Syntheses and molecular structures of 6-halogeno-pyridin-2-olate complexes with the diruthenium(2+) core
摘要:
The complexes [Ru-2(CO)(5)(mu-FpyO)(2)](2) (1), [Ru-2(CO)(4)(mu-ClpyO)(2)](2) (2), and [Ru-2(CO)(4)(mu-BrpyO)(2)](2) (3) were prepared from Ru-3(CO)(12) and 6-fluoro-2-hydroxypyridine (FpyOH), 6-chloro-2-hydroxypyridine (ClpyOH) and 6-bromo-2-hydroxypyridine (BrpyOH), respectively, in hot toluene. Compounds 1-3 are coordination dimers with a cyclo-RuORuO motif. By carrying out the reaction in hot methanol, the dinuclear complexes [Ru-2(CO)(4)-(mu-ClpyO)(2)(CH3OH)] (4) and [Ru-2(CO)(4)(mu-BrpyO)(2)(CH3OH)] (5), respectively, were obtained. Treatment of 2 and 3 with triphenylphosphane provided the complexes [RU2(CO)(4)([mu-ClpyO)(2)(PPh3)] (6) and [Ru-2(CO)(4)(p-BrpyO)(2)(PPh3)] (7), respectively. The solid-state structures of complexes 1, 2, 4, 6, and 7 were determined by single crystal X-ray diffraction. In all cases, a head-head coordination of the two 6-halopyridinolate ligands at the Ru-2(2+) core was found. In all chlorine- or bromine-containing complexes, the axial coordination site at the ruthenium atom neigh-bored by two Cl or Br atoms remains unoccupied due to steric shielding by the halogen atom. In the fluoropyridinolate complex 1, the same coordination site is occupied by a carbonyl ligand. (c) 2005 Elsevier B.V. All rights reserved.