Octahedral complexes angular distortion

Tabie 2. AOM parameters and angular variables for hexa-coordinated complexes where the first coordination spheres [MAg] (A = N, O, Cl) show an octahedral or trigonally distorted geometry. The lower symmetries may be induced, for example, by the chelate geometry or by impacts due to the crystal lattice. The symmetry of the LF potential may be reduced if non-isotropic rr-bonding is apparent The actual structure of the [MAj] entity is very near to an octahedron. For planar chelates ip is not independent from 6 and

complexes investigated in this contribution... 

Two main aspects of the HDW approach are important for the present discussion. One aspect is that the model is valid only in the absence of orbital angular momentum contributions to the system, so that its use has been broadly restricted to (say) binuclear complexes of iron(LLl), octahedral nickel(II), or distorted octahedral copper(II). The other aspect concerns the fact that the parameter is a global parameter of the system sequestering many contributions from various ligands and orbitals and, in this respect, may be compared with how Dq in ligand-field theory represents the net effect of electrostatic and covalent (o and rr) effects in the tjg — eg orbital splitting. Attempts to localize our conception of the exchange phenomenon have been made by various... 

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