Date: 05 Oct 2012

A Strategy for Preparing Star Polymers Containing Metal–Metal Bonds Along the Polymeric Arms Using Click Chemistry

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Abstract

The [(η5-C5H4(CH2)3N3)Mo(CO)3]2 dimer (3) was prepared and used to determine if the Huisgen cycloaddition reaction could be used to synthesize high molecular weight star polymers with metal–metal bonds in the arms. Several different click catalysts were examined. Cp*Ru(PPh3)2Cl (Cp* = η5-C5(CH3)5) was previously shown to catalyze the formation of metal–metal bond-containing polymers using click chemistry; however, this catalyst underwent a Staudinger reaction with dimer 3 when a model coupling reaction was attempted with phenylacetylene. In order to avoid the Staudinger reaction, Cp*Ru(COD)Cl was used as the catalyst in the reaction of 3 with phenylacetylene, and coupling was observed after 14 h. Synthesis of a star polymer was attempted with 3 and 1,3,5-triethynylbenzene. Instead of coupling, Cp*Ru(COD)Cl reacted with the 1,3,5-triethynylbenzene. A third catalyst, Cu(IMes)Cl (IMes = 1,3-dimesityl-imidazol-2-ylidene) was used to couple 3 with 1,3,5-triethynylbenzene in 48 h. Both a high molecular weight polymer (M n  = 77,000 g mol−1) and a tripodal star core (M n  = 1,800 g mol−1) were successfully prepared with this catalyst.

This paper is dedicated to Prof. Dr. Hiroshi Nishihara for his outstanding contribution to the field of metal-containing polymers.