Discrete and Polymeric Coordination Assemblies Derived from 3-Pyridyl Attached Flexible Phosphoric Triamide Ligand and Copper Salts

Abstract

A new example of phosphonium cation, [P(NH3Py)4]+, (2) featuring 3-pyridyl substituents has been reported. Reactivity of 2 with KOH in methanol have resulted in the formation of a neutral phosphine imine [P(N3Py)(NH3Py)3], 2-H. Treatment of 2 with various metal salts of copper have resulted in a P–N bond cleavage in which the in situ generated phosphoramide ligand [PO(NH3Py)3], 1, has shown to yield interesting kinds of self-assembled structures in macrocyclic, cage and 2D-coordination polymers. Thus, the reaction of 2 with Cu(NO3)2 in methanol gave the supramolecular [M6L8]12+ type cage reported earlier with the phosphoramide 1. Treatment of 2 with a Cu(I) salt in CHCl3 under ambient conditions have lead to the formation of a 20-membered macrocyclic Cu(II) compound [(PO(NH3Py)3)CuCl2]2, 3, via the in situ oxidation of Cu(I). In another reaction, treatment of 1 or 2 with Cu(NO3)2 in a reducing solvent such as dimethylformamide (DMF) under hydrothermal conditions gave a Cu(I) coordination polymer {[Cu2(PO(NH3Py)3)3](NO3)2}n, 4. Crystallographic studies on all these newly synthesized compounds have shown interesting kinds of supramolecular organization for these molecules.