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Transition Metal Amino Acid Complexes
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 (including peptide) and ester derivatives of amino acids. Also excluded are the polyamino acids including the chelating agents EDTA and NTA. : Binding modes Most commonly, amino acids coordinate to metal ions as N,O bidentate ligands, utilizing the amino group and the carboxylate. They are "L-X" ligands. A five-membered chelate ring is formed. The chelate ring is only slightly ruffled at the sp3-hybridized carbon and nitrogen centers. For those amino acids containing coordinating substituents, the resulting complexes are more structurally diverse since these substituents can coordinate. Histidine, aspartic acid, methionine, and cysteine sometimes form tride ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordination Complex
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many metal-containing compounds, especially those that include transition metals (elements like titanium that belong to the Periodic Table's d-block), are coordination complexes. Nomenclature and terminology Coordination complexes are so pervasive that their structures and reactions are described in many ways, sometimes confusingly. The atom within a ligand that is bonded to the central metal atom or ion is called the donor atom. In a typical complex, a metal ion is bonded to several donor atoms, which can be the same or different. A polydentate (multiple bonded) ligand is a molecule or ion that bonds to the central atom through several of the ligand's atoms; ligands with 2, 3, 4 or even 6 bonds to the central atom are common. These compl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper(II) Glycinate
Copper(II) glycinate (IUPAC suggested name: bis(glycinato)copper(II)) refers to the coordination complex of copper(II) with two equivalents of glycinate, with the formula u(glycinate)2(H2O)''x''where ''x'' = 1 (''monohydrate'') or 0 (''anhydrous'' form). The complex was first reported in 1841, and its chemistry has been revisited many times, particularly in relation to the isomerisation reaction between the ''cis'' and ''trans'' forms which was first reported in 1890. All forms are blue solids, with varying degrees of water solubility. A practical application of the compound is as a source of dietary copper in animal feeds. Synthesis Bis(glycinato)copper(II) is typically prepared from the reaction of copper(II) acetate in aqueous ethanol with glycine: : Cu(OAc)2 + 2 H2NCH2COOH + ''x'' H2O → u(H2NCH2COO)2(H2O)''x''+ 2 AcOH, ''x'' = 0 or 1 The reaction proceeds through a non-redox dissociative substitution mechanism and usually affords the ''cis'' isomer. Structure Like ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protecting Group
A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic synthesis. In many preparations of delicate organic compounds, some specific parts of their molecules cannot survive the required reagents or chemical environments. Then, these parts, or groups, must be protected. For example, lithium aluminium hydride is a highly reactive but useful reagent capable of reducing esters to alcohols. It will always react with carbonyl groups, and this cannot be discouraged by any means. When a reduction of an ester is required in the presence of a carbonyl, the attack of the hydride on the carbonyl has to be prevented. For example, the carbonyl is converted into an acetal, which does not react with hydrides. The acetal is then called a protecting group for the carbonyl. After the step involving the hydride is complete, the acet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioinorganic Chemistry
Bioinorganic chemistry is a field that examines the role of metals in biology. Bioinorganic chemistry includes the study of both natural phenomena such as the behavior of metalloproteins as well as artificially introduced metals, including those that are non-essential, in medicine and toxicology. Many biological processes such as respiration depend upon molecules that fall within the realm of inorganic chemistry. The discipline also includes the study of inorganic models or mimics that imitate the behaviour of metalloproteins. As a mix of biochemistry and inorganic chemistry, bioinorganic chemistry is important in elucidating the implications of electron-transfer proteins, substrate bindings and activation, atom and group transfer chemistry as well as metal properties in biological chemistry. The successful development of truly interdisciplinary work is necessary to advance bioinorganic chemistry. Composition of living organisms About 99% of mammals' mass are the elements carb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Tris(carbonato)cobalt(III)
