Latent ruthenium initiators containing fluoro aryloxide ligands
Yu Z., Rogan Y., Khosravi E., Musa OM., Hobson L., Batsanov AS.
A new ligand, methyl 2,3,5,6-tetrafluoro-4-oxybenzoate (C8H3F4O3), combining an electron withdrawing group (C6F4) to tune the reactivity with an anchor group (CO2Me) for immobilization on supports, was used to prepare four new ruthenium initiators, viz. Ru(C8H3F4O3)2(CHPh)(3-Br-C5H5N)(H2IMes) and Ru(C8H3F4O3)2XL, where X = C,N-(CHCH2CH2-2-C5H4N) and L = PiPr3, PCy3or H2IMes. The new ligand greatly reduced the reactivity of the ruthenium centre at room temperature. The1H NMR and DSC investigation for the ROMP of norbornene dicarboximide monomers clearly demonstrated that the Ru(C8H3F4O3)2XL initiators were inactive at room temperature and required elevated temperatures for their activation. © 2010 Elsevier B.V. All rights reserved.