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Chapter 22 The Chemistry of the Transition Elements

Chapter 22 The Chemistry of the Transition Elements. Important – Read Before Using Slides in Class

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Chapter 22 The Chemistry of the Transition Elements

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  1. Chapter 22The Chemistry of the Transition Elements

  2. Important – Read Before Using Slides in Class Instructor: This PowerPoint presentation contains photos and figures from the text, as well as selected animations and videos. For animations and videos to run properly, we recommend that you run this PowerPoint presentation from the PowerLecture disc inserted in your computer. Also, for the mathematical symbols to display properly, you must install the supplied font called “Symb_chm,” supplied as a cross-platform TrueType font in the “Font_for_Lectures” folder in the "Media" folder on this disc. If you prefer to customize the presentation or run it without the PowerLecture disc inserted, the animations and videos will only run properly if you also copy the associated animation and video files for each chapter onto your computer. Follow these steps: 1. Go to the disc drive directory containing the PowerLecture disc, and then to the “Media” folder, and then to the “PowerPoint_Lectures” folder. 2. In the “PowerPoint_Lectures” folder, copy the entire chapter folder to your computer. Chapter folders are named “chapter1”, “chapter2”, etc. Each chapter folder contains the PowerPoint Lecture file as well as the animation and video files. For assistance with installing the fonts or copying the animations and video files, please visit our Technical Support at http://academic.cengage.com/support or call (800) 423-0563. Thank you.

  3. Transition Metal Chemistry

  4. Transition Metal Chemistry

  5. Gems & Minerals Citrine and amethyst are quartz (SiO2) with a trace of cationic iron that gives rise to the color.

  6. Gems & Minerals Rhodochrosite, MnCO3

  7. Fe + Cl2 Fe + HCl Fe + O2 Reactions: Transition Metals

  8. Periodic Trends: Atom Radius

  9. Periodic Trends: Density

  10. Periodic Trends: Melting Point

  11. Most common Periodic Trends: Oxidation Numbers

  12. Metallurgy: Element Sources

  13. Pyrometallurgy • Involves high temperature, such as Fe • C and CO used as reducing agents in a blast furnace • Fe2O3 + 3 C f 2 Fe + 3 CO • Fe2O3 + 3 CO f 2 Fe + 3 CO2 • Lime added to remove impurities, chiefly SiO2 SiO2 + CaO f CaSiO3 • Product is impure cast iron or pig iron

  14. Metallurgy:Blast Furnace See Active Figure 22.8

  15. Metallurgy:Blast Furnace Molten iron is poured from a basic oxygen furnace.

  16. Metallurgy: Copper Ores Azurite, 2CuCO3·Cu(OH)2 Native copper

  17. Metallurgy: Hydrometallurgy • Uses aqueous solutions • Add CuCl2(aq) to ore such as CuFeS2 (chalcopyrite)CuFeS2 (s) + 3 CuCl2 (aq) f 4 CuCl(s) + FeCl2 (aq) + 2 S(s) • Dissolve CuCl with xs NaClCuCl(s) + Cl-(aq) f [CuCl2]- • Cu(I) disproportionates to Cu metal2 [CuCl2]-f Cu(s) + CuCl2 (aq) + 2 Cl-

  18. Electrolytic Refining of Cu SeeFigure 22.11

  19. Coordination Chemistry • Coordination compounds • combination of two or more atoms, ions, or molecules where a bond is formed by sharing a pair of electrons originally associated with only one of the compounds.

  20. Coordination Chemistry Pt(NH3)2Cl2 “Cisplatin” - a cancer chemotherapy agent Co(H2O)62+ Cu(NH3)42+

  21. Coordination Chemistry An iron-porphyrin, the basic unit of hemoglobin

  22. Co atom Vitamin B12 A naturally occurring cobalt-based compound

  23. Nitrogenase • Biological nitrogen fixation contributes about half of total nitrogen input to global agriculture, remainder from Haber process. • To produce the H2 for the Haber process consumes about 1% of the world’s total energy. • A similar process requiring only atmospheric T and P is carried out by N-fixing bacteria, many of which live in symbiotic association with legumes. • N-fixing bacteria use the enzyme nitrogenase — transforms N2 into NH3. • Nitrogenase consists of 2 metalloproteins: one with Fe and the other with Fe and Mo.

