Contribution of olefinic ring strain to pentacarbonylchromium-cyclooctene bond strengths

1990 ◽  
Vol 9 (3) ◽  
pp. 874-876 ◽  
Author(s):  
Jane K. Klassen ◽  
Gilbert K. Yang
Keyword(s):  
Ring Strain ◽  
Bond Strengths

Ring strain and the negative pole. IV. Relationships dependent on localized electric field

1971 ◽  
Vol 24 (3) ◽  
pp. 457 ◽  
Author(s):  
IJ Miller
Keyword(s):  
Electric Field ◽  
Bond Length ◽  
Small Ring ◽  
Qualitative Explanation ◽  
Group V ◽  
Ring Strain ◽  
Negative Pole ◽  
Ring Atom ◽  
Bond Strengths ◽  
The Stability

The acidity, infrared stretching frequency, and bond length of a substituent atom on a strained ring is linearly dependent on the contribution of the ring atom to the negative pole as previously defined. Bond strengths are similarly, but non-linearly, proportional. A qualitative explanation for the stability of the molecules of the Group V elements is offered. An explanation for the Schmidt rule is also offered, and it is deduced that this rule should be applicable to any bond α,β to a strained alicyclic small ring.

Physical, Chemical, and Crystallographic Characterization of Anodic Coatings on High Strength Aluminum Base Alloys

1976 ◽  
Vol 34 ◽  
pp. 636-637
Author(s):  
R. E. Herfert ◽  
N. T. McDevitt
Keyword(s):  
Sulfuric Acid ◽  
Salt Spray ◽  
High Strength ◽  
Environmental Stability ◽  
Anodic Films ◽  
Sodium Dichromate ◽  
Corrosion Resistant ◽  
Aerospace Applications ◽  
Bond Strengths ◽  
Adhesive Bonded Joints

Durability of adhesive bonded joints in moisture and salt spray environments is essential to USAF aircraft. Structural bonding technology for aerospace applications has depended for many years on the preparation of aluminum surfaces by a sulfuric acid/sodium dichromate (FPL etch) treatment. Recently, specific thin film anodizing techniques, phosphoric acid, and chromic acid anodizing have been developed which not only provide good initial bond strengths but vastly improved environmental durability. These thin anodic films are in contrast to the commonly used thick anodic films such as the sulfuric acid or "hard" sulfuric acid anodic films which are highly corrosion resistant in themselves, but which do not provide good initial bond strengths, particularly in low temperature peel.The objective of this study was to determine the characteristics of anodic films on aluminum alloys that make them corrosion resistant. The chemical composition, physical morphology and structure, and mechanical properties of the thin oxide films were to be defined and correlated with the environmental stability of these surfaces in humidity and salt spray. It is anticipated that anodic film characteristics and corrosion resistance will vary with the anodizing processing conditions.

Total etch dentin bonding systems: scanning electron microscopy of the resin-dentin hybrid layer

1992 ◽  
Vol 50 (2) ◽  
pp. 1092-1093
Author(s):  
Jorge Perdigao
Keyword(s):  
Composite Resin ◽  
Mechanical Interlocking ◽  
Hybrid Layer ◽  
Agent Based ◽  
Dentin Bonding ◽  
Acid Agent ◽  
Bond Strengths ◽  
Main Component ◽  
Bonding Systems ◽  
New Generation

In 1955, Buonocore introduced the etching of enamel with phosphoric acid. Bonding to enamel was created by mechanical interlocking of resin tags with enamel prisms. Enamel is an inert tissue whose main component is hydroxyapatite (98% by weight). Conversely, dentin is a wet living tissue crossed by tubules containing cellular extensions of the dental pulp. Dentin consists of 18% of organic material, primarily collagen. Several generations of dentin bonding systems (DBS) have been studied in the last 20 years. The dentin bond strengths associated with these DBS have been constantly lower than the enamel bond strengths. Recently, a new generation of DBS has been described. They are applied in three steps: an acid agent on enamel and dentin (total etch technique), two mixed primers and a bonding agent based on a methacrylate resin. They are supposed to bond composite resin to wet dentin through dentin organic component, forming a peculiar blended structure that is part tooth and part resin: the hybrid layer.

Electrostatic effects on ionization equilibria: An MNDO study of proton and hydrogen transfer reactions of 4-fluorobutylamine

1990 ◽  
Vol 55 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Zdeněk Friedl ◽  
Stanislav Böhm
Keyword(s):  
Hydrogen Transfer ◽  
Substituent Effects ◽  
Radical Cations ◽  
Transfer Reactions ◽  
Protonated Forms ◽  
Minor Part ◽  
Bond Strengths ◽  
Ionization Equilibria ◽  
A Minor ◽  
Gas Phase Basicities

The relative enthalpies of proton transfer δ ΔH0and homolytic bond strengths δDH0(B-H+) were calculated by the MNDO method for the sp and ap conformers of 4-flurobutylamine. The data obtained, along with the experimental gas phase basicities, are compared with the values predicted by the electrostatic theory. It is shown that the substituent polar effects FD on the basicities of amines are predominantly due to interactions in their protonated forms (X-B-H+) and/or radical-cations (X-B+.), those in the neutral species (X-B) playing a minor part. A contribution, which is considerably more significant in the sp conformer than in the ap conformer, arises probably also from substituent effects on the homolytic bond strength DH0(B-H+.

Bis(perchlorocatecholato)silane and Heteroleptic Bidonors: Hidden Frustrated Lewis Pairs by Ring Strain

2021 ◽  
Author(s):  
Deborah Hartmann ◽  
Sven Braner ◽  
Lutz Greb
Keyword(s):  
Ammonia Borane ◽  
Frustrated Lewis Pairs ◽  
Ring Strain ◽  
Frustrated Lewis Pair ◽  
Lewis Pairs

Bis(perchlorocatecholato)silane and bidentate N,N- or N,P-heteroleptic donors form hexacoordinated complexes. Depending on the ring strain and hemilability in the adducts, Frustrated Lewis pair reactivity with aldehydes and catalytic ammonia borane...

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