| 2,2'-Bipyridine | |
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2,2'-Bipyridine |
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Other names
Bipyridyl |
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| Identifiers | |
| CAS number | 366-18-7 |
| ChemSpider | 13867714 |
| UNII | 551W113ZEP |
| ChEBI | CHEBI:30351 |
| ChEMBL | CHEMBL39879 |
| RTECS number | DW1750000 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C10H8N2 |
| Molar mass | 156.18 g mol−1 |
| Melting point |
70-73 °C |
| Boiling point |
273 °C |
| Structure | |
| Dipole moment | 0 D |
| Hazards | |
| R-phrases | 25 |
| S-phrases | 36/37-45 |
| Main hazards | toxic |
| Related compounds | |
| Related compounds | 4,4'-Bipyridine Pyridine Phenanthroline Terpyridine Biphenyl |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
2,2'-Bipyridine is a organic compound with the formula (C10H8N2). This colorless solid, commonly abbreviated bipy or bpy (pronounced "bip-ee"), is an important isomer of the bipyridine family. It is a bidentate chelating ligand, forming complexes with many transition metals. Ruthenium complex and platinum complexes of bipy exhibit intense luminescence, which may have practical applications.
Contents |
It is prepared by the dehydrogenation of pyridine using Raney nickel:[1]
Although uncoordinated 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. Only in acidic solution bipyridine adopts a cis conformation.[2] The related N-heterocyclic ligand phenanthroline does not have the same conformational flexibility and tends to bind metal ions more strongly.
Reflecting the popularity of this ligand design, many substituted variants of bipy have been described.[3][4]
Bipyridine complexes absorb intensely in the visible part of the spectrum. The electronic transitions are attributed to metal-to-ligand charge transfer (MLCT). In the "tris(bipy) complexes" three bipyridine molecules coordinate to a metal ion, written as [M(bipy)3]n+ (M = metal ion; Cr, Fe, Co, Ru, Rh and so on; bipy = 2,2'-bipyridine). These complexes have six-coordinated, octahedral structures and two enantiomers as follows:
These and other homoleptic tris-2,2'-bipy complexes of many transition metals are electroactive. Often, both the metal centred and ligand centred electrochemical reactions are reversible one-electron reactions that can be observed by cyclic voltammetry. Under strongly reducing conditions, most tris(bipy) complexes can be reduced to neutral derivatives containing bipy- ligands. Examples include M(bipy)3, where M = Al, Cr, Si.