Coordination Chemistry Transition metal compounds

Transition metals have multiple charges because of the d orbitals. This also gives them lots of color and bonding capabilities.

Figure 23.5 Aqueous oxoanions of transition elements. Mn 2+ MnO 4 2− MnO 4 − VO 4 3− Cr 2 O 7 2− MnO 4 − One of the most characteristic chemical properties of these elements is the occurrence of multiple oxidation states.

Figure 23.6 Colors of representative compounds of the Period 4 transition metals. Titanium(IV) oxide sodium chromate potassium ferricyanide nickel( II ) nitrate hexahydrate zinc sulfate heptahydrate scandium oxide vanadyl sulfate dihydrate manganese( II ) chloride tetrahydrate cobalt( II ) chloride hexahydrate copper( II ) sulfate pentahydrate

[Co(NH 3 ) 4 Cl 2 ]Cl  Complex ion: central metal atom bonded to a group of metals or ions (most are charged)  Ligands: neutral molecule or ion having a lone pair of electrons that forms coordinate covalent bond to the metal ion  Counter ion: anion or cation needed to make the complex ion neutral

Werner’s Theory  Alfred Werner suggested in 1893 that metal ions exhibit what he called primary and secondary valences.  Primary valences were the oxidation number for the metal (+3 on the cobalt at the right).  Secondary valences were the coordination number, the number of atoms directly bonded to the metal (6 in the complex at the right).

Names of Coordination Compounds Rules for naming complexes: 1. The cation is named before the anion. 2. Within the complex ion, the ligands are named, in alphabetical order, before the metal ion. Prefixes do not affect order. 3. Neutral ligands generally have the molecule name, but there are a few exceptions. Anionic ligands drop the -ide and add -o after the root name. 4. A numerical prefix indicates the number of ligands of a particular type. 5. The oxidation state of the central metal ion is given by a Roman numeral (in parentheses) only if the metal ion is variable. 6. If the complex ion is an anion we drop the ending of the metal name and add -ate.

Nomenclature: 1.Determine oxidation # of metal. 2.Ligands are named first, alphabetically with prefixes: mono-, di-, tri-, tetra-, penta-, hexa-. Prefixes do not affect order. 3.Anion ligands = root + o 4.First name ends with metal + variable charge (roman #s) 5.Second name = counter ions/anion **anion use Latin names

Writing Names and Formulas of Coordination Compounds (a) What is the systematic name of Na 3 [AlF 6 ]? (b) What is the systematic name of [Co(en) 2 Cl 2 ]NO 3 ? (c) What is the formula of tetraaminebromochloroplatinum( IV ) chloride? (d) What is the formula of hexaaminecobalt (III ) tetrachloro- ferrate( III )?