Reaction of hexakis(3,5-dimethylpyrazolyl)cyclotriphosphazene (L) with LnCl(3) (Ln = La, Ce, Nd, Sm) affords new mononuclear lanthanophosphazenes [L.LnCl(3)] with hendecahedral coordination polyhedron in which the ligand L employs an unprecedented kappa(5)N binding core consisting of one cyclotriphosphazene ring nitrogen atom and four pyridinic nitrogen atoms of two sets of geminal pyrazolyl groups.