Controlling Substitution Chemistry in Ruthenium(II) Systems. Synthesis of Heteroleptic Complexes Incorporating the [Ru([9]aneS3)]2+ Metal Center

• Published in: Inorganic chemistry 2000-05, Vol.39 (11), p.2385-2390
• Main Authors: Roche, Sue, Adams, Harry, Spey, Sharon E, Thomas, James A
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic991336g

The complex [Ru(py)3([9]aneS3)][PF6]2, 1 (py = pyridine), has proved to be a suitable starting material for the synthesis of heteroleptic Ru(II) complexes. By exploiting unfavorable steric interactions between 2-H and 6-H hydrogens of coordinated pyridyl ligands, we have synthesized half-sandwich complexes incorporating the thiocrown [9]aneS3 and a variety of facially coordinated N-donor ligands. Such complexes are easily prepared:  Stirring 1 at room temperature in the presence of a suitable nitrile ligand leads to the exclusive substitution of one py ligand to produce complexes such as [([9]aneS3)Ru(py)2(NCMe)][PF6]2, 2. However, if the same reaction is carried out at higher temperatures, two py ligands are substituted, leading to complexes such as [([9]aneS3)Ru(py)(NCMe)2][PF6]2, 3. An alternative approach to such heteroleptic species has also been developed which exploits the restricted ability of thioethers to neutralize positive charges through σ-donation. This phenomenon allows the synthesis of heteroleptic complexes in a two-step procedure via monocationic species. By variation of the donor/acceptor properties of ligands incorporated into the [Ru([9]aneS3)]2+ metal center, it is possible to tune the Ru(III)/Ru(II) redox couple over a range of >700 mV. The solid-state structures of 1−3 were confirmed by X-ray crystallography studies. Crystal data:  C22H30F12N4O2P2RuS3 (1·CH3NO2), monoclinic, Cc, a = 23.267(5) Å, b = 11.5457(18) Å, c = 26.192(5) Å, α = 90°, β = 114.836(10)°, γ = 90°, Z = 8; C18H25F12N3P2RuS3 (2), triclinic, P1̄, a = 11.3958(19) Å, b = 11.4280(19) Å, c = 11.930(2) Å, α = 100.518(3)°, β = 100.542(3)°, γ = 112,493(3)°, Z = 2; C15H23F12N3P2RuS3 (3), orthorhombic, Pna21), a = 14.748(5) Å, b = 18.037(18) Å, c = 10.341(5) Å, α = 90°, β = 90°, γ = 90°, Z = 4.