Linnett structures

As an example, we give in Fig. 5 the Linnett structure of the oxygen molecule in its triplet ground state. It is seen that Linnett s formula is quite different from that of Lewis (also given in Fig. 5). This is obviously... 

In conclusion, the Boys localization procedure may be considered as the mathematification of the qualitative Lewis and Linnett theories. As pointed out, in this perspective a formal signification of the symbols used by these authors can be proposed these represent not localized electrons but centroids of charge of localized orbitals. Within this interpretation, the former theories agree much better with the ideas of quantum mechanics such as the wave character of electrons that prevents their localization. Moreover, the results obtained by the Boys procedure allow us to predict the Lewis and (or) Linnett structures of many chemical species without performing explicit calculations. For example, linear and bent 1,3-dipoles are described by the following general formulas ... 

Captodative radicals have both electron donor and electron acceptor substituents at the radical center. The separate stabilizing effects of these substituents appear to have the ability to be synergistic. A Linnett structure gives a similar representation. 

The Linnett structure [12,13] of OF2 contains spatially paired electrons around the O atom. The unshared electrons around the F atoms are not spatially paired [12]. 

The above considerations show that the Green and Linnett structure A B, with one bonding and two non-bonding electrons, provides a better and clearer diagramatic representation of the electron distribution than does the Pauling stmcture A---B. Therefore we shall use the A-B representation in the remainder of this book. However, (perhaps misleadingly), we shall continue to refer to this valence-bond stmcture as a Pauling 3-electron bond stmcture. 

With respect to formal charge distribution, the Linnett structure (Section 2-2)... 

Linnett and Rosenberg have discussed the electronic structure of a number of nitroso and potential nitroso systems, including benzo-furoxans, using the non pairing approach. ... 

J. W. Linnett. There were 11 papers with theoretical inputs but with more emphasis given to new developments in experimental methods including structural (LEED and electron microscopy) and surface spectroscopies. LEED provided crucial evidence for the role of surface steps at platinum single crystals in the dissociation of various diatomic molecules, while electron microscopy revealed the role of dislocations as sites of high reactivity of... 

Linnett used the concept that an octet of valence shell electrons consists of two sets of four opposite-spin electrons to show that in diatomic and other linear molecules the two tetrahedra are not in general formed into four pairs as we have discussed for F2 and the CC triple bond in C2H2. This idea is the basis of the double-quartet model, which Linnett applied to describe the bonding in a variety of molecules. It is particularly useful for the description of the bonding in radicals, including in particular the oxygen molecule, which has two unpaired electrons and is therefore paramagnetic This unusual property is not explained by the Lewis structure... 

Linnett, J. W. The Electronic Structure of Molecules A New Approach Methuen London, 1964. 

Linnett, J. W. (1964). The electronic structure of molecules. London Methuen. 

In an early application to butadiene [16], and later to the ground and excited states of benzene [17], Berry analyzed MO-based wavefunctions using valence bond concepts, simply by considering the overlaps with nonorthogonal VB structures. Somewhat closer than this to a CASVB type of approach, are the procedures employed by Linnett and coworkers, in which small Cl wavefunctions were transformed (exactly) to nonorthogonal representations [18-20]. The main limitation in their case was on the size of systems that may be treated (the authors considered no more than four-electron systems), both because this non-linear transformation must exist, and because it must be possible to obtain it with reasonable effort. 

Linnett s procedure may be viewed as a refinement of classical structural theory In Linnett s theory, the van t Hoff-Lewis tetrahedral model is applied twice, once to each set of spins, with the assumption that, owing to coulombic repulsions between electrons of opposite spin, there may be, in some instances, a relatively large degree of spatial anticoincidence between a system s two spin-sets. 

Looking at the composition of these orbitals, the VB structure (22) is very similar to that involved in the Linnett-type non-paired spatial orbital representation for a four electron, three-centre bonding unit [23], discussed by Harcourt in Ref. [24]. The only difference is related to the number of hybrids involved in the Harcourt paper only three hybrids, one for each atom, are considered while here, owing to the use of an extended basis set, the four localized orbitals in Eq. (22) derive from the six hybrids described above. 

Linnett, J. W. Structure of Silyl and Methyl Azides and Isocyanates. Nature [London] 199, 168—169 (1963). 

Figure 2. Kermack-Robinson [14], Linnett [16] and Prideaux [15] VB structures for CgH6 and PF5.

The (primarily) minimal basis set calculations of Linnett and co-workers [19] demonstrate clearly that the npso structures with one-electron bonds... 

Figure 4. Pauling and Linnett three-electron bond VB structures for He2+, NO, O2 and NO2. (a) Electron spins indicated for the three-electron bond, when Ms = +1/2.

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