Coordination Compounds contain coordinate covalent bonds formed by the reactions Between metal ions with groups of anions polar molecules o o Metal ion acts as lewis acid accepts electrons Complex ion ion that consists of a metal cation bonded to one or more molecules and anions o Coordinate covalent bond occurs when both electrons are donated by polar molecule Forms complex ion with 1 counter ions Ex K2 PtCl6 Complex ion PtCl6 1 2 counter ions K o Some do not contain the complex ions Witness of compounds with complete valence that still reacted to form stable form delineated primary valence and secondary valence Primary oxidation number Secondary coordination number Transition metals exhibits variable oxidation states within their compounds Exhibit highest states in highly electronegative compounds V2O5 for example V 5 Cr 6 Sc 3 Mn 7 Ligands o Molecules of ions that surround the metal in a complex Think of Lewis acid base reaction o Ligands play role as lewis base donates electron pair Coordination Number number of donor atoms surrounding the central metal ion Classification of of donor atoms on ligand o Monodentate 1 o Bidentate 2 o Polydentate 2 atoms Last two are also known as chelating agents because they hold atom together like a claw Nomenclature The cation is named before the anion o o Within complex ion ligands named first in alphabetical order metal ion last o Anionic ligands end with letter o nuetral ligands are molecule named Exceptions H2O aqua CO carbonyl NH3 amine o Use prefixes for multiples of ligands not involved in alphabetizing Structure of Coordination Compounds o o o o 2 4 6 Coordination number Structure Linear Octahedral Tetrahedral square planar o Stereoisomerism Different ways to arrange ligands around an a metal o Geometric o Optical Two types geometric and optical Cannot be interchnaged without breaking chemical bonds Cis Trans Across and opposite transamerica Adjacents sister sister Changes colors BP MP dipole moment etc Nonsuperimposable mirror images Identical physical and chemical properties Differ in interactions with plain polarized light Hand examples If you lay your hands on top of each other palm side down they will not match Mirror image of each other Chiral Optically active compound has two optical isomers Crystal Field Theory and Bonding o In a complex ion two types of electrostatic interaction come into play Attraction between the positive metal ion and negative ligand Electrostatic repulsion between the lone pairs on the ligands and the electrons of the d orbitals Crystal field splitting is the the energy difference between two sets of d orbitals in a metal atom with ligands present Symbol is capital Greek delta the triangle Has direct affect on the color and magnetic properties of complex ions Spectrochemical series determines wavelength absorbed Higher on the series means weaker field ligand and will have lower frequency abosrb Complex ions undergo ligand exchage o o o o Tendency to react kinetic lability Kf formation constant high is stable Labile complexes rapid ligand exchange Inert complex very slow ligand exchange Determined by activation energy Many complex ions containing Co 3 Cr 3 Pt 2 are kinetically inert Applications Chelation Therapy Chemotherapy Chemical Analysis o Metallurgy o o o o Detergents o Sequestrants