![Structure of the [Fe(dmso)6] . Fe(dmso)6(ClO4)3 (ccd code = KEYXES).png](http://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Fe%28dmso%296%28ClO4%293_%28ccd_code_%3D_KEYXES%29.png/220px-Fe%28dmso%296%28ClO4%293_%28ccd_code_%3D_KEYXES%29.png)
A transition metal sulfoxide complex is a coordination complex containing one or more sulfoxide ligands. The inventory is large. [2] [3]
A transition metal sulfoxide complex is a coordination complex containing one or more sulfoxide ligands. The inventory is large. [2] [3]
The most common sulfoxide ligand is dimethyl sulfoxide (dmso). Many sulfoxides are known because an enormous range of organic substituents are possible. When the two substituents differ, the ligand is chiral. Chiral sulfoxides are configurationally stable. One example is methyl phenyl sulfoxide.
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| cis-dichlorotetrakis(dimethylsulfoxide)ruthenium(II) | trans-dichlorotetrakis(dimethylsulfoxide)ruthenium(II) |
Sulfoxides can bind to metals by the oxygen atom or by sulfur. This dichotomy is called linkage isomerism. O-bonded sulfoxide ligands are far more common, especially for 1st row metals. S-bonded sulfoxides are only found for soft metal centers, such as Ru(II). Complexes with both O- and S-bonded sulfoxide ligands are known. [4] In some cases, sulfoxides are bridging ligands, with S bonded to one metal and O bonded to the other.
Being a polar solvent with a high dielectric constants, dmso dissolves many metal salts to give the corresponding complexes. Other ligand-solvent combinations include acetonitrile and water, which respectively form metal-acetonitrile complexes and metal aquo complexes. Treatment of thioether complexes with peroxide reagents gives sulfoxide complex. In rare cases, sulfoxide complexes are prepared by S-alkylation of sulfenito complexes. [5]
Metal thioether complexes are susceptible to sulfoxidation with dimethyldioxirane. [6]
Being weakly basic, sulfoxide ligands are generally labile, i.e. they are rapidly displaced by other more basic ligands.
O-bonded sulfoxide ligands are susceptible to oxidation at sulfur. In this way, the weakly bonded ligand is converted into a leaving group, such as dimethylsulfone. Since dmso is susceptible to deprotonation by strong base, cationic dmso complexes might be expected to undergo H-D exchange under basic conditions. Such behavior is not observed even for the trication [Co(NH3)5(dmso)]3+. [8]
Several metal sulfoxide complexes have been investigated as catalysts. [9] The molybdoenzyme DMSO reductase catalyzes the reduction of dmso to dimethyl sulfide.
Several homoleptic octahedral complexes of sulfoxides have been characterized by X-ray crystallography. These include the [M(dmso)6]2+ complexes for M = Cr(III), Mn(II), Fe(II), Fe(III), Co(II), Co(III), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II). All such derivatives feature O-bonded sulfoxides. The tricationic complex in [Rh(dmso)6](O3SCF3)3 features one S-bonded and five O-bonded sulfoxide ligands. [10] The complex [Cu(Ph2SO)4]2+ is square planar, in contrast to the derivative with dmso ligands. The square planar d8 complex [Rh(dmso)4]+ features a pairs of S- and O-bonded sulfoxide ligands. [11]
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula (CH3)2SO. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is miscible in a wide range of organic solvents as well as water. It has a relatively high boiling point. DMSO has the unusual property that many individuals perceive a garlic-like taste in the mouth after DMSO makes contact with their skin.
In chemistry, linkage isomerism or ambidentate isomerism is a form of isomerism in which certain coordination compounds have the same composition but differ in their metal atom's connectivity to a ligand.
In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are oxidized derivatives of sulfides. Examples of important sulfoxides are alliin, a precursor to the compound that gives freshly crushed garlic its aroma, and dimethyl sulfoxide (DMSO), a common solvent.
Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH3)2S. The simplest thioether, it is a flammable liquid that boils at 37 °C (99 °F) and has a characteristic disagreeable odor. It is a component of the smell produced from cooking of certain vegetables, notably maize, cabbage, beetroot, and seafoods. It is also an indication of bacterial contamination in malt production and brewing. It is a breakdown product of dimethylsulfoniopropionate (DMSP), and is also produced by the bacterial metabolism of methanethiol.
In inorganic chemistry, a homoleptic chemical compound is a metal compound with all ligands identical. The term uses the "homo-" prefix to indicate that something is the same for all. Any metal species which has more than one type of ligand is heteroleptic.
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.
DMSO reductase is a molybdenum-containing enzyme that catalyzes reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS). This enzyme serves as the terminal reductase under anaerobic conditions in some bacteria, with DMSO being the terminal electron acceptor. During the course of the reaction, the oxygen atom in DMSO is transferred to molybdenum, and then reduced to water.
Asymmetric catalytic oxidation is a technique of oxidizing various substrates to give an enantio-enriched product using a catalyst. Typically, but not necessarily, asymmetry is induced by the chirality of the catalyst. Typically, but again not necessarily, the methodology applies to organic substrates. Functional groups that can be prochiral and readily susceptible to oxidation include certain alkenes and thioethers. Challenging but pervasive prochiral substrates are C-H bonds of alkanes. Instead of introducing oxygen, some catalysts, biological and otherwise, enantioselectively introduce halogens, another form of oxidation.
Dichlorotetrakis(dimethyl sulfoxide) ruthenium(II) describes coordination compounds with the formula RuCl2(dmso)4, where DMSO is dimethylsulfoxide. Both cis and trans isomers are known, but the cis isomer is more common. The cis isomer is a yellow, air-stable solid that is soluble in some organic solvents. These compounds have been extremely successful as an intermediate in the synthesis of various ruthenium(ii) complexes. They have also attracted attention as possible anti-cancer drugs.
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).
The White catalyst is a transition metal coordination complex named after the chemist by whom it was first synthesized, M. Christina White, a professor at the University of Illinois. The catalyst has been used in a variety of allylic C-H functionalization reactions of α-olefins. In addition, it has been shown to catalyze oxidative Heck reactions.
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.
Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.
Transition metal amino acid complexes are a large family of coordination complexes containing the conjugate bases of the amino acids, the 2-aminocarboxylates. Amino acids are prevalent in nature, and all of them function as ligands toward the transition metals. Not included in this article are complexes of the amides and ester derivatives of amino acids. Also excluded are the polyamino acids including the chelating agents EDTA and NTA.
cis-Dichlorobis(bipyridine)ruthenium(II) is the coordination complex with the formula RuCl2(bipy)2, where bipy is 2,2'-bipyridine. It is a dark green diamagnetic solid that is a precursor to many other complexes of ruthenium, mainly by substitution of the two chloride ligands. The compound has been crystallized as diverse hydrates.
Transition metal thioether complexes comprise coordination complexes of thioether (R2S) ligands. The inventory is extensive.
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.
Transition metal complexes of 2,2'-bipyridine are coordination complexes containing one or more 2,2'-bipyridine ligands. Complexes have been described for all of the transition metals. Although few have any practical value, these complexes have been influential. 2,2'-Bipyridine is classified as a diimine ligand. Unlike the structures of pyridine complexes, the two rings in bipy are coplanar, which facilitates electron delocalization. As a consequence of this delocalization, bipy complexes often exhibit distinctive optical and redox properties.
Transition metal phosphate complexes are coordination complexes with one or more phosphate ligands. Phosphate binds to metals through one, two, three, or all four oxygen atoms. The bidentate coordination mode is common. The second and third pKa's of phosphoric acid, pKa2 and pKa3, are 7.2 and 12.37, respectively. It follows that HPO2−4 and PO3−4 are sufficiently basic to serve as ligands. The examples below confirm this expectation. Molecular metal phosphate complexes have no or few applications.
Transition metal complexes of thiocyanate describes coordination complexes containing one or more thiocyanate (SCN-) ligands. The topic also includes transition metal complexes of isothiocyanate. These complexes have few applications but played significant role in the development of coordination chemistry.