Consider, for example, the complex
[Ti(H2O)6]
3+, which is violet in colour This is an octahedral complex
where the single electron (Ti
3+ is a 3d
1 system) in the metal d orbital is
in the t2g level in the ground state of the complex The next higher state
available for the electron is the empty eg level If light corresponding to
the energy of blue-green region is absorbed by the complex, it would
excite the electron from t2g level to the eg level (t2g
1eg
0 ® t2g
0eg
1)