Single/double bond relationship

The skeleton immediately above this description of compound number 95 possesses a six-carbon sidechain into which the single double bond must be inserted. Because this sidechain is not part of the cyclic portion of the molecule, the molecular description code, 12(13)E, includes an E defining the steric relationship around the double bond. Thus, sequence rule-preferred C-11 and C-14 are situated on opposite sides of the double bond. 

Carter, E. A., Goddard III, W. A., 1988, Relationships between Bond Energies in Coordinatively Unsaturated and Coordinatively Saturated Transition Metal Complexes A Quantitative Guide for Single, Double, and Triple Bonds , J. Phys. Chem., 92, 5679. 

The same relationships are seen as we go from single bond to double bond to triple bond between carbon and carbon the bond energies increase while the bond lengths decrease. 

The first stereochemical analysis of the polymerization mechanism of unsaturated monomers was proposed by Arcus 30 years ago (58, 269). The diaste-reomeric relationships within a single chain may be connected to monomer configuration by two factors the type of addition to the double bond (cis or trans) and the way in which successive monomer molecules approach the growing chain. For a CHA=CHB olefin the relationship between the stmcture of the monomer and that of the adding monomeric unit is illustrated in Scheme 22 (31), where cis or trans addition indicates that the new bonds are formed in the same half-space or in the two opposite half-spaces, provided there is no rotation aroimd the central C—C single bond. 

The Cope rearrangement is the conversion of a 1,5-hexadiene derivative to an isomeric 1,5-hexadiene by the [3,3] sigmatropic mechanism. The reaction is both stereospecific and stereoselective. It is stereospecific in that a Z or E configurational relationship at either double bond is maintained in the transition state and governs the stereochemical relationship at the newly formed single bond in the product.137 However, the relationship depends upon the conformation of the transition state. When a chair transition state is favored, the EyE- and Z,Z-dienes lead to anli-3,4-diastereomcrs whereas the E,Z and Z,/i-isomcrs give the 3,4-syn product. Transition-state conformation also... 

If one correlates the calculated electron density at the bond critical point p and the CC bond distance R for a variety of hydrocarbons, a linear relationship will be obtained which holds for both single, double, triple, aromatic and homoaromatic CC bonds. On the basis of this relationship, a bond order n(CC) has been defined according to equation 780,82 ... 

Solution Because Jcc is sensitive to the fraction of s character (/) in both carbon orbitals of the a bond, a relationship similar to Eq. (9.2) should prove valid for carbon-carbon coupling. The a component of a triple bond is formed in part by the overlap of two sp orbitals, that of a double bond involves overlap of two sp2 orbitals, and a single bond results from overlap of two sp3 orbitals. Thus, the desired relationship should include the product of both/values ... 

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