Linear-Type S-Bridged Triruthenium Complexes with Aliphatic Aminothiolate Ligands:  Synthesis, Characterization, and Properties

Abstract

Treatment of [RuCl(2)(DMSO)(4)] with 2-aminoethanethiol (Haet) in ethanol gave a dicationic triruthenium complex, [Ru[Ru(aet)(3)](2)]Cl(2) ([1]Cl(2)). Complex [1]Cl(2) was also obtained by treatment of RuCl(3).nH(2)O with excess Haet in water. When [1](2+) was chromatographed on a cation-exchange column of SP-Sephadex C-25, meso (DeltaLambda) and racemic (DeltaDelta/LambdaLambda) isomers of the corresponding tricationic complex, [Ru[Ru(aet)(3)](2)](3+) ([2](3+)), were eluted with aqueous NaNO(3). The racemic isomer of [2](3+) was optically resolved into DeltaDelta and LambdaLambda isomers by using [Sb(2)(R,R-tartrato)(2)](2-) as a resolving agent. The molecular structures of DeltaLambda- and DeltaDelta/LambdaLambda-[2](NO(3))(3) were determined by X-ray crystallography. In these complexes, the central Ru atom is coordinated by six thiolato groups from two terminal fac-(S)-[Ru(aet)(3)] units in an octahedral geometry, forming a linear-type S-bridged triruthenium structure. The spectroelectrochemical studies on the electronic absorption and CD spectra, together with the electrochemical studies, demonstrated that [1](2+) and [2](3+) are interconvertible with each other through a one-electron redox process, retaining the chirality of the triruthenium structure. Their electronic structures were investigated on the basis of EPR and magnetic susceptibility measurements, which indicated that [1](2+) and [2](3+) have spin ground states of S(t) = 0 and S(t) = 1/2, respectively. The corresponding L-cysteinato complex, [Ru[Ru(L-cys-N,S)(3)](2)](3-), which was formed from RuCl(3).nH(2)O and excess L-cysteine (L-H(2)cys) in water followed by air oxidation, is also presented.

Thiolato-Bridged RuIIAgIRuII Trinuclear Complex Composed of Bis(bipyridine)ruthenium(II) Units with Chelating 2-Aminoethanethiolate: Conversion to a Disulfide-Bridged RuIIRuII Dinuclear Complex

“…2-Aminoethanethiolate (aet ) -SCH 2 CH 2 NH 2 ) is the simplest aliphatic aminothiolate ligand that is expected to chelate to a Ru center via N and S donors. 3 However, no bis(diimine)-type ruthenium(II) complexes with a chelating aet ligand have appeared to date. Our previous attempts to prepare [Ru(aet) 4 In our continuing efforts to investigate the binding behavior of aet toward a Ru center, we found that a thiolato-bridged Ru II Ag I Ru II trinuclear complex composed of two [Ru(aet)(bpy) 2 ] + units is produced by the reaction of [Ru(solvent) 2 (bpy) 2 ] 2+ with Haet in the presence of Ag + (Scheme 1).…”

(2-Aminoethanethiolato-κ2N,S)bis[1,2-bis(diphenylphosphanyl)ethane-κ2P,P′]ruthenium(II) hexafluoridophosphate

“…For closely related structures, see: Tamura et al (2007); Matsuura et al (2006); Hanif et al (1999). For conformation descriptors of the chelate rings, see: Gispert (2008).…”

“…It has been recognized that the preparation of ruthenium complexes having non-bridging aliphatic thiolato group(s) is difficult because of the high reactivity of a thiolato group bound to a metal center. For example, the direct reaction of Ru II with 2-aminoethanethiol (Haet) led to the formation of thiolato-bridged trinuclear complex, [Ru{Ru(aet) 3 } 2 ] 2+ (Matsuura et al, 2006), and furthermore, the reaction of [Ag{Ru(aet)(bpy) 2 } 2 ] 3+ (bpy = 2,2′-bipyridine) with HCl did not give an expected mononuclear complex, [Ru(aet)(bpy) 2 ] + , but produced a dinuclear complex with a disulfide bond, [Ru 2 (cysta) (bpy) 4 ] 4+ (cysta = cystamine) (Tamura et al, 2007). Here, we report the synthesis and crystal structure of [Ru(aet) (dppe) 2 ]PF 6 , which is a quite rare example of a crystallographically characterized ruthenium(II) complex with an aliphatic thiolato donor.…”

“…1). The Ru-S [2.431 (2) Å] and Ru-N [2.212 (5) Å] bond distances are slightly longer than those of the related ruthenium(II) complexes with aet ligand(s) (Ru-S = 2.291-2.394 Å, Ru-N = 2.133-2.212 Å) (Tamura et al, 2007;Matsuura et al, 2006;Hanif et al, 1999). On the other hand, the Ru-P bond distances (average 2.380 Å) are similar to those of ruthenium(II) complexes with dppe ligands (av.…”

Synthesis and Linkage Isomerization of Thiolato-Bridged RuIIAgIRuII Trinuclear Complex with d-Penicillaminate

“…During the past decades, chiral ruthenium(II) complexes have attracted considerable interest in connection with their potential applications, such as enantioselective catalysis, enantioselective quenching of luminescence, and DNA recognition. − In particular, the use of bis(diimine)-type ruthenium(II) complexes having a Δ/Λ central chirality as an optically pure agent has been extensively studied − because these complexes are, in general, fairly stable and readily resolved by column chromatography and/or fractional diastereomeric crystallization. − ,− For bis(diimine)-type ruthenium(II) species, dinuclear ruthenium(II) complexes, which form meso (ΔΛ) and racemic (ΔΔ/ΛΛ) isomers, have also been prepared, and the characteristic properties based on the difference in the meso-racemic isomerism have been reported. − While most of diruthenium(II) complexes of this class are made up of two bis(diimine)ruthenium(II) units connected by bridging organic or inorganic ligand(s), we have recently synthesized a new class of a diruthenium(II) complex, [Ag{Ru(aet)(bpy) 2 } 2 ] 3+ (Haet = 2-aminoethanethiol, bpy = 2,2′-bipyridine), in which two octahedral [Ru(aet)(bpy) 2 ] + units with an N,S-chelating aet ligand are linked by an Ag I ion through thiolato groups . While the racemic isomer was isolated for [Ag{Ru(aet)(bpy) 2 } 2 ] 3+ , attempts to resolve this isomer into ΔΔ and ΛΛ forms were unsuccessful most likely because of the rapid exchange of Δ- and Λ-[Ru(aet)(bpy) 2 ] + units in solution, which was suggested by NMR spectroscopy.…”