Trigonal prism complexes

CTP (capped trigonal prism) complexes all the others are the PBP (pentagonal-bipyramidal) complexes. 

FIGURE 3.4 Trigonal prism complex formed by 2 3 self-assembly (24) of linear 8 p,p-ZnjL" ) with TCA. (a) Top view, (b) Side view. 

Ms " clusters have 12 framework bonding electrons as has [BsHs]- (p. 161) the anions are also isoelectronic with the well-known cation [Bis]. Similarly, the alloy NaSn. 2.23 reacts with cryptand in ethylenediamine to give dark-red crystals of [Na(ciypt)]4 [Sng] the anion is the first example of a C41, unicapped Archi-median antiprism (Fig. 10. lOc) and differs from the >3/, structure of the isoelectronic cation [Bis] + which, in the salt Bi+[Bi9] +[HfCl6]5 (p. 591), features a tricapped trigonal prism, as in [BgHg] " (p. 153). The emerald green species [Pb9] , which is stable in liquid NH3 solution, has not so far proved amenable to isolation via ciyptand-complexed cations. 

The structure of these complexes is not regular and has been described as 4 3 (C ) piano stool , which is obtained by slight distortion of a capped trigonal prism (C2d). 

Icosahedron Complex Trigonal prism Trigonal prism... 

FIGU RE 16.2 Geometrical isomers for MX4Y2 complexes having planar hexagonal, trigonal prism, and octahedral structures. 

The real structures of these phases are more complex. The coordination of the Ti atoms is always six, but the coordination polyhedron of sulfur atoms around the metal atoms is in turn modulated by the modulations of the Sr chains. The result of this is that some of the TiS, polyhedra vary between octahedra and a form some way between an octahedron and a trigonal prism. The vast majority of compositions give incommensurately modulated structures with enormous unit cells. As in the case of the other modulated phases, and the many more not mentioned, composition variation is accommodated without recourse to defects. ... 

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