Field Splitting in Octahedral Complexes

This value is very small, but it is the energy absorbed by only one ion. If the wavelength of the photon absorbed by an ion lies outside the visible region, then the transmitted light looks the same (to us) as the incident light— white—and the ion appears colorless. 

This is the energy required to excite one [TiCHiO) ] ion. To express this energy difference in the more convenient units of kJ/mol, we write 

I Solution Because en is a strong-field ligand, we expect [Cr(en)3] to be a low-spin complex. 

Practice Problem How many unpaired spins are in [Mn(H20)6j ligand.) 

Bonding in Coordination Compounds Crystal Field Theory 

Fignre 22.18 shows the distribution of electrons among d orbitals that results in low- and high-spin complexes. The actual arrangement of the electrons is determined by the amount of 

Sample Problem 22.4 shows how to determine the number of spirrs in an octahedral complex. 

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Crystal Field Splitting in Octahedral Complexes Color Magnetic Properties Tetrahedral and Square-Planar Complexes... 

The value of crystal field splitting in tetrahedral complexes is about half of that in octahedral complexes. 

In octahedral complexes, the e -orbitals (dz< and dx2 -yi) lie higher in energy than the t2 -orbitals (dxy, dyz, and dzx). The opposite is true in a tetrahedral complex, for which the ligand field splitting is smaller. 

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

M Figure 24.32 Crystal-field splitting in a series of octahedral chromiurn(lll) complexes. 

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