Coordination Compounds Complex Ions Coordination Compounds

What are complex ions? Metal Complexes: Central metal ion bonded to a group of surrounding molecules Complex Ions: Metal ions with a charge Coordination Compounds: Compounds containing metal complexes Ligands: Molecules or ions that surround the metal ion in a complex

Development of Coordination Chemistry: Werner’s Theory Establish the idea that metal ions exhibit both primary and secondary valences. Primary valence is the oxidation state of the metal Secondary valence is # of atoms directly bonded to the metal ion. Also called Coordination Number. Coordination Sphere: Central metal and ligands bound to it Write formula using brackets around coordination sphere

Naming Coordination Compounds Cations before anions Ligands before metal ions Name ligands by adding an o to the root name of the anion. Ex: floro, chloro, hydroxo For a neutral ligand use name of molecule Use prefixes to denote number of ligands Oxidation state of central atom designated with roman numerals Name multiple ligands alphabetically If the complex ion has a negative charge, the suffix – ate is added to the name of the metal

Examples of Names [Co(NH3)5Cl]Cl2 K3Fe(CN)6 [Fe(en)2(NO2)2]2SO4 Pentaamminechlorocobalt(III) chloride K3Fe(CN)6 Potassium hexacyanoferrate(III) [Fe(en)2(NO2)2]2SO4 diethylenediamminebisnitroiron(III) sulfate Triamminebromoplatinum(II)chloride [Pt(NH3)3Br] Cl Potassium hexaflorocobalt(III) K3[CoF6]

Metal-Ligand Bond: Example of Lewis acid and Lewis Base Ligands have unshared pairs of electrons, function as Lewis base Metal ions have empty valence orbitals, function as Lewis acid Ag+(aq) + 2 N-H (aq)  (aq) Formation of the metal ligand bond greatly affects the properties of the metal ion. Some insoluble will become soluble

Copper is not highly reactive, but it will slowly corrode in air forming basic copper sulfate 3 Cu(s) + 2 H2O(l) + SO2(g) + 2 O2(g)  Cu3(OH)4SO4 Basic copper sulfate Ammonia complexes with copper turn the solution from light blue to much darker blue Cu2+aq) + 2 NH3(aq)  Cu(NH3)42+ Insoluble silver chloride (AgCl) dissolved in ammonia solutions to produce a soluble complex AgCl(s) + NH3  Ag(NH3)2+ + Cl-