6-Halogenopyridin-2-olato complexes with the diruthenium(2+) core: Equilibria between head-to-head and head-to-tail structures |
| |
| Authors: | Lutz Schä ffler,Gerhard Maas |
| |
| Affiliation: | Institute for Organic Chemistry I, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany |
| |
| Abstract: | The dinuclear bis(6-X-pyridin-2-olato) ruthenium complexes [Ru2(μ-XpyO)2(CO)4(PPh3)2] (X = Cl (4B) and Br (5B)), [Ru2(μ-XpyO)2(CO)4(CH3CN)2] (X = Cl (6B), Br (7B) and F (8B)) and [Ru2(μ-ClpyO)2(CO)4(PhCN)2] (9B) were prepared from the corresponding tetranuclear coordination dimers [Ru2(μ-XpyO)2(CO)4]2 (1: X = Cl; 2: X = Br) and [Ru2(μ-FpyO)2(CO)6]2 (3) by treatment with an excess of triphenylphosphane, acetonitrile and benzonitrile, respectively. In the solid state, complexes 4B-9B all have a head-to-tail arrangement of the two pyridonate ligands, as evidenced by X-ray crystal structure analyses of 4B, 6B and 9B, in contrast to the head-to-head arrangement in the precursors 1-3. A temperature- and solvent-dependent equilibrium between the yellow head-to-tail complexes and the red head-to-head complexes 4A-7A and 9A, bearing an axial ligand only at the O,O-substituted ruthenium atom, exists in solution and was studied by NMR spectroscopy. Full 1H and 13C NMR assignments were made in each case. Treatment of 1 and 2 with the N-heterocyclic carbene (NHC) 1-butyl-3-methylimidazolin-2-ylidene provided the complexes [Ru2(μ-XpyO)2(CO)4(NHC)], X = Cl (11A) or Br (12A). An XRD analysis revealed the head-to-head arrangement of the pyridonate ligands and axial coordination of the carbene ligand at the O,O-substituted ruthenium atom. The conversion of 11A and 12A into the corresponding head-to-tail complexes was not possible. |
| |
| Keywords: | Ruthenium compounds Dinuclear complexes Pyridonate ligand N-Heterocyclic carbene X-ray crystal structures |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
