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Nickel(II) Bis(acetylacetonate)
Nickel(II) bis(acetylacetonate) is a coordination complex with the formula i(acac)2sub>3, where acac is the anion C5H7O2− derived from deprotonation of acetylacetone. It is a dark green paramagnetic solid that is soluble in organic solvents such as toluene. It reacts with water to give the blue-green diaquo complex Ni(acac)2(H2O)2. Structure and properties Anhydrous nickel(II) acetylacetonate exists as molecules of Ni3(acac)6. The three nickel atoms are approximately collinear and each pair of them is bridged by two μ2 oxygen atoms. Each nickel atom has tetragonally distorted octahedral geometry, caused by the difference in the length of the Ni-O bonds between the bridging and non-bridging oxygens. Ni3(acac)6 molecules are almost centrosymmetric, despite the non-centrosymmetric point group of the ''cis''-Ni(acac)2 "monomers," which is uncommon. The trimeric structure allows all nickel centers to achieve an octahedral coordination. The trimer is only formed if intramolecular ... [...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] |
Magnetic Moment
In electromagnetism, the magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field. Examples of objects that have magnetic moments include loops of electric current (such as electromagnets), permanent magnets, elementary particles (such as electrons), various molecules, and many astronomical objects (such as many planets, some moons, stars, etc). More precisely, the term ''magnetic moment'' normally refers to a system's magnetic dipole moment, the component of the magnetic moment that can be represented by an equivalent magnetic dipole: a magnetic north and south pole separated by a very small distance. The magnetic dipole component is sufficient for small enough magnets or for large enough distances. Higher-order terms (such as the magnetic quadrupole moment) may be needed in addition to the dipole moment for extended objects. The magnetic dipole moment of an object is readily defined in terms of the torque that the objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dean–Stark Apparatus
upDean–Stark apparatus setup for an azeotrope with a solvent whose density is ''less than'' that of water: The Dean–Stark apparatus, Dean–Stark receiver, distilling trap, or Dean–Stark Head is a piece of laboratory glassware used in synthetic chemistry to collect water (or occasionally other liquid) from a reactor. It is used in combination with a reflux condenser and a distillation flask for the separation of water from liquids. This may be a continuous removal of the water that is produced during a chemical reaction performed at reflux temperature, such as in esterification reactions. It was invented by the American chemists Ernest Woodward Dean (1888–1959) and David Dewey Stark (1893–1979) in 1920 for determination of the water content in petroleum. Function left, A Dean–Stark apparatus in use; aluminium foil is used to reduce heat losses Two types of Dean–Stark traps exist – one for use with solvents with a density ''less'' than that of water and anoth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base (chemistry)
In chemistry, there are three definitions in common use of the word base, known as Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century. In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form Hydroxide ions OH−. These ions can react with hydrogen ions (H+ according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction An acid–base reaction is a chemical reaction that occurs between an acid and a base. It can be used to determine pH via titration. Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their applica .... A base was therefore a metal hydroxide such as Sodium hydroxide, NaOH or Calcium hydroxide, Ca(OH)2. Such aqueous hydroxide solutions were also described by certain characteristic properties. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel Nitrate
Nickel nitrate is the inorganic compound Ni(NO3)2 or any hydrate thereof. The anhydrous form is not commonly encountered, thus "nickel nitrate" usually refers to nickel(II) nitrate hexahydrate. The formula for this species is written in two ways: Ni(NO3)2.6H2O and, more descriptively i(H2O)6NO3)2. The latter formula indicates that the nickel(II) center is surrounded by six water molecules in this hydrated salt. In the hexahydrate, the nitrate anions are not bonded to nickel. Also known are three other hydrates: Ni(NO3)2.9H2O, Ni(NO3)2.4H2O, and Ni(NO3)2.2H2O. Anhydrous Ni(NO3)2 is also known. It is prepared by the reaction of nickel oxide with nitric acid: : NiO + 2 HNO3 + 5 H2O → Ni(NO3)2.6H2O The anhydrous nickel nitrate is typically not prepared by the heating the hydrates. Rather is generated by reaction of hydrates with dinitrogen pentoxide or of nickel carbonyl with dinitrogen tetroxide: : Ni(CO)4 + 2 N2O4 → Ni(NO3)2 + 2 NO + 4 CO The hydrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ni(acac)2
