The Group 14 Element Chlorides

The first four elements of Group 13 form trichlorides that are stable at normal temperatures and pressures. BCI3 is a volatile liquid at room temperature and monomeric in the gas phase. AICI3, GaCl3, and lnCl3 form solids at room temperature. Evaporation at moderate temperatures yields mixtures of monomeric and dimeric species. At higher temperatures aU the gaseous trichlorides suffer partial decomposition to form monochlorides and CI2  

At a given temperature and pressure, the equihbrium shifts to the right as the group is descended from B to In. 

TICI3 has been synthesized and isolated as a sohd, but decomposes at temperatures above 40°C to yield the solid monochloride and chlorine gas  

The mass spectra of the gas formed by evaporation of solid TICI3 show that it contains significant amounts of monochloride and chlorine in addition to trichloride. Neither the molecular structure nor the enthalpy of formation of gaseous, monomeric TICI3 has been determined. 

TlBrs and TII3 may not exist. The former is only known as a crystalline tetrahydrate, presumably [(H20)4Tl]Br3, that decomposes on dehydration. A solid of composition TII3 was later shown to be the salt Tl (l3) . 

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The spherical ion model and the bond energies of the Group 13 element chlorides... 

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