Crystal-field theory octahedral complexes

Crystal field theory d-orbital splitting in octahedral and tetrahedral complexes... 

Co(ni) acetylacetonates show frequencies closer to the low spin high spin. Co(tfac)3 has an even lower v(Co—O) band than calculated for low spin, i.e. 445 vi. 451 cm , respectively . Therefore, metal-ligand vibrations for a series of octahedral metal complexes are in order Co(II) < Ni(II) and Zn(II) < Ni(II) within the same ligand system. Fe(III) < Mn(III) < Cr(III) is observed, as expected from crystal field theory . 

The crystal field theory as applied to octahedral, tetragonal, tetrahedral and sejuare planar metal complexes... 

Crystal field theory was developed, in part, to explain the colors of transition-metal complexes. It was not completely successful, however. Its failure to predict trends in the optical absorption of a series of related compounds stimulated the development of ligand field and molecular orbital theories and their application in coordination chemistry. The colors of coordination complexes are due to the excitation of the d electrons from filled to empty d orbitals d-d transitions). In octahedral complexes, the electrons are excited from occupied t2g levels to empty Cg levels. The crystal field splitting Ao is measured directly from the optical absorption spectrum of the complex. The wavelength of the strongest absorption is called Amax and it is related to Ao as follows. E = hv, so Ao = hv = Because en-... 

---