Search results
Results from the WOW.Com Content Network
In chemistry the polyhedral skeletal electron pair theory (PSEPT) provides electron counting rules useful for predicting the structures of clusters such as borane and carborane clusters. The electron counting rules were originally formulated by Kenneth Wade , [ 1 ] and were further developed by others including Michael Mingos ; [ 2 ] they are ...
In chemistry, the Jemmis mno rules represent a unified rule for predicting and systematizing structures of compounds, usually clusters.The rules involve electron counting. They were formulated by E. D. Jemmis to explain the structures of condensed polyhedral boranes such as B 20 H 16, which are obtained by condensing polyhedral boranes by sharing a triangular face, an edge, a single vertex, or ...
The bonding of the clusters ushered in Polyhedral skeletal electron pair theory and Wade's rules, which can be used to predict the structures of boranes. [3] These rules were found to describe structures of many cluster compounds.
Polyhedral skeletal electron pair theory for polyhedral cluster compounds, including transition metals and main group elements and mixtures thereof, such as boranes. Atoms are called " electron-deficient " when they have too few electrons as compared to their respective rules, or " hypervalent " when they have too many electrons.
In 1978, Mingos, Stephen G. Davies and Malcolm Green compiled a set of rules that summarise where nucleophilic additions will occur on pi ligands. [9] Mingos' 1984 paper on the polyhedral skeletal electron pair theory develops Wade's electron counting rules for predicting the molecular geometry of cluster compounds. [10]
An extended version of the 3c–2e bond model features heavily in cluster compounds described by the polyhedral skeletal electron pair theory, such as boranes and carboranes. These molecules derive their stability from having a completely filled set of bonding molecular orbitals as outlined by Wade's rules.
Gilbert N. Lewis introduced the concepts of both the electron pair and the covalent bond in a landmark paper he published in 1916. [1] [2] MO diagrams depicting covalent (left) and polar covalent (right) bonding in a diatomic molecule. In both cases a bond is created by the formation of an electron pair.
This shape is found when there are four bonds all on one central atom, with no extra unshared electron pairs. In accordance with the VSEPR (valence-shell electron pair repulsion theory), the bond angles between the electron bonds are arccos(− 1 / 3 ) = 109.47°. For example, methane (CH 4) is a tetrahedral molecule.