Purity testing of air-sensitive organometallic compounds by capillary supercritical fluid chromatography

Capillary supercritical fluid chromatography with flame ionization detection has been used to test the purity of air-sensitive organometallic compounds such as bisethenepentamethylcyclopentadienylcobalt (Cp*Co(C₂H₄)₂), dicarbonylcyclopentadienylcobalt (CpCo(CO)₂), dicarbonylpentamethylcyclopentadienylcobalt (Cp*Co(CO)₂), bisethenepentamethyl cyclopentadienylrhodium (Cp*Rh(C₂H₄)₂), bisethenecyclopentadienylrhodium (CpRh(C₂H₄)₂), carbonyl(1,3-dimesitylimidazol-2-ylidene)cyclopentadienylcobalt (CpCo(CO)(carbene)) and ethene(1,3-dimesitylimidazol-2-ylidene)pentamethylcyclopentadienylrhodium (Cp*Rh(C₂H₄)(carbene)). A sample introduction cell was constructed for loading of 10–40 mg of the air-sensitive compounds in 100% N₂ atmosphere. The sample cell was subsequently filled with toluene or pentane and the analytes in solution were injected onto the 50 μm i.d. capillary column using a timed split injector with 60 nL loop. A nonpolar (5% phenylsiloxane/95% methyl siloxane) stationary phase was used and a mobile phase consisting of 100% CO₂ with pressure programming. No signs of air-induced decomposition of the analytes were observed and impurities down to 1% could be determined using SFC-FID. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 156–162, 2001