Interaction diagram bonding

The construction of the pair of (bond orbitals is carried out by combining a carbon hybrid with the Is orbital on hydrogen in a manner similar to the construction of the CC bond orbitals. The interaction diagram is shown below in Fig. 3. The bonding orbital is occupied by the two bond electrons. These two... 

Figure 4.46 Orbital interaction diagram for the Au6C framework in (H3PAu)6C2+showing the important bonding interactions of the carbon 2s and 2p orbitals with the MOs of the gold cluster. (Reprinted from J. Organomet. Chem., 384, 405, 1990, with kind permission from Elsevier Science S.A., P.O. Box 564, 1001 Lausanne, Switzerland.)...

In calculations and interaction diagrams, only the most simplistic MO models will be chosen to represent ground and excited states of reactants. An olefin then has a bond framework largely neglected in discussing the reactivity of the molecule. The bonding level will be characterized by a jr-electron wave function with no nodes between the two basis fi orbitals of the ir-bond. The first jr-antibonding level has one node in the wave function, and a first excited state has electron-occupancy of unity in each level. 

Photolysis of benzaldehyde and trimethylethylene yields a mixture of cis and trans oxetanes with the two orientations shown in Eq. 42. Orientation 7 predominates and biradical intermediates generated after formation of a bond involving the lone nonbonding electron of an n, n excited benzaldehyde have been postulated. 66> Fig. 5 is the interaction diagram, the molecular parameters being based on HMO calculations, and spectroscopic experiments. 55,56,109) The orbital interaction E(n) F(n) is obviously dominant since the energy gap between F n ) and E n ) is over 4 eV. Therefore, a biradical mechanism should be postulated. The dominant orbital interaction is largest for attack of the... 

The regioselectivity of each one of the previously cited reactions, Eqs. 29—31, is well-correlated by the interaction diagram. The degenerate interaction of the bonding levels is controlling, and whether the reaction is concerted or biradical the major orientation should be as shown in 19. The olefin 1,1-dichloroethylene was taken as the model for 1,1-dimethoxy-ethylene. 

Figure 4.107 Perturbative interaction diagrams (on a common vertical energy scale cf. Fig. 4.106) depicting significant localized bonding interactions for PtH42 (a) metal hybrid formation (NAO NHO), (b) interaction of bonding hybrids to form bonding (a) and antibonding (a ) NBOs (NHO- NBO), and (c) nH

Focusing now on the sigma lone pair interactions, we can simplify the interaction diagram as shown in Fig. 11. The relative stabilization of the cis and trans geometries due to the interaction of the lone pairs with the central C-C bond can be assessed from consideration of all orbital interactions shown in Fig. 11. These interactions and their impact upon geometrical preference are discussed below. 

MO s of the component system can be easily developed. The final simplified interaction diagram is shown in Scheme 1. Clearly, we now have an additional interaction, as compared to the 1,2-difluoroethylene case, which stabilizes the cis isomer. Hence, the sigma nonbonded interaction of bonds is expected to favor a cis structure when the two bonds are coupled through another sigma bond. 

The appropriate interaction diagram is shown in Fig. 21. The energies of the unperturbed orbitals are independent of the degree of rotation about the C-C single bond. Consequently, we need only consider changes in the overlap integrals that accompany rotation. 

The appropriate interaction diagram is shown in Fig. 50. Arguing as before, we predict that the W conformation is preferred since there is an anti relationship between the carbon lone pair and the X-H bond in this conformation. 

Fig. 53. LCFC interaction diagram for (a) F20 and (b) H20. 6 EG is the energy change due to the geminal interactions and 8 E is the energy change due to back bonding of the lone pairs of F to the oxygen...

Planet offers a 2-D representation (similar to that used in LIGPLOT [36]) of the protein-ligand interaction called a PLAID (Protein-Ligand Accessibility and Interaction Diagram, Figure 10.3). It is automatically calculated from the PDB data and shows van der Waals interactions, hydrogen bonds and solvent accessible areas. The interaction can be also viewed in 3 D or as the original PDB entry. 

The cation-radical version of diene synthesis, in which the diene is in a strongly electron-deficient state, is characterized by an unusual high endoselectivity. In this case, endoselectivity is sig-nihcantly higher than that of thermal or photochemical initiation of a neutral molecule (cf. Mlcoch and Steckhan 1987). As follows from the charge diagram depicted in Scheme 7.21, when a cation-radical and neutral molecule approach each other, not only the C(l)-C(6) and C(4)-C(5) interactions are bonding (indeed, these interactions result in cyclization), but C(2)-C(7) and C(3)-C(8) interactions are also bonding. As a result, the endo product is formed. 

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