Preparation of mononuclear and dinuclear Rh hydrotris(pyrazolyl)borato complexes containing arenethiolato ligands and conversion of the mononuclear complexes into dinuclear Rh–Rh and Rh–Ir complexes with bridging arenethiolato ligands

Abstract

Reactions of [Tp*Rh(coe)(MeCN)] (1; Tp* = HB(3,5-dimethylpyrazol-1-yl)₃; coe = cyclooctene) with one equiv. of the organic disulfides, PhSSPh, TolSSTol (Tol = 4-MeC₆H₄), PySSPy (Py = 2-pyridyl), and tetraethylthiuram disulfide in THF at room temperature afforded the mononuclear Rh^III complexes [Tp*Rh(SPh)₂(MeCN)] (3a), [Tp*Rh(STol)₂(MeCN)] (3b), [Tp*Rh(η²-SPy)(η¹-SPy)] (6), and [Tp*Rh(η²-S₂CNEt₂)(η¹-S₂CNEt₂)] (7), respectively, via the oxidative addition of the organic disulfides to the Rh^I center in 1. For the Tp analogue [TpRh(coe)(MeCN)] (2, Tp = HB(pyrazol-1-yl)₃), the reaction with TolSSTol proceeded similarly to give the bis(thiolato) complex [TpRh(STol)₂(MeCN)] (4) as a major product but the dinuclear complex [{TpRh(STol)}₂(μ-STol)₂] (5) was also obtained in low yield. Complex 3 was treated further with the Rh^III or Ir^III complexes [(Cp*MCl)₂(μ-Cl)₂] (Cp* = η⁵-C₅Me₅) in THF at room temperature, yielding the thiolato-bridged dinuclear complexes [Tp*RhCl(μ-SPh)₂MCp*Cl] (8a: M = Rh, 8b: M = Ir). Dirhodium complex [TpRhCl(μ-STol)₂RhCp*Cl] (9) was obtained similarly from 4 and [(Cp*RhCl)₂(μ-Cl)₂]. Anion metathesis of 8a proceeds only at the Rh atom with the Cp* ligand to yield [Tp*RhCl(μ-SPh)₂RhCp*(MeCN)][PF₆] (10), when treated with excess KPF₆ in CH₂Cl₂–MeCN. The X-ray analyses have been undertaken to determine the detailed structures of 3b, 4, 5, 6, 7, 8a, 9, and 10.