Structure of the dye Naphthol Green B, which features of nitroso ligand bound to Fe(III).
Transition metal nitroso complexes are coordination complexes containing one or more organonitroso ligands (RNO). [1]
Transition metal nitroso complexes are coordination complexes containing one or more organonitroso ligands (RNO). [1]
Organic nitroso compounds bind to metals in several ways, but most commonly as monodentate N-bonded ligands. Also known are O-bonded, η2-N,O-bonded. Dimers of organic nitroso compounds also bind in a κ2--O,O bidentate manner. Illustrative are Ru(acac)2(C6H5NO)2, where a pair nitrosobenzenes are monodentate, and [Ru(acac)2(μ−C6H5NO)]2 where two nitrosobenzenes bridge. [2]
Arylnitroso compounds with a flanking hydroxy group are a well-developed, e.g. 1-nitroso-2-naphthol. They are precursors to anionic N,O chelating ligands. Chelating dinitrosoarenes are uncommon but have been investigated. [3]
Organic nitroso complexes can be prepared from preformed organic nitroso precursors. These precursors usually exist as N-N bonded dimers, but the dimer dissociates readily. This direct method is used to give W(CO)5(tert-BuNO) (where tert-Bu is (CH3)3C). [4] The Fe-porphyrin complex depicted below is prepared by this route. More complicated but more biorelevant routes involve degradation of precursors such as nitrobenzene and phenylhydroxylamine. [5]
The coupling of organic ligands and nitric oxide is yet another route. [1]
Methemoglobinemia is a disorder where a large fraction of hemoglobin in one's blood has converted to inactive forms, generically called methemoglobin. Since methemoglobin is not an oxygen-carrier, methemoglobinemia is a serious disorder, sometimes fatal. Exposure to nitrobenzene, aniline, and their derivatives cause this disorder, which is attributed to their conversion to nitrosobenzene (and derivatives), which inactivate hemoglobin by forming a complex with the Fe center, precluding binding of O2. [6]
As indicated by the applications in dyeing, chelating aryl nitroso compounds often form deeply colored complexes
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands".
Acetylacetone is an organic compound with the chemical formula CH3−C(=O)−CH2−C(=O)−CH3. It is classified as a 1,3-diketone. It exists in equilibrium with a tautomer CH3−C(=O)−CH=C(−OH)−CH3. The mixture is a colorless liquid. These tautomers interconvert so rapidly under most conditions that they are treated as a single compound in most applications. Acetylacetone is a building block for the synthesis of many coordination complexes as well as heterocyclic compounds.
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.
The trispyrazolylborate ligand, abbreviated Tp−, is an anionic tridentate and tripodal ligand. Trispyrazolylborate refers specifically to the anion [HB(C3N2H3)3]−. However, the term can also be used to refer to derivatives having substituents on the pyrazolyl rings. This class of compounds belongs to the family of ligands called scorpionate ligands.
Nitrosobenzene is the organic compound with the formula C6H5NO. It is one of the prototypical organic nitroso compounds. Characteristic of its functional group, it is a dark green species that exists in equilibrium with its pale yellow dimer. Both monomer and dimer are diamagnetic.
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.
Organoruthenium chemistry is the chemistry of organometallic compounds containing a carbon to ruthenium chemical bond. Several organoruthenium catalysts are of commercial interest and organoruthenium compounds have been considered for cancer therapy. The chemistry has some stoichiometric similarities with organoiron chemistry, as iron is directly above ruthenium in group 8 of the periodic table. The most important reagents for the introduction of ruthenium are ruthenium(III) chloride and triruthenium dodecacarbonyl.
Dioxygen complexes are coordination compounds that contain O2 as a ligand. The study of these compounds is inspired by oxygen-carrying proteins such as myoglobin, hemoglobin, hemerythrin, and hemocyanin. Several transition metals form complexes with O2, and many of these complexes form reversibly. The binding of O2 is the first step in many important phenomena, such as cellular respiration, corrosion, and industrial chemistry. The first synthetic oxygen complex was demonstrated in 1938 with cobalt(II) complex reversibly bound O2.
Organomolybdenum chemistry is the chemistry of chemical compounds with Mo-C bonds. The heavier group 6 elements molybdenum and tungsten form organometallic compounds similar to those in organochromium chemistry but higher oxidation states tend to be more common.
