Diphenylphosphine containing macromolecules in the methoxycarbonylation of ethene: the effect of macromolecular architecture on the selectivity of the reaction

Various polyhedral oligomeric silsesquioxanes containing diphenylphosphine moieties at their periphery have been used in the methoxycarbonylation of ethene. Those with a -CH(2)CH(2)- spacer between the silicon and the phosphorus atoms (G0-8ethylPPh(2) and G1-16ethylPPh(2)) only produce methyl propanoate whilst a similar macromolecule with a -CH(2)- spacer between Si and P (G1-16methylPPh(2)) gives only copolymer. The effect of the molecular architecture is discussed in comparison with the selectivities observed when using small molecule analogues.