Cyclohexaphosphates of Alcaline Metals

Abstract

The fast progress of chemistry of condensed phosphates resulted in a great attention to this kind of inorganic polymers all over the world. This paper reports preparation by ion exchange with lithium salt (1), solubility in water, some structural data and thermal transformation of alcaline metals cyclohexaphosphates (CHP). The crystal structures of all the compounds (table) were determined (Na₆P₆O₁₈·6H₂O one has been described previously (2)). The crystals are built up of CHP-rings and alcaline metal (M^I) polyhedra, so that during the transition from Li to Cs coordination number (c.n.) of M^I increases from 4 to 9. In crystal Li₆P₆O₁₈ · 5H₂O only 4 water molecules are coordinated by metal, moreover, there are channels where 2 additional water molecules may be placed. Rb₆P₆O₁₈·6H₂O and Cs₆P₆O₁₈·6H₂O were found to be isomorphous, as well as anhydrous K₆P₆O 18 and Rb₆P₆O₁₈.