Coordination+Chemistry

 Be able to define the following terms:
 * // Coordination Chemistry //**

¡ Coordination chemistry - it is the study of metal ions and their interations with other molecules or ions. In chemistry,a coordination complex or metal complex, is a structure consisting of a central atom or ion (usually metallic), bonded to a surrounding array of molecules or anions. ¡ Ligand- the molecules or ions that surround the metal in a complex ion. Monodentate ligand is a molecule or an atom that has only one donor atom that will donate a lone pair of electrons to form the covalent bond with the complex ion. So this ligand will occupy only one site on the complex ion. § Bidentate-a ligand that can form two bonds with the central atom. So this ligand will occupy two sites on the complex ion. § Polydentate- a ligand that can form more than two bonds with the central atom. The polydentate we need to know is EDTA (ethylendiaminetetraacetato) which gives six bonds and has a charge of -4 ¡ ** Central metal ion ** The central metal ion is also called the complex ion. It's a lewis acid that that accepts electrons from the ligand thus forming the covalent bond. The central metal ion has a positive charge. ¡ Chemical bonds § Covalent bond - a shared pair of electrons. This is a bond between nonmetals in which each atom donates one electron to their bond. It is the strongest form of bond. The combination of two or more atoms by sharing electrons so as to achieve chemical stability under the octet rule. Atoms that form covalent bonds generally have outer energy levels containing three, four, or five electrons. Covalent bonds are generally stronger than other bonds

§ Ionic Bond - an electrostatic attraction that holds oppositely charged ions together in an ionic compound. a chemical bond in which one atom loses an electron to form a positive ion and the other atom gains an electron to form a negative ion § Coordinate covalent bond- a covalent bond in which one of the atoms donates both electrons. ¡ Coordination Complex- a complex with a structure containing a central atom with an array of ligands bonded to it. ¡ Coordination Number - he number of atoms surrounding an atom in a crystal lattice. The number of donor atoms surrounding a metal in a complex. The most common coordination numbers are 4 and 6, although they are not the only possible numbers. ¡ Lewis Acid - a species that can accept a pair of electrons. Accepts a previously nonbonded pair of electrons to form a coordinate covalent bond. ¡ Lewis Base- a species that donates electrons. Donates a previously nonbonded pair of electrons to form a coordinate covalent bond. ¡ Tridimensional conformation § Linear- coordination # =2, bond angles=180 0 lone electron pairs § Bent - coordination # = 2, bond angles< 120 1 lone electron pair § Trigonal planar- coordination # =3, bond angles=120 , 0 lone electron pair § Trigonal pyramidal- coordination # is 3, bond angle is <120, 1 lone pair  § Square planar- coordination # is 4, bond angle is 90, 2 lone pair § Tetrahedral- coordination # is 4, bond angle is 109.5, 0 lone pair. This is one of the most common structures in coordination compounds. § Octahedral - coordination number 6, bond angel 90 degree. This is one of the most common structures in coordination compounds.  ¡ Isomers § Geometric-change in bond geometry, cis and trans isomers § Coordination sphere- exchange of the central atoms between two interacting complexes § Ionization-ligand and the counter ion exchange roles § Linkage: example: The complex [Co(NH3)5(NO2)]2+ has two isomeric forms, which are known as **linkage isomers**

¡ Crystal field theory explains the bonding in complex ions purely in terms of electrostatic forces: a ligand with a negative charge tries to bond to a positive metal. Which can also help you find color and magnetic properties.  Be able to explain and apply the theory of coordination bonding  Be able to correlate physical and chemical properties of a coordination complex to: ¡ Electron configuration: Depending on the electron configuration the complex absorb different colors. ¡ Coordination number ¡ Oxidation state  Be able to determine: ¡ Systematic nomenclature of a coordinate complex based on a chemical formula 1) cation first and then anion (cation is positive) 2) within complex, ligands are named first 3)anionic ligands end with the letter o 4)use Greek prefixes when two or more ligands present an example would be di-two... tetra, penta, hexa... ect 5)oxidation number of metal should be represented by roman numerals 6)if the complex is an anion, its name ends in ate

¡ Chemical formula of the complex based on the systematic name of the complex  Be able to predict the angle between ligands in a coordination complex based on: ¡ Number of ligands ¡ Coordination number ¡ Tridimensional conformation of the complex  Be able to predict the relative coordination number of a complex based on: ¡ Ligand’s size - The smaller the size of the ligand, the greater the coordination number will be for the molecule. The greater the size of the ligand, the smaller the coordination number will be for the molecule. ¡ Ligand’s charge - The greater the negative charge, -4, the greater the coordination number The lesser the negative charge, -1 (closer to neutral), the lesser the coordination number ¡ Metal’s size - The larger the size of the Metal, the greater the coordination number will be. The smaller the size of the Metal, the smaller the coordination number will be. ¡ Metal’s charge - The greater the positive charge, +4, the greater the coordination number will be. The lesser the positive charge, +1 (closer to neutral), the lesser the coordination number  Be able to predict the tridimensional structure of a coordinate complex

 Be able to recognize and name the following class of ligands: A couple common monodentate ligands include water, ammonia, fluoride/chloride ion, cyanide/thiocyanide ion, hydroxide ion and nitrate and nitrite. The respective name of each particular ligand when they form a complex is as follows: aqua, ammine, fluoro, chloro, cyano, thiocyano, hydroxo, nitrato and nitro. ¡ Bidentates: oxalate and ethylendiamine are examples of bidentates. Bidentates form two bonds with the central atom. ¡ Polydentates-An example of a polydentate is EDTA or Ethylenediaminetetraacetate which forms 6 bonds with the central atom. Polydentate is a ligand that forms more than 3 bonds with the central atom.  Be able to predict the color of a coordination complex based on the crystal field theory ¡ Focus on D orbital splitting. D-orbital splitting occurs because as the electrons from a ligand move to the metal, they hit the d-orbitals and experience repulsion from the electrons that are already occupied there. The orbitals that are hit by the electrons jump to a higher energy level, which causes the orbitals to split. The amount of energy needed for the electrons to go to the higher energy level determines the color of absorption. ¡ Spectrochemical series- summarizes the effects of ligands on the absorption value of the complex. It puts the energy needed to traverse the d-orbital split for different ligands in order.  Be able to recognize and draw the following isomers: Geometric A chemical compound having the same molecular formula as another but a different geometric configuration, as when atoms or groups of atoms are attached in different spatial arrangements on either side of a bond or a ring.
 * ¡ Monodentates - A ligand that makes one coordinate covalent bond to a metal ion. **

¡ Coordination sphere - occurs only in complexes, where the central atoms exchange places ¡ Ionization - occurs only in compounds where the cation or anion opposite to the complex ion changes its place with one of the ligans. ¡ Linkage - ligans are linked differently to central atom, that is the donor atom is different in the same ligand.