Tetrahedral complexes Orgel diagrams

Furlani and Morpurgo (98) have, however, obtained very good spectra of the complex anions in nitromethane addition of a small excess of halide was necessary in most cases. Their results are summarized in Table VI, together with the assignment in a regular tetrahedral field. The symbols used may be understood by reference to the Orgel diagram of Fig. 8. 

Additionally, we note that octahedral and tetrahedral complexes have opposite energy orderings (Fig. 8.1.5). Hence d1 octahedral and d9 tetrahedral have the same Orgel diagram the same is true for d6 octahedral and d4 tetrahedral complexes. In other words, the Orgel diagram in Fig. 8.5.2 is also applicable to d1, d4, d6, and d9 tetrahedral complexes. Since tetrahedral complexes are not centrosymmetric, their states do nothave g or u designations. States in Fig. 8.5.2 do not carry subscripts they should be put back on for octahedral complexes. 

If some of the solution of the product of photoreduction in Sec.9.4.2 is quickly dispensed into a vacuum 1 cm spectrophotometer cell and its spectrum is run over the visible range, a broad band appears at 460 nm. A similar band is seen in the Ti(III) solution prepared in Sec.9.3.1. An examination of the generalised Orgel diagram (Fig.A9.2) shows that in both octahedral or tetrahedral complexes, only one d-d transition is expected. On the other hand, the single u.v. band of the complex analysed in Sec.9.3.1 is due to ligand to metal charge transfer since no d-d transitions are expected. (Fig.A9.3 sketches all the possible electronic transitions for a metal complex). 

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