Coordination-induced polymerization of P=C bonds leads to regular (P-C)n polycarbophosphanes

Abstract

The replacement of carbon in (C─C)n chains of polyolefins by phosphorus leads to polycarbophosphanes (P─C)n, which may possess unique chemical and physical properties. However, macromolecules with a regular (P─C)n chain have never been unambiguously identified. Here, we demonstrate that addition polymerization, a general concept to polymerize olefins, can be extended to P═C double bonds. The polymerization of monomeric 2-phosphanaphthalenes is mediated by copper(I) halides and leads to polycarbophosphanes with an Mn of 14 to 34 kDa. Each phosphorus is coordinated to Cu(I), which can be easily removed. Unlike long-term durable polyolefins, the metal-free polymers depolymerize rapidly back to monomers under sunlight or ultraviolet irradiation at λ = 365 nm. The monomers can be recycled for repolymerization, demonstrating a cradle-to-cradle life cycle for polycarbophosphanes.