5.3 - Transition Metals

Elements that can form stable ions with an incomplete d sub shell

Sc^3+ ions have an empty 3d sub-shell and Zn2+ have a completely full subshell

Variable oxidation states Catalytic action Coloured compounds Formation of complexes

Metal ion surrounded by co-ordinately bonded ligands

Covalent bond in which both electrons in the shared pair come from the same atom

No. of coordinate bonds to ligands that surround a transition metal ion

An ion/molecule that forms a coordinate bond w/ a transition metal by donating its lone pairs (acts as a base)

Ligand that can only form one coordinate bond

H2O NH3 Cl- OH- CN-

Ligand that can form two coordinate bonds by donating two lone pairs to central metal ion

Ligand that can form >1 coordinate bonds

Size and electronic configuration of the cation Size and charge of the ligands

6, 4, 2

6 coordinate bonds (90 degrees)

2 on the plane 2 going back into the plane 2 coming out of the plane

4 coordinate bonds (109.5 degrees) Usually chloro complexes

2 on the plane 1 going back into the plane 1 coming out of the plane

4 coordinate bonds (90 degrees) Requires TM w/ a 3d8 subshell e.g. Pt

2 going back into the plane 2 coming out of the plane

Only occurs in octahedral or square planar Need two ligands that are different to the rest

Occurs in octahedral complexes w/ bidentate ligands Can also be cis/trans

3+

+5

+5