SINGLE-COMPONENT RUTHENIUM(IV) CATALYSTS FOR THE RING-OPENING POLYMERIZATION OF NORBORNENE

The neutral complexes [Ru(eta(3):eta(3)-C10H16){Sb(C6H5)(3)}Cl-2] 2a and [Ru(eta(3):eta(3)-C10H16){P(OC6H5)(3)}Cl-2] 2b were obtained by addition of neutral ligands [Sb(C6H5)(3) and P(OC6H5)(3)] to [{Ru(eta(3):eta(3)-C10H16)(mu-Cl)Cl}(2)] 1 and their structure was determined by both NMR spectroscopy and crystal structure analysis in case of 2a (triclinic, space group P (1) over bar, a = 10.556(6) Angstrom, b = 10.823(5) Angstrom, c = 13.156(7) Angstrom, alpha = 93.34 degrees, beta = 108.47(3)degrees, gamma = 112.64(3)degrees, V = 1288(1) Angstrom(3), Z = 2, D-calc = 1.71 g cm(-3), R(W) = 0.021). The compounds 2a and 2b are very active single component catalysts for ring-opening polymerization of norbornene. Their catalytic activity depends on the displacement of the ligand L [L = Sb(C6H5)(3), P(OC6H5)(3)] by the olefin. The polymers thus produced have high molecular weights M(n) of 4.5 . 10(5) g mol(-1) with a monomodal distribution and with polydispersities from 2.4 to 5.3. The cis selectivity of 2a and 2b (up to 30%) is higher than that of many other ruthenium-based catalysts for the polymerization of strained cyclo-olefins.