Advanced Chemistry: Coordination, Bonding, and Dyes

The term hapticity is used to describe, how a group of contiguous atoms of a ligand are coordinated to a central atom. Hapticity of a ligand is indicated by the Greek character 'eta', η. A superscripted number following the η denotes the number of contiguous atoms of the ligand that are bound to the metal.

Transmetalation is a general chemical reaction type in organometallic chemistry describing the exchange of ligands between two metal centers. The metal centers need not be the same. The ligands R and R' can be organic or inorganic. The double displacement reaction is conceptually related. Transmetalation is important in the synthesis of various organometallic compounds.

The Monsanto process is an important method for the manufacture of acetic acid by catalytic carbonylation of methanol. This process operates at a pressure of 30-60 atm and a temperature of 150-200 °C and gives a selectivity greater than 99%.

A transition metal carbene complex is a organometallic compound featuring a divalent organic ligand. The divalent organic ligand coordinated to the metal center is called a carbene. Carbene complexes for almost all transition metals have been reported.

The cyanate ion is an anion with the chemical formula written as [OCN]⁻ or [NCO]⁻. In aqueous solution,  it acts as a base, forming isocyanic acid, HNCO. The cyanate ion is an ambidentate ligand, forming complexes with a metal ion in which either the nitrogen or oxygen atom may be the electron-pair donor. It can also act as a bridging ligand.

The carbides of the group 4, 5 and 6 transition metals (with the exception of chromium) are often described as interstitial compounds.These carbides have metallic properties and are refractory. Some exhibit a range of stoichiometries, e.g. titanium carbide, TiC. Titanium carbide and tungsten carbide are important industrially and are used to coat metals in cutting tools.

Tungsten carbide (WC) is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine grey powder, but it can be pressed and formed into shapes for use in industrial machinery, tools, abrasives, as well as jewellry.

In these anti-bimetallic compounds, the metals are found to be bridged by a single carbocyclic ring. Examples include {(THF)₃Ca}₂(1,3,5-triphenylbenzene) and {(Ar) Sn}₂COT.

Several carbides are assumed to be salts of the acetylide anion C₂^2- (also called percarbide), which has a triple bond between the two carbon atoms. Alkali metals, alkaline earth metals, and lanthanoid metals form acetylides, e.g., sodium carbide Na₂C₂, calcium carbide CaC₂, and LaC₂ Lanthanoids also form acetylides with formula M₂C₃.

Fischer carbenes can be likened to ketones, with the carbene carbon being electrophilic, much like the carbonyl carbon of a ketone. Like ketones, Fischer carbene species can undergo Aldol-like reactions. The hydrogen atoms attached to the carbon α to the carbene carbon are acidic, and can be deprotonated by a base such as n-butyllithium, to give a nucleophile which can undergo further reaction.

London dispersion forces is a type of force acting between atoms and molecules.The LDF is a weak intermolecular force arising from quantum induced instantaneous polarization multipoles in molecules. They can therefore act between molecules without permanent multipole moments.

An entropic force acting in a system is a phenomenological force resulting from the entire system's statistical tendency to increase its entropy, rather than from a particular underlying microscopic force.

A peptide bond (amide bond) is a covalent chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, causing the release of a molecule of water (H2O), hence the process is a dehydration synthesis reaction (also known as a condensation reaction), and usually occurs between amino acids.

A dipolar bond, also known as dative covalent bond or coordinate bond is a kind of 2-centre, 2-electron covalent bond in which the two electrons derive from the same atom. Typically, a dipolar bond is formed when a Lewis base donates a pair of electrons to a Lewis acid.

A quadruple bond is a type of chemical bond between two atoms involving eight electrons. This bond is an extension of the more familiar types double bonds and triple bonds. Stable quadruple bonds are most common among the middle members transition metal elements such as rhenium, tungsten, molybdenum and chromium. Typically the ligands that support quadruple bonds are π-donors, not π-acceptors.

Bent bonds, also known as banana bonds, are bonds in strained or otherwise sterically hindered molecules whose binding orbitals are forced into a banana-like form. Bent bonds are often more susceptible to reactions than ordinary bonds.

A symmetric hydrogen bond is a special type of hydrogen bond in which the proton is spaced exactly halfway between two identical atoms. The strength of the bond to each of those atoms is equal. It is an example of a 3-center 4-electron bond. This type of bond is much stronger than normal hydrogen bonds, in fact, its strength is comparable to a covalent bond.

Rose Bengal is a stain. Its sodium salt is commonly used in eye drops to stain damaged conjunctival and corneal cells and thereby identify damage to the eye. The stain is also used in the preparation of Foraminifera for microscopic analysis.

Salt bond fall into the broader category of noncovalent interactions. A salt bond is actually a combination of two noncovalent interactions: hydrogen bonding and electrostatic interactions .This is most commonly observed to contribute stability to the entropically unfavourable folded conformation of proteins.

Orange G or orange gelb is a synthetic azo dye used in histology in many staining formulations. It usually comes as a disodium salt. It has the appearance of orange crystals or powder.

In chemistry, intercalation is the reversible inclusion of a molecule (or group) between two other molecules (or groups). Examples include DNA intercalation and graphite intercalation compounds.

Fuchsine or rosaniline hydrochloride is a magenta dye .It becomes magenta when dissolved in water; as a solid, it forms dark green crystals. As well as dying textiles, fuchsine is used to stain bacteria and sometimes as a disinfectant.

A classic molecular solid consists of small, non-polar covalent molecules, and is held together by London dispersion forces (van der Waals forces); a classic example is paraffin wax. These forces are weak, resulting in pairwise interatomic binding energies on the order of 1/100 those of covalent, ionic, and metallic bonds. Binding energies tend to increase with increasing molecular size and polarity.

Crystal violet i a triarylmethane dye. The dye is used as a histological stain and in Gram's method of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelmintic properties and is used as a topical antiseptic.

Alizarin or 1,2-dihydroxyanthraquinone is an organic compound that is historically important as a prominent dye, originally derived from the roots of plants of the madder genus.