End-Functionalized Palladium SCS Pincer Polymers via Controlled Radical Polymerizations.

A direct and facile route toward semitelechelic polymers, end-functionalized with palladated sulfur-carbon-sulfur pincer (Pd-II-pincer) complexes is reported that avoids any post-polymerization step. Key to our methodology is the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization with functionalized chain-transfer agents. This strategy yields Pd end-group-functionalized materials with monomodal molar mass dispersities (D) of 1.18-1.44. The RAFT polymerization is investigated using a Pd-II-pincer chain-transfer agent for three classes of monomers: styrene, tert-butyl acrylate, and N-isopropylacrylamide. The ensuing Pd-II-pincer end-functionalized polymers are analyzed using H-1 NMR spectroscopy, gel-permeation chromatography, and elemental analysis. The RAFT polymerization methodology provides a direct pathway for the fabrication of Pd-II-pincer functionalized polymers with complete end-group functionalization.