Bond properties multicentered

For example, MeLi forms a distorted cubic structure of the tetramer of Li4C4 skeleton as shown in Figure 3.2. MeLi forms a multicenter bond one lithium bonds with three lithium atoms and three carbon atoms, and one carbon bonds with three lithium atoms. These multicenter bonds have ionic bond properties [37-41]. 

This article covers only a part of the chemistry of boron. Boron-carbon compounds are covered in other articles in this volume see Boron Organoboranes Boron Metallacarbaboranes, and Boron Polyhedral Carboranes). The main subject of the latter two articles, and the separate one on Boron Hydrides is the extensive chemistry of the multicenter bonded boron-hydride systems. This area has been a major focus of boron research for the past 60 years. There is some direct overlap between the two articles Borides Solid-state Chemistry and Borates Solid-state Chemistry, and this more general one covering the inorganic chemistry of boron. Boron-Nitrogen Compounds are also covered separately. These articles should be consulted for more detailed discussions of the structure, bonding, and properties of borides, solid-state borates, and boron-nitrogen compounds. 

In Other words one may state that the hydrogen bond is the Lewis acid-Lewis base interaction which leads to the formation of the A-H... B link where A-H and B play the role of the Lewis acid (electron accepting) and Lewis base (electron donating) centers, respectively. Further the numerous properties of this link may be specified, as for example that B may be mono-center (atom of any species or ion) or multicenter (ir-electron or o-electron system). 

Theoretical investigations of the molecule P4 show that the valence shell electron density in this species should be concentrated inside and on the faces of the tetrahedron taking part in multicenter molecular bonding. Although after such a description little or no nucleophilic properties of P4 can be expected, there are some metallic compounds in which the unit participates as a whole. Examples of some transition metal complexes containing the unit P4 are shown in Table 4.15. 

A property of main group atoms which have the ability to acquire coordination numbers greater than 4 (which would comply with the Lewis octet rule). Hypercoordination may be associated with hypervalency, but usually is referred to peculiar atomic centers in electron-deficient species with multicenter cr-bonding, in which pairs of electrons are spread over more than two atoms. 

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