2,2′-Bipyridine (bipy or bpy, pronounced ) is an
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
with the formula . This colorless solid is an important
isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...
of the
bipyridine
Bipyridines are a family of organic compounds with the formula (C5H4N)2, consisting of two pyridyl (C5H4N) rings. Pyridine is an aromatic nitrogen-containing heterocycle. The bipyridines are all colourless solids, which are soluble in organic sol ...
family. It is a
bidentate chelating
Chelation () is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These l ...
ligand
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
, forming complexes with many
transition metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. The lanthanide and actinid ...
s.
Ruthenium
Ruthenium is a chemical element; it has symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is unreactive to most chem ...
and
platinum
Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...
complexes of bipy exhibit intense
luminescence
Luminescence is a spontaneous emission of radiation from an electronically or vibrationally excited species not in thermal equilibrium with its environment. A luminescent object emits ''cold light'' in contrast to incandescence, where an obje ...
.
Preparation, structure, and general properties
2,2'-Bipyridine was first prepared by decarboxylation of divalent metal derivatives of
pyridine-2-carboxylate:
It is prepared by the
dehydrogenation
In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...
of
pyridine
Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom . It is a highly flammable, weak ...
using
Raney nickel
Raney nickel , also called spongy nickel, is a fine-grained solid composed mostly of nickel derived from a nickel–aluminium alloy. Several grades are known, of which most are gray solids. Some are pyrophoric, but most are used as air-stable s ...
:
Substituted 2,2'-bipyridines
Unsymmetrically substituted 2,2'-bipyridines can be prepared by
cross coupling reaction
In organic chemistry, a cross-coupling reaction is a reaction where two different fragments are joined. Cross-couplings are a subset of the more general coupling reactions. Often cross-coupling reactions require metal catalysts. One important reac ...
of 2-pyridyl and substituted pyridyl reagents.
Structure
Although bipyridine is often drawn with its nitrogen atoms in ''cis'' conformation, the lowest energy conformation both in solid state and in solution is in fact coplanar, with nitrogen atoms in ''trans'' position. Monoprotonated bipyridine adopts a ''cis'' conformation.
Reactions
2,2'-bipyridine produces
multiple coordination complexes. It binds metals as a
ligand
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
for
chelation
Chelation () is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These l ...
, forming a 5-membered chelate ring.
See also
*
2,2'-Biquinoline
2,2′-Biquinoline is an organic compound with the formula (C9H6N)2. It is one of several biquinolines. It is prepared by reductive coupling of 2-chloroquinoline. It is a colorimetric indicator for organolithium compounds.
Ligand properties
...
*
1,10-Phenanthroline
1,10-Phenanthroline (phen) is a heterocyclic organic compound. It is a white solid that is soluble in organic solvents. The 1,10 refers to the location of the nitrogen atoms that replace CH's in the hydrocarbon called phenanthrene.
Abbreviated " ...
*
Dimethyl-2,2'-bipyridine
Dimethyl-2,2'-bipyridine can refer to many isomers of 2,2'-bipyridine containing two methyl substituents. All have the formula , but the most common are symmetrical derivatives listed below. These compounds are used as ligands in coordination che ...
References
{{DEFAULTSORT:Bipyridine, 2,2'-
Chelating agents
Bipyridines
2-Pyridyl compounds