Crystal field splitting tetragonal complexes

Figure 9 The crystal field splitting of Fe and Fe d orbitals in cubic O/, tetragonal D41, and rhombic C2 environments (a). Only the latter two are typically observed for metal porphyrinoid complexes. The axial and rhombic ligand field parameters are denoted as A and V. The low-, intermediate- and high-spin states for Fe and Fe " based on a tetragonal environment (b). (Reprinted from Mack, Stillman and Kobayashi, Elsevier 2007)...

Figure 2.13 Crystal field splittings and electron distributions for some metal complexes. The struetures of the first two complexes are oetahedral, and the others (left to right) are tetragonal, square planar, and tetrahedral (see Figure 2.10).

Since the splitting parameter in the tetrahedral field is smaller than in the octahedral field, the tetrahedral field is always a weak field, Aptetrahedral field, the highest values of CFSE correspond to d and d configurations. Figure 3.9 presents the comparative crystal field splitting of d orbitals of the central ion in complexes of geometry tetrahedral, octahedral, tetragonal, and square-planar. 

For tetragonal complexes, one component of the first d-d band 82) will retain the energy (10 Dq) of the parent, while the other ( E) will be separated from it by 35/4 Dt, if configuration interaction is neglected. For the cyanoaquo complexes listed above, the splitting is predicted to be 35/4 (260 cm = 2275 cm for single substitution, according to simple crystal field theory, and twice that amount for disubstituted trans complexes. These predictions for the frequencies of the components of the first d-d band are compared in Fig. 5 with the observed frequencies of the band components for the entire series of cyanoaquochromium(III) complexes. 

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