Which of the following is correct related to the colours of TiCl 3 X Ti H 2 O 6 Cl 3 Y

Atomic number of Titanium is 22.

Electronic configuration of Ti is $\left[\mathrm{Ar}\right]3{\mathrm{d}}^{2}4{\mathrm{s}}^2$

The colour of transition metal compounds is due to the presence of unpaired electrons in their metal ions which are responsible for d-d transitions.

The colour in the coordination compounds can be readily explained in terms of the crystal field theory. Consider, for example, the complex [Ti(H₂O)₆ ]³⁺, which is violet in colour. This is an octahedral complex where the single electron (Ti³⁺ is a 3d¹ system) in the metal d orbital is in the t_2g 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 t_2g level to the e_g level (t_2g1 e_g0 → t_2g 0 e_g1 ). Consequently, the complex appears violet in colour. The crystal field theory attributes the colour of the coordination compounds to d-d transition of the electron.

It is important to note that in the absence of ligand, crystal field splitting does not occur and hence the substance is colourless. For example, removal of water from [Ti(H₂O)₆ ]Cl₃ on heating renders it colourless.Hence TiCl₃ is colourless.