Structures of one-dimensional PdII–PdIV mixed-valence complexes, [PdIIL][PdIVCl2L]Y4 (Y= ClO4 and PF6), and their parent PdII and PdIV complexes, [PdIIL](ClO4)2 and [PdIVCl2L](NO3)2.HNO3.H2O, with 1,4,8,11-tetraazacyclotetradecane (L)