Orbital rules

The predictions of the orbital rules are straightforward when apphed to migrations in which transition states involve relatively little strain. Difficulty arises when the allowed states are difficult to achieve. 

Some Electron Configurations Ignore the Orbital Rules... 

A full account of the crystal structure determination of potassium heptacyano-vanadate(m) dihydrate has appeared.387 Apart from clearing up the uncertainty surrounding the nature of the vanadium(m) cyanide complex, this study has established the V(CN)7- ion as one of the very few examples of a seven-co-ordinate complex containing only simple unidentate ligands. The choice of this co-ordination number has been rationalized on the basis of the nine-orbital rule. The two electrons of the paramagnetic V(CN)4 ion (pef = 2.8 BM) occupy two separate orbitals,... 

Larsson, S. (1981) Electron transfer in chemical and biological systems orbital rules for non-adiabatic transfer. Journal of the American Chemical Society, 103, 4034 4040. 

LarssonS. (1981), Electrontransferinchemicalandbiological systems. Orbital rules for nonadiabatic transfer , J. Am. Chem. Soc. 103, 4034 040. 

Molecules are also examples of the special stability of filled shells. The simple molecular orbital rule is that a molecule is thermodynamically stable if all the bonding MOs are filled, and all the anti-bonding ones are empty. Other examples are the Octet Rule of Lewis and Langmuir and the 18-Electron Rule of Sidgwick. These relate hardness to stability just as Figure 4.1 does. So do the famous Hiickel rule (4 + 2), and the Wadc Mingos rule (2 2) ... 

Phys. 74 6746 (1981) b) G. L. Gloss, L. T. Calcaterra, N. J. Green, K. W. Penfield, and J. R. Miller, Distance, stereoelectronic effects, and the Marcus inverted region in intramolecular electron transfer in organic radical anions, J. Phys. Chem. 90 3673 (1986). a) S. Larsson, Electron transfer in chemical and biological systems. Orbital rules for nonadiabatic transfer, J. Am. Chem. Soc. 103 4034 (1981) b) S. Larsson, n Systems as bridges for electron transfer between transition metal ions, Chem. Phys. Lett. 90 136 (1982) c) S. Larsson, Electron transfer in proteins, J. Chem. Soc., Faraday Trans. 2 79 1375 (1983) d) S. Larsson, Electron-exchange reaction in aqueous solution, J. Phys. Chem. 88 1321 (1984) e) S. Larsson,... 

Since, it is 1, 3-sigmatropic rearrangement, hence, on the basis of orbital rules there should be inversion at migrating centre. 

Hund s rules Rules which describe the electronic configuration of degenerate orbitals in the ground state. The electronic configuration will have the maximum number of unpaired... 

The so-ealled Slater-Condon rules express the matrix elements of any one-eleetron (F) plus two-eleetron (G) additive operator between pairs of antisymmetrized spin-orbital produets that have been arranged (by permuting spin-orbital ordering) to be in so-ealled maximal eoineidenee. Onee in this order, the matrix elements between two sueh Slater determinants (labelled >and are summarized as follows ... 

The Woodward-Hoffmann method [52], which assumes conservation of orbital symmetry, is another variant of the same idea. In it, the emphasis is put on the symmetries of molecular orbitals. Longuet-Higgins and Abramson [53] noted the necessity of state-to-state correlation, rather than the orbital correlation, which is not rigorously justified (see also, [30,44]). However, the orbital symmetry conservation rules appear to be very useful for most themial reactions. 

Hiickel-type systems (such as Hilcfcel pericyclic reactions and suprafacial sigmatropic shifts) obey the same rules as for sigma electron. The rationale for this observation is clear If the overlap between adjacent p-electron orbitals is positive along the reaction coordinate, only the peraiutational mechanism can... 

For many reasons, including the Woodward-IIoffm an rules that describe the likelihood of reaction based on arguments about the shapes of orbitals, it is desirable to be able to visualize molecular orbitals. 

Slater provided a series of empirical rules for choosing the orbital exponents (, which are... 

Alder Endo Rule In order to maximize secondary orbital interactions, the endo TS is favored in the D-A rxn. Tetrahedron 1983, 3,9, 2095... 

---