Question

Would a molecular orbital diagram be appropriate to describe bonding in Ti? Explain.

Answer 1

Solution:

The valence orbitals of the titanium atom are the five 3d-, 4s-, and three 4p orbitals. Yes, Titanium can form co-ordinate covalent bond in organometallic complexes, which can be explained with the help of MO theory. Ligand field theory (LFT), an application of MO can describe the bonding, in Ti coordination complexes. A transition metal ion like Ti consisting of five nd, three (n+1)p, and one (n+1)s valance atomic orbitals. These orbitals are of appropriate energy to form bonding interaction with ligands. An example of titanium co-ordination complex can be better explained with the help of an octahedral Ti complex e.g. [Ti(H₂O)₆]³⁺.

In this octahedral complex, the molecular orbitals are created by coordination of two electrons from each of six σ-donor ligands, H₂O to the d-orbitals on the metal, Ti. In octahedral complexes, ligands approach along the x-, y- and z-axes, so their σ-symmetry orbitals form bonding and anti-bonding combinations with the d_z² and d_x²_−y² orbitals. The d_xy, d_xz and d_yz orbitals remain non-bonding orbitals. Some weak bonding/anti-bonding interactions with the s and p orbitals of the metal also occur, to make a total of 6 bonding and 6 anti-bonding molecular orbitals as shown in figure below.