名称:
Synthesis of conjugated diene complexes of ruthenium(0) derived from Ru(η6-naphthalene)(η4-1,5-COD): Z to E isomerisation of coordinated 1,3-pentadiene
摘要:
The naphthalene complex of zerovalent ruthenium, [Ru(eta(6)-C10H8)(eta(4)-1,5-COD)] (1), readily reacts with 1,3-dienes in the presence of a ligand (L) to produce complexes [Ru(eta(4)-cisoid-1,3-diene)(eta(4)-1,5-COD)(L)] [1,3-diene butadiene, 2,3-dimethylbutadiene, isoprene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-cyclohexadiene; L = MeCN, (BuCN)-Bu-t, PhCN, NCC6H4CN, CO, (BuNC)-Bu-t, pyridine, P(OMe)(3), P(OPh)(3), PMe3, PEt3, PPh3, PCy3]. The single-crystal X-ray structures of [Ru(eta(4)-cisoid-1,3-butadiene)(eta(4)-1,5-COD)(MeCN)] (2a) and [Ru{eta(4)-(E)-cisoid-1.3-pentadiene}(eta(4)-1,5-COD)(PPh3)}](E-5l) show the expected, approximately square pyramidal geometry about the metal atom, with the auxiliary ligand occupying the axial site. [Ru {eta(4)-(Z)-cisoid-1,3-pentadiene}(eta(4)-1,5-COD)(PPh3)] (Z-5l) irreversibly isomerises to E-5l in benzene-d(6) at 30 degrees C, the reaction obeying a first-order rate law [k = (2.89 +/- 0.06) x 10(-4) s(-1)]. This reaction is significantly retarded by addition of PPh3 suggesting that a vacant site is required for the E/Z isomerisation. (C) 2012 Elsevier B.V. All rights reserved.