Metalation Studies of Carbophosphazene-Based Coordination Ligands: Metallacages to Polymeric Networks

The metalation behavior of [NC­(NMe₂)]₂[NP­(p-OC₅H₄N)₂] (L1) and [NC­(NMe₂)]₂[NP­(m-OC₅H₄N)₂] (L2) is described. The ligands L1 and L2 were prepared by the reaction of the carbophosphazene, [NC­(NMe₂)]₂[NPCl₂] with 4-hydroxy pyridine or 3-hydroxy pyridine. The disposition of the coordinating nitrogen atoms does not allow the coordinating groups within the same molecule to bind to a single metal ion. This leads to the formation of molecular complexes (di- and tetranuclear) and coordination polymers (one- and two-dimensional). Thus, the interaction of L1 with a Hg­(II) salt afforded a dinuclear complex, [Hg­(Cl)₂(L1)]₂ (1). The reaction of L2 with Ag­(I) salts afforded both dinuclear complexes and tetranuclear complexes, [Ag­(CF₃SO₃)­(L2)]₂ (2) and [Ag­(NO₃)­(L2)]₄·2MeOH (3), respectively. The reaction of copper acetate with L1 or L2 afforded one-dimensional polymeric networks [Cu₂(CH₃COO)₄(L1)]_n (4) and [Cu₂(CH₃COO)₄(L2)]_n (5). In 4 and 5, the basic dinuclear motif of copper acetate is preserved. In contrast to the reaction of L1 with HgCl₂ which afforded a dinuclear complex 1, a similar reaction with L2 resulted in a two-dimensional polymeric network, [Hg­(Cl)₂(L2)]_n (6). Similarly, the interaction of L2 with CoCl₂ afforded a two-dimensional coordination polymer, [Co­(Cl)₂(L2)₂]_n (7). The latter contains 40-membered metallacylces, which are fused to each other in the formation of the coordination polymer.