Nickel(II) bis(acetylacetonate) is a coordination complex with the formula i(acac)2sub>3, where acac is the anion C5H7O2− derived from deprotonation of acetylacetone. It is a dark green paramagnetic solid that is soluble in organic solvents such as toluene. It reacts with water to give the blue-green diaquo complex Ni(acac)2(H2O)2. Structure and properties Anhydrous nickel(II) acetylacetonate exists as molecules of Ni3(acac)6. The three nickel atoms are approximately collinear and each pair of them is bridged by two μ2 oxygen atoms. Each nickel atom has tetragonally distorted octahedral geometry, caused by the difference in the length of the Ni-O bonds between the bridging and non-bridging oxygens. Ni3(acac)6 molecules are almost centrosymmetric, despite the non-centrosymmetric point group of the ''cis''-Ni(acac)2 "monomers," which is uncommon. The trimeric structure allows all nickel centers to achieve an octahedral coordination. The trimer is only formed if intramolecular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridine-N-oxide
Pyridine-''N''-oxide is the heterocyclic compound with the formula C5H5NO. This colourless, hygroscopic solid is the product of the oxidation of pyridine. It was originally prepared using peroxyacids as the oxidising agent. The compound is used infrequently as an oxidizing reagent in organic synthesis. Structure The structure of pyridine-N-oxide is very similar to that of pyridine with respect to the parameters for the ring. The molecule is planar. The N-O distance is 1.34Å. The C-N-C angle is 124°, 7° wider than in pyridine. Synthesis The oxidation of pyridine can be achieved with a number of peracids including peracetic acid and perbenzoic acid. Oxidation can also be effected by a modified Dakin reaction using a urea-hydrogen peroxide complex, and sodium perborate or, using methylrhenium trioxide () as catalyst, with sodium percarbonate. Reactions Pyridine ''N''-oxide is five orders of magnitude less basic than pyridine, but it is isolable as a hydrochloride salt, 5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inorganica Chimica Acta
''Inorganica Chimica Acta'' is a peer-reviewed scientific journal published since 1967 that covers original research and reviews of fundamental and applied aspects of inorganic chemistry. See also * List of scientific journals in chemistry A ''list'' is any set of items in a row. List or lists may also refer to: People * List (surname) Organizations * List College, an undergraduate division of the Jewish Theological Seminary of America * SC Germania List, German rugby unio ... External links * Elsevier academic journals Inorganic chemistry journals Publications established in 1967 English-language journals Journals published between 13 and 25 times per year {{chem-journal-stub ... [...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] |
Coordination Sphere
In coordination chemistry, the first coordination sphere refers to the array of molecules and ions (the ligands) directly attached to the central metal atom. The second coordination sphere consists of molecules and ions that attached in various ways to the first coordination sphere. First coordination sphere The first coordination sphere refers to the molecules that are attached directly to the metal. The interactions between the first and second coordination spheres usually involve hydrogen-bonding. For charged complexes, ion pairing is important. In hexamminecobalt(III) chloride ( o(NH3)6l3), the cobalt cation plus the 6 ammonia ligands comprise the first coordination sphere. The coordination sphere of this ion thus consists of a central MN6 core "decorated" by 18 N−H bonds that radiate outwards. Second coordination sphere Metal ions can be described as consisting of series of two concentric coordination spheres, the first and second. More distant from the second coo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ni(acac)2(H2O)2
NI or Ni may refer to: Arts and entertainment * Ni, or Nishada, the seventh note of the Indian musical scale in raga * ''New Internationalist'', a magazine * Knights Who Say "Ni!", characters from the film ''Monty Python and the Holy Grail'' Businesses * National Instruments, a U.S. producer of automated test equipment and virtual instrumentation software * National Insurance, a system of taxes and related social security benefits in the United Kingdom * Native Instruments, a music software production company * News International, a British newspaper publisher * Portugália airline (IATA code NI) Language * Ni (letter), or Nu, a letter in the Greek alphabet: uppercase Ν, lowercase ν * Ni (kana), romanisation of the Japanese kana に and ニ * Ni (cuneiform), a sign in cuneiform writing Names * Ni (surname) (倪), a Chinese surname * Ní, a surname prefix from the shortened form of the Irish word for a daughter * Ni, female prefix to some Balinese names Places * Ni Ri ... [...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] |
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