Carbyne
Encyclopedia
In chemistry
, a carbyne is a monovalent
carbon
radical species containing an electrically neutral univalent carbon atom with three non-bonded electrons.
. For instance, fluoromethylidyne
(CF) can be detected in the gas phase by spectroscopy as an intermediate in the flash photolysis of CHFBr2
. The carbon atom was generally found to be an electronic doublet
: the valence electrons are arranged as one radical
(unpaired electron) and one electron pair, leaving a vacant atomic orbital
, rather than being a tri-radical. The carbon atom is a complex hybridization, so the simple Hund's rule analysis of a simple atom containing 3 p orbitals (or 4 sp3 hybrids) is not correct.
. For example, in [W
Br
(CO
)2(2,2'-bipyridine
)C
-Aryl
] and [WBr(CO)2(P
Ph3)2C-NR2]. An example of how to make such a compound would be to react [W(CO)6] with Lithium diisopropylamide
to form [(iPr
2N)(OLi)C=W(CO)5]. This is then reacted with either oxalyl bromide or triphenylphosphine dibromide followed by triphenyl phosphine. Another method is to treat a methoxy metal carbene
with a lewis acid
.
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, a carbyne is a monovalent
Monovalent
Monovalent may refer to:*In chemistry, valence is a measure of the number of chemical bonds formed by the atoms of a given element. Monovalent is a synonym of univalent.*Monovalent ions contain one valence electron....
carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
radical species containing an electrically neutral univalent carbon atom with three non-bonded electrons.
Gas phase/reactive intermediate
A carbyne can occur as a short-lived reactive intermediateReactive intermediate
In chemistry a reactive intermediate is a short-lived, high energy, highly reactive molecule. When generated in a chemical reaction it will quickly convert into a more stable molecule. Only in exceptional cases can these compounds be isolated and stored, e.g. low temperatures, matrix isolation...
. For instance, fluoromethylidyne
Fluoromethylidyne
Fluoromethylidyne is not a stable chemical species but a metastable radical containing one highly reactive carbon atom bound to one fluorine atom with the formula CF...
(CF) can be detected in the gas phase by spectroscopy as an intermediate in the flash photolysis of CHFBr2
Dibromofluoromethane
Dibromofluoromethane is a mixed halomethane. It is soluble in alcohol, acetone, benzene and chloroform.It can be used to prepare bromofluoromethane by reductive debromination with organotin hydride as tributyltin hydride....
. The carbon atom was generally found to be an electronic doublet
Doublet (physics)
In quantum mechanics, a doublet is a quantum state of a system with a spin of 1/2, such that there are two allowed values of the spin component, −1/2 and +1/2. Quantum systems with two possible states are sometimes called two-level systems...
: the valence electrons are arranged as one radical
Radical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
(unpaired electron) and one electron pair, leaving a vacant atomic orbital
Atomic orbital
An atomic orbital is a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus...
, rather than being a tri-radical. The carbon atom is a complex hybridization, so the simple Hund's rule analysis of a simple atom containing 3 p orbitals (or 4 sp3 hybrids) is not correct.
Organometallic ligand
Carbynes are incorporated in Transition metal carbyne complex]]es as a trivalent ligandLigand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
. For example, in [W
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
Br
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
(CO
Carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....
)2(2,2'-bipyridine
2,2'-Bipyridine
2,2'-Bipyridine is a organic compound with the formula . This colorless solid, commonly abbreviated bipy or bpy , is an important isomer of the bipyridine family. It is a bidentate chelating ligand, forming complexes with many transition metals...
)C
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
-Aryl
Aryl
In the context of organic molecules, aryl refers to any functional group or substituent derived from an aromatic ring, be it phenyl, naphthyl, thienyl, indolyl, etc....
] and [WBr(CO)2(P
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
Ph3)2C-NR2]. An example of how to make such a compound would be to react [W(CO)6] with Lithium diisopropylamide
Lithium diisopropylamide
Lithium diisopropylamide is the chemical compound with the formula [2CH]2NLi. Generally abbreviated LDA, it is a strong base used in organic chemistry for the deprotonation of weakly acidic compounds. The reagent has been widely accepted because it is soluble in non-polar organic solvents and it...
to form [(iPr
Propyl
In organic chemistry, propyl is a three-carbon alkyl substituent with chemical formula -C3H7. It is the substituent form of the alkane propane...
2N)(OLi)C=W(CO)5]. This is then reacted with either oxalyl bromide or triphenylphosphine dibromide followed by triphenyl phosphine. Another method is to treat a methoxy metal carbene
Carbene
In chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is RR'C:, but the carbon can instead be double-bonded to one group. The term "carbene" may also merely refer to the compound H2C:, also called...
with a lewis acid
Lewis acid
]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...
.