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Transition Metal Chemistry and Coordination Compounds Chapter 22 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Presentation on theme: "Transition Metal Chemistry and Coordination Compounds Chapter 22 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display."— Presentation transcript:

1 Transition Metal Chemistry and Coordination Compounds Chapter 22 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 22.1 The Transition Metals

3 22.1

4

5 Oxidation States of the 1 st Row Transition Metals (most stable oxidation numbers are shown in red) 22.1

6 Ionization Energies for the 1 st Row Transition Metals

7 ScandiumTitaniumVanadium ChromiumManganeseIron CobaltNickelCopper 22.2

8 Coordination Compounds A coordination compound typically consists of a complex ion and a counter ion. A complex ion contains a central metal cation bonded to one or more molecules or ions. The molecules or ions that surround the metal in a complex ion are called ligands. A ligand has at least one unshared pair of valence electrons H O H H N H H Cl - C O 22.3

9 Coordination Compounds 22.3 The atom in a ligand that is bound directly to the metal atom is the donor atom. H O H H N H H The number of donor atoms surrounding the central metal atom in a complex ion is the coordination number. Ligands with: one donor atom monodentate two donor atoms bidentate three or more donor atoms polydentate H 2 O, NH 3, Cl - ethylenediamine EDTA

10 Coordination Compounds 22.3 H 2 N CH 2 CH 2 NH 2 bidentate ligand polydentate ligand (EDTA) Bidentate and polydentate ligands are called chelating agents

11 22.3

12 EDTA Complex of Lead 22.3

13 What are the oxidation numbers of the metals in K[Au(OH) 4 ] and [Cr(NH 3 ) 6 ](NO 3 ) 3 ? OH - has charge of -1 K + has charge of +1 ? Au x(-1) = 0 Au = +3 NO 3 - has charge of -1 NH 3 has no charge ? Cr + 6x(0) + 3x(-1) = 0 Cr =

14 Naming Coordination Compounds 22.3 The cation is named before the anion. Within a complex ion, the ligands are named first in alphabetical order and the metal atom is named last. The names of anionic ligands end with the letter o. Neutral ligands are usually called by the name of the molecule. The exceptions are H 2 O (aquo), CO (carbonyl), and NH 3 (ammine). When several ligands of a particular kind are present, the Greek prefixes di-, tri-, tetra-, penta-, and hexa- are used to indicate the number. If the ligand contains a Greek prefix, use the prefixes bis, tris, and tetrakis to indicate the number. The oxidation number of the metal is written in Roman numerals following the name of the metal. If the complex is an anion, its name ends in –ate.

15 22.3

16 What is the systematic name of [Cr(H 2 O) 4 Cl 2 ]Cl ? tetraaquodichlorochromium(III) chloride Write the formula of tris(ethylenediamine)cobalt(II) sulfate [Co(en) 3 ]SO 4

17 Structure of Coordination Compounds 22.4 Coordination numberStructure Linear Tetrahedral or Square planar Octahedral

18 Structure of Coordination Compounds 22.4 Stereoisomers are compounds that are made up of the same types and numbers of atoms bonded together in the same sequence but with different spatial arrangements. Geometric isomers are stereoisomers that cannot be interconverted without breaking a chemical bond. cis-[Pt(NH 3 ) 2 Cl 2 ] trans-[Pt(NH 3 ) 2 Cl 2 ]

19 Structure of Coordination Compounds 22.4 cis-[Co(NH 3 ) 4 Cl 2 ]trans-[Co(NH 3 ) 4 Cl 2 ] Are these additional geometric isomers of [Co(NH 3 ) 4 Cl 2 ]? cis trans

20 Structure of Coordination Compounds 22.4 Optical isomers are nonsuperimposable mirror images. cis-[Co(en) 2 Cl 2 ]trans-[Co(en) 2 Cl 2 ] optical isomers chiral not optical isomers achiral

21 Structure of Coordination Compounds 22.4 Chiral molecules are optically active.

22 Bonding in Coordination Compounds 22.5 All equal in energy in the absence of ligands!

23 Bonding in Coordination Compounds 22.5 Isolated transition metal atom Bonded transition metal atom Crystal field splitting (  ) is the energy difference between two sets of d orbitals in a metal atom when ligands are present

24 Bonding in Coordination Compounds 22.5  E = h

25 The absorption maximum for the complex ion [Co(NH 3 ) 6 ] 3+ occurs at 470 nm. What is the color of the complex and what is the crystal field splitting in kJ/mol? Absorbs blue, will appear orange.  = h hc = (6.63 x J s) x (3.00 x 10 8 m s -1 ) 470 x m = = 4.23 x J  (kJ/mol) = 4.23 x J/atom x x atoms/mol = 255 kJ/mol 22.5

26 Bonding in Coordination Compounds 22.5 I - < Br - < Cl - < OH - < F - < H 2 O < NH 3 < en < CN - < CO Spectrochemical Series Strong field ligands Large  Weak field ligands Small 

27 Bonding in Coordination Compounds 22.5

28 Orbital Diagrams for High Spin and Low Spin Octahedral Complexes

29 Bonding in Coordination Compounds 22.5

30 Bonding in Coordination Compounds 22.5

31 Chemistry In Action: Coordination Compounds in Living Systems

32 Chemistry In Action: Cisplatin – The Anticancer Drug


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