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Xantphos
Xantphos is an organophosphorus compound derived from the heterocycle xanthene. It is used as a bidentate diphosphine ligand and is noteworthy for having a particularly wide bite angle (108°). Such ligands are useful in the hydroformylation of alkenes. Illustrative of its wide bite angle, it forms both cis and trans adducts of platinum(II) chloride. In the latter context, xantphos is classified as a trans-spanning ligand. A related bidentate ligand with a greater bite angle is spanphos. The ligand is prepared by double directed lithiation of 9,9-dimethylxanthene with sec-butyllithium followed by treatment with chlorodiphenylphosphine.{{cite journal , author = Mirko Kranenburg, Yuri E. M. van der Burgt, Paul C. J. Kamer, Piet W. N. M. van Leeuwen, Kees Goubitz, and Jan Fraanje , title = New Diphosphine Ligands Based on Heterocyclic Aromatics Inducing Very High Regioselectivity in Rhodium-Catalyzed Hydroformylation: Effect of the Bite Angle , year = 1995 , journal = Organome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphosphines
Diphosphines, sometimes called bisphosphanes, are organophosphorus compounds most commonly used as bidentate phosphine ligand, phosphine ligands in inorganic chemistry, inorganic and organometallic chemistry. They are identified by the presence of two phosphino groups linked by a backbone, and are usually chelate, chelating. A wide variety of diphosphines have been synthesized with different linkers and R-groups. Alteration of the linker and R-groups alters the electronic and steric properties of the ligands which can result in different coordination geometries and catalytic behavior in Homogeneous catalysis, homogeneous catalysts. Synthesis image:IPr2PCl.png, 220px, Chlorodiisopropylphosphine is a popular building block for the preparation of diphosphines. From phosphide building blocks Many widely used diphosphine ligands have the general formula Ar2P(CH2)nPAr2. These compounds can be prepared from the reaction of X(CH2)nX (X=halogen) and MPPh2 (M = alkali metal): :Cl(CH2)nCl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bite Angle
In coordination chemistry, the bite angle is the angle on a central atom between two bonds to a bidentate ligand. This ligand–metal–ligand geometric parameter is used to classify chelation, chelating ligands, including those in organometallic complexes. It is most often discussed in terms of catalysis, as changes in bite angle can affect not just the activity and selectivity of a catalytic reaction but even allow alternative reaction pathways to become accessible. Although the parameter can be applied generally to any chelating ligand, it is commonly applied to describe diphosphine ligands, as they can adopt a wide range of bite angles. Diamines Diamines form a wide range of coordination complexes. They typically form 5- and 6-membered chelate rings. Examples of the former include ethylenediamine and 2,2'-bipyridine, 2,2′-bipyridine. Six-membered chelate rings are formed by 1,3-diaminopropane. The bite angle in such complexes is usually near 90°. Longer chain diamines, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trans-spanning Ligand
Trans-spanning ligands are bidentate ligands that can span opposite sites of a complex with square-planar geometry. A wide variety of ligands that chelate in the cis fashion already exist, but very few can link opposite vertices on a coordination polyhedron. Early attempts to generate trans-spanning bidentate ligands relied on long hydrocarbon chains to link the donor functionalities, but such ligands often lead to coordination polymers. History A diphosphane linked with pentamethylene was claimed to span across a Square planar molecular geometry, square planar complex. This early attempt was followed by ligands with more rigid backbones. "TRANSPHOS" was the first trans-spanning diphosphane ligand that usually coordinates to palladium(II) and platinum(II) in a trans manner. TRANSPHOS features Benzo(c)phenanthrene, benzo[c]phenanthrene substituted by diphenylphosphinomethyl (Ph2PCH2) groups at the 1 and 11 positions. The polycyclic framework suffers sterically clashing hydrogen cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenyl
