|
Methylthioirontricarbonyl Dimer
Methylthioirontricarbonyl dimer, also known as methanethiolatoirontricarbonyl dimer, is an organometallic compound with the formula Fe2(SCH3)2(CO)6. It is a red volatile solid that is classified as a transition metal thiolate complex. It exists as air-stable red crystals with two isomers, where the methyl groups are either ''anti'' (isomer A) or ''syn'' (isomer B) with respect to each other. Synthesis It was first synthesized 1940 with the discovery of isomers in 1962. Synthesis involves treating triiron dodecacarbonyl with dimethyl disulfide: :2 Fe3(CO)12 + 3 (CH3)2S2 → 3 e(CO)3SCH3sub>2 + 6 CO It can be purified by recrystallization or by sublimation. The isomers can be separated by chromatography. Structure The methylthioirontricarbonyl dimer is a butterfly cluster compound, consisting of two iron atoms with distorted square pyramidal coordination geometry. The geometry is octahedral if the Fe-Fe bond is included. Each iron has three terminal carbon monoxide ligands ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organometallic Compound
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide (metal carbonyls), cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term "metalorganics, metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Metal Thiolate Complex
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. Synthesis Metal thiolate complexes are commonly prepared by reactions of metal complexes with thiols (RSH), thiolates (RS−), and disulfides (R2S2). The salt metathesis reaction route is common. In this method, an alkali metal thiolate is treated with a transition metal halide to produce an alkali metal halide and the metal thiolate complex: :LiSC6H5 + CuI → Cu(SC6H5) + LiI The thiol ligand can also effect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which ''bonds'' between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the ''relative positions'' of the atoms differ. Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest. The English word "isomer" () is a back-for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triiron Dodecacarbonyl
Triiron dodecarbonyl is the organoiron compound with the formula Fe3(CO)12. It is a dark green solid that sublimes under vacuum. It is soluble in nonpolar organic solvents to give intensely green solutions. Most low-nuclearity clusters are pale yellow or orange. Hot solutions of Fe3(CO)12 decompose to an iron mirror, which can be pyrophoric in air.The solid decomposes slowly in air, and thus samples are typically stored cold under an inert atmosphere. It is a more reactive source of iron(0) than iron pentacarbonyl. Synthesis It was one of the first metal carbonyl clusters synthesized. It was occasionally obtained from the thermolysis of Fe(CO)5: :3 Fe(CO)5 → Fe3(CO)12 + 3 CO Traces of the compound are easily detected because of its characteristic deep green colour. UV-photolysis of Fe(CO)5 produces Fe2(CO)9, not Fe3(CO)12. The usual synthesis of Fe3(CO)12 starts with the reaction of Fe(CO)5 with base: :3 Fe(CO)5 + (C2H5)3N + H2O → C2H5)3NHHFe3(CO)11] + 3 CO + CO2 follow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethyl Disulfide
Dimethyl disulfide (DMDS) is an organic chemical compound with the molecular formula which is the simplest disulfide. It is a flammable liquid with an unpleasant, garlic-like odor. Occurrence Dimethyl disulfide is a widespread natural odoriferous compound emitted from many sources such as bacteria, fungi, plants and animals. It is an oxidation product of methanethiol in air. Along with dimethyl sulfide and dimethyl trisulfide it has been confirmed as volatile compounds given off by the fly-attracting plant known as dead-horse arum ('' Helicodiceros muscivorus''). These flies are attracted to the odor resembling that of fetid meat, and thus help pollinate this plant. DMDS can be produced by the oxidation of methanethiol, e.g. with iodine: : Chemical reactions Important reactions include chlorination giving methanesulfenyl chloride (), methanesulfinyl chloride (), and methanesulfonyl chloride () as well as oxidation with hydrogen peroxide or peracetic acid giving the thiosulf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recrystallization (chemistry)
In chemistry, recrystallization is a technique used to purify chemicals. By dissolving a mixture of a compound and impurities in an appropriate solvent, either the desired compound or impurities can be removed from the solution, leaving the other behind. It is named for the crystals often formed when the compound precipitates out. Alternatively, ''recrystallization'' can refer to the natural growth of larger ice crystals at the expense of smaller ones. Chemistry In chemistry, recrystallization is a procedure for purifying compounds. The most typical situation is that a desired "compound A" is contaminated by a small amount of "impurity B". There are various methods of purification that may be attempted (see Separation process), recrystallization being one of them. There are also different recrystallization techniques that can be used such as: Single-solvent recrystallization Typically, the mixture of "compound A" and "impurity B" is dissolved in the smallest amount of hot solv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sublimation (phase Transition)
