Substitution of the tosyl substituent of 24 for a methoxy functionality was attempted (Scheme 4). After several attempts (Table ), the optimized conditions for an SN2 type substitution of 24 utilizing a 10:1 mixture of toluene and MeOH and one equivalent of NaOMe stirring at RT for 1 week were identified. The crude yellow coloured polymer, 28, was gravity filtered to remove the resulting salts and the volatile components were then removed under reduced pressure. The substituted product, 28, was further purified by redissolving the crude polymer in a minimum of THF and induced precipitation from this solution by adding it to an excess of cold hexanes. NMR spectroscopic analysis ( 1 H, 119 Sn) of the substituted polymer suggests that 28 is ≈ 50% methoxy substituted. The 119 Sn NMR (Figure ) reveals chemical shift values typically of both the homopolymer 25 in open and closed conformations, as well as a resonance for the unsubstituted polymer 24. A GPC analysis of the partially substituted polymer was not performed, as purified 28 was found to be insufficiently soluble in THF.