Structure Analysis of Tantalum Chloride–Graphite Intercalation Compound Using Molecular Simulations

Structure analysis of graphite intercalated with TaCl-6 and TaOCl3 has been carried out using molecular mechanics simulations and compared to previously published experimental data obtained by X-ray powder diffraction, electron diffraction, and other techniques. The basal spacing calculated for the second stage of graphite intercalated with tantalum(V) chloride c2(calc)= 12.80 ? was in agreement with the experimental value c2(exp)=12.79 ? obtained from X-ray powder diffraction. Modeling revealed the two-dimensional ordering of TaCl-6 octahedra in the interlayer space of graphite lattice. This ordered interlayer structure of TaCl-6 is incommensurate with the graphite lattice and can be described as the two-dimensional space group 17pm6, hexagonal plane lattice with the lattice parameter 6.54 ?. The simulated electron diffraction pattern for calculated structure was in good agreement with that seen in the experiment. The guest layer lattice parameter obtained from electron diffraction was 6.5 ?. The simulations gave evidence that this guest structure can be obtained only with TaCl-6 octahedra as guests; other possible guests––TaCl5 dimers––can be definitely excluded. In case of tantalum oxychloride the fragments of TaOCl3 chain structure are arranged in the interlayer space, giving the basal spacing of the second stage c2(calc)=13.39 ?.