1. Unless otherwise stated, all images in this file have been reproduced from: Blackman, Bottle, Schmid, Mocerino and Wille, Chemistry, 2007 (John Wiley) ISBN: 9 78047081 0866

2. Slide 2/23 e CHEM1002 [Part 2] A/Prof Adam Bridgeman (Series 1) Dr Feike Dijkstra (Series 2) Weeks 8 – 13 Office Hours: Monday 2-3, Friday 1-2 Room: 543a e-mail: adam.bridgeman@sydney.edu.au e-mail: feike.dijkstra@sydney.edu.au

3. Slide 3/15 e Complexes I Solutions of metal ions are acidic because coordinated water loses H + and this increases with the charge of the metal ion Ligands use lone pairs to bond to transition metal ions Coordination compounds are made up of a complex ion, containing a metal ion and ligands, and counter ions to balance the charge The common geometries of complex ions are tetrahedral and square planar (both 4 coordinate) and octahedral (6 coordinate) Summary of Last Lecture

4. Slide 4/15 e Lecture 13 Isomerism Stability Blackman Chapter 13, Sections 13.1-13.4 Lecture 14 Transition Metals Electron Configuration Oxidation States Colours Magnetism Blackman Chapter 13, Sections 13.4 and 13.7 Complexes II

5. Slide 5/15 e Isomerism in Metal Complexes (1) Structural Isomerism: different atom connectivities  If the counter ions are also potential ligands, they can swap places to produce coordination sphere isomers: [Cr(OH 2 ) 4 Br 2 ]Cl[Cr(OH 2 ) 4 BrCl]Br

6. Slide 6/15 e Isomerism in Metal Complexes (2) Stereoisomerism: same atom connectivities but different arrangement of atoms in space  geometric isomerism cis trans

7. Slide 7/15 e mirror images superposable (i.e. the same!) mirror images non-superposable mirror image OPTICALLY ACTIVE Isomerism in Metal Complexes trans isomer cis isomer Stereoisomerism: same atom connectivities but different arrangement of atoms in space  optical isomerism

8. Slide 8/15 e Isomerism in Metal Complexes Stereoisomerism: same atom connectivities but different arrangement of atoms in space  optical isomerism [Ni(en) 3 ] 3+

9. Slide 9/15 e Equilibria Involving Complexes Unlike the covalently bonded polyatomic ions such as NO 3 -, SO 4 2-, etc., which do not dissociate into their components, metal complexes in solution are in an equilibrium: [M(OH 2 ) 6 ] 2+ + 6NH 3 [M(NH 3 ) 6 ] 2+ + 6H 2 O [M(NH 3 ) 6 ] 2+ + 3en [M(en) 3 ] 2+ + 6NH 3

10. Slide 10/15 e [Ni(H 2 O) 6 ] 2+ + 3en[Ni(en) 3 ] 2+ + 6H 2 O K stab = K stab = K 1  K 2  K 3 = 10 18.28 [Ni(en) 2 (H 2 O) 2 ] 2+ + en[Ni(en) 3 ] 2+ + 2H 2 O purple [Ni(en)(H 2 O) 4 ] 2+ + en[Ni(en) 2 (H 2 O) 2 ] 2+ + 2H 2 O light blue [Ni(H 2 O) 6 ] 2+ + en[Ni(en)(H 2 O) 4 ] 2+ + 2H 2 O greenblue-green Stepwise Formation Constants [[Ni(H 2 O) 6 ]] 2+ ][en] 3 [[Ni(en) 3 ] 2+ ] = 10 18.28 K2K2 K1K1 K3K3

11. Slide 11/15 e Metal complex formation can greatly influence the apparent solubility of a compound. AgCl(s) + 2NH 3 (aq)  [Ag(NH 3 ) 2 ] + (aq) + Cl - (aq) This is actually a two stage process: AgCl(s) Ag + (aq) + Cl - (aq) (1) Ag + (aq) + 2NH 3 (aq) [Ag(NH 3 ) 2 ] + (aq) (2) Complex formation (reaction 2), removes free Ag + from solution and so drives the dissolution of AgCl (reaction 1) forward. Metal Complex Formation and Solubility

12. Slide 12/15 i The One Pot Reaction Ag + (aq) + OH - (aq) AgOH(s) brown AgOH(s) + H 2 PO 4 - (aq) AgH 2 PO 4 (s) yellow AgH 2 PO 4 (s) + HNO 3 (aq) Ag + (aq) + H 3 PO 4 (aq) Ag + (aq) + Cl - (aq) AgCl(s) white K sp = 1.8 x 10 -10 M 2 AgCl(s) + 2 NH 3 (aq) [Ag(NH 3 ) 2 ] + (aq) + Cl - (aq) K stab = 1.7 x 10 7 M -2 [Ag(NH 3 ) 2 ] + (aq) + Br - (aq) AgBr(s) (green/white), K sp = 5 x 10 -13 M 2 AgBr(s) + 2 S 2 O 3 2- (aq) [Ag(S 2 O 3 ) 2 ] 3- (aq)+Br - (aq) K stab = 2.5 x 10 13 M -2 [Ag(S 2 O 3 ) 2 ] 3- (aq) + I - (aq) AgI(s) (yellow) K sp = 8.3 x 10 -17 M 2 AgI(s) + 2 CN - (aq) [Ag(CN) 2 ] - (aq) + I - (aq) K stab = 6.3 x 10 19 M -2 [Ag(CN) 2 ] - (aq) + S 2- (aq) Ag 2 S(s) (black) K sp = 8 x 10 -51 M 3

13. Slide 13/15 e Summary: Complexes II Learning Outcomes - you should now be able to: Complete the worksheet Identify isomers of complexes correctly Answer review problems 13.59-13.62 in Blackman Next lecture: Colour

14. Slide 14/15 x Practice Examples 1. What are the possible geometries of a metal complex with a coordination number of 4? A. square planar or tetrahedral or octahedral B. square planar or tetrahedral C. octahedral only D. tetrahedral only E. square planar only 2. Which one of the following is a coordination isomer of the complex salt, trans- [Cr(H 2 O) 4 Cl 2 ]Br? A. cis- [Cr(H 2 O) 4 Cl 2 ]Br B. trans- [Cr(H 2 O) 4 BrCl]Cl C. trans- [Cr(H 2 O) 4 Br 2 ]Cl D. trans- [CrBr 2 (H 2 O) 4 ]Cl E. trans- [CrCl 2 (H 2 O) 4 ]Br

15. Slide 15/15 x Practice Examples 3. Which of the following species exist as isomers? [Co(NH 3 ) 6 ] 3+, [PtCl 2 (NH 3 ) 2 ], [Co(OH 2 ) 6 ]Cl 3, [Co(OH 2 ) 6 ] 2+, [CdI 4 ] 2– A. [PtCl 2 (NH 3 ) 2 ] and [Co(OH 2 ) 6 ]Cl 3 B. [PtCl 2 (NH 3 ) 2 ] only C. [CdI 4 ] 2– only D. [Co(NH 3 ) 6 ] 3+ and [Co(OH 2 ) 6 ] 2+ E. [Co(OH 2 ) 6 ]Cl 3 and [Co(OH 2 ) 6 ] 2+ 4. How many geometrical isomers are possible for the complex [CrCl 3 (NH 3 ) 3 ]? A. 1 B. 2 C. 3 D. 4 E. 6