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Diradicals
In chemistry, a diradical is a molecular species with two electrons occupying molecular orbitals (MOs) which are degenerate. The term "diradical" is mainly used to describe organic compounds, where most diradicals are extremely reactive and non-Kekulé molecules that are rarely isolated. Diradicals are even-electron molecules but have one fewer bond than the number permitted by the octet rule. Examples of diradical species can also be found in coordination chemistry, for example among bis(1,2-dithiolene) metal complexes. Spin states Diradicals are usually triplets. The phrases ''singlet'' and ''triplet'' are derived from the multiplicity of states of diradicals in electron spin resonance: a singlet diradical has one state (S=0, Ms=2*0+1=1, ms=0) and exhibits no signal in EPR and a triplet diradical has 3 states (S=1, Ms=2*1+1=3, ms=-1; 0; 1) and shows in EPR 2 peaks (if no hyperfine splitting). The triplet state has total spin quantum number S=1 and is paramagnetic. Therefor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphosphadiboretanes
1,3-Diphospha-2,4-diboretanes, or B2P2, is a class of 4-member cyclic compound, cyclic compounds of alternating boron and phosphorus atoms. They are often found as dimers during the synthesis of Group 13/15 multiple bonds#Boraphosphenes(P=B), boraphosphenes (RB=PR'). Compounds can exhibit localized Singlet state, singlet diradical character (diradicaloid) between the boron atoms in the solution and solid state. Synthesis The first suggested synthesis of a diphosphadiboretane compound was with phosphinoarylboranes Dimer (chemistry), dimerization in 1961. Concurrently, a diphosphadiboretane was determined to be produced from the reaction with phosphinosilanes and boron halides. The following Thermal decomposition, thermolysis treatment formed boraphosphenes by cleavage of the σ P-Si bonds. Dimerization of these compounds are highly favored (upward to 90 kcal mol−1), which results in isolated diphosphadiboretanes. Alternative routes of synthesis utilizing facile Leaving group, lea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrene
In chemistry, a nitrene or imene () is the nitrogen analogue of a carbene. The nitrogen atom is uncharged and valence (chemistry)#monovalent, monovalent, so it has only 6 electrons in its valence level—two covalent bonded and four non-bonded electrons. It is therefore considered an electrophile due to the octet rule, unsatisfied octet. A nitrene is a reactive intermediate and is involved in many chemical reactions. The simplest nitrene, HN, is called imidogen, and that term is sometimes used as a synonym for the nitrene class. Electron configuration In the simplest case, the linear N–H molecule (imidogen) has its nitrogen atom sp hybrid orbital, sp hybridized, with two of its four non-bonded electrons as a lone pair in an sp orbital and the other two occupying a degenerate orbital, degenerate pair of p orbitals. The electron configuration is consistent with Hund's rule: the low energy form is a triplet state, triplet with one electron in each of the p orbitals and the high en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during chemical reaction, reactions with other chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spin Quantum Number
In physics and chemistry, the spin quantum number is a quantum number (designated ) that describes the intrinsic angular momentum (or spin angular momentum, or simply ''spin'') of an electron or other particle. It has the same value for all particles of the same type, such as = for all electrons. It is an integer for all bosons, such as photons, and a half-odd-integer for all fermions, such as electrons and protons. The component of the spin along a specified axis is given by the spin magnetic quantum number, conventionally written . The value of is the component of spin angular momentum, in units of the reduced Planck constant , parallel to a given direction (conventionally labelled the –axis). It can take values ranging from + to − in integer increments. For an electron, can be either or . Nomenclature The phrase ''spin quantum number'' refers to quantized spin angular momentum. The symbol is used for the spin quantum number, and is described as the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inorganic Chemistry
Inorganic chemistry deals with chemical synthesis, synthesis and behavior of inorganic compound, inorganic and organometallic chemistry, organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, as there is much overlap in the subdiscipline of organometallic chemistry. It has applications in every aspect of the chemical industry, including catalysis, materials science, pigments, surfactants, coatings, pharmaceutical drug, medications, fuels, and agriculture. Occurrence Many inorganic compounds are found in nature as minerals. Soil may contain iron sulfide as pyrite or calcium sulfate as gypsum. Inorganic compounds are also found multitasking as biomolecules: as electrolytes (sodium chloride), in energy storage (Adenosine triphosphate, ATP) or in construction (the polyphosphate backbone in DNA). Bonding Inorganic compounds exhibit a range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteroleptic
In inorganic chemistry, a homoleptic chemical compound is a Coordination complex, metal compound with all ligands identical. The term uses the "homo-" prefix to indicate that something is the same for all. Any metal species which has more than one type of ligand is heteroleptic. Some compounds with names that suggest that they are homoleptic are in fact heteroleptic, because they have ligands in them which are not featured in the name. For instance dialkyl magnesium complexes, which are found in Schlenk equilibrium, the equilibrium which exists in a Solution (chemistry), solution of a Grignard reagent in an ether, have two ether ligands attached to each magnesium centre. Another example is a solution of Trimethylaluminium, trimethyl aluminium in an ether solvent (such as THF); similar chemistry should be expected for a triaryl or trialkyl Boranes, borane. It is possible for some ligands such as dimethyl sulfoxide, DMSO to bind with two or more different coordination modes. It would ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homoleptic
