Chapter 24 Transition Metals & Coordination Compounds 24.2 Properties of Transition Metals Review Electron Configuration Trends in the Periodic Table 24.3 Coordination Compounds The Basics Example of Naming 24.4 Structure and Isomerization

Transition Metals contain e- in d Orbitals Breath – slow down! http://www.can-do.com/uci/lessons98/Periodic.html http://www.can-do.com/uci/lessons98/Periodic.html 

Why Are Transition Metals & Coordination Compounds Important? Therapeutic drugs Chemical Sensors Coloring agents Paints Cosmetics Biological Molecules Hemeglobin Chlorophyll Gems (Jewelry & Technological Applications) Rubies, Emeralds, Garnets, etc. Lasers

24.2 Properties of Transition Metals Moderate to High Densities Good Electrical Conductivity High Melting Points Moderate to Extreme Hardness Due to the delocalization of d electrons in metallic bonding Exceptions: Elements with filled d orbitals, which prevents d-d bonding. Hg has a low melting point and is liquid at room temperature. http://www.tutorvista.com/chemistry/shapes-of-d-orbitals

Electron Configuration Increasing Energy (n-1)d (n-2)f

Electron Configuration [noble gas] ns2 (n-1)dx [noble gas] ns2 (n-2)f14 (n-1)dx Slow down - Breath

Electron Configuration [Kr] 5s2 4d2 http://malaxoschemistry.wikispaces.com/Periodic+Table

Atomic Size Decreasing Size Increas Ing S i ze http://malaxoschemistry.wikispaces.com/Periodic+Table

Atomic Size Keep it simple! breath Exception to the trend: Electrons in the f-orbitals are not effective at shielding outer shell electrons from nuclear charge. So, the outer electrons are held in close – this is known as lanthanide contraction.

Ionization Energy Increases Decreases http://malaxoschemistry.wikispaces.com/Periodic+Table

Ionization Energy Exception to the trend: Note that 5d elements have a greater ionization energy. This is again due to outer shell electron being held closer to the nucleus, so it take more energy to pull them away.

Electronegativity Increases Decreases http://malaxoschemistry.wikispaces.com/Periodic+Table

Electronegativity Au: EN = 2.4 Compared to P: EN = 2.1 !! Gold breath slow down Exception to the trend: There is an increase in electronegativity from the 3d (1st row transition metals) to the 4d (2nd row transition metals).

Oxidation States Scandium In general, stability is found in full or half-full shells, and in a configuration that looks like a noble gas.

24.3 Coordination Compounds Complex Ion - Central Metal bound to one or more ligands Ligands are Lewis Base* (electron donors) and can be either neutral or negatively charged The charge on the complex ion is balance by counter ions of opposite charge The combination of a complex ion and counter ions results in a coordination compound *Corrected 4/15/11 @ 2:30 pm) David N. Blauch - http://www.chm.davidson.edu/vce/index.htm

A Little Background In 1893, Swiss chemist Alfred Werner came up with the idea that a central metal could have 2 types of interactions Primary Valence – Oxidation State of the central metal Secondary Valence – Number of molecules or ions directly attached to the central metal or Coordination Number Example: [Co(NH3)6]Cl3 The Primary Valence or Oxidation State of Co is +3 The Secondary Valence or Coordination Number is 6 (6 ammonia ligands are directly attached to Co Other cobalt(III) coordination compounds [Co(NH3)6]Cl3 [Co(NH3)5Cl]Cl2 [Co(NH3)4Cl2]Cl

Coordinate Covalent Bonds Lewis Acid-Base Adduct – the ligand donates it’s electrons to the empty metal orbitals to form a coordinate covalent bond L : M Lewis Acid Lewis Base Adduct

Some Common Ligands

Chelating Agents Ligands can have one or more bonding pairs of electrons Monodentate Bidentate or Polydentate Complex ions with bidentate or polydentate ligands are chelates, and the coordinating ligands are chelating agents Co EDTA is hexadentate http://library.kiwix.org:4201/A/Inorganic_chemistry.htm

Geometries Anne Marie Helmenstine, Ph.D., About.com Guide

Naming Coordination Compounds [Mn(CO)(NH3)5]SO4 (neutral ligands are written before charged ligands in the formula) Cation 1st Name the ligands in alphabetical order ammine carbonyl Add a prefix to indicate the number of ligands pentaammine Name the metal ion Manganese(II) Anion 2nd Sulfate Pentaamminecarbonylmanganese(II) sulfate

24.4 Structure & Isomerism Isomers Structural Isomers Stereoisomers Coordination Isomers Linkage Isomers Stereoisomers Geometric Isomers cis-trans fac-mer Optical Isomers Same formula – different structures Same connectivities –different spacial arrangements Different connectivities Ligands & counter ions trade places Ligands coordinate in different ways Different spacial arrangements Mirror images

Structural Isomers Coordination Isomers pentaamminesulfatochromium(III) bromide pentaamminebromochromium(III) sulfate David N. Blauch - http://www.chm.davidson.edu/vce/index.htm

Structural Isomers Linkage Isomers pentaamminenitrocobalt(III) ion pentaamminenitritocobalt(III) ion David N. Blauch - http://www.chm.davidson.edu/vce/index.htm

Stereoisomers Geometric Isomers: cis-trans cis-diamminedichloroplatinum(II) trans-diamminedichloroplatinum(II) David N. Blauch - http://www.chm.davidson.edu/vce/index.htm

Stereoisomers Geometric Isomers: fac-mer fac-triamminetrichlorocobalt(III) mer-triamminetrichlorocobalt(III) David N. Blauch - http://www.chm.davidson.edu/vce/index.htm

Stereoisomers Optical Isomers Mirror Images Non-superimposable Enantimomers Chiral: optically active (rotates polarized light) http://www.wikidoc.org/index.php/Chirality_%28chemistry%29 http://en.wikipedia.org/wiki/Chirality_%28electromagnetism%29

Chirality Determining Optical Activity fac mer David N. Blauch - http://www.chm.davidson.edu/vce/index.htm

Chirality Determining Optical Activity Superimposable - No optical activity