Vibrational spectra of monosubstituted pyridines

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]

Section: Resultsmentioning

confidence: 99%

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

Silva¹,

Toma²

1994

“…The descriptions of the fundamental vibrations in Table VI are according to the previous assignments (18,19). It was found that the lowest band of the B2 species is sensitive to the mass of the metal ion in the complex, and therefore it might be assigned to the metal-ligand asymmetric vibration.…”

Section: Table IVmentioning

confidence: 98%

Nature of the coordination bond in metal complexes of substituted pyridine derivatives. II. The far infrared spectra and metal–ligand force constants of copper complexes of 4-substituted pyridines

Wong¹,

Brewer²

1968

Infrared spectra, including the lower frequency region, of copper (11) complexes of the type [CuLrC12], where L = 4-methylpyridine, 4-carbinyIpyridine, pyridine, 4-acetylpyridine, 4-pyridinecarboxamide, 4-carbomethoxypyridine, and 4-cyanopyridine have been measured. The substituent effect upon the copper-nitrogen (ligand) and copper-chlorine stretching frequencies has also been examined. It was found that the substituents on the pyridine ring not only affected the nature of copper-nitrogen bond, but also the copper-chlorine bond. It appears that an entirely delocalized system exists, involving the chlorine atoms and the substituents in the complexes. Force constants associated with the coordination bond between copper and the nitrogen of the ligands have been calculated by means of an IBM 1620 computer. By comparison of the copper-nitrogen stretching frequencies with the corresponding force constants, and the heats of coordination, it may be concluded that the magnitude of the metal-ligand stretching frequency is directly related to the metal-ligand coordination bond strength for the systems under study.

“…topic substitution may be assigned to a pyridine ring skeletal vibration (15,16) coupled with a copper ligand mode (see Fig. 2).…”

Section: Complexmentioning

confidence: 99%

Isotopic Studies of the Metal–Ligand Bond. Part II. The Far Infrared Spectra of Some Binuclear and Polymeric Copper Carboxylate Derivatives; Variable Temperature and Isotopic Studies of the Copper–Ligand Vibrations

Lever¹,

Ramaswamy²

1973

The far infrared spectra of 16 adducts of pyridine, quinoline, isoquinoline, urea, aniline, o- and p-toluidine with copper acetate, propionate, and butyrate, and of copper formate tetrahydrate were recorded at ambient temperature and at −196 °C. A range of derivatives were prepared containing isotopically pure 65Cu. The spectra of these derivatives were used to identify, unequivocally, the copper–oxygen stretching frequencies.Complexes believed to be polymeric (aniline and toluidine adducts) exhibit one copper–oxygen stretching vibration between 300 and 350 cm−1 A second band, lying between 350 and 400 cm−1 is not isotopically sensitive. The dimeric complexes exhibit one or two bands in the 300–400 cm−1 region, all of which are isotopically sensitive. Certain of the amine adducts exhibit an isotopically sensitive band near 240 cm−1 assignable to a Cu—N stretching mode.