Pyramidal structures decomposition

Compound 18 adopts the now-familiar square-pyramidal structure. Reaction between it and PyO causes its decomposition to MTO and a disulfide... 

Gep2 is formed as a volatile white solid (mp 110°) by the action of Gep4 on powdered Ge at 150-300° it has a unique structure in which trigonal pyramidal [GePsI units share 2 P atoms to form infinite spiral chains (Pig. 10.2). Pale-yellow GeCl2 can be prepared similarly at 300° or by thermal decomposition of GeHCls at 70°. Typical reactions are summarized in the scheme ... 

The interesting Mo204(Et2Dtc)2 complex is a decomposition product of the 1 1 adduct of Mo(XEt2Dtc)2 with dimethyl acetylenedicarboxylate (551). The structure of this molecule has been determined (Fig. 26). The Mo(V) ions in the dimer are five-coordinate and show square pyramidal coordination (197). 

All four scandium(III) halides are known, all but the fluoride (WO3 structure) having the FeCfr structure. They can be obtained as white solids directly from the elements and in some cases by dehydration of the hydrated salts, as well as by thermal decomposition of (NH4)3ScX6 (X = Cl, Br), a method also used for the lanthamdes. Gas-phase studies have identified isolated planar SCF3 molecules at 1750K ScCfr molecules with a very slight pyramidal distortion and both monomers and dimers in Scfr vapour at 1050 K. 

Whilst the 2D-DWT provides an efficient space-frequency characterisation of a given image, it only uses a fixed decomposition of the pixel space. As in the case of the 1-D wavelet packet transform, we can extend the wavelet packets to two dimensions. That is, the 2D wavelet packet transform (2D-WPT) generates a more general, full m -ary tree representation with a total of m + m + m sub-bands for h levels. Each sub-band in a given level of the tree splits into a smoothed sub-band and m"-l detailed sub-bands, resulting in a tree that resembles an m-way pyramidal stack of sub-bands. For the case of a dyadic decomposition scheme, this corresponds to a pyramidal sub-band structure where each sub-band is decomposed into 2 = 4 sub-bands at each successive (higher) level (see Fig. 2). Fig. 7 shows results of the third level of the 2D WPT for the dyadic case - a total of = 64... 

In many of the studies it is assumed that the particles are nuclei of Ba metal, although barium nitrides are also found. Studies have been made of the rate of particle formation and the rate of particle growth during thermal decomposition [184,186]. The particles are initially round, but after a certain size is reached, they become diamond shaped [184,186]. The formation is structure sensitive. Torkar et al, reported that particle formation starts at the surface but that the particles or nuclei which are found are oblique pyramids, oriented relative to the crystal axes [187]. By X-ray diffraction and other techniques approximately 75% of thermally decomposed Ba(Na)2 has been identified as BaaN2 with the remaining 25% being Ba, presumably in metallic form. 

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