CHEM 1312H 1st Edition Lecture 11LECTURE MATERIALCoordination compounds: a compound composed of a central atom (metal) directly bonded to a number of groups (ligands)Monodentate ligands: binds to a metal through one atomPolydentate ligands: binds through 2+ atomsSequestering agents: bind to metal and make it less reactiveASSIGNED READING MATERIAL23.4 NOMENCLATURE AND ISOMERISM IN COORDINATION CHEMISTRYNaming Rules- when naming complexes that are salts, the cation name comes before the anion- when naming complex ions or molecules, the ligands come before the metal- ligands are listed in alphabetical order (disregard charges)- prefixes that denote the number of ligands are not considered- anionic ligand names end in the letter o, but electronically neutral ligands use the molecule names- Greek prefixes (di-, tri-, tetra-, penta-, hexa-) are used to indicate the number of each ligand when there’s more than one present- if the complex is an anion, its name ends in –ate- oxidation number of the metal is given by the Roman numeral in parentheticals following the name of the metalIsomerismIsomers: when two ore more compounds have the same composition but a different arrangement of atoms- structural isomers: isomers with different bonds- stereoisomers: isomers with the same bonds whose ligands are arranged differently around the metal center; aka different spatial arrangementsStructural Isomers- linkage isomerism: arises when a ligand is capable of coordinating to a metal in two wayso for ex, NO2- can coordinate to a metal ion either through its nitrogen, or one of its oxygens- coordination-sphere isomers: isomers that differ in which species in the complex are ligands andwhich are outside the coordination sphere in the solidStereoisomerism- geometric isomerism: when the arrangement of atoms is different but the same bonds are presento cis isomer: when ligands are adjacent to each otherThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o trans isomer: when ligands are on opposite sides of the central atomo see Figure 23.21 for illustration- optical isomerism, otherwise known as:o enantiomers: mirror images that cannot be superimposed on each other (no way to rotate one of the enantiomers to make it identical to another) this inability to be superimposed upon something else makes them chiral molecules or ionso properties of optical isomers only differ if they are in a chiral environmento when a polarized light is passed through a solution containing an optical isomer: an isomer that rotates the plan of polarization to the right is dextrorotatory its mirror image rotates the plan of polarization to the left and is called levorotatory if a mixture is racemic, this means it does not rotate polarized light because when equal amounts of the two isomers are obtained, their effects cancel each other out23.5 COLOUR AND MAGNETISM IN COORDINATION CHEMISTRY- the colour of a complex depends on the identity of its metal ion, its oxidation state, and the ligands bound to it- for a substance to have colour, it has to absorb some portion of the visible light spectrum; absorption takes place when there’s enough energy to move an electron from the substance in the ground state to an excited stateMagnetism of Coordination Compounds- recall that a lot of transition-metal complexes exhibit
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