Molecular, 1D and 2D assemblies from hexakis(3-pyridyloxy)cyclophosphazene containing 20-membered metallamacrocyclic motifs.

The coordination behaviour of hexakis(3-pyridyloxy)cyclophosphazene (L) towards divalent metal ions is described. The reaction of L with hydrated metal nitrates afforded [{N3P3(O-C5H4N-3)6}2{Zn(H2O)3(NO3)}2{Zn(H2O)2(NO3)}2]n[NO3]2n·4nH2O·nCH3OH (1), [{N3P3(O-C5H4N-3)6}2{Zn(H2O)3(NO3)}2{Cu(NO3)}2]n[NO3]2n·4nH2O·nCH3CN (2), [{N3P3(O-C5H4N-3)6}2{(NO3)Cd-(μ-(NO3)-Cd(NO3)2(μ-(NO3)Cd(NO3)}]n·2nCH3OH·3nH2O (3), and [{N3P3(O-C5H4N-3)6}2{Cd(H2O)3(NO3)}2][NO3]2·9H2O (4). 1 and 2 are one-dimensional coordination polymers while 3 is a two-dimensional coordination polymer. On the other hand 4 is a molecular metallamacrocycle. A common feature of 1-4 is the presence of a 20-membered dimetallamacrocyclic motif constructed through the involvement of a pair of cyclophosphazene ligands through their geminal pyridyloxy substituents. The P-N bond distances in L and its metal complexes 1-4 are nearly the same indicating the flexible nature of the coordination pyridyloxy arms present on the cyclophosphazene scaffold.