ISOLOBAL ANALOGY PDF

A graphic representation of isolobal structures, with the isolobal pairs connected through a double-headed arrow with half an orbital below, is found in Figure 1. Construction of isolobal fragments To begin to generate an isolobal fragment, the molecule needs to follow certain criteria. Molecules should satisfy the octet rule and all bonding and nonbonding molecular orbitals MOs are filled and all antibonding MOs are empty. For example methane is a simple molecule from which to form a main group fragment. The removal of a hydrogen atom from methane generates a methyl radical. The molecule retains its molecular geometry as the frontier orbital points in the direction of the missing hydrogen atom.

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He developed the concept of isolobal analogy or principle to show the connection between two important areas of chemistry. According to this concept, the molecular fragments of a cluster are deemed to be isolobal if they possess same number of frontier molecular orbitals with: i similar shape, symmetry and radial extent; ii approximately the same energy; iii same number of electrons available for cluster bonding.

The isolobal fragments may not be isostructural and isoelectronic. They only possess similar characteristics for the frontier molecular orbitals.

The relation between isolobal fragments is indicated by double headed twirly arrows i. These isolobal fragments provide electrons for cluster bonding that lead to variety of cluster molecules, at least theoretically. Examples: 1 The C-H group carbyne , P atom and Co CO 3 fragment are isolobal since each of them possesses 3 similar orbitals and can contribute 3 electrons for cluster bonding.

These can contribute 2 electrons for cluster bonding. Note: The number of skeletal electrons SE that can be contributed for cluster bonding by a molecular fragment can be calculated as follows. In this case, the Cr metal is replaced by Mn to remove the negative charge when the proton number increases, the excess negative charge is neutralized.

It may or may not be possible to synthesize the new molecule generated by the isolobal transformation.

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ISOLOBAL ANALOGY (principle and application)

He developed the concept of isolobal analogy or principle to show the connection between two important areas of chemistry. According to this concept, the molecular fragments of a cluster are deemed to be isolobal if they possess same number of frontier molecular orbitals with: i similar shape, symmetry and radial extent; ii approximately the same energy; iii same number of electrons available for cluster bonding. The isolobal fragments may not be isostructural and isoelectronic. They only possess similar characteristics for the frontier molecular orbitals. The relation between isolobal fragments is indicated by double headed twirly arrows i. These isolobal fragments provide electrons for cluster bonding that lead to variety of cluster molecules, at least theoretically.

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Isolobal principle

Grogar Anaolgy addition of two ligands to linear compounds, ML2, can afford square planar complexes, for example, XeF2 adds fluorine to give square planar XeF4. Predicting the reactivity of complexes can also be accomplished using the isolobal analogy. Molecular orbital — In chemistry, a molecular orbital is a mathematical function describing the wave-like behavior of an electron in a molecule. Norbornyl Cation Electron Density.

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ISOLOBAL ANALOGY PDF

For example, methane is a simple molecule from which to form a main group fragment. The removal of a hydrogen atom from methane generates a methyl radical. The molecule retains its molecular geometry as the frontier orbital points in the direction of the missing hydrogen atom. Further removal of hydrogen results in the formation of a second frontier orbital. Figure 2 demonstrates this example of step-by-step generation of isolobal fragments.

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