Ring Expansion Alkyne Metathesis Polymerization
Andrew M. Beauchamp, Jhonti Chakraborty, Ion Ghiviriga, Khalil A. Abboud, Daniel W. Lester, Adam S. Veige
Abstract
The synthesis, characterization, and preliminary activity of an unprecedented tethered alkylidyne tungsten complex for ring expansion alkyne metathesis polymerization (REAMP) are reported. The tethered alkylidyne 7 is generated rapidly by combining alkylidyne W(C t Bu)(CH 2 t Bu)(O-2,6- i - Pr 2 C 6 H 3 ) 2 ( 6 ) with 1 equiv of an yne-ol proligand ( 5 ). Characterized by NMR studies and nuclear Overhauser effect spectroscopy, complex 7 is a dimer. Each metal center contains a tungsten–carbon triple bond tethered to the metal center via an alkoxide ligand. The polymerization of the strained cycloalkyne 3,8-didodecyloxy-5,6-dihydro-11,12-didehydrodibenzo[ a, e ]-[8]annulene, 8, to generate cyclic polymers was demonstrated. Size exclusion chromatography (SEC) and intrinsic viscosity (η) measurements confirm the polymer’s cyclic topology.