Tetrahedral silicon bond arrangements

Although the stereochemistry of silicon in these compounds presents no points of special interest, the bond arrangement being the normal tetrahedral one, the siloxanes include some interesting ring systems. 

Crystalline silicon has the tetrahedral diamond arrangement, but since the mean thermochemical bond strength between the silicon atoms is less than that found between carbon atoms (Si—Si, 226 kJmol , C—C, 356kJmol ), silicon does not possess the great hardness found in diamond. Amorphous silicon (silicon powder) is microcrystalline silicon. 

Our discussion to this point has been limited to molecules m which the chirality center IS carbon Atoms other than carbon may also be chirality centers Silicon like carbon has a tetrahedral arrangement of bonds when it bears four substituents A large number of organosilicon compounds m which silicon bears four different groups have been resolved into their enantiomers... 

There are a variety of silicates, which can be viewed as various arrangements of tetrahedral oxoanions of silicon in which each Si—O bond has considerable covalent character. The differences in properties between the various silicates are related to the number of negative charges on each tetrahedron, the number of corner O atoms shared with other tetrahedra, and the manner in which chains and sheets of the linked tetrahedra lie together. Differences in the internal structures of... 

Triphenylsilanol has 16 molecules in the unit cell, arranged as two sets of two independent tetrameric hydrogen-bonded units. These units each have a flattened tetrahedral arrangement of silicon atoms, Fig. 

Disregarding the type of bond, the tetrahedral group [Si04] is usually represented in the conventional ways outlined in figure 5.3, with the oxygen atoms at the corners and silicon at the center of the tetrahedron, and the structure of sih-cates is normally described as a function of the relative arrangements of the... 

With atoms such as carbon and silicon, the valence-state electronic configuration to form four covalent bonds has to be (s)1(px)1(py)1(ps)1. Repulsion between the electron pairs and between the attached nuclei will be minimized by formation of a tetrahedral arrangement of the bonds. The same geometry is predicted from hybridization of one s and three p orbitals, which gives four sp3-hybrid orbitals directed at angles of 109.5° to each other. The predicted relative overlapping power of s -hybrid orbitals is 2.00 (Figure 6-10). 

Figure 3.33a shows the diamond structure. Each of the carbon atoms in the giant structure is covalently bonded to four others. They form a tetrahedral arrangement similar to that found in silicon(iv) oxide (p. 50). This bonding scheme gives rise to a very... 

---