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Ligand Cone Angle
In coordination chemistry, the ligand cone angle (θ) is a measure of the steric bulk of a ligand in a transition metal coordination complex. It is defined as the solid angle formed with the metal at the vertex of a cone and the outermost edge of the van der Waals spheres of the ligand atoms at the perimeter of the base of the cone. Tertiary phosphine ligands are commonly classified using this parameter, but the method can be applied to any ligand. The term ''cone angle'' was first introduced by Chadwick A. Tolman, a research chemist at DuPont. Tolman originally developed the method for phosphine ligands in nickel complexes, determining them from measurements of accurate physical models. Asymmetric cases The concept of cone angle is most easily visualized with symmetrical ligands, e.g. PR3. But the approach has been refined to include less symmetrical ligands of the type PRR′R″ as well as diphosphines. In such asymmetric cases, the substituent angles' half angles, , are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1,2-Bis(dimethylphosphino)ethane
1,2-Bis(dimethylphosphino)ethane (dmpe) is a diphosphine ligand in coordination chemistry. It is a colorless, air-sensitive liquid that is soluble in organic solvents. With the formula (CHPMe), dmpe is used as a compact strongly basic spectator ligand (Me = methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated as ...), Representative complexes include V(dmpe)(BH), Mn(dmpe)(AlH), Tc(dmpe)(CO)Cl, and Ni(dmpe)Cl. Synthesis It is synthesised by the reaction of methylmagnesium iodide with 1,2-bis(dichlorophosphino)ethane: :ClPCHCHPCl + 4 MeMgI → MePCHCHPMe + 4 MgICl Alternatively it can be generated by alkylation of sodium dimethylphosphide. The synthesis of dmpe from thiophosphoryl chloride has led to serious accidents and has been abandoned. Related ligands * Bis(dicyclohexy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of The Chemical Society
The ''Journal of the Chemical Society'' was a scientific journal established by the Chemical Society in 1849 as the ''Quarterly Journal of the Chemical Society''. The first editor was Edmund Ronalds. The journal underwent several renamings, splits, and mergers throughout its history. In 1980, the Chemical Society merged with several other organizations into the Royal Society of Chemistry. The journal's continuity is found in '' Chemical Communications'', '' Dalton Transactions'', '' Faraday Transactions'', and '' Perkin Transactions'', all of which are published by the Royal Society of Chemistry. History ;'' Proceedings of the Chemical Society'' * ''Memoirs of the Chemical Society of London'' (1841) * ''Proceedings of the Chemical Society of London'' (1842–1843) * ''Memoirs and Proceedings of the Chemical Society'' (1843–1848) * ''Proceedings of the Chemical Society, London'' (1885–1914) * Published as a supplement to ''Journal of the Chemical Society'' from 1914 to 1956 * ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homogeneous Catalysis
In chemistry, homogeneous catalysis is catalysis where the catalyst is in same phase as reactants, principally by a soluble catalyst in a solution. In contrast, heterogeneous catalysis describes processes where the catalysts and substrate are in distinct phases, typically solid and gas, respectively. The term is used almost exclusively to describe solutions and implies catalysis by organometallic compounds. Homogeneous catalysis is an established technology that continues to evolve. An illustrative major application is the production of acetic acid. Enzymes are examples of homogeneous catalysts. Examples Acid catalyst The proton is a pervasive homogeneous catalyst because water is the most common solvent. Water forms protons by the process of self-ionization of water. In an illustrative case, acids accelerate (catalyze) the hydrolysis of esters: :CH3CO2CH3 + H2O CH3CO2H + CH3OH At neutral pH, aqueous solutions of most esters do not hydrolyze at practical rates. Transition met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Computational Chemistry
The ''Journal of Computational Chemistry'' is a peer-reviewed scientific journal published since 1980 by John Wiley & Sons. It covers research, contemporary developments in theory and methodology, and applications in all areas of computational chemistry, including ab initio quantum chemistry methods and semiempirical methods, density functional theory, molecular mechanics, molecular dynamics, statistical mechanics, cheminformatics, biomolecular structure prediction, molecular design, and bioinformatics. According to the ''Journal Citation Reports'', the journal has a 2020 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 3.376, ranking it 80th out of 179 journals in the category "Chemistry, Multidisciplinary". References External links * Chemistry journa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesityl
