Cyano-organophosphorus compounds react by a metathesis reaction in a liquid medium with tetravalent metal ions yielding layered crystalline to amorphous inorganic polymers having the empirical formula M(O3 PRCN)2 or M(O3 PORCN)2 where M is a tetravalent metal and R is a an organic group covalently bonded to phosphorus and the terminal cyano group.