Silicon tetrahalides physical properties

The physical properties of silicon tetrahalides are listed in Table 1 those of the halohydrides are listed in Table 2. A more complex review of the physical properties of these chemicals is available (2). Detailed lists of properties of the colorless fuming liquids, silicon tetrachloride and trichlorosilane, are given in Table 3. A review of the physical and thermodynamic properties of silicon tetrachloride is given in Reference 3. 

Selected physical properties of the tetrahalides of C and Si are listed in Table 13.3. The carbon tetrahalides differ markedly from those of the later group 14 elements they are inert towards water and dilute alkali and do not form complexes with metal halides. The distinction has been attributed to the absence of d orbitals in the valence shell of a C atom look back at the electronic versus steric debate, outlined in Section 13.3. However, one must be cautious. In the case of CX4 being inert towards attack by water, the lack of C d orbitals presupposes that the reaction would proceed through a 5-coordinate intermediate (i.e. as is proposed for hydrolysis of silicon halides). Of course, it is impossible to establish the mechanism of a reaction that does not occur Certainly, CF4 and CCI4 are thermodynamically unstable with respect to hydrolysis compare the value of AjG° for equation 13.35 with that of —290 kJ mol for the hydrolysis of SiCl4. 

Table 13.3 Selected physical properties of the carbon and silicon tetrahalides.

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