ImPAC: immobilised phosphines for applications in catalysis Jake Backhouse 1 , Dr Stephen Bennett 2 , Dr Stephen Poulston 2 , Dr Philip Dyer 1 1 Durham University, UK, 2 Johnson Matthey PLC, UK Rhodium-catalysed hydroformylation is an important industrial reaction for the production of aldehydes used as intermediates in the synthesis of detergent alcohols and surfactants. Current hydroformylation processes suffer from costly purification steps required to separate the aldehyde products and transition metal catalyst. A possible solution is the application of transition metal complexes immobilised onto solid oxide supports, hence allowing separation via a simple filtration. One approach to this immobilisation is to use an appropriately-functionalised diphosphine ligand to tether the catalyst to an insoluble support such as silica. To this end, bidentate phosphines functionalised with an Si(OMe) 3 silica tethering group have been synthesised with varying electronic and steric properties and P^P bite angles. The P V selenide derivatives of these compounds have been prepared in order to investigate the Lewis basicity of the phosphine lone pairs via an assessment of their | 1 J SeP | coupling constants. The electronic demands of the phosphine moieties of the bidentate ligand ensembles were probed through FT-IR spectroscopic analysis of their [Mo(CO) 4 (P^P)] complexes. The phosphorus compounds were then immobilised on AEROPERL 300/30 silica and characterised by solid state MAS 29 Si and 31 P NMR spectroscopies to determine their binding mode to silica. The coordination chemistry of the compounds with Rh I precursors Rh(acac)(CO) 2 and Rh(acac)(COD) was also explored in preparation for future work to investigate silica-immobilised rhodium complexes for application as heterogenised hydroformylation catalysts.
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