In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula , and is often represented by the symbol Ph (archaically φ) or Ø. The phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen atom, which may be replaced by some other element or compound to serve as a functional group. A phenyl group has six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the remaining carbon bonded to a substituent. Phenyl groups are commonplace in organic chemistry. Although often depicted with alternating double and single bonds, the phenyl group is chemically aromatic and has equal bond lengths between carbon atoms in the ring. Nomenclature Usually, a "phenyl group" is synonymous with and is represented by the symbol Ph (archaically, Φ), or Ø. Benzene is sometimes denoted as PhH. Phenyl groups are generally attached to other atoms or groups. Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platinum(II) Chloride
Platinum(II) chloride describes the inorganic compounds with the formula Pt Cl2. They are precursor used in the preparation of other platinum compounds. Platinum(II) chloride exists in two crystalline forms ( polymorphs), but the main properties are somewhat similar: dark brown, insoluble in water, diamagnetic, and odorless. Structure The structures of PtCl2 and PdCl2 are similar. These dichlorides exist in both polymeric, or "α", and hexameric, or "β" structures. The β form converts to the α form at 500 °C. In the β form, the Pt-Pt distances are 3.32–3.40 Å, indicative of some bonding between the pairs of metals. In both forms of PtCl2, each Pt center is four-coordinate, being surrounded by four chloride ligands. Complementarily, each Cl center is two-coordinate, being connected to two platinum atoms. The structure of α-PtCl2 is reported to be disordered and contain edge- and/or corner-sharing square-planar PtCl4 units. Preparation β-PtCl2 is prepared by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorodiphenylphosphine
Chlorodiphenylphosphine is an organophosphorus compound with the formula (C6H5)2PCl, abbreviated Ph2PCl. It is a colourless oily liquid with a pungent odor that is often described as being garlic-like and detectable even in the ppb range. It is useful reagent for introducing the Ph2P group into molecules, which includes many ligands.Quin, L. D. ''A Guide to Organophosphorus Chemistry''; Wiley IEEE: New York, 2000; pp 44-69. Like other halophosphines, Ph2PCl is reactive with many nucleophiles such as water and easily oxidized even by air. Synthesis and reactions Chlorodiphenylphosphine is produced on a commercial scale from benzene and phosphorus trichloride (PCl3). Benzene reacts with phosphorus trichloride at extreme temperatures around 600 °C to give dichlorophenylphosphine (PhPCl2) and HCl. Redistribution of PhPCl2 in the gas phase at high temperatures results in chlorodiphenylphosphine. :2PhPCl2 → Ph2PCl + PCl3 Alternatively such compounds are prepared by redistri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sec-butyllithium
''sec''-Butyllithium is an organometallic compound with the Chemical formula, formula CH3CHLiCH2CH3, abbreviated ''sec''-BuLi or ''s''-BuLi. This Chiral (chemistry), chiral organolithium reagent is used as a source of ''sec''-butyl carbanion in organic synthesis.. Synthesis ''sec''-BuLi can be prepared by the reaction of ''sec''-butyl halides with lithium metal: Properties Physical properties ''sec''-Butyllithium is a colorless viscous liquid. Using mass spectrometry, it was determined that the pure compound has a tetrameric structure. It also exists as tetramers when dissolved in organic solvents such as benzene, cyclohexane or cyclopentane. The cyclopentane solution has been detected with 6Li-NMR spectroscopy to have a hexameric structure at temperatures below −41 °C. In electron-donating solvents such as tetrahydrofuran, there exists an equilibrium between monomeric and dimeric forms. Chemical properties The carbon-lithium bond is highly polar, rendering the carbon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directed Ortho Metalation
