Vanadium dichloride, VC12, is a green crystalline solid obtained when the tetrachloride is reduced with hydrogen at a dull red heat.
Molybdenum monoxide, MoO.n(H 2 O), is a black powder obtained when the dichloride is boiled with concentrated potash solution.
Germanium dichloride, GeCl2, and germanium chloroform, GeHCl3, have also been described.
Ruthenium dichloride, RuC1 2, is obtained (in solution) by reducing the sesquichloride by sulphuretted hydrogen or zinc. It is stable in the cold.
It is remarkable that the position of the halogen in the molecule has no effect on the heat of formation; for example, chlorpropylene and allylchloride, and also ethylene dichloride and ethylidene dichloride, have equal heats of formation.