Mamak Bakhtiari, Ludwig Zapf, Tanja Kunz, Brandon L. Frenette, Michael J. Ferguson, Eric Rivard
An unprecedented diene-capped carbene (DECC), Diene IPr ( 2 ) [{(H 2 C═C)NDipp} 2 C:; Dipp = 2,6- i Pr 2 C 6 H 3 ] is accessed by a convenient oxidation/double-deprotonation pathway starting from a widely utilized N -heterocyclic carbene. Functionalization of the carbene donor site in 2 with Se ( 3 ) and PPh ( 5 ) revealed exceptional π-accepting character within the carbene unit. The phosphinidene complex Diene IPr═PPh ( 5 ) undergoes diene-localized [4 + 2] cycloaddition with cyclooctyne, while anionic copolymerization of 5 with isoprene yields a “natural rubber”-type copolymer ( 11 ) that becomes an active alkyne hydration precatalyst upon P atom coordination to gold.