  24. Coordination Compounds of Ni2+

  25. Nomenclature Ni(NH3)6]2+ A Ni2+ ion surrounded by 6, neutral NH3 ligands Gives coordination complex ion with 2+ charge.

  26. Nomenclature Inner coordination sphere Ligand: monodentate + Cl- Ligand: bidentate Co3+ + 2 Cl- + 2 neutral ethylenediamine molecules Cis-dichlorobis(ethylenediamine)cobalt(II) chloride

  27. Bipyridine (bipy) Acetylacetone (acac) Oxalate (ox) Ethylenediamine (en) Common Bidentate Ligands

  28. Acetylacetonate Complexes Commonly called the “acac” ligand. Forms complexes with all transition elements.

  29. Multidentate Ligands EDTA4- - ethylenediaminetetraacetate ion Multidentate ligands are sometimes called CHELATING ligands

  30. Multidentate Ligands Co2+ complex of EDTA4-

  31. Nomenclature Cis-dichlorobis(ethylenediamine)cobalt(III) chloride 1. Positive ions named first 2. Ligand names arranged alphabetically 3. Prefixes -- di, tri, tetra for simple ligands bis, tris, tetrakis for complex ligands 4. If M is in cation, name of metal is used 5. If M is in anion, then use suffix -ate [CuCl4]2- = tetrachlorocuprate 6. Oxidation no. of metal ion indicated

  32. Nomenclature [Co(H2O)6]2+ Hexaaquacobalt(II) H2O as a ligand is aqua [Cu(NH3)4]2+ Tetraamminecopper(II) Pt(NH3)2Cl2 diamminedichloroplatinum(II) NH3 as a ligand is ammine

  33. Nomenclature Tris(ethylenediamine)nickel(II) Pt( [Ni(NH2C2H4NH2)3]2+ IrCl(CO)(PPh3)2 Vaska’s compound Carbonylchlorobis(triphenylphosphine)iridium(I)

  34. Structures of Coordination Compounds

  35. Isomerism • Two forms of isomerism • Constitutional • Stereoisomerism • Constitutional • Same empirical formula but different atom-to-atom connections • Stereoisomerism • Same atom-to-atom connections but different arrangement in space.

  36. Constitutional Isomerism Aldehydes & ketones Peyrone’s chloride: Pt(NH3) 2Cl2 Magnus’s green salt: [Pt(NH3)4][PtCl4]

  37. sunlight Linkage Isomerism Such a transformation could be used as an energy storage device.

  38. cis trans Stereoisomerism • One form is commonly called geometric isomerism or cis-trans isomerism. Occurs often with square planar complexes. Note: there are VERY few tetrahedral complexes. Would not have geometric isomers.

  39. Geometric Isomerism Cis and trans-dichlorobis(ethylenediamine)cobalt(II) chloride

  40. Geometric Isomerism Mer isomer Fac isomer

  41. Stereoisomerism • Enantiomers: stereoisomers that have a non-superimposable mirror image • Diastereoisomers: stereoisomers that do not have a non-superimposable mirror image (cis-trans isomers) • Asymmetric: lacking in symmetry—will have a non-superimposable mirror image • Chiral: an asymmetric molecule

  42. An Enantiomeric Pair [Co(NH2C2H4NH2)3]2+

  43. Stereoisomerism[Co(en)(NH3)2(H2O)Cl]2+ These two isomers have a plane of symmetry. Not chiral. These two are asymmetric. Have non-superimposable mirror images.

  44. Stereoisomerism These are non-superimposable mirror images [Co(en)(NH3)2(H2O)Cl]2+

  45. Bonding in Coordination Compounds • Model must explain • Basic bonding between M and ligand • Color and color changes • Magnetic behavior • Structure • Two models available • Molecular orbital • Electrostatic crystal field theory • Combination of the two fligand field theory

  46. Bonding in Coordination Compounds • As ligands L approach the metal ion M+, • L/M+ orbital overlap occurs • L/M+ electron repulsion occurs • Crystal field theory focuses on the latter, while MO theory takes both into account

  47. Bonding in Coordination Compounds

  48. Crystal Field Theory • Consider what happens as 6 ligands approach an Fe3+ ion All electrons have the same energy in the free ion Orbitals split into two groups as the ligands approach. Value of ∆o depends on ligand: e.g., H2O > Cl-

  49. Octahedral Ligand Field

  50. Tetrahedral & Square Planar Ligand Field

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