Nitric oxide is a colorless gas with the formula NO. It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula. Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern theories of chemical bonding.
Nitrous acid is a weak and monoprotic acid known only in solution, in the gas phase, and in the form of nitrite salts. It was discovered by Carl Wilhelm Scheele, who called it "phlogisticated acid of niter". Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes.
The nitrite ion has the chemical formula NO−
2. Nitrite is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid.
Classical qualitative inorganic analysis is a method of analytical chemistry which seeks to find the elemental composition of inorganic compounds. It is mainly focused on detecting ions in an aqueous solution, therefore materials in other forms may need to be brought to this state before using standard methods. The solution is then treated with various reagents to test for reactions characteristic of certain ions, which may cause color change, precipitation and other visible changes.
Iron–sulfur proteins are proteins characterized by the presence of iron–sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Iron–sulfur clusters are found in a variety of metalloproteins, such as the ferredoxins, as well as NADH dehydrogenase, hydrogenases, coenzyme Q – cytochrome c reductase, succinate – coenzyme Q reductase and nitrogenase. Iron–sulfur clusters are best known for their role in the oxidation-reduction reactions of electron transport in mitochondria and chloroplasts. Both Complex I and Complex II of oxidative phosphorylation have multiple Fe–S clusters. They have many other functions including catalysis as illustrated by aconitase, generation of radicals as illustrated by SAM-dependent enzymes, and as sulfur donors in the biosynthesis of lipoic acid and biotin. Additionally, some Fe–S proteins regulate gene expression. Fe–S proteins are vulnerable to attack by biogenic nitric oxide, forming dinitrosyl iron complexes. In most Fe–S proteins, the terminal ligands on Fe are thiolate, but exceptions exist.
Nitrosylsulfuric acid is the chemical compound with the formula HSO4NO. It is a colourless solid that is used industrially in the production of caprolactam, and was formerly part of the lead chamber process for producing sulfuric acid. The compound is the mixed anhydride of sulfuric acid and nitrous acid.
In organic chemistry, nitroso refers to a functional group in which the nitric oxide group is attached to an organic moiety. As such, various nitroso groups can be categorized as C-nitroso compounds, S-nitroso compounds, N-nitroso compounds, and O-nitroso compounds.
A nitrate test is a chemical test used to determine the presence of nitrate ion in solution. Testing for the presence of nitrate via wet chemistry is generally difficult compared with testing for other anions, as almost all nitrates are soluble in water. In contrast, many common ions give insoluble salts, e.g. halides precipitate with silver, and sulfate precipitate with barium.
Iron shows the characteristic chemical properties of the transition metals, namely the ability to form variable oxidation states differing by steps of one and a very large coordination and organometallic chemistry: indeed, it was the discovery of an iron compound, ferrocene, that revolutionalized the latter field in the 1950s. Iron is sometimes considered as a prototype for the entire block of transition metals, due to its abundance and the immense role it has played in the technological progress of humanity. Its 26 electrons are arranged in the configuration [Ar]3d64s2, of which the 3d and 4s electrons are relatively close in energy, and thus it can lose a variable number of electrons and there is no clear point where further ionization becomes unprofitable.
Metal nitrosyl complexes are complexes that contain nitric oxide, NO, bonded to a transition metal. Many kinds of nitrosyl complexes are known, which vary both in structure and coligand.
Roussin's black salt is a chemical compound with the formula KFe4S3(NO)7. It consists of the potassium salt of the [Fe4S3(NO)7]− anion, metal nitrosyl compound. First described by Zacharie Roussin in 1858, it is one of the first synthetic iron-sulfur clusters along with the red salt also bearing his name.
Transition metal thiolate complexes are metal complexes containing thiolate ligands. Thiolates are ligands that can be classified as soft Lewis bases. Therefore, thiolate ligands coordinate most strongly to metals that behave as soft Lewis acids as opposed to those that behave as hard Lewis acids. Most complexes contain other ligands in addition to thiolate, but many homoleptic complexes are known with only thiolate ligands. The amino acid cysteine has a thiol functional group, consequently many cofactors in proteins and enzymes feature cysteinate-metal cofactors.
Sodium nitroprusside (SNP), sold under the brand name Nitropress among others, is a medication used to lower blood pressure. This may be done if the blood pressure is very high and resulting in symptoms, in certain types of heart failure, and during surgery to decrease bleeding. It is used by continuous injection into a vein. Onset is nearly immediate and effects last for up to ten minutes.
Sulfoxylic acid (H2SO2) (also known as hyposulfurous acid or sulfur dihydroxide) is an unstable oxoacid of sulfur in an intermediate oxidation state between hydrogen sulfide and dithionous acid. It consists of two hydroxy groups attached to a sulfur atom. Sulfoxylic acid contains sulfur in an oxidation state of +2. Sulfur monoxide (SO) can be considered as a theoretical anhydride for sulfoxylic acid, but it is not actually known to react with water.
In biochemistry, dinitrosyl iron complexes (DNIC's) are coordination complexes with the formula [Fe(NO)2(SR)2]−. Together with Roussin esters (Fe2(NO)4(SR)2), they result from the degradation of iron-sulfur proteins by nitric oxide. Commonly the thiolate ligands are cysteinyl residues or glutathione. These metal nitrosyl complexes have attracted much attention because they serve as biochemical signals in response to oxidative stress, manifested in the formation of NO. The anions are tetrahedral.
Transition metal dithiocarbamate complexes are coordination complexes containing one or more dithiocarbamate ligand, which are typically abbreviated R2dtc−. Many complexes are known. Several homoleptic derivatives have the formula M(R2dtc)n where n = 2 and 3.
In organometallic chemistry, transition metal complexes of nitrite describes families of coordination complexes containing one or more nitrite ligands. Although the synthetic derivatives are only of scholarly interest, metal-nitrite complexes occur in several enzymes that participate in the nitrogen cycle.
Trichloronitrosomethane is a chlorinated nitrosoalkane. It is a deep blue liquid with powerful lachrymatory effects.
Nitrosyl perchlorate is the inorganic compound with the formula NO(ClO4). A hygroscopic white solid, it is the salt of the nitrosonium cation with the perchlorate anion. It is an oxidant and strong electrophile, but has fallen out of use with the availability of the closely related salt nitrosonium tetrafluoroborate NO(BF4).
Disulfidobis(tricarbonyliron), or Fe2(μ-S2)(CO)6, is an organometallic molecule used as a precursor in the synthesis of iron-sulfur compounds. Popularized as a synthetic building block by Dietmar Seyferth, Fe2(μ-S2)(CO)6 is commonly used to make mimics of the H-cluster in [FeFe]-hydrogenase. Much of the reactivity of Fe2(μ-S2)(CO)6 proceeds through its sulfur-centered dianion, [Fe2(μ-S)2(CO)2]2-.
