Polymerization of 1‐Phosphaisoprene: Synthesis and Characterization of a Chemically Functional Phosphorus Version of Natural Rubber

Macromolecules derived from 1,3‐dienes, such as polyisoprene (or natural rubber), are of considerable importance in polymer science. Given the parallels between P=C and C=C bonds, the prospect of polymerizing P‐containing 1,3‐dienes, such as 1‐phosphaisoprene, is intriguing due to the unique chemical functionality imparted by the heavier element combined with their structural relationship to natural rubber. Herein, we report the synthesis, characterization and coordination chemistry of the first polymers derived from Mes*P=CR−CH=CH2 (Mes*=2,4,6‐t‐Bu3C6H2; R=H, Me). In the case of 1‐phosphaisoprene (R=Me), the monomer is isolable and its anionic polymerization affords a polymer that retains P=C bonds in its microstructure. The chemical functionality of these novel materials is demonstrated by forming the macromolecular gold(I) complex where the P=C bond is retained for further chemical elaboration. Un‐natural rubber: A phosphorus‐containing polyisoprene is obtained by polymerization of 1‐phosphaisoprene with anionic initiators to afford the first example of a P‐polymer of isoprene, the monomer in natural rubber. The chemical functionality of poly(1‐phosphaisoprene) is demonstrated by its binding of gold(I) to give novel metal‐containing macromolecules.