Bài soạn Chapter 24 Transition Metals and Coordination Compounds

Chapter 24 Transition Metals and Coordination Compounds 2011, NKMB Co., Ltd. Chemistry, Julia Burdge, 2 st Ed. McGraw Hill. Mr. Truong Minh Chien ; losedtales@yahoo.com http://tailieu.vn/losedtales http://mba-programming.blogspot.com 2 Gemstones • the colors of rubies and emeralds are both due to the presence of Cr 3+ ions – the difference lies in the crystal hosting the ion Some Al 3+ ions in Al 2 O 3 are replaced by Cr 3+ Some Al 3+ ions in Be 3 Al 2 (SiO 3 ) 6 are replaced by Cr 3+ Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 3 Properties and Electron Configuration of Transition Metals • the properties of the transition metals are similar to each other  and very different to the properties of the main group metals  high melting points, high densities, moderate to very hard, and very good electrical conductors • in general, the transition metals have two valence electrons – we are filling the d orbitals in the shell below the valence  Group 1B and some others have 1 valence electron due to “promotion” of an electron into the d sublevel to fill it  form ions by losing the ns electrons first, then the (n – 1)d Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 4 Atomic Size • the atomic radii of all the transition metals are very similar  small increase in size down a column Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 5 Ionization Energy • the first ionization energy of the transition metals slowly increases across a series • third transition series slightly higher 1 st IE  trend opposite to main group elements Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 6 Electronegativity • the electronegativity of the transition metals slowly increases across a series  except for last element in the series • electronegativity slightly increases down the column  trend opposite to main group elements Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 7 Oxidation States • often exhibit multiple oxidation states • vary by 1 • highest oxidation state is group number for 3B to 7B Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 8 Coordination Compounds • when a complex ion combines with counterions to make a neutral compound it is called a coordination compound • the primary valence is the oxidation number of the metal • the secondary valence is the number of ligands bonded to the metal  coordination number • coordination number range from 2 to 12, with the most common being 6 and 4 CoCl 3 ⋅6H 2 O = [Co(H 2 O) 6 ]Cl 3 Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 9 Coordination Compound Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 10 Complex Ion Formation • complex ion formation is a type of Lewis acid- base reaction • a bond that forms when the pair of electrons is donated by one atom is called a coordinate covalent bond Chemistry, Julia Burdge, 2 nd e., McGraw Hill. [...]... NH3 H NH3 N H2C Fe H2C NH3 N H NH3 Chemistry, Julia Burdge, 2nd e., McGraw Hill Common Metals found in Anionic Complex Ions Chemistry, Julia Burdge, 2nd e., McGraw Hill 19 Naming Coordination Compounds 1) List ligand names in alphabetical order  name each ligand alphabetically, adding a prefix in front of each ligand to indicate the number found in the complex ion 1) follow with the name of the metal... differ in the spatial orientation of ligands fac-mer isomerism in octahedral complexes MA4B2 square-planar complexes 3B3 • cis-transisomerism in octahedral complexes MAMA2B2 Tro, Chemistry: A Molecular Approach 27 Ex 24. 5 – Draw the structures and label the type for all isomers of [Co(en)2Cl2]+ the ethylenediamine ligand (en = H2NCH2CH2NH2) is bidentate each Cl ligand is monodentate octahedral MA4B2 Tro,... Molecular Approach 28 Bonding in Coordination Compounds Valence Bond Theory • bonding takes place when the filled atomic orbital on the ligand overlaps an empty atomic orbital on the metal ion • explain geometries well, but doesn’t explain color or magnetic properties Tro, Chemistry: A Molecular Approach 31 Tro, Chemistry: A Molecular Approach 32 Bonding in Coordination Compounds Crystal Field Theory... attraction of the electrons on the • • • ligand for the charge on the metal cation electrons on the ligands repel electrons in the unhybridized d orbitals of the metal ion the result is the energies of orbitals the d sublevel are split the difference in energy depends on the complex and kinds of ligands  crystal field splitting energy  strong field splitting and weak field splitting Tro, Chemistry:... Structural isomers are molecules that have the same number and type of atoms, but they are attached in a different order • Stereoisomers are molecules that have the same number and type of atoms, and that are attached in the same order, but the atoms or groups of atoms point in a different spatial direction Tro, Chemistry: A Molecular Approach 24 25 Linkage Isomers Tro, Chemistry: A Molecular Approach...Ligands with Extra Teeth • some ligands can form more than one coordinate covalent bond with the metal atom lone pairs on different atoms that are separate enough so that both can reach the metal • chelate is a complex ion containing a multidentate ligand ligand is called the chelating agent 11 Chemistry, Julia Burdge, 2 e., McGraw... e., McGraw Hill nd Chemistry, Julia Burdge, 2nd e., McGraw Hill 12 EDTA a Polydentate Ligand Chemistry, Julia Burdge, 2nd e., McGraw Hill 13 Complex Ions with Polydentate Ligands Chemistry, Julia Burdge, 2nd e., McGraw Hill 14 Geometries in Complex Ions Chemistry, Julia Burdge, 2nd e., McGraw Hill 15 Common Ligands Chemistry, Julia Burdge, 2nd e., McGraw Hill 16 H 2N NH2 ethylene diamine phenanthroline... suffix “ate” is added to the metal name Ligands Names • anions ending with ate or ide change to “o” as in • • nitrate to nitrato or cyanide to cyano anions with ite change to “e” molecules uses common name except for:  water changes to aqua  ammonia to ammine  CO to carbonyl • multiple simple ligands are prefixed with di, tri, • tetra, penta, or hexa Complex ligands are prefixed with bis, tris, tetrakis,... crystal field splitting energy  strong field splitting and weak field splitting Tro, Chemistry: A Molecular Approach 33 Splitting of d Orbital Energies due to Ligands in a Octahedral Complex Tro, Chemistry: A Molecular Approach 34 Strong and Weak Field Splitting Tro, Chemistry: A Molecular Approach 35 36 How we see color If we see black, the material absorbs all color If we see white, the material . Chapter 24 Transition Metals and Coordination Compounds 2011, NKMB Co., Ltd. Chemistry, Julia Burdge,. Hill. 3 Properties and Electron Configuration of Transition Metals • the properties of the transition metals are similar to each other  and very different