Reduction and deoxygenation of (1) leads to the cembrane (12). The position of the primary hydroxyls is fixed by a stereochemical argument and the relationship of the 1-hydroxy-1-methylethyl group and the double bond is established through the pyrrole (14).

Long-range coupling and conformation in some thienylmethylene and furfurylidene derivatives

1977 ◽  
Vol 30 (2) ◽  
pp. 357 ◽  
Author(s):  
GC Brophy ◽  
PJ Newcombe ◽  
RK Norris
Keyword(s):  
Aromatic Ring ◽  
Long Range ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Vicinal Coupling Constant

The p.m.r, spectra of 12 2-thienylmethylene and furfurylidene derivatives are reported. The average conformation about the Ar-CHXY bond is deduced from the magnitude of the meta (and ortho) long-range benzylic coupling constants. In thiophens, conformations in which the benzylic hydrogen is in or near the plane of the aromatic ring and anti to the ring sulphur are preferred. In furans the hydrogen-in-plane conformations are again favoured. The signs of the meta and ortho benzylic coupling constants have been determined and are positive and negative respectively with respect to the vicinal coupling constant J3,4.

Israeli Law and Jewish Law — Interaction and Independence

1990 ◽  
Vol 24 (3-4) ◽  
pp. 507-524 ◽  
Author(s):  
Brahyahu Lifshitz
Keyword(s):  
Legal System ◽  
Point Of View ◽  
The Other ◽  
Jewish Law ◽  
Positive Law ◽  
Social Nature ◽  
Two Systems ◽  
The One ◽  
The Relationship

Jewish law is an independent legal system embracing most of the subjects to be found in any system of positive law. The hopes and efforts of many people notwithstanding, Israeli law is not identical to Jewish law, nor does it constitute one of its branches. The generally accepted view is that Jewish law is not influenced, nor affected in any way, by the acts of the Israeli legislature or judiciary. There is, however, little doubt that to a certain extent, Israeli law is influenced by Jewish law. It is therefore a legitimate exercise to discuss the nature of the relationship between the two systems from the point of view of Israeli law. We may also comment upon the amount of satisfaction or disappointment which may legitimately be felt, on the one hand, by those in favour of reinforcing the relationship between the two systems and making it stronger and more active and, on the other, by those opposed to such a relationship. It should also be observed that the interrelationship between Israeli and Jewish law is not only to be perceived from the standpoint of pure law. Any discussion of this question involves issues of a political, religious and social nature; a study focussing on the bare legal facts alone would provide a necessarily distorted picture.

Bond Localization Energy. I. Definition, Methods of Computation, and Relation to Bond Order

1949 ◽  
Vol 2 (4) ◽  
pp. 564
Author(s):  
RD Brown
Keyword(s):  
Bond Order ◽  
Theoretical Discussion ◽  
Localization Energy ◽  
Resonance Energies ◽  
The Relationship ◽  
Bond Localization ◽  
Activated Complex ◽  
Mobile Order

A new quantity-the bond localization energy-which has some advantages in the theoretical discussion of the chemical reactivities of various bonds, is introduced. Its relationship to the activated complex is indicated. It is shown to be expressible in terms of the resonance energies of certain molecules related to the molecule being considered. The various methods available for computing resonance energies by the LCAO method are outlined and some of these are used to derive numerical values for the localization energies of particular bonds. The relationship between bond localization energy and mobile order is investigated, and the significance of the relations thus found is indicated.

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