Linkage isomerization and electrochemical behavior of two geometrical isomers of dichlorobis(dimethylsulfoxide)bis(t-butylpyridine)ruthenium(II)

Abstract

DENISE 0 . SILVA and HENRIQUE E. TOMA. Can. J. Chem. 72, 1705Chem. 72, (1994. The reaction of cis- [RuCl,(dmso),] (dmso = dimethylsulfoxide) with 4-tert-butylpyridine (tbpy) in chloroform leads to the all cis (ccc) and the cis,cis,trans (cct) geometrical isomers of [RuCl,(S-dmso),(tbpy),]. The cct isomer exhibits a reversible cyclic voltammogram, ascribed to the RU"'"' redox couple with Ell, = 1.12 V versus SHE. The ccc isomer can be oxidized at Ell, = 1.27 V; however, the oxidized species undergoes a relaxation equilibrium, (K,,, = 1.59), involving the S-to-0 linkage isomerization of a coordinated dmso ligand (k,,, 1.9 s-I and kojS = 1.2 s-I). The isomerization reaction in the RU"' ccc isomer is discussed in terms of the competitive effects between the S-bound dmso and the tbpy ligands. DENISE 0 . SUVA et HENRIQUE E. TOMA. Can. J. Chem. 72, 1705 (1994). La rkaction du cis-[RuCl,(dmso),] (dmso = dimCthylsulfoxyde) avec la 4-tert-butylpyridine (tbpy) dans le chloroforme conduit B la formation des isomkres gkomktriques complktement cis (ccc) et cis,cis,trans (cct) du [RuCl,(drnso),(tbpy),]. L'isomkre cct prksente un voltampCrogramme cyclique rkversible, attribuC au couple rkdox R U~~" ' , avec Ell, = 1,12 V versus SHE.L'isomkre ccc peut Ctre oxydC i i E,/, = 1.27 V; toutefois, les espkces oxydCes subissent un Cquilibre de relaxation (K,,, = 1,59) impliquant 1'isomCrisation d'un coordinat dmso de la liaison S vers 0 (k,,, = 1,9 s-I et k, , , = 1,2 s-I). On discute de la rkaction d7isomCrisation de l'isomkre ccc du RU"' en fonction des effets compktitifs entres les coordinats tbpy et dmso liC par le S.[Traduit par la redaction]

Mono(2,2′‐bipyridyl)RuII Complex with Four Dimethyl Sulfoxide Ligands as Precursor for cis‐Bis‐heteroleptic RuII Complex: Syntheses, Structures, and Substitution Reactions

“…The linkage isomerization between S ‐bonded and O ‐bonded dmso ligands in Ru II ‐dmso complexes commonly occurs by photochemical and electrochemical redox processes, because the electron‐transfer of a Ru II ion induces the linkage isomerization of the dmso ligand . Thus, our case is very unusual from the viewpoint of linkage isomerization.…”

“…In the aromatic region, the minor four signals (marked with black arrows in Figure ) are observed with the same intensities, and the two pyridyl groups of the bpy are equivalent in the species, which is assigned as the isomer fac ( S )‐[Ru(bpy)(dmso‐ O )(dmso‐ S ) 3 ] 2+ ( 1 iso 2+ , Figure ). The likelihood of the formation of fac (O)‐[Ru(bpy)(dmso‐ O ) 3 (dmso‐ S )] 2+ would be small, because based on HSAB theory one would expect an S ‐bonded dmso ligand to be more favorable relative to an O ‐bonded dmso ligand . The ratio of the two isomers in the 1 H NMR spectrum of 1· (OTf) 2 in [D 6 ]DMSO, [ 1 iso 2+ ]/[ 1 2+ ], is 3:97 at 298 K. At 373 K (Figure b), the minor signals increase in intensity ([ 1 iso 2+ ]/[ 1 2+ ] = 33:67), but after cooling to 298 K, the temperature of sample reached to 298 K for 10 min and the linkage isomerization also achieved the equilibrium; [ 1 iso 2+ ]/[ 1 2+ ] = 3:97, again.…”

“…Furthermore, we report the uncommon linkage isomerization of the dmso ligands in 1 2+ in DMSO. There are many reports on the electrochemical linkage isomerization of Ru III /Ru II complexes with dmso ligands during cyclic voltammetry, and photo‐induced linkage isomerization of dmso ligand on Ru II complex . This is the first report of thermodynamic data for the linkage isomerization of a dmso ligand on a Ru II complex, determined by 1 H NMR spectroscopy, to the best of our knowledge.…”

Electron transfer triggered sulfoxide isomerization in ruthenium and osmium complexes

“…One of the first of these is the electrochemical and photochemical behavior of cis,cis,cis-and cis,cis,trans-[RuCl 2 (dmso) 2 (tbpy) 2 ] (tbpy is tbutylpyridine) [31][32][33]. While neither of these complexes were crystallographically characterized, 1 H NMR, IR and UV-vis absorption data support the geometry of these two complexes.…”

Synthesis and Reactivity of Ru-, Os-, Rh-, and Ir-Halide−Sulfoxide Complexes

“…94,98 It has to be noted that in early works trans,cis,cisRuCl 2 (dmso-S) 2 (L) 2 complexes with L ) 2,6-dimethylpyrazine or 4-tert-butylpyridine had been erroneously assigned the cis,cis,trans geometry. 99,100 There are also examples in which L is a complexed bridging ligand: treatment of 8 with 2 equiv of a pyrazine-capped cyclam copper complex (Chart 8) led to the replacement of two dmso ligands by the remote nitrogen atoms of pyrazine and produced a trimetallic …”