| 20023970 |
Chisholm DM, Oliver AG, McIndoe JS: Mono-alkylated bisphosphines as dopants for ESI-MS analysis of catalytic reactions. Dalton Trans. 2010 Jan 14;(2):364-73. Epub 2009 Oct 14.
Bisphosphines Ph (2) P (CH (2))(n) PPh (2) (n = 1, 2, 4, 6) may be easily monobenzylated to generate cationic phosphine/phosphonium ligands [Ph (2) P (CH (2))(n) PPh (2) CH (2) Ph](+). These ligands may be doped into a catalytic reaction involving neutral complexes with labile phosphine ligands, and replacement of a neutral phosphine with a charged analogue renders the resulting complex amenable to electrospray ionisation mass spectrometry (ESI-MS). Examination of olefin hydrogenation with Wilkinson's catalyst, RhCl (PPh (3))(3), revealed that this approach yielded rapid identification of all off-cycle solution species as well as catalyst poisons. Reactive intermediates could be generated using collision-induced dissociation (CID) of a triphenylphosphine ligand to make three-coordinate RhClP (2) species, and these react with alkenes in the gas phase to form RhClP (2)(alkene). The solution speciation and gas phase behaviour revealed by ESI-MS match closely to what is already known about the system from kinetic and NMR studies. |
81(1,1,1,1) |