Thermolytic Transformation of Organometallic Polymers Containing the Cr(CO)5 Precursor into Nanostructured Chromium Oxide

Journal of Cluster Science (Impact Factor: 1.3). 12/2005; 16(4). DOI: 10.1007/s10876-005-0033-x
Source: OAI


Thermal treatment in air of the organometallic polymer
\(\{\left[\hbox{NP}(\hbox{O}_2\hbox{C}_{12}\hbox{H}_8)\right]_{0.8}\left[\hbox{NP}(\hbox{OC}_6\hbox{H}_4\hbox{CH}_2\hbox{CN} \bullet[\hbox{Cr}(\hbox{CO})_5]_{0.13})_2\right]_{0.18}\}_{n}\) (1) results in the formation of nanometer-size metal oxide particles. Cr particles in the 35–85 nm range, mostly 54 nm, immersed in an phosphorus oxides matrix were found. ATG studies in air suggest that the formation of the nanostructures occurs in four steps, the first involving loss of the carbonyl groups of the Cr(CO)5 fragment. The following steps involve the oxidation of the organic matter and finally the oxidation of the chromium to give the pyrolytic product. The use of these kinds of organometallic polymers as precursors for a general and potential new route to materials having metal/metal oxide nanostructures is discussed.

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    ABSTRACT: Pyrolysis in air of the carborane-substituted polyphosphazene, {[NP({OCH2}2C2B10H10)]0.5 [NP({OCH2}2C2B9H10· NBu4)]0.5}n affords BPO4 crystals of varied sizes in the micro and nano regime.The materials were characterised by IR spectroscopy, SEM-EDAX, TEM, X-ray diffraction, and DTA analysis. A possible mechanism for the formation of these materials is discussed and compared with that found for the formation of metallic nanostructured materials from the pyrolysis of anchored organometallic derivatives of polyphosphazenes.
    Preview · Article · Nov 2006 · Journal of Inorganic and Organometallic Polymers and Materials
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    ABSTRACT: Co-polyphosphazenes containing anchored organometallic fragments are useful precursors for nanostructured metallic materials. Pyrolysis in air at 800°C yields metallic nanoparticles of the type, M°/Mx Oy /Mz (Px Oy )/P4O7, depending on the metal used; i.e., M° when the metal is a noble metal, metal oxide when the metal is Cr, W and Ru, metallic pyrophosphate when M = Mn and Fe. The organic spacer of the polyphosphazene influences strongly the morphology of the pyrolytic product. The mechanism of formation of the nanostructured materials involves carbonization of the organic matter, which produces holes where the nanoparticles are grown. Reaction of the phosphorus polymeric chain with O2 yield phosphorus oxide units, which act as a P4O7 matrix to stabilize the nanoparticles and/or Px O y −n for the formation of metallic pyrophosphates. The method appears to be a general and versatile new route to metallic nanostructured materials.
    Preview · Article · Nov 2006 · Journal of Inorganic and Organometallic Polymers and Materials
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    ABSTRACT: Pyrolysis of the organometallic polymer: {{[N=P(R1)]0.8[N=P(OC6H4CH2CN[Ru])2]0.15[N=P((OC6H5)(OC6H4CH2CN[Ru]]0.05}{Cl}0.31} n , [Ru]=CpRu(PPh3)2, R1=O2C12H8 (1) as well of the cyclic specie {N3P3 (OC6H5)5(OC6H4CH2CN[Ru])}{PF6} (2) under a flow of air at 800°C affords nanostructured RuO2. Nanoparticles near to 10nm were observed. The differences in the use of cyclic or polymeric phosphazenes, as solid state template, influence strongly the morphology and slightly the composition of the pyrolytic product. Temperature variable (SQUID) measurements in the range of 5–300K of the material obtained from the polymer, indicate an antiferromagnetic interaction between the Ru atoms, although lower than that found for the crystalline ruthenium oxide, probably due to some amorphous product present in the pyrolytic material. The possible formation mechanism is discussed and the differences in using the cyclic or the polymeric compound as precursor is analyzed in terms of the relative content of Ru to P, N. A general formation method of nanostructured metal oxides is proposed.
    No preview · Article · Nov 2007 · Journal of Cluster Science
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