New molecular compounds of the layer lattice type. I. New molecular compounds of graphite

Abstract

An extension of previous work (Croft 1952) on molecular compounds of graphite has led to the discovery of over 30 new molecular compounds of the layer lattice type. In addition, the experimental data revealed some necessary conditions for compound formation. Thus, intercalation was found to be most probable with multivalent chlorides of the transition metals, but only when the latter are in their higher valence states. Chlorides of all Group IIIA elements can also form molecular compounds with graphite. Intercalation is related to the position of the cation of the test substance in the periodic table. Molecular shape, polarity, and the covalent nature of the test substance have little, if any, relation to its reactivity with graphite. Graphite compounds formed from Group IIIA chlorides are distinguished from those containing transition metal chlorides by the possibility of hydrolysing intercalated cations of the former but not those of the latter. The metal cations of graphite-ZrCl₄ and graphite-YCl₃ are also capable of hydrolysis in situ. The results of this investigation suggest the possibility of employing graphite compound formation to effect many chemical separations and purifications.