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. Sublimation is an endothermic process that occurs at temperatures and pressures below a substance's triple point in its phase diagram, which corresponds to the lowest pressure at which the substance can exist as a liquid. The reverse process of sublimation is deposition or desublimation, in which a substance passes directly from a gas to a solid phase. Sublimation has also been used as a generic term to describe a solid-to-gas transition (sublimation) followed by a gas-to-solid transition ( deposition). While vaporization from liquid to gas occurs as evaporation from the surface if it occurs below the boiling point of the liquid, and as boiling with formation of bubbles in the interior of the liquid if it occurs at the boiling point, there is no such distinction for the solid-to-gas transition which always occurs as sublimation from the surface. At ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Column Chromatography
Column chromatography in chemistry is a chromatography method used to isolate a single chemical compound from a mixture. Chromatography is able to separate substances based on differential adsorption of compounds to the adsorbent; compounds move through the column at different rates, allowing them to be separated into fractions. The technique is widely applicable, as many different adsorbents (normal phase, reversed phase, or otherwise) can be used with a wide range of solvents. The technique can be used on scales from micrograms up to kilograms. The main advantage of column chromatography is the relatively low cost and disposability of the stationary phase used in the process. The latter prevents cross-contamination and stationary phase degradation due to recycling. Column chromatography can be done using gravity to move the solvent, or using compressed gas to push the solvent through the column. A thin-layer chromatograph can show how a mixture of compounds will behave when puri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butterfly Cluster Compound
In the area of metal cluster chemistry, a butterfly cluster compound usually describes tetrametallic clusters containing five M-M bonds. A prototype of this motif is e4(CO)16sup>2−. Most butterfly clusters have additional bridging ligand In coordination chemistry, a bridging ligand is a ligand that connects two or more atoms, usually metal ions. The ligand may be atomic or polyatomic. Virtually all complex organic compounds can serve as bridging ligands, so the term is usually r ...s. One example is the penta phosphide Rh4(CO)5(PPh2)5− where all Rh---Rh edges are bridged by PPh2. A carbide-containing butterfly cluster is e4C(CO)12sup>2− where the carbide is bonded to all four Fe centers.{{cite journal, authors=Sappa, E.; Tiripicchio, A.; Carty, A. J.; Toogood, G. E., title=Butterfly Cluster Complexes of the Group VIII Transition Metals, journal=Progress in Inorganic Chemistry, year=1987, volume=35, page=437, doi=10.1002/9780470166369.ch5, isbn=9780470166369 Bond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Square Pyramidal Molecular Geometry
In molecular geometry, square pyramidal geometry describes the shape of certain compounds with the formula where L is a ligand. If the ligand atoms were connected, the resulting shape would be that of a pyramid with a square base. The point group symmetry involved is of type C4v. The geometry is common for certain main group compounds that have a stereochemically-active lone pair, as described by VSEPR theory. Certain compounds crystallize in both the trigonal bipyramidal and the square pyramidal structures, notably . As a transition state in Berry pseudorotation As a trigonal bipyramidal molecule undergoes Berry pseudorotation, it proceeds via an intermediary stage with the square pyramidal geometry. Thus even though the geometry is rarely seen as the ground state, it is accessed by a low energy distortion from a trigonal bipyramid. Pseudorotation also occurs in square pyramidal molecules. Molecules with this geometry, as opposed to trigonal bipyramidal, exhibit heavier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octahedral Molecular Geometry
In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The octahedron has eight faces, hence the prefix ''octa''. The octahedron is one of the Platonic solids, although octahedral molecules typically have an atom in their centre and no bonds between the ligand atoms. A perfect octahedron belongs to the point group Oh. Examples of octahedral compounds are sulfur hexafluoride SF6 and molybdenum hexacarbonyl Mo(CO)6. The term "octahedral" is used somewhat loosely by chemists, focusing on the geometry of the bonds to the central atom and not considering differences among the ligands themselves. For example, , which is not octahedral in the mathematical sense due to the orientation of the bonds, is referred to as octahedral. The concept of octahedral coordination geometry was developed by Alfred Wern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steric Effects
Steric effects arise from the spatial arrangement of atoms. When atoms come close together there is a rise in the energy of the molecule. Steric effects are nonbonding interactions that influence the shape ( conformation) and reactivity of ions and molecules. Steric effects complement electronic effects, which dictate the shape and reactivity of molecules. Steric repulsive forces between overlapping electron clouds result in structured groupings of molecules stabilized by the way that opposites attract and like charges repel. Steric hindrance Steric hindrance is a consequence of steric effects. Steric hindrance is the slowing of chemical reactions due to steric bulk. It is usually manifested in ''intermolecular reactions'', whereas discussion of steric effects often focus on ''intramolecular interactions''. Steric hindrance is often exploited to control selectivity, such as slowing unwanted side-reactions. Steric hindrance between adjacent groups can also affect torsional ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
16_2-.svg "Click for more on -> Butterfly Cluster Compound")
