2,2′-Bipyridine

2,2′-Bipyridine (bipy or bpy, pronounced /ˈbɪpiː/) 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 and platinum complexes of bipy exhibit intense luminescence, which may have practical applications.

2,2′-Bipyridine

Names
Preferred IUPAC name 2,2′-Bipyridine
Other names Bipyridyl Dipyridyl Bipy Bpy Dipy
Identifiers
CAS Number	366-18-7 Y
3D model (JSmol)	Interactive image
Beilstein Reference	113089
ChEBI	CHEBI:30351 Y
ChEMBL	ChEMBL39879 Y
ChemSpider	13867714 Y
ECHA InfoCard	100.006.069
EC Number	206-674-4 923-456-0
Gmelin Reference	3720 936807
PubChem CID	1474
RTECS number	DW1750000
UNII	551W113ZEP Y
CompTox Dashboard (EPA)	DTXSID9040635
InChI InChI=1S/C10H8N2/c1-3-7-11-9(5-1)10-6-2-4-8-12-10/h1-8H Y Key: ROFVEXUMMXZLPA-UHFFFAOYSA-N Y InChI=1/C10H8N2/c1-3-7-11-9(5-1)10-6-2-4-8-12-10/h1-8H Key: ROFVEXUMMXZLPA-UHFFFAOYAP
SMILES n1ccccc1-c2ccccn2
Properties
Chemical formula	C10H8N2
Molar mass	156.188 g·mol−1
Appearance	Colorless solid
Melting point	70 to 73 °C (158 to 163 °F; 343 to 346 K)
Boiling point	273 °C (523 °F; 546 K)
Structure
Dipole moment	0 D
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	toxic
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H302, H311, H312, H319, H412
Precautionary statements	P264, P270, P273, P280, P301+P310, P301+P312, P302+P352, P305+P351+P338, P312, P321, P322, P330, P337+P313, P361, P363, P405, P501
Lethal dose or concentration (LD, LC):
LD50 (median dose)	15-78 mg/kg (oral, rat); 20-140 mg/kg (oral, mouse)
Related compounds
Related compounds	4,4′-Bipyridine Pyridine Phenanthroline 3-Pyridylnicotinamide Terpyridine Biphenyl
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Preparation, structure, and general properties

2,2'-Bipyridine was first prepared by decarboxylation of divalent metal derivatives of pyridine-2-carboxylate:^[1]

M(O₂CC₅H₄N)₂ → (C₅H₄N)₂ + 2 CO₂ + ...

It is prepared by the dehydrogenation of pyridine using Raney nickel:^[2]

2 C₅H₅N → (C₅H₄N)₂ + H₂

Substituted 2,2'-bipyridines

Unsymmetrically substituted 2,2'-bipyridines can be prepared by cross coupling reaction of 2-pyridyl and substituted pyridyl reagents.^[3]

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.^[4] Monoprotonated bipyridine adopts a cis conformation.^[5]

Reactions

A large number of complexes of 2,2'-bipyridine have been described. It binds metals as a chelating ligand, forming a 5-membered chelate ring.

See also

• 2,2'-Biquinoline
• 1,10-Phenanthroline
• Dimethyl-2,2'-bipyridine

References

1. Constable; Housecroft (2019). "The Early Years of 2,2'-Bipyridine—A Ligand in its Own Lifetime". Molecules. 24 (21): 3951. doi:10.3390/molecules24213951. PMC 6864536. PMID 31683694.
2. Sasse, W. H. F. (1966). "2,2′-Bipyridine". Organic Syntheses. 46: 5; Collected Volumes, vol. 5, p. 102.
3. Liu, Tiandong; Fraser, Cassandra L. (2012). "Discussion Addendum for: Synthesis of 4-, 5-, and 6-Methyl-2,2'-bipyridine by a Negishi Cross-Coupling Strategy: 5-Methyl-2,2'-bipyridine". Organic Syntheses. 89: 76. doi:10.15227/orgsyn.089.0076.
4. Merritt, L. L.; Schroeder, E. (1956). "The Crystal Structure of 2,2′-Bipyridine". Acta Crystallographica. 9 (10): 801–804. doi:10.1107/S0365110X56002175.
5. Göller, A.; Grummt, U.-W. (2000). "Torsional barriers in biphenyl, 2,2′-bipyridine and 2-phenylpyridine". Chemical Physics Letters. 321 (5–6): 399–405. Bibcode:2000CPL...321..399G. doi:10.1016/S0009-2614(00)00352-3.