Purity testing of organometallic catalysts by packed capillary supercritical fluid chromatography

A packed capillary column supercritical fluid chromatography system with flame ionization detection has been used for purity testing of candidates for homogeneous catalysis such as methyl tricarbonyl pentamethylcyclopentadienyl tungsten [Cp*W(CO)3Me], methyl tricarbonyl cyclopentadienyl tungsten [CpW(CO)3Me], tetramethyl pentamethylcyclopentadienyl iridium (Cp*IrMe4), trimethyl (1,4,7-trimethyl-1,4,7-triazocyclononane) rhodium (CnRhMe3), trimethylphosphine hydride dicarbonyl cyclopentadienyl molybdenum [η5-CpMoH(CO)2PMe3] and triphenylphosphine hydride dicarbonyl cyclopentadienyl molybdenum [η5-CpMoH(CO)2PPh3]. A mass limit of detection of 240 pg was found for η5-CpMoH(CO)2PMe3 when using a 60-nl injection volume and pure CO2 as mobile phase on a 5 μm Kromasil C18 column. The stability of the catalysts in solution has been examined. After 24 h more than 70% of η5-CpMoH(CO)2PMe3 and 50% of η5-CpMoH(CO)2PPh3 had decomposed. Due to the instability of the compounds the purity testing had to take place rapidly after sample dissolution.