Metal acetylacetonates are coordination complexes derived from the acetylacetonate anion (CH
3COCHCOCH−
3) and metal ions, usually transition metals. The bidentate ligand acetylacetonate is often abbreviated acac. Typically both oxygen atoms bind to the metal to form a six-membered chelate ring. The simplest complexes have the formula M(acac)3 and M(acac)2. Mixed-ligand complexes, e.g. VO(acac)2, are also numerous. Variations of acetylacetonate have also been developed with myriad substituents in place of methyl (RCOCHCOR′−). Many such complexes are soluble in organic solvents, in contrast to the related metal halides. Because of these properties, acac complexes are sometimes used as catalyst precursors and reagents. Applications include their use as NMR "shift reagents" and as catalysts for organic synthesis, and precursors to industrial hydroformylation catalysts. C
5H
7O−
2 in some cases also binds to metals through the central carbon atom; this bonding mode is more common for the third-row transition metals such as platinum(II) and iridium(III).
Cyclopentadienyliron dicarbonyl dimer is an organometallic compound with the formula [(η5-C5H5)Fe(CO)2]2, often abbreviated to Cp2Fe2(CO)4, [CpFe(CO)2]2 or even Fp2, with the colloquial name "fip dimer". It is a dark reddish-purple crystalline solid, which is readily soluble in moderately polar organic solvents such as chloroform and pyridine, but less soluble in carbon tetrachloride and carbon disulfide. Cp2Fe2(CO)4 is insoluble in but stable toward water. Cp2Fe2(CO)4 is reasonably stable to storage under air and serves as a convenient starting material for accessing other Fp (CpFe(CO)2) derivatives (described below).
A transition metal fullerene complex is a coordination complex wherein fullerene serves as a ligand. Fullerenes are typically spheroidal carbon compounds, the most prevalent being buckminsterfullerene, C60.
Half sandwich compounds, also known as piano stool complexes, are organometallic complexes that feature a cyclic polyhapto ligand bound to an MLn center, where L is a unidentate ligand. Thousands of such complexes are known. Well-known examples include cyclobutadieneiron tricarbonyl and (C5H5)TiCl3. Commercially useful examples include (C5H5)Co(CO)2, which is used in the synthesis of substituted pyridines, and methylcyclopentadienyl manganese tricarbonyl, an antiknock agent in petrol.
Transition-metal allyl complexes are coordination complexes with allyl and its derivatives as ligands. Allyl is the radical with the connectivity CH2CHCH2, although as a ligand it is usually viewed as an allyl anion CH2=CH−CH2−, which is usually described as two equivalent resonance structures.
An N-Heterocyclic silylene (NHSi) is a neutral heterocyclic chemical compound consisting of a divalent silicon atom bonded to two nitrogen atoms. The isolation of the first stable NHSi, also the first stable dicoordinate silicon compound, was reported in 1994 by Michael Denk and Robert West three years after Anthony Arduengo first isolated an N-heterocyclic carbene, the lighter congener of NHSis. Since their first isolation, NHSis have been synthesized and studied with both saturated and unsaturated central rings ranging in size from 4 to 6 atoms. The stability of NHSis, especially 6π aromatic unsaturated five-membered examples, make them useful systems to study the structure and reactivity of silylenes and low-valent main group elements in general. Though not used outside of academic settings, complexes containing NHSis are known to be competent catalysts for industrially important reactions. This article focuses on the properties and reactivity of five-membered NHSis.
A transition metal phosphido complex is a coordination complex containing a phosphido ligand (R2P, where R = H, organic substituent). With two lone pairs on phosphorus, the phosphido anion (R2P−) is comparable to an amido anion (R2N−), except that the M-P distances are longer and the phosphorus atom is more sterically accessible. For these reasons, phosphido is often a bridging ligand. The -PH2 ion or ligand is also called phosphanide or phosphido ligand.
Transition metal isocyanide complexes are coordination compounds containing isocyanide ligands. Because isocyanides are relatively basic, but also good pi-acceptors, a wide range of complexes are known. Some isocyanide complexes are used in medical imaging.
Hexa(tert-butoxy)ditungsten(III) is a coordination complex of tungsten(III). It is one of the homoleptic alkoxides of tungsten. A red, air-sensitive solid, the complex has attracted academic attention as the precursor to many organotungsten derivatives. It an example of a charge-neutral complex featuring a W≡W bond, arising from the coupling of a pair of d3 metal centers.
Transition metal complexes of aldehydes and ketones describes coordination complexes with aldehyde (RCHO) and ketone (R2CO) ligands. Because aldehydes and ketones are common, the area is of fundamental interest. Some reactions that are useful in organic chemistry involve such complexes.
Transition metal acyl complexes describes organometallic complexes containing one or more acyl (RCO) ligands. Such compounds occur as transient intermediates in many industrially useful reactions, especially carbonylations.