Copper(I) complexes of cyclodiphosphazanes

Cyclodiphosphazanes or diazadiphosphetidines are four-membered saturated inorganic ring systems containing alternate nitrogen and phosphorus atoms. These rings with a planar structure exist in cis-and trans-isomeric forms with respect to exocyclic phosphorus substituents with a small energy difference and repeated crystallization leads to thermodynamically preferred cis-isomers. Reactions of cyclodiphosphazane derivatives with CuX resulted in the formation of simple monomeric to tri-, tetra-, or octameric complexes to three-dimensional coordination polymers showing very rare sodalite and diamondoid topologies. This chapter summarizes the details on copper(I) complexes of several cyclodiphosphazane derivatives and their antitumor properties.