Introduction to Inorganic

What is ? 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 and nomenclature 8.5 Representative ligands 8.6 Nomenclature Isomerism and 8.7 Square-planar complexes 8.8 Tetrahedral complexes 8.9 Trigonal-bipyramidal and square-pyramidal complexes 8.10 Octahedral complexes 8.11 chirality History

What is coordination compound? Coordination compounds include compound composed of a or and one or more ligands that formally donate electrons to the metal.

More specifically, a surrounded by neutral or anions with a definite geometry. What is ligand? Ligand can be a atom, ion, and molecules. Prussian blueHistory(German: Preußischblau or Berliner Blau, in English Berlin blue) is a dark blue pigment used in paints and formerly in blueprints. was discovered by accident by painter Heinrich Diesbach in Berlin in 1704-5,What which is is coordinationwhy it is also known compound? as Berlin blue. (Diesbach was Coordinationattempting to complexescreate a paint were with known a red - hue.) although It has not several understood different chemicalin any names, sense these- since being the begi (III)nning , of chemistry, ferric e.g. ferrocyanide,Prussian iron(III)blue hexacyanoferrate(II),, Aureolin, and and vitriol ferric. hexacyanoferrate. Commonly and conveniently it is simply called "PB. The key breakthrough occurred when proposed, Aureolininter alia(sometimes, that Co(III) called bears six ligands Yellow in) isan a octahedralpigment 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 cobaltinitrite.

Copper(II) sulfate ("sulphate" in most Commonwealth nations) is the with the formula CuSO4. 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" Nobel Prize for Chemistry Alfred Werner 1913

For complexes with more than one type of ligand, Werner succeeded in Inexplaining 1893, Werner the number was the of firstisomers to proposobserved.e correct For structuresexemple, hefor explained coordination the compoundsexistence of containingtwo complex of "Co(NH ions3), 4inCl which3", one a green central and transition one purple. metal Werneratom is surroundedproposed that by theseneutral are or two anionic geometric ligands isomers. of formula - [Co(NHFor example,3)4Cl2]Cl, it was with known one Cl thation coba dissociatedlt forms aas "complex" confirmed with by conductivityformula measurements. The Co atom is surrounded by four NH and two Cl ligands CoCl3•6NH3, but the nature of the association indicated3 by the dot was at the vertices of an octahedron. The green is "trans" with the two mysterious. Werner proposed the structure [Co(NH3)6]Cl3, with the Co3+ Cl ligands at opposite vertices, and the purple is "cis" with the two Cl at ion surrounded by six NH3 at the vertices of an octahedron. The three Cl- areadjacent dissociated vertices. as free , 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 . History

What is ligand? In chemistry, a ligand is an atom, ion, or that generally donates one or more of its electrons through a coordinate to one or more central or ions (these ligands act as a Lewis ).

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 .

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 .

Organometallic: Ligands are organic (, , 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 . Example:

Cluster: Ligands are all of the above but also include other metals as ligands.

Example Ru3(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.

2+ 2- Size: ligand, central atom or ion {[Mn(H2O)6] SO4 } vs Electron density [Mn(H2O)5SO4] Multiple bond 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 . Constitution and geometry 8.2 Intermediate coordination numbers

Coordination number 4, 5, 6. They include the vast majority of complexes.


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 d8 configurations (Rh+, Ir+, Pd2+, Pt2+, Au3+). Constitution and geometry 8.2 Intermediate coordination numbers

Geometric isomerism Constitution and geometry 8.2 Intermediate coordination numbers Five-coordination:

The energies of the various geometries of five-coordinate complexes differ little from one another and such complexes are often fluxional.

Square pyramidal or trigonal bipyramidal.

Distortions from these ideal geometries are common. Constitution and geometry 8.2 Intermediate coordination numbers Berry pseudorotation

[Fe(CO)5]; crystal, NMR, IR