In inorganic chemistry, a homoleptic chemical compound is a metal compound with all ligands identical. The term uses the " homo-" prefix to indicate that something is the same for all. Any metal species which has more than one type of ligand is heteroleptic. Some compounds with names that suggest that they are homoleptic are in fact heteroleptic, because they have ligands in them which are not featured in the name. For instance dialkyl magnesium complexes, which are found in the equilibrium which exists in a solution of a Grignard reagent in an ether, have two ether ligands attached to each magnesium centre. Another example is a solution of trimethyl aluminium in an ether solvent (such as THF); similar chemistry should be expected for a triaryl or trialkyl borane. It is possible for some ligands such as DMSO to bind with two or more different coordination modes. It would still be reasonable to consider a complex which has only one type of ligand but with different coordination ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disulfur Dinitride
Disulfur dinitride is the chemical compound with the formula . Preparation and reactions Passing gaseous over silver metal wool at 250–300 °C at low pressure (1 mmHg) yields cyclic . The silver reacts with the sulfur produced by the thermal decomposition of the to form , and the resulting catalyzes the conversion of the remaining into the four-membered ring , : : An alternative uses the less explosive . decomposes explosively above 30°C, and is shock sensitive. It readily sublimes, and is soluble in diethyl ether Diethyl ether, or simply ether, is an organic compound with the chemical formula , sometimes abbreviated as . It is a colourless, highly Volatility (chemistry), volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It belongs .... Traces of water cause it to polymerize into . In the solid state it spontaneously polymerizes forming . It forms adducts with Lewis acids via a nitrogen atom, e.g. , , , . Structure and bonding The mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrenium Ion
A nitrenium ion (also called: aminylium ion or imidonium ion (obsolete)) in organic chemistry is a reactive intermediate based on nitrogen with both an electron lone pair and a positive charge and with two substituents (). Nitrenium ions are isoelectronic with carbenes, and can exist in either a singlet or a triplet state. The parent nitrenium ion, , is a ground state triplet species with a gap of to the lowest energy singlet state. Conversely, most arylnitrenium ions are ground state singlets. Certain substituted arylnitrenium ions can be ground state triplets, however. Nitrenium ions can have microsecond or longer lifetimes in water. Aryl nitrenium ions are of biological interest because of their involvement in certain DNA damaging processes. They are generated upon ''in vivo'' oxidation of arylamines. The regiochemistry and energetics of the reaction of phenylnitrenium ion with guanine has been investigated using density functional theory computations. Nitrenium species have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbene
In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a Valence (chemistry), valence of two and two unshared valence electrons. The general formula is or where the R represents substituents or hydrogen atoms. The term "carbene" may also refer to the specific compound , also called methylene radical, methylene, the parent hydride from which all other carbene compounds are formally derived. There are two types of carbenes: singlet state, singlets or triplet state, triplets, depending upon their electronic structure. The different classes undergo different reactions. Most carbenes are extremely reactive and short-lived. A small number (the diHalogen, halocarbenes, carbon monoxide, and carbon monosulfide) can be isolated, and can stabilize as Coordination complex, metal ligands, but otherwise cannot be stored in bulk. A rare exception are the persistent carbenes, which have extensive application in modern organometallic chemistry. Generatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triplet Oxygen
Triplet oxygen, 3O2, refers to the ''S'' = 1 electronic ground state of molecular oxygen (dioxygen). Molecules of triplet oxygen contain two unpaired electrons, making triplet oxygen an unusual example of a stable and commonly encountered diradical: it is more stable as a triplet state, triplet than a singlet state, singlet. According to molecular orbital theory, the electron configuration of triplet oxygen has two electrons occupying two π molecular orbitals (MOs) of equal energy (that is, degenerate energy levels, degenerate MOs). In accordance with Hund's rules, they remain electron pair, unpaired and spin-parallel, which accounts for the paramagnetism of molecular oxygen. These half-filled orbitals are antibonding in character, reducing the overall bond order of the molecule to 2 from the maximum value of 3 that would occur when these antibonding orbitals remain fully unoccupied, as in dinitrogen. The molecular term symbol for triplet oxygen is 3Σ. Spin The ''s'' = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Singlet Oxygen
Singlet oxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemistry, inorganic chemical with the formula O=O (also written as or ), which is in a quantum state where all electrons are Radical (chemistry), spin paired. It is kinetically unstable at ambient temperature, but the rate of decay is slow. The lowest excited state of the dioxygen, diatomic oxygen molecule is a singlet state. It is a gas with physical properties differing only subtly from those of the more prevalent triplet oxygen, triplet ground state of O2. In terms of its chemical reactivity, however, singlet oxygen is far more reactive toward organic compounds. It is responsible for the photodegradation of many materials but can be put to constructive use in organic synthesis, preparative organic chemistry and photodynamic therapy. Trace amounts of singlet oxygen are found in the upper atmosphere and in polluted urban atmospheres where it contributes to the formation of lung-damagin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
