Dodecahedral complex

Fig. 2. In the centre of this drawing there is shown a dodecahedral complex. The polyhedra that surround it are tetrakaidecahedra, each having two hexagonal faces...

Eight-coordinate dodecahedral complexes of the general type W(L-L)4 are known for several bidentate ligands such as dithiocarbamate, 8-quinolinol, substituted quinolinols, picoline and substituted picolines. 

In the structure of [ThCl4(Ph2SO)4] the Cl atoms occupy the B sites and the sulfoxide O atoms the A sites in the dodecahedral complex.131... 

Monomeric, paramagnetic chlorohydrides snch as MH2CI2 (PR3)4 derive from facile oxidative addition of H2 to MCl2(PR3)4 complexes. Of these 17e dodecahedral complexes, (32) is the most interesting (eqnation 17). Its thermolysis in solution offers a qnadruply bridged hydride (33) and it can also be rednced to a monomeric Ta 16e species (34). Ta hydrides display a hydridic character (see Hydride Complexes of the Transition Metals), as shown by the reduction of CO by cyclopentadienyl derivatives. (see Niobium Tantalum Organometallic Chemistry)... 

A further example of an eight-coordinate dodecahedral complex of titanium(IV) is the volatile, anhydrous Ti(N03)4 in which the nitrate groups are bidentate, coordinating through two oxygen atoms (11). The nitrate groups are arranged symmetrically about the metal atom with Dxd symmetry in a flattened tetrahedral manner. ... 

The salt K4[Mo(CN)g]-2H20 was the first example (in 1939) of an 8-coordinate (dodecahedral) complex. However, studies on a range of salts of [Mo(CN)8]" and [W(CN)g]" reveal cation dependence, both dodecahedral and square antiprismatic anions being found. The K4[M(CN)g] salts are formed by reactions of K2MO4, KCN and KBH4 in the presence of acetic acid the [M(CN)8]" ions are kinetically inert with respect to hgand substitution (see Section 25.2), but can be oxidized to [M(CN)g] as described earlier. 

The structure of Zr(acac)2(N03)2, 8-coordinate by virtue of bidentate nitrate ligands, is a classic dodecahedral complex. Coordination of two tetradentate thiolate ligands like that in Figure 9.33e, but with trimethylsilyl substitutents ortho to each thiolate group, results in a dodecahedral V(V) anion (Figure 9.34e) with an interesting electronic ground state. ... 

The salt K4[Mo(CN)s]-2H20 was the first example (in 1939) of an 8-coordinate (dodecahedral) complex. However, studies on a range of salts of [Mo(CN)8] and [W(CN)8] reveal cation dependence, both dodecahedral and square... 

Fig. 8 Valency counting picture and the nonbonding densities for dodecahedral complexes...

We may apply this protocol to understand the 18g complexes discussed above. Note that there are only two choices of the d orbital for the lone pair d 2 or any four-lobe d orbital (e.g., dxy). For the d 2 nonbonding orbital, with a nonbonding density that resembles a bicone, the eight ligands can be arranged in the dual positions in the square-antiprismatic manner. Similar analysis can be done for the four-lobe dxy orbital, which will easily result in dodecahedral complexes. 

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