Tetragonal symmetry complexes

The results presented in Figures 1 and 2 are typical of Cu(ll) complexes with tetragonal symmetry and can be interpreted in terms of an axial spin Hamiltonian. 

Term symbols, 26-27, A7-A12 Tetrachloroiodate anion. 209 Tetragonal crystal system, 75, 78 Tetragonal symmetry. 403-404 Tetrahedral complexes, 401-403, 418-420, 441. 448-455, 474-477... 

Low-symmetry LF operators are time-even one-electron operators that are non-totally symmetric in orbit space. They thus have quasi-spin K = 1, implying that the only allowed matrix elements are between 2P and 2D (Cf. Eq. 28). Interestingly in complexes with a trigonal or tetragonal symmetry axis a further selection rule based on the angular momentum theory of the shell is retained. Indeed in such complexes two -orbitals will remain degenerate. This indicates that the intra-t2g part of the LF hamiltonian has pseudo-cylindrical D h symmetry. As a result the 2S+1L terms are resolved into pseudo-cylindrical 2S+1 A levels (/l = 0,1,..., L ). It is convenient to orient the z axis of quantization along the principal axis of revolution. In this way each A level comprises the ML = A components of the L manifold. In a pseudo-cylindrical field only levels with equal A are allowed to interact, in accordance with the pseudo-cylindrical selection rule ... 

Approximate tetragonal symmetry is often also assumed for chelate complexes of the type trans-M(A A)2B2. Without this assumption, but specifying that the B ligands have a cylindrically symmetric 7t-interaction with the metal, the ligand field potential matrix has the general form... 

Figure 22 visualizes the spin hamiltonian parameters calculated for five coordinate CoA5 complexes with geometries intermediate between a trigonal bipyramid (

In addition to the 72 and states, the T, state lies some 500cm above in pseudo-octahedral complexes. In lower symmetry complexes both E and Tj are split, and in strong tetragonal fields, one of the Tj components is below E [32] as evidenced by the markedly broader emission spectrum [33]. There appears to be good thermalization between the Ti and E states. As a result of the thermalization, all of the photophysical rates for steps originating in E/ T, are population weighted averages of the rate constants for the individual states. If all reaction occurs in doublet states, the same conclusion applies to calculated from Eq. (21). 

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