Mesitylene or 1,3,5-trimethylbenzene is a derivative of benzene with three methyl substituents positioned symmetrically around the ring. The other two isomeric trimethylbenzenes are 1,2,4-trimethylbenzene (pseudocumene) and 1,2,3-trimethylbenzene (hemimellitene). All three compounds have the formula C6H3(CH3)3, which is commonly abbreviated C6H3Me3. Mesitylene is a colorless liquid with sweet aromatic odor. It is a component of coal tar, which is its traditional source. It is a precursor to diverse fine chemicals. The mesityl group (Mes) is a substituent with the formula C6H2Me3 and is found in various other compounds. Preparation Mesitylene is prepared by transalkylation of xylene over solid acid catalyst:Karl Griesbaum, Arno Behr, Dieter Biedenkapp, Heinz-Werner Voges, Dorothea Garbe, Christian Paetz, Gerd Collin, Dieter Mayer, Hartmut Höke “Hydrocarbons” in Ullmann's Encyclopedia of Industrial Chemistry 2002 Wiley-VCH, Weinheim. . :2 C6H4(CH3)2 ⇌ C6H3(C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tris(o-tolyl)phosphine
Tris(''o''-tolyl)phosphine is an organophosphorus compound with the formula P(C6H4CH3)3. It is a white, water-insoluble solid that is soluble in organic solvents. In solution it slowly converts to the phosphine oxide. As a phosphine ligand, it has a wide cone angle of 194°. Consequently, it tends to cyclometalate when treated with metal halides and metal acetates. Complexes of this ligand are common in homogeneous catalysis. {{clear-left See also *Triphenylphosphine Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a l ... References Tertiary phosphines 2-Tolyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tricyclohexylphosphine
Tricyclohexylphosphine is the tertiary phosphine with the formula P( C6H11)3. Commonly used as a ligand in organometallic chemistry, it is often abbreviated to PCy3, where Cy stands for cyclohexyl. It is characterized by both high basicity (p''K''a = 9.7) and a large ligand cone angle (170°).{{cite journal , last1 = Immirzi , first1 = A. , last2 = Musco , first2 = A. , title = A Method to Measure the Size of Phosphorus Ligands in Coordination Complexes , doi = 10.1016/S0020-1693(00)95635-4 , year = 1977 , journal = Inorg. Chim. Acta , volume = 25 , pages = L41–42 Important complexes containing P(Cy)3 ligands include the 2005 Nobel Prize-winning Grubbs' catalyst and the homogeneous hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or Saturated ... catalyst Crab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether. Preparation and structure Triphenylphosphine can be prepared in the laboratory by treatment of phosphorus trichloride with phenylmagnesium bromide or phenyllithium. The industrial synthesis involves the reaction between phosphorus trichloride, chlorobenzene, and sodium: :PCl3 + 3 PhCl + 6 Na → PPh3 + 6 NaCl Triphenylphosphine crystallizes in triclinic and monoclinic modification. In both cases, the molecule adopts a pyramidal structure with propeller-like arrangement of the thre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triethylphosphine
Triethylphosphine is the organophosphorus compound with the formula P(CH2CH3)3, commonly abbreviated as PEt3. It is a colorless liquid with an unpleasant odor characteristic of alkylphosphines. The compound is a common ligand in organometallic chemistry, such as in auranofin. Structure and simple reactions It is a pyramidal molecule with approximate ''C''3''v'' symmetry. PEt3 is usually prepared using Grignard reagents: : 3 CH3CH2MgCl + P(OC6H5)3 → P(CH2CH3)3 + 3 C6H5OMgCl PEt3 reacts with strong acids to give salts PEt3.Annette Schier and Hubert Schmidbaur "P-Donor Ligands" in Encyclopedia of Inorganic Chemistry 2006, Wiley-VCH, Weinheim. This reaction is reversible. Similarly, it is also easily alkylated to give phosphonium derivatives. PEt3 is easily oxidised to the phosphine oxide with oxygen. Coordination chemistry Triethylphosphine is a highly basic ligand that forms coordination complexes with many metals. As a ligand, triethylphosphine's Tolman cone angle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1,3-Bis(diphenylphosphino)propane
1,3-Bis(diphenylphosphino)propane (dppp) is an organophosphorus compound with the formula PhP(CH)PPh. The compound is a white solid that is soluble in organic solvents. It is slightly air-sensitive, degrading in air to the phosphine oxide. It is classified as a diphosphine ligand in coordination chemistry and homogeneous catalysis. The diphosphine can be prepared by the reaction of lithium diphenylphosphide and 1,3-dichloropropane (Ph = CH): : 2 PhPLi + Cl(CH)Cl → PhP(CH)PPh + 2 LiCl However, it can be synthesised via a much more controllable (and cheaper) route, via metal-halogen exchange and then metathesis: :Br(CH)Br + 2 BuLi → Li(CH)Li + 2 BuBr :Li(CH)Li + 2 PCl → ClP(CH)PCl + 2 LiCl :ClP(CH)PCl + 4 PhLi → PhP(CH)PPh + 4 LiCl Coordination chemistry and use as co-catalyst The diphosphine serves as a bidentate ligand forming six-membered CPM chelate ring with a natural bite angle of 91°. For example, the complex dichloro(1,3-bis(diphenylphosphino)propane)n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
