The 129 reported interstellar and circumstellar molecules. Updated 2005 Nov by HAW.

NRAO National Radio Astronomy Observatory

Resources for Frequencies

NIST Recommended Rest Frequencies for Observed Interstellar Molecular Microwave Transitions by Frank J. Lovas

NIST Physical Reference Data .

Molecular Spectroscopy Home Page (Includes transitions not yet observed in the ISM) by Herb Pickett

The Cologne Database for Molecular Spectroscopy additions.
 
 

The Astrochemistry Working Group of the International Astronomical Union home page lists other resources

The DEMIRM List of the Known Interstellar Molecules.

Molecules below are found in interstellar clouds of various sorts. Molecules in this color have been found in Comet 1995 O1 Hale-Bopp. H2O+ and C2H6 are seen in the Comet but not in Interstellar Clouds.

Diatomic Triatomic Four Atoms Five Atoms  Six Atoms Seven Atoms Eight Atoms Nine Atoms Ten Atoms Eleven Atoms Twelve Atoms Thirteen Atoms
H2 C3 c-C3H  C5 C5H  C6H  CH3C3N  CH3C4H  CH3C5N?  HC9N  CH3OC2H5
 HC11N
AlF  C2H l-C3H  C4H l-H2C4 CH2CHCN  HCOOCH3 CH3CH2CN  (CH3)2CO 


AlCl  C2O C3N  C4Si C2H4  CH3C2H  CH3COOH?  (CH3)2O  NH2CH2COOH? 


C2 C2S C3O  l-C3H2 CH3CN HC5N  C7H  CH3CH2OH   CH3CH2CHO  


CH  CH2 C3S  c-C3H2 CH3NC  HCOCH3  H2C6 HC7N 



CH+  HCN C2H2 CH2CN CH3OH NH2CH3   CH2OHCHO  C8H 



CN HCO CH2D+?  CH4 CH3SH   c-C2H4O   CH2CHCHO  




CO HCO+ HCCN  HC3N HC3NH+  CH2CHOH 





CO+ HCS+ HCNH+  HC2NC HC2CHO 






CP  HOC+ HNCO HCOOH NH2CHO






CSi  H2O HNCS  H2CHN C5N 






HCl  H2S HOCO+  H2C2O HC4N






KCl  HNC H2CO H2NCN







NH HNO H2CN  HNC3







NO  MgCN H2CS SiH4







NS  MgNC H3O+ H2COH+







NaCl  N2H+ NH3








OH N2O  SiC3








PN  NaCN C4








SO OCS









SO+  SO2









SiN  c-SiC2









SiO  CO2









SiS  NH2









CS H3+









HF  SiCN









SH  AlNC









FeO(?) SiNC









Molecules with Two Atoms

AlF AlCl C2 CH CH+ CN CO CO+ CP CS CSi HCl H2 KCl NH NO NS NaCl OH PN SO S0+ SiN SiO SiS HF   SH, FeO(?) 

Molecules with Three Atoms

C3 C2H C20 C2S CH2 HCN HCO HCO+ HCS+ HOC+ H20 H2S HNC HNO MgCN MgNC N2H+ N20 NaCN OCS S02 c-SiC2 CO2 NH2 H3+ AlNC

Molecules with Four Atoms

c-C3H l-C3H C3N C30 C3S C2H2 CH2D+? HCCN HCNH+ HNCO HNCS HOCO+ H2CO H2CN H2CS H30+ NH3 SiC3

Molecules with Five Atoms

C5 C4H C4Si l-C3H2 c-C3H2 CH2CN CH4 HC3N HC2NC HCOOH H2CHN H2C20 H2NCN HNC3 SiH4 H2COH+

Molecules with Six Atoms

C5H C50 C2H4 CH3CN CH3NC CH30H CH3SH HC3NH+ HC2CHO HCONH2 l-H2C4 C5N

Molecules with Seven Atoms

C6H CH2CHCN CH3C2H HC5N HCOCH3 NH2CH3 c-C2H4O  CH2CHOH 

Molecules with Eight Atoms

CH3C3N HCOOCH3 CH3COOH C7H, H2C6,CH2OHCHO, CH2CHCHO  

Molecules with Nine Atoms

CH3C4H CH3CH2CN (CH3)20 CH3CH20H HC7N C8H

Molecules with Ten Atoms

CH3C5N? (CH3)2CO NH2CH2COOH?    CH3CH2CHO  

Molecules with Eleven Atoms

HC9N

Molecules with Thirteen Atoms

HC11N

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