Sodium tris(carbonato)cobalt(III) is the name given to the inorganic compound with the formula Na3Co(CO3)3•3H2O. The salt contains an olive-green metastable cobalt(III) coordination complex. The salt is sometimes referred to as the “Field-Durrant precursor” and is prepared by the “Field-Durrant synthesis”. It is used in the synthesis of other cobalt(III) complexes. Otherwise cobalt(III) complexes are generated from cobalt(II) precursors, a process that requires an oxidant. Synthesis An aqueous solution of cobalt(II) nitrate and hydrogen peroxide is added to a solution of sodium bicarbonate, leading to precipitation of the olive solid. The method is a modification of the synthesis of what has been described as “Co2(CO3)3”. Structure and synthetic applications The identity of this complex anion is uncertain, suggestions include o(κ2-CO3)3sup>3-, o(κ1-CO3H)3(OH)3sup>3-, and o(κ2-CO3)2(κ1-CO3)(OH2)sup>3-. Thermal gravimetric analysis favors the presence of on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tris(glycinato)cobalt(III)
Tris(glycinato)cobalt(III) describes coordination complexes with the formula . Several isomers exist of these octahedral complexes formed between low-spin d6 Co(III) and the conjugate base of the amino acid glycine. Structures Both a meridional isomer and a facial isomer are known. In the former the Co-O bonds share a plane, and in the facial isomer they do not. Each of these two isomers exists also as pairs of stereoisomers, termed Δ and Λ. This set of compounds are prototypes of many tris(aminocarboxylate) complexes, with the notable distinction that the Co(III) derivatives do not isomerize readily and can thus be separated. The violet isomer is obtained anhydrous, whereas the red derivative is the monohydrate. X-ray crystallographic characterization of the mer isomer demonstrates the existence of a dihydrate, however. Synthesis The reaction of glycine with sodium tris(carbonato)cobalt(III) produces both the violet meridional and red-pink facial isomers in approxima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylenediamine
Ethylenediamine (abbreviated as en when a ligand) is the organic compound with the formula C2H4(NH2)2. This colorless liquid with an ammonia-like odor is a basic amine. It is a widely used building block in chemical synthesis, with approximately 500,000 tonnes produced in 1998.Karsten Eller, Erhard Henkes, Roland Rossbacher, Hartmut Höke "Amines, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH Verlag, Weinheim. Ethylenediamine is the first member of the so-called polyethylene amines. Synthesis Ethylenediamine is produced industrially by treating 1,2-dichloroethane with ammonia under pressure at 180 °C in an aqueous medium:Hans-Jürgen Arpe, Industrielle Organische Chemie, 6. Auflage (2007), Seite 245, Wiley VCH : In this reaction hydrogen chloride is generated, which forms a salt with the amine. The amine is liberated by addition of sodium hydroxide and can then be recovered by . Diethylenetriamine (DETA) and triethylenetetramine (TETA) a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Metal Thioether Complex
Transition metal thioether complexes comprise coordination complexes of thioether (R2S) ligands. The inventory is extensive. Dimethylsulfide complexes As the simplest thioether, dimethyl sulfide forms complexes that are illustrative of the class. Well characterized derivatives include ''cis''- iCl4L2 VCl3L2, NbCl5L, NbCl4L2, Cr(CO)5L, CrCl3L3, RuCl2L4, RuCl3L3, RhCl3L3, ''cis''- and ''trans''- rCl4L3, ''cis''-MCl2L2 (M = Pd, Pt), tCl3Lsup>−, ''cis''- and ''trans''- tCl4L2(L = SMe2). With respect to donor properties, dimethyl sulfide is a soft ligand with donor properties weaker than phosphine ligands. Such complexes are generally prepared by treating the metal halide with the thioether. Chloro(dimethyl sulfide)gold(I) can however be prepared by redox reaction of elemental gold and DMSO in the presence of hydrochloric acid. Stereochemistry Thioether complexes feature pyramidal sulfur centers. Typical C-S-C angles are near 99° in both free thioethers and their complexe ... [...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] |
Transition Metal Imidazole Complex
A transition metal imidazole complex is a coordination complex that has one or more imidazole ligands. Complexes of imidazole itself are of little practical importance. In contrast, imidazole derivatives, especially histidine, are pervasive ligands in biology where they bind metal cofactors. Bonding and structure : Only the imine nitrogen (HC=N-CH) of imidazole is basic, and it is this nitrogen that binds to metal ions. The pyrrole-like nitrogen ((HC-NH-CH) projects away from the metal. The pKa of protonated imidazolium cation is about 6.95, which indicates that the basicity of imidazole is intermediate between pyridine (pKa of pyridinium = 5.23) and ammonia (pKa = 9,24 of ammonium). The donor properties of imidazole are also indicated by the redox properties of its complexes. Imidazole is a pure sigma-donor ligand. There is no evidence for pi backbonding in metal-imidazole complexes, a property that can be attributed to the presence of the pi-donor pyrrole-like NH center. F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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