Titanium Group Phosphides

The phosphides of the elements of Group IV A have in most cases been prepared, although their compositions have not been established with certainty. A method which seems to succeed in cases where others fail is the double decomposition of phosphine with the chlorides (Wohler's reaction), i.e. with those of silicon, titanium and zirconium. This method was not successful, however, with ThCl₄

The phosphides of titanium and zirconium to which were assigned the formulae TiP and ZrP₂ are described as yellow or grey crystalline substances, which conduct electricity. They burned when heated in air, but were not affected by aqueous acids or aqueous oxidising agents. Thorium phosphide has been made by reducing ThCl₄ with phosphorus vapour.