Bidentate & Multidentate Bidentate & Multidentate LigandsLigands

-Explain and use the term bidentate ligandExplain and use the term bidentate ligand

- Describe stereoisomerism in transition Describe stereoisomerism in transition element multidentate complexes (cis-trans & element multidentate complexes (cis-trans &

optical isomerism) optical isomerism)

Bidentate Ligands – Able to donate two lone pairs to central metal ion

Ethane 1,2 diamine (shortened to ‘en’)

NH2CH2CH2NH2

Octahedral shape[Ni(en)3]2+

3 x bidentate ligands...each able to form 2 x coordinate

bonds... coordination number =

6

Cis & Trans Isomers

[Cr(C2O4)2(H2O) 2]-

Hexadentate Ligand - EDTA

6 lone pairs to use to form coordinate bonds

Optical Isomers:- non-superimposable mirror images

Requirements:•3 x bidentate ligands•2 x bidentate + 2 x monodentate ligands•1 x hexadentate ligand

Summary Question

• Iron (III) can form the complex ion [Fe(C2O4)3]3-

with three ethanedioate ions. The ethanedioate ion is a bidentate a) Explain the term “bidentate ligand”.b) What is the coordination number of the [Fe(C2O4)3]3-

complex.c) Use your answer to part (b) to suggest what shape

the [Fe(C2O4)3]3- complex is and draw it.