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

摘要

The cyclic phosphazene trimers [N_3P_3(OC_6H_5)_5 OC_5H_4N·Ti(Cp)_2Cl][PF_6] (3), [N_3P_3(OC_6H_4CH_2CN·Ti(Cp)_2 Cl)_6][PF_6]_6 (4), [N_3P_3(OC_6H_4-Bu~1)_5(OC_6H_4CH_2CNTi(Cp)_2 C1)][PF_6] (5), [N_3P_3(OC_6H_5)_3C_6H_4CH_2CN-Ru(Cp)(PPh_3)_2] [PF_6] (6), [N_3P_3(OC_6H_5)_5C_6H_4CH_2CN·Fe(Cp)(dppe)][PF_6] (7) and N_3P_3(OC_6H_5)_5OC_5H_4N·W(CO)_5 (8) were prepared and characterized. As a model, the simple compounds [HOC_5H_5N·Ti(Cp)_2Cl]PF_6(1) and [HOC_6H_4CH_2CNTi(Cp)_2 Cl]PF_6 (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 TR 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 nanostruclures. 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.