Directed ortho metalation (DoM) is an adaptation of electrophilic aromatic substitution in which electrophiles attach themselves exclusively to the ortho- position of a direct metalation group or DMG through the intermediary of an aryllithium compound. The DMG interacts with lithium through a hetero atom. Examples of DMG's are the methoxy group, a tertiary amine group and an amide group. The compound can be produced by directed lithiation of anisole. The general principle is outlined in ''scheme 1''. An aromatic ring system with a DMG group 1 interacts with an alkyllithium such as ''n''-butyllithium in its specific aggregation state (hence (R-Li)n) to intermediate 2 since the hetero atom on the DMG is a Lewis base and lithium the Lewis acid. The very basic alkyllithium then deprotonates the ring in the nearest ortho- position forming the aryllithium 3 all the while maintaining the acid-base interaction. An electrophile reacts in the next phase in an electrophilic aromati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spanphos
SPANphos is an organophosphorus compound used as a ligand in organometallic chemistry, organometallic and coordination chemistry. The compound is a rare example of a trans-spanning ligand and rigidly links mutually trans coordination sites. By virtue of its C2-symmetric backbone, SPANphos forms a chiral cavity over the face of a square planar complexes, e.g. in MCl2(SPANphos) (M = Pd, Pt). Synthesis SPANphos can be prepared synthesized from relatively inexpensive reagents. In the first step 4,4,4',4',6,6'-hexamethyl-2,2'-spirobichromane is prepared via an acid-catalyzed reaction of p-cresol and acetone. The resultant spirocycle is halogenated with N-bromosuccinimide followed by lithium-bromide exchange using butyl lithium, n-BuLi. Treatment of the resulting organolithium, dilithio compound with chlorodiphenylphosphine completes the synthesis.{{cite journal , author = Z. Freixa, M. S. Beentjes, G. D. Batema, C. B. Dieleman, G. P. F. van Strijdonck, J. N. H. Reek, P. C. J. Kamer, J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkene
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins. The International Union of Pure and Applied Chemistry (IUPAC) Preferred IUPAC name, recommends using the name "alkene" only for Open-chain compound, acyclic hydrocarbons with just one double bond; alkadiene, alkatriene, etc., or polyene for acyclic hydrocarbons with two or more double bonds; cycloalkene, cycloalkadiene, etc. for Cyclic compound, cyclic ones; and "olefin" for the general class – cyclic or acyclic, with one or more double bonds. Acyclic alkenes, with only one double bond and no other functional groups (also known as mono-enes) form a homologous series of hydrocarbons with the general formula with ''n'' being a >1 natural number (which is two hydrogens less than the corresponding alkane). When ''n'' is four or more, isomers are possible, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reviews
''Chemical Reviews'' is peer-reviewed scientific journal published twice per month by the American Chemical Society. It publishes review articles on all aspects of chemistry. It was established in 1924 by William Albert Noyes (University of Illinois). The editor-in-chief is Sharon Hammes-Schiffer. Abstracting and indexing The journal is abstracted and indexed in Chemical Abstracts Service, CAB International, EBSCOhost, ProQuest, PubMed, Scopus, and the Science Citation Index. According to the ''Journal Citation Reports'', the journal has a 2023 impact factor of 51.4. Journal ranking summary Based on the latest announced rankings, ''Chemical Reviews'' is positioned among the top journals in the field of chemistry across multiple citation databases. The following table summarizes its performance across Scopus and Web of Science. Journal ranking summary (2023)JRank: Chemical Reviewshttps://jrank.net/journals/chem-rev/metrics/ref> See also * Accounts of Chemical Research ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organophosphorus Compound
Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective insecticides, although some are extremely toxic to humans, including sarin and VX (nerve agent), VX nerve agents. Phosphorus, like nitrogen, is in pnictogen, group 15 of the periodic table, and thus phosphorus compounds and nitrogen compounds have many similar properties. The definition of organophosphorus compounds is variable, which can lead to confusion. In industrial and environmental chemistry, an organophosphorus compound need contain only an organic substituent, but need not have a direct phosphorus-carbon (P-C) bond. Thus a large proportion of pesticides (e.g., malathion), are often included in this class of compounds. Phosphorus can adopt a v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
