Trigonal-prismatic complexes

The redox potentials of trigonal prismatic complexes span a similar range as that observed for octahedral V(III) complexes. The complexes V(bpy)(Cl4Cat)2 (bpy = 2, 2 -bipyridine, CUCat = tetrachlorocatecholato) and V(bpy)(acac)(Cl4Cat) have V(III/II) couples at —1.74 and —1.75 V versus Cp2Fe/MeCN respectively. The V(III/IV) couples are —0.35 and —0.50 V, respectively, values which are comparable to the octahedral TAN complexes above. However, the V(IV/V) couples are at 0.92 and 0.06 V versus Cp2Fe/MeCN respectively, a significant difference when compared to the other two couples [28]. 

As for V(III), trigonal prismatic complexes, and trigonally distorted octahedral complexes are not uncommon for V(IV) [56]. The ligand set exerts a stronger influence on the redox potentials, whether the coordination geometry is octahedral or trigonal prismatic, at least to a first approximation. A series of compounds made with tridentate and tetradentate ligands with N- and O-donor atoms such as the azophenol derivative shown in Fig. 8 has both reversible oxidations and reductions. 

Another example of a trigonal prismatic complex is the porphyrin prism 24, also reported by Fujita and coworkers [139]. This complex is formed upon coordination of three face bridging zinc(II)-coordinated porphyrin ligands to six palladium(II) ions at the corners of the prism. Although... 

Formally similar complexes (11-XXIV) can be given by orthoquinones. Thus interaction of Cr(CO)6 with tetrachlorobenzoquinone (L) gives CrL, the oxygen atoms can also bind to separate metals so that a bridged quinone results. The tris species tend to form distorted trigonal prismatic complexes. 

Type II. In this category, ligand field restrictions are nonexistent. Consider the example 42 - 43. In the trigonal prismatic complex 42 the two... 

The same ligand [C2S2(CF3)2] coordinated to molybdenum forms pseudo-octahedral (the actual structure is intermediate between octahedral and trigonal prismatic) complexes of the type [Mo C2S2(CF3)2 3] , which have been employed as acceptors [44]. Two CT complexes with different stoichiometries with [FeCpf] have been described. The 1 1 material shows in the solid state a ID-DADA type structure and turns out to be ferromagnetic (0 = - - 8.4 K, but no bulk ferromag-... 

In VII, the metal atomic dyz and dzx orbitals are of SA and AS symmetries, respectively. A number of ligand distributions about the metal would leave these orbitals nonbonding with respect to the ligand bond network. In the trigonal prismatic complex VIII, for example, dyz and dzx are nonbonding and degenerate, exclusive of the two olefin ligands. 

Fig. 15 View of the structure of the trigonal prismatic complex [(Me3tacn)6Mn Mog (CN)i8]2+...

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