Trigonal prism structure

Figure 1-5 The tricapped trigonal prism structure found in many 9-coordinate complexes.

Cages with nine vertices are rare. Representative ones are Bi + (in Bi24Cl26), B9Hi , and B7QH9, all of which have the tricapped trigonal prism structure (Fig. 1-5), and Sn9, which is a square antiprism capped on one square face. 

Such a procedure was used successfully by Wemer to demonstrate that six-coordinate complexes have an octahedral structure. The method starts with the assumption that a six-coordinate system has a structure in which the six ligands are situated at positions symmetrically equidistant from the central atom. If it is further assumed that three of the more probable structures are (1) planar, (2) a trigonal prism, and (3) octahedral (Table 1.5), then it is possible to compare the number of known isomers with the number theoretically predicted for each of these structures. Such a comparison shows that for the second and third compounds in Table 1.5 planar and trigonal prism structures predict there should be three isomers. Instead, complexes of these types were... 

Rh.2(C)2(COh4] - c Z)2h, C atoms are in holes of two units having trigonal prism structure 2... 

From the analysis of the solid-state structure of the pseudorotaxane formed by 4 and a non-symmetric axle 18 I Br (Scheme 29.6), it emerged that the calixarene wheel possesses a trigonal prism structure 1.65 nm in length with an internal width of about 0.75 nm [34]. 

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