Organometallic Derivatives of Cyclotriphosphazene as Precursors of Nanostructured Metallic Materials: A New Solid State Method

The cyclic phosphazene trimers N₃P₃(OC₆H₅)₅OC₅H₄N·Ti(Cp)₂Cl]PF₆] (3), N₃P₃(OC₆H₄CH₂CN·Ti(Cp)₂Cl)₆]PF₆]₆ (4), N₃P₃(OC₆H₄-Bu^t)₅(OC₆H₄CH₂CN·Ti(Cp)₂Cl)]PF₆] (5), N₃P₃(OC₆H₅)₅C₆H₄CH₂CN·Ru(Cp)(PPh₃)₂]PF₆] (6), N₃P₃(OC₆H₅)₅C₆H₄CH₂CN·Fe(Cp)(dppe)]PF₆] (7) and N₃P₃(OC₆H₅)₅OC₅H₄N·W(CO)₅ (8) were prepared and characterized. As a model, the simple compounds HOC₅H₅N·Ti(Cp)₂Cl]PF₆ (1) and HOC₆H₄CH₂CN·Ti(Cp)₂Cl]PF₆ (2) were also prepared and characterized. Pyrolysis of the organometallic cyclic trimers in air yields metallic nanostructured materials, which according to transmission and scanning electron microscopy (TEM/SEM), energy-dispersive X-ray microanalysis (EDX), and IR data, can be formulated as either a metal oxide, metal pyrophosphate or a mixture in some cases, depending on the nature and quantity of the metal, characteristics of the organic spacer and the auxiliary substituent attached to the phosphorus cycle. Atomic force microscopy (AFM) data indicate the formation of small island and striate nanostructures. A plausible formation mechanism which involves the formation of a cyclomatrix is proposed, and the pyrolysis of the organometallic cyclic phosphazene polymer as a new and general method for obtaining metallic nanostructured materials is discussed.