Nitrido-ruthenium(vi) and -osmium(vi) complexes of multianionic chelating (N, O) ligands. Reactions with nucleophiles, electrophiles and oxidizing agents

Abstract

This account presents the diverse reactivity of nitridoruthenium(VI) complexes with nucleophilic, electrophilic and oxidizing agents. [Ru^VI(N)(L¹)Cl] (1) [H₂L¹ = 2,6-bis(2,2-diphenyl-2-hydroxyethyl)pyridine] reacted with excess phosphines such as PPh₃, PPhMe₂ and dppe to give [Ru^III(HL¹)(PPh₃)Cl₂] (2a), [Ru^III(L¹)(PPhMe₂)₂Cl] (2b) and [Ru^III(L¹)(dppe)Cl] (2c), respectively. In the presence of py or Hpz, 1 was converted to [Ru^III(L¹)(py)₂Cl] (3a) and [Ru^III(L¹)(Hpz)₃]Cl (3b), respectively. A dinuclear μ-nitridoruthenium complex, [Ru^IV(L¹)Cl₂(μ-N)Ru^VI(L¹)(C₈H₁₀N)Cl] (4), was obtained by treating 1 with 2,6-dimethylaniline. Based on X-ray crystallographic study, the compound is characterized by an unsymmetrical Ru–NRu moiety with the measured Ru–N distances being 1.661(5) and 1.837(5) Å. Complex 1 reacted with dmf to give [Ru^III(HL¹)(dmf)Cl₂] (5) in 17% yield. Excess (Me₃O)BF₄ reacted with 1 to give a dinuclear μ-OH ruthenium complex, [Ru₂(N)₂(L¹)₂(OH)]PF₆ (6). The measured Ru–O_(OH) distance is 1.984(3) Å and the average Ru–O–Ru angle was found to be 100.4(2)°. Other nitrido-metal complexes, [n-Bu₄N][M^VI(N)(L)] [L = L² and L³; M = Os and Ru; H₄L² = 1,2-dichloro-4,5-bis(2-hydroxybenzamido)benzene, H₄L³ = 1,2-bis(2-hydroxybenzamido)benzene], underwent ligand protonation to form [M^VI(N)(HL)] complexes, which have been characterized by X-ray crystallography. Oxidation of [n-Bu₄N][Os^VI(N)(L²)] by PhI(OAc)₂ produced [n-Bu₄N][Os^VI(N)(L²O₂)] (8) in 10% yield. X-ray structure analysis of 8 showed that the coordinated phenoxy moiety was converted to a benzoquinone moiety while the OsN group remained intact.