|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Melting point||70 to 73 °C (158 to 163 °F; 343 to 346 K)|
|Boiling point||273 °C (523 °F; 546 K)|
|GHS Signal word||Danger|
|H301, H302, H311, H312, H319, H412|
|P264, P270, P273, P280, P301+310, P301+312, P302+352, P305+351+338, P312, P321, P322, P330, P337+313, P361, P363, P405, P501|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
2,2?-Bipyridine (bipy or bpy, pronounced ) is an organic compound with the formula C10H8N2. This colorless solid 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.
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. Protonated bipyridine adopts a cis conformation.
Upon complexation, the related N,N-heterocyclic ligand phenanthroline does not incur an enthalpic and entropic penalty, and thus its complexes tend to be more stable. With respective pKa's of 4.86 and 4.3 for their conjugate acids, phenanthroline and bipy are of comparable basicity.
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.