Ligand-Induced Ring Slippage of η6- to η4-Naphthalene. Preparation and Structural Characterization of Ru(η4-C10H8)(η4-1,5-C8H12)(L) [L = PMe3, PEt3, P(OMe)3] and of Derived Binuclear Complexes Containing Bridging Naphthalene, Ru2(μ-η6:η4-C10H8)(η4-1,5-C8H12)2(L) [L = PEt3, P(OMe)3]
journal contributionposted on 25.09.1998, 00:00 by Martin A. Bennett, Zhaobin Lu, Xianqi Wang, Mark Bown, David C. R. Hockless
Treatment of (η6-naphthalene)(η4-1,5-cyclooctadiene)ruthenium(0), Ru(η6-C10H8)(η4-1,5-C8H12) (1), with a slight excess of trimethylphosphine, triethylphosphine, trimethyl phosphite, triethyl phosphite, or tert-butyl isocyanide below room temperature gives η4-naphthalene complexes Ru(η4-C10H8)(η4-1,5-C8H12)(L) [L = PMe3 (3), PEt3 (4), P(OMe)3 (5), P(OEt)3 (6), t-BuNC (7)], which provide the first examples of the often postulated η6 to η4 transformation of naphthalene induced by two-electron donor ligands. The η4-naphthalene is easily displaced by an excess of the ligands to give RuL3(η4-1,5-C8H12). At room temperature, complex 1 reacts with a deficiency of PMe3, PEt3, or P(OMe)3 to give binuclear complexes containing bridging naphthalene, (η4-1,5-C8H12)Ru(μ-η6:η4-C10H8)Ru(η4-1,5-C8H12)(L) [L = PMe3 (8), PEt3 (9), P(OMe)3 (10)]. Single-crystal X-ray studies of complexes 3, 4, 5, 9, and 10 show the presence in each case of a folded naphthalene ring with a hinge angle of ca. 40°. In 9 and 10 the metal atoms adopt an anti arrangement relative to the bridging naphthalene.