Heterobimetallic rhenium nitrido complexes containing the Kläui tripodal ligand [Co(η5-C5H5){P(O)(OEt)2}3]−

Abstract

Rhenium nitrido complexes containing the Kläui tripodal ligand [Co(η⁵-C₅H₅){P(O)(OEt)₂}₃]⁻ (L_OEt⁻) have been synthesised and their reactions with [Ir^I(cod)Cl]₂ (cod = 1,5-cyclooctadiene) and [Rh^II₂(OAc)₄] (OAc⁻ = acetate) have been studied. The treatment of [Buⁿ₄N][Re^VI(N)Cl₄] with NaL_OEt in methanol afforded the Re^VI nitride [Re^VI(L_OEt)(N)Cl(OMe)] (1). Reactions of 1 with [Ir^I(cod)Cl]₂ and [Rh^II₂(OAc)₄] gave the μ-nitrido complexes [(L_OEt)(OMe)ClRe^VI(μ-N)Ir^I(cod)Cl] (2) and [Rh^II₂(OAc)₄{(μ-N)Re^VI(L_OEt)(OMe)Cl}₂] (4), respectively. [(L_OEt)Cl(PPh₃)Re^V(μ-N)Ir^I(cod)Cl] (3) and [(L_OEt)Cl(PPh₃)Re^VI(μ-N)Ir^I(cod)Cl][PF₆] (3·PF₆) have been synthesised from the reactions of [Ir^I(cod)Cl]₂ with [Re^VL_OEt(N)Cl(PPh₃)] and [Re^VIL_OEt(N)Cl(PPh₃)](PF₆), respectively. Similarly, the redox pair [Rh^II₂(OAc)₄{(μ-N)Re^V(L_OEt)(PPh₃)Cl}₂] (5) and [Rh^II₂(OAc)₄{(μ-N)Re^VI(L_OEt)(PPh₃)Cl}₂](PF₆)₂ (5·(PF₆)₂) have been synthesised from the reactions of [Rh₂(OAc)₄] with [Re^VL_OEt(N)Cl(PPh₃)] and [Re^VIL_OEt(N)Cl(PPh₃)](PF₆), respectively. While [(L_OEt)Cl₂Ru^VI(μ-N)Ir^I(cod)] (6) was obtained from [Ru^VI(L_OEt)(N)Cl₂] and [Ir^I(cod)Cl]₂, the interaction between [Ru^VI(L_OEt)(N)Cl₂] and [Rh^II₂(OAc)₄] in CH₂Cl₂ is reversible. The crystal structures of complexes 2, 3, 3·PF₆, 5, 5·(PF₆)₂ and 6 have been determined. X-ray crystallography indicates that the nitrido bridges in 2, 3, 3·PF₆ and 6 can be described as MN—Ir (M = Re, Ru) showing Ir–N multiple bond character, whereas the interaction between ReN and Rh in 5 and 5·(PF₆)₂ is mostly of the donor–acceptor type. The electrochemistry of the Re nitrido complexes has been investigated by cyclic voltammetry.