A second method to determine the geometry of boranes are the wade rules. Polyhedral skeletal electron pair theory wikipedia. Wade s rules tlv february 11, 2019 bonding in the polyhedral boranes wade s rules since alfred stocks early preparation of the boron hydrides, b x h y, these molecules have played an important role in understanding covalent bonding. The type of structure adopted by a particular compound has been shown to related to the number of electrons that are available in the compound for bonding within the polyhedral framework. To use this method, the total number of valence electrons that are forming the bonds must be determined n number of boron atoms.
A way of correlating the number of framework electrons with the structure is by wade rules and it proposed. The structure of the numerous boranes and carboranes falls into the closo nido and arachno categories. The chemistry of the boranes was first studied systematically by alfred stock. The isolobal principle and application of wade s rules last updated. In chemistry, the jemmis mno rules represent a unified rule for predicting and systematizing. The isolobal principle and application of wades rules. Wades rules are used to rationalize the shape of borane clusters by calculating the total number of skeletal electron pairs sep available for.
Boranes boranes are compounds composed solely of boron and. Boranes assigning closo, nido, arachno, hypo nomenclature. Wades rules though the lipscombs topological model involving styx numbers and rules was good in the rationalization of structures of some of the boranes and related species, it was not enough to higher boranes and carbonyl clusters. In the past, borane molecules were often labeled electrondeficient because of their multicenter bonding in which a pair of bonding electrons links more than two atoms, as in 3center2electron bonds. Therefore, a more sophisticated and comprehensive method was needed. This video shows what are closo, nido and archano boranes. An important class of electrondeficient borane compounds. Wades rules for structural elucidation of boranes and. The wade rules are a correlation between the number of electrons, the formula and the shape of the molecule. The jemmis mno rule provides the relationship between polyhedral boranes, condensed.
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