Introduction to Inorganic Chemistry What is inorganic chemistry? Inorganic Chemistry Organimetallic Bioinorganic Organic vs Inorganic
Introduction to Inorganic Chemistry Organic vs Inorganic
Introduction to Inorganic Chemistry Organic vs Inorganic
Chapter 8 An Introduction to Coordination Compounds Constitution and geometry 8.1 Low coordination numbers 8.2 Intermediate coordination numbers 8.1 High coordination numbers 8.4 Polymetallic complexes Ligands and nomenclature 8.5 Representative ligands 8.6 Nomenclature Isomerism and chirality 8.7 Square-planar complexes 8.8 Tetrahedral complexes 8.9 Trigonal-bipyramidal and square-pyramidal complexes 8.10 Octahedral complexes 8.11 Ligand chirality
History What is coordination compound? Coordination compounds include compound composed of a metal atom or ion and one or more ligands that formally donate electrons to the metal. More specifically, a transition metal surrounded by neutral molecules or anions with a definite geometry. What is ligand? Ligand can be a atom, ion, and molecules.
History Prussian blue (German: Preußischblau or Berliner Blau, in English Berlin blue) is a dark blue pigment used in paints and formerly in blueprints. Prussian blue was discovered by accident by painter Heinrich Diesbach in What is coordination compound? Berlin in 1704-5, which is why it is also known as Berlin blue. (Diesbach was Coordination attempting to complexes create a paint were with known a red - hue.) although It has not several understood different chemical in any names, sense these - since being the beginning iron(iii) ferrocyanide, of chemistry, ferric e.g. ferrocyanide, Prussian iron(iii) blue, hexacyanoferrate(ii), Aureolin, and copper and vitriol. ferric hexacyanoferrate. Commonly and conveniently it is simply called "PB. The key breakthrough occurred when Alfred Werner proposed, Aureolin inter alia, (sometimes that Co(III) called bears Cobalt six ligands Yellow) in is an a octahedral pigment used geometry. in oil and watercolor painting. Its color index name is PY40 (40th entry on list of yellow pigments). It was first made in 1851 and its chemical composition is potassium cobaltinitrite. Copper(II) sulfate ("sulphate" in most Commonwealth nations) is the chemical compound with the formula CuSO 4. This salt exists as a series of compounds that differ in their degree of hydration. The anhydrous form is a pale green or gray-white powder, while the pentahydrate, the most commonly encountered salt, is bright blue. This hydrated copper sulfate occurs in nature as the mineral called chalcanthite. The archaic name for copper(ii) sulfate is "blue vitriol" or "bluestone"
Alfred Werner Nobel Prize for Chemistry 1913 For complexes with more than one type of ligand, Werner succeeded in In explaining 1893, Werner the number was the of first isomers to propose observed. correct For structures exemple, he for explained coordination the compounds containing complex ions, in which a central transition metal existence of two isomers of "Co(NH 3 ) 4 Cl 3 ", one green and one purple. Werner proposed that these are two geometric isomers of formula atom is surrounded by neutral or anionic ligands. [Co(NH For example, 3 ) 4 Cl 2 ]Cl, it was with known one Cl that - ion cobalt dissociated forms a as "complex" confirmed with by conductivity formula CoCl measurements. 3 6NH 3, but The the Co nature atom of is the surrounded association by indicated four NH 3 by and the two dot Cl was ligands at mysterious. the vertices Werner of an proposed octahedron. the The structure green [Co(NH isomer is 3 ) 6 ]Cl "trans" 3, with with the the Co3+ two Cl ion ligands surrounded at opposite by six NH vertices, 3 at the and vertices the purple of an is octahedron. "cis" with the The two three Cl at Clare adjacent dissociated vertices. as free ions, which he confirmed by measuring the electrical conductivity of the compound in aqueous solution.
History What is coordination compound? Coordination complexes were known - although not understood in any sense - since the beginning of chemistry, e.g. Prussian blue, Aureolin, and copper vitriol. The key breakthrough occurred when Alfred Werner proposed, inter alia, that Co(III) bears six ligands in an octahedral geometry. The theory allows one to understand the difference between coordinated and ionic chloride in the cobalt ammine chlorides and to explain many of the previously inexplicable isomers. He resolved the first coordination complex into optical isomers, overthrowing the theory that chirality was necessarily associated with carbon compounds.
History What is ligand? In chemistry, a ligand is an atom, ion, or molecule that generally donates one or more of its electrons through a coordinate covalent bond to one or more central atoms or ions (these ligands act as a Lewis base). The ligands that are directly bonded to the metal (that is, share electrons), are called "inner sphere" ligands. If the inner-sphere ligands do not balance the charge of the central atom, this may be done by simple ionic bonding with another set of counter ions (the "outer-sphere" ligands). The complex of the metal with the inner sphere ligands is then called a complex ion (which can be either cationic or anionic). The complex, along with its counter ions, is called a coordination compound. The size of a ligand is indicated by its cone angle.
History Organometallic Compound Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Organometallic chemistry combines aspects of inorganic chemistry and organic chemistry. Organometallic compounds find practical use in stoichiometric and catalytically active compounds. Electron counting is key in understanding organometallic chemistry. The 18-electron rule is helpful in predicting the stabilities of organometallic compounds. Organometallic compounds which have 18 electrons (filled s, p, and d orbitals) are relatively stable. This suggests the compound is isolable, but it can result in the compound being inert.
Nomenclature Common Monodentate Ligands Classical (or "Werner Complexes"): Ligands in classical coordination chemistry bind to metals. Organometallic: Ligands are organic (alkenes, alkynes, alkyls) as well as "organic-like" ligands such as phosphines, hydride, and CO. Bioinorganic: Ligands are those provided by nature, especially including the side chains of amino acids, and many cofactors such as porphyrins. Example: hemoglobin Cluster: Ligands are all of the above but also include other metals as ligands. Example Ru 3 (CO) 12
Constitution and geometry In an inner-sphere complex, the ligands are attached directly to a central metal ion: the number of ligands depends on the size of the metal, the identity of the ligands, and the electronic interactions. Size: ligand, central atom or ion Electron density Multiple bond {[Mn(H 2 O) 6 ] 2+ SO 2-4 } vs [Mn(H 2 O) 5 SO 4 ]
Constitution and geometry 8.1 Low coordination numbers Coordination number 2; Cu +, Ag +, Au +, they often gain additional ligands to form three- or four- coordinate complexes. Coordination number 3: with bulky ligands Position of these complexes in periodic table.
Constitution and geometry 8.2 Intermediate coordination numbers Coordination number 4, 5, 6. They include the vast majority of complexes. Four-coordination: Tetrahedral complexes are favoured over higher coordinate complexes if the central atom is small or the ligands large. - ligand-ligand repulsions override the energy advantage of forming more metal-ligand bonds Square-planar complexes are typically observed for metals with d 8 configurations (Rh +, Ir +, Pd 2+, Pt 2+, Au 3+ ).
Constitution and geometry 8.2 Intermediate coordination numbers Geometric isomerism