Parameter axial splitting

The EPR powder spectra of the low-spin complexes [0s(NH3)5L][CF3S03]3 (L = H20 or (5)) have been analyzed the negative sign obtained for the axial splitting when L = (5) has been rationalized in terms of Os L backbonding. Crystal field parameters have also been derived. The spectral and electrochemical properties of [Ru(NH3)5L]" (Ru or Ru L =RC02 R = 4-py-A-Me+ or L = RCONH R = Ph, 4-py-A-Me", 4-py-A-H+) have been studied in detail as a function of pH the carboxamido Ru complexes are weak bases and are deprotonated only in strongly acidic solution. ... 

The axial splitting parameter Aax (which is positive when the A-term is the ground state),... 

The axial splitting parameter is Aax < 0 when the ground Eg term arises from the splitting of the octahedral T-term then Aax > 0 applies when the ground state is either A- or fi-type. 

However, the reduced parameter alters the sign when passing from the less-than-half-filled shells to more-than-half-filled ones (since A. alters the sign) then, also, the axial splitting parameter v = A/ alters the sign. 

Fig. 9. Zero-field splitting of the S = 2 ground state of [Fe3S4] clusters. Constructed for D = -2.5 and E/D = 0.23, where D and E are the axial and rhombic zero-field splitting parameters, respectively.

Foyt et al. [137] interpreted the quadrupole-splitting parameters of low-spin ruthenium(II) complexes in terms of a crystal field model in the strong-field approximation with the configuration treated as an equivalent one-electron problem. They have shown that, starting from pure octahedral symmetry with zero quadrupole splitting, A q increases as the ratio of the axial distortion to the spin-orbit coupling increases. 

The first term is characterized by a scalar, 7, and it is the dominant term. Be aware of a convention disagreement in the definition of this term instead of -27, some authors write -7, or 7, or 27, and a mistake in sign definition will turn the whole scheme of spin levels upside down (see below). The second and third term are induced by anisotropic spin-orbit coupling, and their weight is predicted to be of order Ag/ge and (Ag/ge)2, respectively (Moriya 1960), when Ag is the (anisotropic) deviation from the free electron -value. The D in the second term has nothing to do with the familiar axial zero-field splitting parameter D, but it is a vector parameter, and the x means take the cross product (or vector product) an alternative way of writing is the determinant form... 

EPR. The EPR for 48 has been reported. The frozen solution spectrum measured in concentrated sulfuric acid is typical of a monomeric square-planar Cu(II) complex with axial g tensor and 63 65Cu hyperfine splitting (hfs) tensor. The measured parameters are compared to Cu(TPP) and Cu pc in Table XI. 

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